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Impact of changing pesticide availability on
horticulture
Issued by ADAS UK Ltd
31 March 2010
Submitted to:
Jemilah Bailey
Defra
Prepared by:
Sarah Wynn
ADAS UK Ltd
Boxworth
Cambridge
CB23 4NN
ACKNOWLEDGEMENTS This report has been written by a team of consultants including Sarah Wynn (project management and data co-ordination), Janet Allen, John Atwood, Wayne Brough, Kim Green, Chris Nicholson, Tim O’Neill, Tom Pope, David Talbot and Don Tiffin (Horticultural crops). The project director was James Clarke. The authors would like to thank the eternal experts who assisted with this work in particular Derek Hargreaves for his assistance with tomato and cucumbers.
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1 EXECUTIVE SUMMARY Pesticides are fundamental to the way many horticultural crops are currently grown in the UK. They provide very cost-effective options for controlling the major weeds, pests and diseases. The availability of pesticides is currently under pressure. This is due to changes in European pesticide approvals legislation, with the replacement of EU Directive 91/414/EEC with Regulation (EC) No. 1107/2009 (changing approvals legislation) and the implementation of water quality requirements (including Water Framework Directive, WFD, and Drinking Water Directive) along with other non-legislative reasons such as increasing resistance of target organisms and market acceptability driven by residues in food products. These pressures may lead to potential reductions in the availability of pesticides which may affect horticultural crop production. The objective of this study was to evaluate the current status of control of weeds, pests and disease in horticultural crop production and how this might be affected by changes in pesticide availability. Crops assessed in this work were; Brassicas Carrots Leeks Onions Outdoor Lettuce Apples Pears Plums (stone fruit) Blackcurrants Raspberries Strawberries Cucumbers Tomatoes Hardy nursery stock Ornamentals The key weeds, pests and diseases that affect each of the horticultural crops above were identified along with the area affected. Estimates of harvest yield and market yield impacts on an area weighted basis were made for a business as usual scenario, untreated scenario and different pesticide availability scenarios. These were based on research, surveys and expert opinion. Under current production methods and available treatments, broad-leaved and grass weeds cause the largest losses in potential yield and quality with an industry value of about £110 million per year (across all crops), with strawberries being the crop most severely affected by weeds. Botrytis is the second greatest cause of losses, worth nearly £53 million, mainly affecting strawberries (£33M) but also impacting on onions, lettuce, raspberries, tomatoes, hardy nursery stock and ornamentals. Weevils are also a problem, causing almost £52 million worth of losses across all sectors, with strawberries (due in part to the high value of the industry) again seeing some of the highest losses (£44M). In untreated situations, the lack of herbicide control of weeds would drastically increase costs as a result of increased requirements for hand weeding. Weed populations would gradually build up over time and could result in almost complete crops losses as a result of competition decreasing yield, contamination with seeds affecting marketability and
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difficulties in harvesting. Overall the cost to the industry (across all 15 crops) of not using herbicides could exceed £1 billion. If left untreated pests could have a damaging effect across all crops. Losses from aphids in the absence of pesticides are estimated at £306 million, with lettuce and hardy nursery stock particularly badly affected. Fly pests could cost the industry £216 million with the largest losses from cabbage root fly on brassicas (£145 million) followed by carrot fly on carrots (£25.6 million). Foliar diseases would cause significant losses across all crops with botrytis and downy mildew having the largest effects (£192 million and £134 million respectively) Future pesticide availability will be affected by legislation, environmental factors and market requirements. Most of these changes will result in reduced availability, however the agrochemical industry is developing new actives that may replace or improve current pesticides. There is still some uncertainty over impacts of changes in pesticide approvals legislation as the final wording of Regulation (EC) No. 1107/2009 has not been agreed, although there are clear indications that the losses of pesticides will not be as severe as was once forecast. A scenario, based on a PSD report released in December 2008, was assessed to determine the effect of this changing approvals legislation on horticultural crops. After the vote in the European Parliament (13th January 2009), it is likely that the least severe of the four PSD scenarios (scenario 2c) will be close to the final outcome, but much will depend on final implementation. If this is the case it would result in the loss of about 23 active substances, of which only 19 are approved for use in the UK. Of these 19 active substances, most are used in the production of one or more horticultural crop. This is the scenario that has been modelled in this assessment, referred to as the changing approvals legislation scenario. Under the changing approvals legislation scenario the greatest economic losses to horticultural crops are forecast to be due to poorer weed control, especially broad-leaved weeds (£103 million) due, predominantly, to the loss of pendimethalin, glufosinate ammonium and amitrole. The loss of key downy mildew fungicides such as mancozeb could lead to this disease causing significant losses especially in outdoor lettuce (£29 million) and onions (£26 million). The loss of bifenthrin would make control of weevils (e.g. blossom weevil) very difficult with few effective alternatives available in crops such as strawberries (£40 million), raspberries (£12.6 million) and hardy nursery stock (£6.5 million). Weed, pest and disease control in horticultural crops will also be affected by actives failing to achieve Annex 1 listing before the end December 2009. Under 91/414/EEC all active substances had to be reassessed for approval onto Annex 1. Companies had until June 2009 to provide data for the active substances affected, or they would not be assessed. Active ingredients that are not included on Annex 1 before end December 2010, will cease to be approved. Notable substances in this category, that are used on horticultural crops are bifenthrin and metaldehyde. The cost of these losses has not been calculated in this assessment, although where withdrawals have already occurred this has been taken into account in the business as usual scenario. Where losses are of particular importance to a crop they have been discussed. We have not made any assumptions, and therefore assessment, on restrictions on actives gaining Annex 1 inclusion or re-registration. For example, the use of metazachlor has recently been reduced to a maximum dose rate of 1.0 kg/ha only every third year on the same field. Meeting the water quality requirements, such as of the Water Framework Directive (2000/60/EC) WFD and Drinking Water Directive (1998/83/EC) DWD, is likely to impact on a number of important active substances, particularly in catchments with high usage rates of a particular active ingredient. A number of approaches to minimising active substances
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reaching water are being adopted including farm advice and voluntary measures (e.g. English Catchment Sensitive Farming Delivery Initiative), including the use of buffer zones and unsprayed areas. In the future the introduction of restrictions in use (timing, crop or rate) of specific active substances in affected catchments may be necessary. Ultimately, if these restrictions on use are not sufficiently effective approval may be withdrawn although this is a last resort and unlikely to occur unless mitigation measures completely fail to prevent active substances entering water in concentrations which lead to failure of WFD objectives for surface and groundwaters, including failure of Drinking Water Protected Area (DrWPA) objectives1. In this assessment we have looked at a worst case scenario. This could be either the complete withdrawal of approvals or more likely severe restrictions on use that reduce the effectiveness of these pesticides. This enabled us to identify where the most important priorities for research or knowledge transfer are in order to reduce the impacts of these chemicals on water. The active substances that are most likely to be affected by water quality requirements are those that are used on a large area (i.e. on broad acre crops such as cereals) and or used at high rates at regular intervals such a those used in some horticultural crops. However, any reduction in the availability of active substances for use within a crop may risk displacement of the problem with other active substances. Many horticulture crops rely on Specific Off-label Approvals (SOLAs) for minor uses, which may not be supported if a major use is withdrawn. The potential restriction in use or complete loss of any herbicides could have significant effects on horticultural crops, as the number of herbicides that are available are limited. If broad spectrum herbicides such as glyphosate are affected there are limited alternatives for keeping some crops weed free. The loss of both broad-leaved weed and grass weed herbicides to water quality requirements could prove very costly (£132 million and £49 million respectively in the worst case scenario). The potential for chlorpyrifos to be affected by the legislation means that in certain crops, such as strawberries, the ability to control capsids and weevils would be limited (with poor control of weevils potentially costing £68 million, across all 15 crops). Slugs in particular could be difficult to control. Metaldehyde is used widely in combinable crops, as well as in certain horticultural crops, and is already under scrutiny due to water contamination. There are alternatives to metaldehyde in the form of methiocarb and ferric phosphate. However both of these products are more costly than metaldehyde and are not necessarily as effective in the control of certain molluscs, such as snails (poor control and increased cost of substitutes could cost £14 million across the 15 horticultural crops). For many pests there are plenty of alternative insecticides that remain available, and although a little more costly these should provide adequate control. However it is unclear how many insecticides could fail to meet environmental quality standards in relation to water. If significant numbers of insecticides failed to meet these standards there could be serious pest concerns in certain crops with aphids, and flies (Cabbage root fly and carrot fly) of particular concern. Summaries of the important losses to the industry are presented in tables ES2-ES4.
1 (Note for info – under WFD failure of the DWD limit (0.1ug/) in a watercourse, or in an isolated part of a
groundwater body is only a problem if the downstream water treatment plant can’t treat the water, so levels remain above 0.1ug/l at the tap, or if it can treat, but it has to put in extra treatment not previously needed at plant))
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The loss of active substances as a result of needing to meet water quality requirements would be additional to any losses from the changing pesticide legislation. As a result if all the predicted losses to changing approvals legislation and water quality requirements were to occur the impacts on weed, pest and disease control could be even greater than estimated in this report, where the impacts are looked at separately. Residues and market acceptability may also limit usage of pesticides on particular crops. One of the actives being found as residues on raw product or in food products, chlorothalonil (fungicide), has already had its approval withdrawn from raspberries due to failure to achieve new MRL levels set at the limit of determination. New products and options will become available. There are some new herbicides (ethametasulfuron), insecticides (indoxacarb, rynaxypyr, cyazapyr & spirotetramat) and fungicides (carboxamides) that are starting to appear on the market, or are due to appear within the next few years. Of these, the insecticides are of most interest in horticultural crop production as they are able to control Lepidoptera (butterflies and moths) and sucking pests in a range of crops. Table ES 1 - Key reasons for change in availability of crop protection options, the major substances at risk, their impact and likely timescale
Measure Major active substances at risk
Key impacts Timescale
pendimethalin glufosinate-ammonium
Weed control – most field crops
2011-2020
bifenthrin Weevils 2011-2020
Changing approvals legislation
mancozeb Downy mildew 2011-2020
metaldehyde Slugs Failure to achieve Annex 1 listing bifenthrin Weevils & other
pests
By December 2010
Water quality requirements*
Herbicides glyphosate propyzamide, asulam
Weed control – most field crops
Now onwards
metaldehyde Slugs Now onwards
chlorpyifos All pests esp. weevils
Now onwards
Market acceptability chlorothalonil Raspberry disease Now * NB these active substances are those which are already known to be found in water, they are not necessarily current Priority Substances.
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Table ES 2
Financial im
plications weeds in 3 scenarios £K to the industry (RFI – room for im
provement, Approvals – changing approvals
legislation & W
Q – water quality requirements)
Impact of
herbicide losses
£K
Scenario
Brassicas
Carrots
Leeks
Onions
Lettuce
Apples
Pears
Plums
Blackcurrants
Raspberries
Strawberries
Cucumbers
Tomatoes
Hardy nursery stock
Ornamentals
Total
Broad-leaved
RFI
1,111
4,524
1,060
797
9,505
00
0170
9,492
29,414
00
2,169
058,241
weeds
Approvals
3,126
25,852
10,160
13,745
11,952
00
198
214
6,311
23,716
00
8,674
0103,949
WQ
2,457
0327
577
51,446
19,126
2,708
5,025
6,318
11,189
33,362
00
434
0132,968
Grass weeds
RFI
03,176
2,120
1,898
00
00
85
4,746
37,257
00
2,169
051,451
(inc Couch)
Approvals
015,285
12,633
10,880
00
0121
79
10,998
15,992
00
8,674
074,662
WQ
00
00
0734
61
113
10,114
11,273
25,816
00
434
048,545
Volunteer potatoes
RFI
777
7,146
707
224
00
00
00
00
00
08,854
Approvals
014,455
1,814
1,784
00
00
00
00
00
018,054
WQ
719
11,458
424
346
00
00
00
00
00
012,947
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Table ES 3
Financial im
plications of pests in 3 scenarios £K to the industry (RFI – room for im
provement, Approvals – changing approvals
legislation & W
Q – water quality requirements)
Impact of insecticide
losses £K
Scenario
Brassicas
Carrots
Leeks
Onions
Lettuce (outdoors)
Apples
Pears
Plums
Blackcurrants
Raspberries
Strawberries
Cucumbers
Tomatoes
Hardy nursery stock
Ornamentals
Total
Aphids
RFI
5,927
13,572
00
20,113
00
15
01,329
01
551
3,123
122
44,753
Approvals
200
00
07,706
00
00
15,234
00
062
252
23,454
WQ
00
00
7,706
00
00
00
00
1,041
119
8,866
Cabbage root fly
RFI
15,003
00
00
00
00
00
00
00
15,003
Approvals
00
00
00
00
00
00
00
00
WQ
2,405
00
00
00
00
00
00
00
2,405
Carrot fly
RFI
04,284
00
00
00
00
00
00
04,284
Approvals
00
00
00
00
00
00
00
00
WQ
00
00
00
00
00
00
00
00
Moth and butterfly
RFI
6,650
2,936
00
6,165
00
18
0190
1,471
276
1,652
1,952
122
21,431
Carterpillars
Approvals
200
551
00
00
00
0280
958
00
39
455
2,483
(Inc cut worm
)WQ
00
00
00
00
0285
7,326
00
651
08,262
Thrips
RFI
00
309
448
00
00
00
01
03,253
178
4,189
Approvals
00
00
00
00
00
00
01,340
01,340
WQ
00
00
00
00
00
00
065
065
Spider mites
RFI
00
00
00
00
0949
8,236
79
275
4,337
913,885
Approvals
00
00
00
00
0311
270
00
51
23
656
WQ
00
00
00
00
00
00
00
00
Weevils
RFI
00
00
00
00
0949
44,121
00
6,506
051,576
Approvals
00
00
00
00
012,635
40,685
00
6,583
059,902
WQ
00
00
00
00
00
55,208
00
13,011
068,219
Slugs and snails
RFI
4,742
00
06,165
00
00
237
20,394
00
013
31,551
Approvals
00
00
00
00
00
00
00
00
WQ
00
00
17
00
0646
2,041
10,914
00
0593
14,211
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Table ES 4
Financial im
plications of disease in 3 scenarios £K to the industry (RFI – room for im
provement, Approvals – changing approvals
legislation & W
Q – water quality requirements)
Impact of
fungicide losses
£K
Scenario
Brassicas
Carrots
Leeks
Onions
Lettuce
Apples
Pears
Plums
Blackcurrants
Raspberries
Strawberries
Cucumbers
Tomatoes
Hardy nersury stock
Ornamentals
Total
Powdery m
ildew
RFI
11,906
00
00
00
02,373
24,708
39
5,508
4,337
33
38,905
Approvals
40
1,390
00
00
59
00
11,847
668
00
00
14,003
WQ
00
00
00
00
00
00
2,203
00
2,203
Downy m
ildew
RFI
890
00
3,486
9,965
00
00
00
59
01,735
244
16,379
Approvals
00
026,338
29,289
00
00
00
59
02,602
487
58,775
WQ
276
00
00
00
00
00
00
00
276
Botrytis
RFI
00
03,498
4,983
02
00
4,746
33,336
197
551
4,337
1,067
52,716
Approvals
00
00
00
00
00
00
00
00
WQ
00
04,912
84
00
00
00
01
3,501
720
9,218
Sclerotinia
RFI
08,124
00
5,395
00
00
00
20
00
213,542
Approvals
01,316
00
00
00
00
00
00
01,316
WQ
00
00
00
00
00
00
00
66
Leaf spots
RFI
9,855
3,811
00
00
00
68
00
00
00
13,735
(Alternaria)
Approvals
187
4,049
00
00
00
81
00
00
00
4,318
WQ
00
00
00
00
00
00
00
00
Leaf spots
RFI
9,855
00
00
00
00
00
00
00
9,855
(Mycosphaerella)
Approvals
187
00
00
00
00
00
00
00
187
WQ
00
00
00
00
00
00
00
00
Rusts
RFI
00
2,120
00
00
00
475
00
0607
93,210
Approvals
00
10
00
00
00
8,999
00
00
09,009
WQ
00
00
00
00
00
00
00
00
Pythium
RFI
02,936
00
00
00
00
099
441
0133
3,608
Approvals
00
00
00
00
00
00
00
00
WQ
00
00
00
00
00
00
00
00
Phytophthora
RFI
00
1,272
00
60
00
00
00
551
00
1,883
Approvals
00
70
00
00
00
00
00
07
WQ
00
00
00
00
00
00
00
00
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The economic impacts on gross margin (£ million per year):
• Improvements over Business as Usual – assuming no current options are lost � Improved broad-leaved weed control could increase output by up to £58 million. � Botrytis affects most crops and currently costs the industry £52 million, in
reduced harvest yields and marketability. � Imperfect weevil control cost the industry up to £52 million, £44 million on
strawberries. � Powdery mildew currently costs the industry £39 million. � Slugs currently cost the industry £32 million, with £20 million lost to strawberries
alone.
• Losses due to changing approvals legislation � The impact of changes weed management as a result of reduced herbicide
availability would add additional costs, but still not completely reduce yield impacts, potential cost across all horticulture sectors assessed £103 million.
� There would be minimal impact from changes to weed control by using alternative actives or mechanical weeding, but increased costs would reduce gross margin by £13 million.
• Water quality – could potentially have the most significant impact, if active substances were to be withdrawn, or have their use restricted:
� Loss of herbicides could cost almost £200 million in increased costs and reduced yields as a result of poor control of both broad-leaved weeds and grass weeds.
� Loss of slug control could cost the industry £14 million
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2 CONTENTS Acknowledgements ........................................................................................................... 2 1 Executive Summary.................................................................................................... 3 2 Contents....................................................................................................................11 3 Introduction................................................................................................................13 3.1 Background.......................................................................................................13 3.2 Potential pesticide losses ..................................................................................14 3.2.1 Changing approvals legislation scenario .......................................................14 3.2.2 Water Quality Legislation...............................................................................15 3.2.3 Other reasons for pesticide losses ................................................................18
4 Method ......................................................................................................................19 5 Analysis.....................................................................................................................20 5.1 Brassicas ..........................................................................................................21 5.1.1 Business as usual and untreated scenarios...................................................22 5.1.2 Changing approvals legislation scenario .......................................................26 5.1.3 Water Quality ................................................................................................28 5.1.4 Other reasons for pesticide losses ................................................................29
5.2 Carrots ..............................................................................................................30 5.2.1 Business as usual and untreated scenarios...................................................31 5.2.2 Changing approvals legislation......................................................................34 5.2.3 Water Quality ................................................................................................35 5.2.4 Other reasons for losses ...............................................................................36
5.3 Leeks ................................................................................................................36 5.3.1 Business as usual and untreated scenarios...................................................37 5.3.2 Changing approvals legislation scenario .......................................................39 5.3.3 Water Quality ................................................................................................41 5.3.4 Other reasons for pesticide losses ................................................................42
5.4 Onions ..............................................................................................................42 5.4.1 Business as usual and untreated scenarios...................................................43 5.4.2 Changing approvals legislation scenario .......................................................46 5.4.3 Water Quality ................................................................................................47 5.4.4 Other reasons for pesticide losses ................................................................48
5.5 Outdoor Lettuce ................................................................................................48 5.5.1 Business as usual and untreated scenarios...................................................49 5.5.2 Changing approvals legislation scenario .......................................................52 5.5.3 Water Quality ................................................................................................54 5.5.4 Other reasons for pesticide losses ................................................................55
5.6 Apple.................................................................................................................56 5.6.1 Business as usual & untreated ......................................................................56 5.6.2 Changing approvals legislation......................................................................60 5.6.3 Water Quality ................................................................................................62
5.7 Pear ..................................................................................................................63 5.7.1 Business as usual & untreated scenarios ......................................................63 5.7.2 Changing approvals legislation scenario .......................................................67 5.7.3 Water Quality ................................................................................................69
5.8 Plum (stone fruit)...............................................................................................70 5.8.1 Business as usual and untreated scenarios...................................................70 5.8.2 Changing approvals legislation scenario .......................................................74 5.8.3 Water Quality ................................................................................................76
5.9 Blackcurrants ....................................................................................................76 5.9.1 Business as usual and untreated scenarios...................................................78 5.9.2 Changing approvals legislation......................................................................81 5.9.3 Water Quality ................................................................................................83
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5.10 Raspberry .........................................................................................................85 5.10.1 Business as usual and untreated scenarios...............................................86 5.10.2 Changing approvals legislation scenario....................................................95 5.10.3 Water Quality.............................................................................................98 5.10.4 Other reasons for pesticide losses.............................................................99
5.11 Strawberry.........................................................................................................99 5.11.1 Business as usual and untreated scenarios.............................................100 5.11.2 Changing approvals legislation................................................................107 5.11.3 Water Quality...........................................................................................109 5.11.4 Other reasons for pesticide losses...........................................................110
5.12 Cucumber .......................................................................................................110 5.12.1 Business as usual and untreated scenarios.............................................111 5.12.2 Changing approvals legislation scenario..................................................115 5.12.3 Water Quality...........................................................................................115 5.12.4 Other reasons for pesticide losses...........................................................115
5.13 Tomatoes........................................................................................................117 5.13.1 Business as usual and untreated scenarios.............................................117 5.13.2 Changing approvals legislation................................................................121 5.13.3 Water Quality...........................................................................................121 5.13.4 Other reasons for pesticide losses...........................................................121
5.14 Hardy Nursery Stock .......................................................................................123 5.14.1 Business as usual and untreated scenarios.............................................123 5.14.2 Changing approvals legislation scenario..................................................128 5.14.3 Water Quality...........................................................................................131 5.14.4 Other reasons for pesticide losses...........................................................133
5.15 Protected Ornamentals ...................................................................................134 5.15.1 Business as usual and untreated scenarios.............................................135 5.15.2 Changing approvals legislation scenario..................................................138 5.15.3 Water Quality...........................................................................................140 5.15.4 Other reasons for pesticide losses...........................................................141
5.16 Appendix 1 ......................................................................................................141
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3 INTRODUCTION This report aimed to provide an economic review of the impacts of legislation that may affect pesticide availability. The reason for doing this was to identify and drive research priorities for the future. It also demonstrates the importance of mitigation measures in protecting production from the impacts of reduced pesticide availability. The data that is contained within this report should be considered to provide an indication of the potential scale of the cost if no mitigation measures were put in place to prevent pesticides from being lost, not an absolute value of the cost of the legislation being implemented. In order to calculate the cost of the impacts a scenario of complete withdrawal was used. However in the case of water quality legislation it is unlikely that there will be widespread withdrawals of active ingredients. Instead there may be severe restrictions in timing of use that could result in the active ingredient no longer being effective in controlling the target weed, pest or disease.
3.1 Background Most horticultural crops in the UK are currently produced using a variety of pesticides to control weeds, pests and diseases. Due to the relatively small area they occupy compared with arable crops, and therefore the relatively small pesticide market they provide, the availability of pesticides on horticultural crops is already limited due to lack of specific approvals, despite the development of the ‘off-label’ system for minor uses. However the number of pesticides that are currently approved for use on horticultural crops is under increasing pressure from a number of different sources:
• Replacement of EU Directive 91/414/EEC for the approvals of pesticides with Regulation (EC) No. 1107/2009
• Water quality requirements – including Water Framework Directive and the Drinking Water Directive
• Failure of pesticides to gain annex 1 listing under 91/414/EEC
• Increased resistance of pests, diseases and weeds, changes to the specified maximum residue limits and commercial pressures, for example the costs of providing additional data for regulatory bodies to maintain product registration, compared with the likely value of future product sales.
This report aims to assess the cost of these potential reductions in pesticide availability and identify research priorities and the importance of mitigation measures for a number of horticultural crops:
• Brassicas (Cauliflower, Cabbage, Brussels Sprouts)
• Carrots
• Leeks
• Onions
• Outdoor Lettuce
• Apples
• Pears
• Plums
• Blackcurrants
• Raspberries
• Strawberries
• Cucumbers
• Tomatoes
• Hardy Nursery Stock
Page 14
• Bedding Plants and Ornamentals In all cases, a worst case scenario of complete active substance withdrawal was applied to the affected area, with an estimated yield loss and impact on quality (reduction in value) for the crop calculated. It was also possible, using these calculations, to assess the impact per affected hectare. This figure could be applied if losses, for example as a result of water quality requirements, were for a specific catchment or area, rather than a total loss of approval.
3.2 Potential pesticide losses
3.2.1 Changing approvals legislation scenario
The replacement of EU Directive 91/414/EEC for the pesticide approval with Regulation (EC) No 1107/2009 will result in a number of changes to the approvals system. This replacement introduces hazard-based criteria for the ‘placing of plant protection products on the market’. As a result of this change in legislation, and following the implementation of the new Regulation on 14 June 2011, there will be pesticide active substances that will not receive approval when their current approval falls due for renewal. The number of different potential actives that could be affected by this changing legislation was initially unclear, dependent in part upon the definition of ‘endocrine disruptors’. Endocrine disruptors interfere with the function of the endocrine system (production of hormones) by mimicking naturally produced hormones, inhibiting that action of normal hormones or by altering the concentration of hormones in the body. This can lead to disruption of reproductive cycles and birth defects. In a report dated December 20082, PSD (Pesticides Safety Directorate, now CRD Chemical Regulation Directorate) identified pesticides ‘at risk’ in a series of scenarios, with a number of different definitions of endocrine disruptors. A series of votes have taken place within Europe to establish what this legislation will contain; these include votes by the European Council in September 2008, by the European Parliament Environment Committee in November 2008 and a full MEP vote in January 2009. As a result of these votes it is expected that the Swedish definition3 of endocrine disruptors (scenario 2C in the PSD report) is the one most likely to be used. The European commission currently have a project underway4 to define endocrine disruptors in advance of the final publication of this legislation. In our assessment, we have assumed that the active substances listed by PSD in their scenario 2c are most likely to be lost, see Table 1. Although it is most likely that these actives will only be lost once their current approval expires, this assessment has been based on all actives being lost at a point in the future.
2 Revised assessment of the impact on crop protection in the UK of the ‘cut-off criteria’ and substitution provisions in the proposed Regulation of the European Parliament and of the Council concerning the placing of plant protection products on the market. Pesticides Safety Directorate Dec 2008 http://www.pesticides.gov.uk/uploadedfiles/Web_Assets/PSD/Revised_Impact_Report_1_Dec_2008(final).pdf 3 Swedish Chemicals Agency September 2008 http://www.kemi.se/upload/Bekampningsmedel/Docs_eng/SE_positionpapper_annenII_sep08.pdf (18/02/10) 4 http://ec.europa.eu/research/endocrine/index_en.html (05/03/10)
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Table 1. Active substances expected to be lost due to the changing approvals legislation (Council position 2C – Swedish definition of endocrine disruption) – Source PSD report Dec 2008
2
Active substance Action Reason for revoking approval
Date current approval expires
bifenthrin Insecticide PBT / vPvB + endocrine?
2018
esfenvalerate Insecticide PBT 2011 bitertanol Fungicide R2 + endocrine? 2020 carbendazim Fungicide M2 / R2 +
endocrine? 2009
flusilazole Fungicide R2 + endocrine? quinoxyfen Fungicide vPvB 2014 cyproconazole Fungicide R3 C3 – triazole not
assessed by Sweden
2020
epoxiconazole Fungicide R3 C3 endocrine 2018 fenbuconazole Fungicide R3 – triazole not
assessed by Sweden
2020
mancozeb Fungicide R3 – endocrine 2016 maneb Fungicide R3 – endocrine 2016 metconazole Fungicide R3 – endocrine 2017 tebuconazole Fungicide R3 – endocrine 2019 flumioxazine Herbicide R2 2012 glufosinate ammonium
Herbicide R2 2017
linuron Herbicide R2 + endocrine 2013 pendimethalin Herbicide PBT 2013 amitrole Herbicide R3 – endocrine 2011 Ioxynil Herbicide R3 – endocrine 2015 PBT – Persistent Bio-accumulating Toxic vPvB – very Persistent, very Bio-accumulating M – mutagenic (category 2) R – reproductive toxin (category 2 or 3) C – carcinogen (category 3)
3.2.2 Water Quality Legislation
Meeting the water quality requirements of the Water Framework Directive (2000/60/EC) (WFD) and the Drinking Water Directive (1998/83/EC) (DWD), is likely to impact on a number of important active substances. The WFD requires that all rivers, lakes, ground and coastal waters should reach good ecological and chemical status by 2015, as well as a deterioration in water quality avoided within Drinking Water Protected Areas in order to reduce the level of treatment required during the production if drinking waters. The Drinking Water Directive sets a maximum allowable concentration of 0.1ug/l for any pesticide and 0.5ug/l for total pesticides in drinking water at the tap. A number of current pesticide active substances are intermittently detected, in surface and groundwater at levels that exceed the limits set in the DWD. If these can not be mitigated for, such as through catchment management or treatment, potentially more severe approaches become a necessity. A number of approaches to minimising active substances reaching water are being adopted including farm advice and voluntary measures (e.g. English Catchment Sensitive Farming Delivery Initiative, Voluntary Initiative), including the use of buffer zones and
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unsprayed areas. In the future the introduction of restrictions in use (timing, crop or rate) of specific active substances in affected catchments may be necessary. An example of the voluntary approach to protect water comes from metaldehyde. This molluscicide is currently being detected in water. A Metaldehyde Stewardship Group was established in 2008 in response to the detection of metaldehyde in catchments used for water supply production. At certain times of year the levels of metaldehyde detected were found to exceed the drinking water standards, despite treatment of the water using state of the art water treatments processes. The aim of the group is to establish best practice for slug pellet application and disseminate information to farmers, spray operators and distributors. As part of their work new best practice guidance has been issued for the 2010 slug pelleting season. This maintains the maximum rate of application at 700 g a.i. per hectare per annum, but reduces the maximum individual application down from 250 g to 210 g a.i. per hectare. There is also a restriction in the total amount of metaldehyde that can be applied between August and December. There are also extensions to the buffer zones between the water course and area treated with metaldehyde (to not within 6m). It is hoped that these measures will reduce the amount of metaldehyde that is able to reach water. Restrictions applied might be limited to the affected catchment or sub catchment, however many of these active substances are applied to very large areas and for some the implications could encompass a large area of the crop. For many active substances the restrictions put in place could be so difficult to work around that the product is no longer an effective option. As a result we have modelled a scenario where products are not available on substantial areas to give a worst case scenario. This approach was used in order to highlight the importance of the particular active ingredients within horticulture and therefore the importance of taking action to prevent these active ingredients from reaching water. At no point should it be considered that a complete withdrawal of all active ingredients listed under water quality implications would ever actually occur. We have assessed losses on an area (ha) basis so that, if a restriction for use was placed on a specific catchment, the impact of this on a crop within that catchment could be assessed. The pesticides that are currently causing concerns in ground water and surface water in England and Wales are listed in Table 2. This list includes Priority Substances, UK Specific Pollutants and pesticides that are putting Article 7 compliance at risk. Article 7 of the WFD requires member states to protect water bodies with ‘the aim of avoiding deterioration in quality in order to reduce the level of purification required in the production of drinking water’. There are a number of Drinking Water Protected Areas (DrWPAs) where assessments of water have found that the levels of certain pesticides could cause non-compliance with WFD. The levels of pesticides in these water bodies does not necessarily mean that they fail DWD requirements, although to meet these a large investment in water treatment may be required.
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Table 2. Actives included in the assessment of the impact of water quality requirements
Fungicides Herbicides Insecticides Molluscicides captan A7 MCPA A7 cypermethrin (UK SP, cPS) Metaldehyde A7,A7 iprodione A7 Chlorotoluron A7 diazinon (UK SP, A7) carbendazim A7 mecoprop (UK SP, A7) 2, 4-D (UK SP) asulam A7 Propyzamide A7 glyphosate (UK SP, A7) carbetamide A7 bentazone A7 linuron (UK SP) A7 metazachlor A7 clopyralid A7 MCPB A7 fluroxypyr A7 chlorpyrifos (PS) NB This list is wider than the list of current Priority Substances and UK Specific Pollutants as it includes active substances that are used over a wide area and have been detected in water and are putting article 7 compliance at risk.
PS Priority Substance, cPS candidate Priority Substance, UK SP UK Specific Pollutant, A7 article 7 compliance. If a water body fails to meet the necessary criteria the provisions under WFD allow for localised management plans. The preference would be for these on a voluntary basis to be implemented with the aim of improving the water quality in that area. However, many of the active substances which are listed under article 7 are used on large areas (outside horticulture) and very often the use of one active substance if restricted would be replaced by the use of another active substance which is also likely to exceed relevant criteria. This report, therefore, focuses on worst case scenarios, which assume severe restrictions on use and it should be noted that local and voluntary options would be attempted before major regulatory based changes were made. The impacts of the potential loss of the active substances listed in Table 2 were assessed in this report. A number of active substances that have caused problems in Drinking Water Protected Areas (DrWPAs) and ground water have already been withdrawn. These active substances include; isoproturon, atrazine, diuron, simazine, dalapon, terbutryn, methabenzthiazuron and dichlobenil. There are also a number of insecticidal actives that have caused Ecosystem concerns that have been withdrawn from sale, these include; hexachlorocyclohexane, aldrin, dieldrin, endrin’, and permethrin. The loss of these active substances has already occurred and it is assumed in the business as usual scenario that they are not available, so no further assessment of the impacts of these losses has been conducted. In this assessment we have looked at the potential impact of the loss of the active substances causing concern in ground water and surface water. There are a number of active substances that are classified by the EU as Priority Substances (PS), Priority Hazardous Substances (PHS) because they are considered to be ‘pollutants presenting a significant risk to or via the aquatic environment, including such risks to waters used for abstraction of drinking water’. In addition to the Priority Substances and Priority Hazardous substances member states are required to identify Environmental Quality standards for Specific Pollutants. All Priority Hazardous Substances have already been withdrawn from use in the UK, as have the majority of Priority Substances (alachlor, atrizine, chlorfenvinphos, diuron, isoproturon, simazine and trifluralin). However, chlorpyrifos is also categorised as a Priority Substance and it currently remains on the market. Given that all other actives in this group have been withdrawn it has been considered in this assessment that chlorpyrifos could also be at risk from restrictions on its use or in the worst case scenario it could be withdrawn from sale.
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UK Specific Pollutants (UK SP) are listed as 2,4-D, cypermethrin, diazinon, dimethoate, linuron and mecoprop. Permethrin was also listed but has had its approval withdrawn.
3.2.3 Other reasons for pesticide losses
Potential Future Priority Substances Other active substances may be included in a list of Potential Future Priority Substances and UK Specific Pollutants. This list is reviewed every four years; the substances to be added to the list have not been confirmed but the review is currently underway. However AMPA (the breakdown product of glyphosate), glyphosate, mecoprop and quinoxyfen have all been suggested as additions to the Priority Substances list (this information was correct at time of writing in March however as of August 2010 it is just quinoxyfen that is left on this list; AMPA, glyphosate and mecoprop have been removed from the list). UK Specific Pollutants candidates suggested include carbendazim, chlorothalonil, glyphosate, methiocarb and pendimethalin, these actives may all be at risk restrictions on their approvals at some point in the future if they are placed on these lists. Impacts of these losses have not been calculated in this project, unless the actives were also at risk from either water quality requirements or changing approvals legislation. Those actives highlighted in bold are not included in the assessment of impact of water quality requirements or the changing approvals legislation scenario on pesticide availability, whilst the other active substances have been included for other reasons. However, where losses of other active substances are likely to cause an increase in the use of these active substances this has been taken into account in the discussion of the impacts. Annex 1 review As part of the original Council Directive 91/414/EEC legislation, a set of safety criteria had to be met by all existing pesticides in order to gain approval on to Annex 1. If insufficient evidence was provided to demonstrate that chemicals met these safety criteria by December 2010, then these active substances will lose their European approval and subsequently be withdrawn from the market. There are a number of active substances that have recently had their approvals withdrawn as a result of failure to gain Annex 1 approval these include the actives listed Table 3 (this list is not exhaustive).
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Table 3. Active substances that have failed to gain annex 1 approval
Active Substance Category Final use date
bifenthrin5 Insecticide March 2011 bromuconazole (cereals) Fungicide May 2010 carbendazim Fungicide December 2009 chorthal-dimethyl6 Herbicide March 2011 cyproconazole Fungicide Withdrawal date not set dichlobenil7 (woody crops & non-crop uses)
Herbicide March 2010
dithianon (apples & pears) Fungicide Withdrawal date not set fenbuconazole (top fruit) Fungicide Withdrawal date not set fluquinconazole (cereals) Fungicide Withdrawal date not set guazatine (cereals) Fungicide (seed dressing) 2013 isoxaben Herbicide metaldehyde Molluscicide Withdrawal date not set metam sodium Soil sterilant March 2014 myclobutanil Fungicide (voluntary withdrawal) prochloraz Fungicide Withdrawal date not set propachlor8 Herbicide March 2010 terbuthylazine (maize & pulses)
Herbicide Withdrawal date not set
There remain a number of active substances which it is unclear whether or not there is sufficient data available for them to achieve Annex 1 listing. There are also commercial reasons for the withdrawal of active ingredients. It costs a significant amount of money to produce and maintain the data required for approvals. Where a product has a small market share this cost can out weigh the value of the product. There have also been recent changes in the Maximum residue level limits for crops. This has meant that certain uses of active substances on particular crops are no longer possible reducing the availability of pesticides on that particular crop.
4 METHOD A gross margin calculation was established for each crop based on values taken from Nix 20099 and expert opinion. Crop areas were taken from Defra statistics for harvest year 2009 (where available). The most important weeds, pests and diseases of each crop were identified, together with the area affected by those weeds pests and diseases. For each crop or crop group, four scenarios were assessed:
• Business as usual – this assessed the current yield losses that occur despite currently approved active substances being available, or the potential to increase yield if 100% control of the weed pest or disease was possible.
5 http://www.pesticides.gov.uk/uploadedfiles/Web_Assets/PSD/Bifenthrin_Revocation_Notice(1).doc 6 http://www.pesticides.gov.uk/uploadedfiles/Web_Assets/PSD/chlorthal_dimethyl_revocation_notice.doc 7 http://www.pesticides.gov.uk/approvals.asp?id=2562 8 http://www.pesticides.gov.uk/approvals.asp?id=2562andlink=%2Fuploadedfiles%2FWeb_Assets%2FPSD%2FPropachlor_Decision_2008_742_EC.pdf 9 Nix J. (2009) The John Nix Field Management Pocketbook (39
th Edition – 2009)
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• Untreated – predicted yield losses and impacts on quality if no active substances were used for the control of the specific weed, pest or disease.
• Replacement of 91/414/EEC with Regulation (EC) No 1107/2009 (from here on referred to as the changing approvals legislation scenario) – predicted yield losses and impacts on quality if the active substances affected by the replacement of 91/414/EEC, failed to gain approval (part of the initial assessment was completed in an earlier project completed for HDC with funding from Defra).
• Water quality requirements – predicted yield losses and impacts on quality if the active substances that are currently causing concerns in Drinking Water Protected Areas, in groundwater or to ecosystems were to be completely withdrawn from sale, these loses have been calculated separately to the losses that could occur to the changing approvals legislation. (The withdrawal of approvals to protect ground water is an unlikely extreme, but has been used to demonstrate the importance of these active ingredients to the industry and therefore highlight the need for research to either find ways to stop these pesticides entering water or to find alternative ways of controlling the weeds pests or disease that are controlled by these active ingredients)
If pesticide losses occurred due to both water quality and the changing approvals legislation scenario the impacts could be considerably greater. For each scenario an estimate of the potential yield loss was made, where possible based on research data, but in many cases expert opinion was used, especially with reference to the scenarios, as there is very limited research data available on distribution of weeds, pest and diseases, and the yield impacts of specific pesticide losses. Potential yield losses were calculated based on the potential for the weed, pest or disease to cause yield loss in that scenario. In the event of multiple weeds, pests or diseases being present, the total yield loss caused by single pathogen might be less than this estimate, due to interactions between the weed, pest or disease species. Consequently, the potential yield reductions given for the individual weeds, pests or diseases should not be added together. If this approach was adopted, calculated losses could actually exceed the potential yield of the crop. The pesticide active substances that are applied to the crop often control more than one weed, pest or disease. Because multiple weeds, pests or diseases are controlled by a spray programme, the allocation of the cost of that programme to each weed, pest or disease species is variable dependent upon the level of each pathogen present in the crop at any one time. In the untreated scenario therefore, it has been assumed that as there are no actives applied the entire cost of weed, pest or disease control has been removed from the gross margin calculation. For weeds only the cost of herbicides has been removed, for pests only the cost of the insecticides and for diseases only the cost of fungicides, so as to separate out the impacts of that specific weed, pest or disease. In some cases, where control of a minor disease is incidental to more expensive applications made for other pathogens, this can make the untreated scenario actually appear more economically viable than treatment.
5 ANALYSIS Each crop was analysed separately. For each crop there is a brief description of the crop assessed (where relevant assumptions made have been included in an appendix at the end of the document). This is followed by a table of the gross margin information used in the calculations. For each crop the weeds, pests and diseases that had the largest impacts on the crop were identified by the crop experts (and from the previous work
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carried out for the HDC and Defra on the impacts of 91/414/EEC). Each of these weeds pests and diseases was assessed for their impact on the crop in each of the four scenarios. For each weed, pest or disease an estimate was made of the percent area of the crop affected based on expert opinion. Having established the area affected the impact of the weed, pest or disease on harvestable yield, marketable yield and price, on the affected crop, were determined using expert opinion. For each crop the business as usual and untreated scenarios are described first, with the impacts of specific weeds, pests and diseases identified. This is followed by tables showing the data for each weed, pest and disease in the business as usual and untreated scenarios. This is followed by sections for the other two scenarios; changing approvals legislation scenario and Water Quality. Each section starts with list of active substances that could potentially be affected on that crop in that scenario. There is then a description of what the impact of the loss of these active substances with be on the specific weeds, pests of diseases affected. Where relevant, suitable mitigation methods have been identified to enable production to be maintained at the highest level.
5.1 Brassicas Of all the vegetable crops, leaf and flower head brassicas occupy the largest area of land at 26,000 ha10 though this has been in decline for the past ten years, particularly for cauliflowers, Brussels sprouts and, to a lesser extent, winter cabbage. Cauliflower is the most important brassica by area (9,440 ha, farm gate value £51.8M), that by value is calabrese (7,232 ha farm gate value £65.9M). Profitability of many brassicas, particularly cauliflower has been challenging with demand decreasing and the prices being realised not matching increases in production costs. Most brassica crops are established from module-raised transplants as this technique means land is occupied for a shorter period as well as ensuring that crops mature evenly, aiding continuity and reducing harvesting costs. The average gross margin assumptions (across all brassica crops) used in this assessment are given in Table 4. [Total value] Table 4. Brassica gross margin
Crop BrassicasCrop area* ha 26,719
Yield* t/ha 18
Value* £/t 473
Seed cost £/ha 720
Fertiliser cost £/ha 270
Spray cost £/ha 425
Bio-control cost £/ha
Cultivation costs £/ha 232
Other costs £/ha 3,410
Total Value £/ha 8,325
Total costs £/ha 5,057
Gross margin £/ha 3,268
10 Basic Horticultural Statistics 2008
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5.1.1 Business as usual and untreated scenarios
Under ‘business as usual’, the largest potential gains could come from improved control of cabbage root fly (£15M), white blister (£13M), dark leaf spot and ring spot (£10M), (Table 5). The figures in brackets are the potential increase in value to the industry that could occur if 100% control was achievable. In the absence of pesticides, major losses in brassicas when using sensible non-pesticide mitigation measures are caused by cabbage root fly (62% reduction in production), dark leaf spot (12% reduction in production), peach-potato aphids and white blister (11% reduction in production).(Table 6)
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Table 5.
Impact of weeds, pests and diseases on brassicas under business as usual (potential yield and gross m
argin increases if better
control was possible - despite use of available pesticides)
Business as usual
Broad-leaved weeds
Volunteer potatoes
Mealy Cabbage
Aphid
Peach -Potato Aphid
Flea Beetles
Caterpillar
Cutworms
Cabbage Root Fly
Diamond back Moth
Slugs
Downy mildew
Dark Leaf Spot
Light leaf spot
Phoma Leaf
Spot/canker
Powdery Mildew
Ring spot
White blister
Area affected (ha)
4,008
2,672
5,344
8,016
1,336
4,008
1,336
24,047
10,688
10,688
5,344
18,703
2,672
18,703
4,008
18,703
21,375
Potential increase in yield if
100% control possible (t)
2,349
1,643
5,012
7,519
235
3,759
274
31,718
10,025
10,025
1,881
20,835
2,036
14,252
3,054
20,835
27,574
Potential increase in value to
industry if 100% control
possible (£K)
1,111
777
2,371
3,556
111
1,778
130
15,003
4,742
4,742
890
9,855
963
6,741
1,445
9,855
13,043
Added value per affected
hectare (£K)
0.3
0.3
0.4
0.4
0.1
0.4
0.1
0.6
0.4
0.4
0.2
0.5
0.4
0.4
0.4
0.5
0.6
Table 6.
Impact of weeds, pests and diseases on brassicas in the absence of pesticide applications – whilst using sensible m
itigation, e.g.
biological controls. (Worst case scenario)
Untreated
Broad-leaved weeds
Volunteer potatoes
Mealy Cabbage Aphid
Peach -Potato Aphid
Flea Beetles
Caterpillar
Cutworms
Cabbage Root Fly
Diamond back Moth
Slugs
Downy mildew
Dark Leaf Spot
Light leaf spot
Phoma Leaf
Spot/canker
Powdery Mildew
Ring spot
White blister
Area affected (ha)
4,008
2,672
5,344
8,016
1,336
4,008
1,336
24,047
10,688
10,688
5,344
18,703
2,672
18,703
4,008
18,703
21,375
Yield Loss (t)
17,843
7,829
35,242
52,864
705
18,797
548
292,533
29,765
33,527
19,585
57,548
2,749
46,025
4,118
38,362
52,603
Cost to the industry (£K)
-11,574
-3,687
-18,342-27,513
-752-10,145
-76
-145,895-17,424-15,217
-8,248-23,666
-792
-18,216
-1,186
-14,591
-20,820
Cost per affected hectare (£K)
-2.9
-1.4
-3.4
-3.4
-0.6
-2.5
-0.1
-6.1
-1.6
-1.4
-1.5
-1.3
-0.3
-1.0
-0.3
-0.8
-1.0
Percentage reduction in production (%)
3.8
1.7
7.5
11.2
0.2
4.0
0.1
62.2
6.3
7.1
4.2
12.2
0.6
9.8
0.9
8.2
11.2
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Weeds
Broad-leaved weeds: Weeds in leaf and flowerhead brassicas can reduce yield and quality due to competition, resulting in size grade specifications not being met, and crop contamination with weed seeds. Increased harvesting costs can occur and also an increased threat of pest and disease mainly due to changes in microclimate, but also due to weeds acting as hosts. However, leaf and flowerhead brassica crops are relatively competitive against most weeds and the range of herbicides available until recently has provided good control. Currently pendimethalin is applied pre-planting is being used as a partial replacement for trifluralin, but the soil disturbance at planting tends to reduce its efficacy. After establishment metazachlor is used, often in combination with clomazone though there can be transient crop yellowing/bleaching from use on very light soils or sands. Pyridate is also available for control of black nightshade, cleavers, corn marigold, fat hen, fumitory, groundsel and speedwells, but experience has shown the importance of transplants being fully hardened off before its application. Napropamide is available pre-planting and formerly was used in conjunction with trifluralin. Mechanical inter-row weeding is already well established and a small but increasing number of growers are also using intra-row cultivators. Whilst mechanical weed control is generally effective in dry conditions, it is largely impractical when soil conditions are wet. There is increasing emphasis on tackling weeds elsewhere in the rotation. However, there are still the issues of volunteer potatoes and cruciferous weeds after cereals. For the ‘business as usual’ scenario, the threat with regard to weed control is currently considered to be low. In the absence of herbicides, increased cultivations would be needed, or the use of flame and/or brush weeders pre-planting to minimise weeds in the crop. Greater reliance on mechanical weeding supplemented by hand weeding, costed at £700/ha would be integral to control.
Pests
The control of insect pests in leaf and flowerhead brassicas is extremely important, otherwise yield can be reduced and more importantly quality compromised as there is no tolerance for insect pest damage or contamination of harvested produce. Cabbage aphid (Brevicoryne brassicae): An important and widespread pest of brassicas. Pirimicarb is still effective against this species as long as the air temperature has not dropped too low and is favoured where peach-potato aphid is not present because it has unrestricted use and is fairly benign to natural enemies. New insecticides are becoming available, for example the recent addition of the systemic insecticide spirotetramat for brassica crops. However, like all insecticides spirotetramat should be used as part of an integrated pest management programme; in particular it complements neonicotinoids (e.g. thiacloprid). Peach-potato aphid (Myzus persicae): A widespread pest of a number of crops including brassicas. There is widespread resistance to pyrethroids and carbamates in this species but pymetrozine (Plenum WG) continues to be effective when used with an adjuvant oil, as do the neonicotinoid insecticides.
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The Rothamsted Insect Survey operates a national network for monitoring insect populations in the UK including cabbage aphid and peach-potato aphid. Cabbage root fly (Delia radicum): The larvae feed on the roots of all brassicas but particularly cabbage and cauliflower. Larvae can also tunnel into the buttons of early-maturing Brussels sprouts. Control using chlorpyrifos (e.g. Dursban WG) as a propagation treatment remains very cost-effective and there are still no reports of control failure due to resistance, despite the industry largely relying on this active substance. Some growers have nevertheless switched to using spinosad (Tracer) instead of chlorpyrifos but at an increased cost. The HDC Pest bulletin provides information on predicted egg laying. Large white butterfly (Pieris brassicae) and small white butterfly (Pieris rapae): Second generation butterflies of both species start to emerge and lay eggs from early August onwards. This generation is usually more damaging than the first generation - which normally occurs in May-June. Diamond-back moth (Plutella xylostella): Diamond-back moth does not survive UK winters in large numbers, so new infestations are usually the result of the immigration of moths from the continent. In spite of high numbers in some crops and widespread insecticide resistance worlwide, pyrethroids continue to give good control in the UK. Slugs (Deroceras reticulatum and others): Brussels sprout buttons and the undersides of cabbage heads are often attacked and, to a lesser extent, cauliflower heads. Incidence depends very much on the weather, with crops being most at risk in a wet summer and/or autumn, particularly on heavy-textured soils. Pellet baits containing metaldehyde, methiocarb or ferric phosphate are currently used for control. In the absence of insecticides, pest damage in brassicas would be extensive with the majority of crops failing to meet the demanding standards set by the multiple retailers. The alternative of using crop covers would be prohibitively expensive in most circumstances and impractical for the scale of production in the main growing areas.
Diseases
Leaf and flowerhead brassicas are very susceptible to a number of foliar diseases as well as root diseases such as clubroot. Effective control is therefore crucial, otherwise yield and quality would be compromised. There is no tolerance for any blemish on marketed produce. In addition, storage of winter white cabbage can be affected by disease occurence. Downy mildew (Peronospora parasitica): Potentially troublesome and widespread in plant propagation, but control can be achieved by using the correct growing regime and fungicides. All field brassicas are susceptible though there are varietal differences and fungicidal control is available. Dark leaf spot (Alternaria brassicae): Symptoms usually occur from July on the heads of cabbage and cauliflower and on Brussels sprout buttons, but are also present on cruciferous weeds and in oilseed rape. A disease forecasting system is available to assist crop scheduling and fungicide application. Light leaf spot (Pyrenopeziza brassicae): Particularly troublesome on Brussels sprouts but also winter white cabbage. NIAB have noted useful differences in varietal resistance for Brussels sprouts and likewise differences have been recorded in cabbage varieties.
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Phoma leaf spot/canker (Phoma lingam): Symptoms occur on the stem as light brown or purplish cankers and on the foliage large lesions with necrotic areas. Triazole fungicides are used for control. Powdery mildew (Erysiphe cruciferarum): Incidence varies from year to year and from variety to variety as recorded by NIAB for Brussels sprouts. The use of sulphur as a foliar feed gives some control as does the use of irrigation to alleviate drought stress. Ringspot (Mycosphaerella brassicicola): Very common in brassicas particularly in coastal and high rainfall locations such as the southwest and northwest. A forecasting system is available to identify periods of disease activity and aid fungicide timing. White blister (Albugo candida): Incidence is widespread from June onwards with severe infection causing leaf distortion and affecting marketability. Chlorothalonil + metalaxyl-M or mancozeb + metalaxyl-M provide good curative control. There is a forecasting system available. Effective control of the main brassica diseases (ringspot, dark leaf spot, phoma, light leaf spot, powdery mildew) would be impossible without the use of the triazole fungicides (tebuconazole, difenoconzale and prothioconazole) though there is an over-reliance on difenaconazole because it is the cheapest. Boscalid + pyraclostrobin, tebuconazole + trifloxystrobin and azoxystrobin are also used, but on occasions only after all the permitted applications of difenoconazole have been used.
5.1.2 Changing approvals legislation scenario
Under the changing approvals legislation, the following active substances that are currently used on brassicas could be lost;
• Bifenthrin (insecticide)
• Pendimethalin (herbicide)
• Tebuconazole (fungicide) The impact of these losses on weeds pests and diseases is identified in Table 7. The most significant impacts of these losses increases the cost of insecticides for the control of Diamond back moths, Peach potato and other insect pests as a result of Bifenthrin failing to gain Annex 1 approval. The replacement insecticides currently cost about £15 a hectare more than bifenthrin. The loss of tebuconazole will result in increased yield losses from white blister (9% reduction in production). The loss of pendimethalin would result in weed control becoming more difficult with broad-leaved weeds causing some yield losses (1% reduction in production).
Page 27
Table 7.
Impact of weeds, pests and diseases on brassicas as a result of the pesticide losses caused by the changing approvals legislation
scenario– whilst using sensible m
itigation, e.g. biological controls. Cost to the industry is the additional cost
Changing approvals
legislation
Broad-leaved weeds
Volunteer potatoes
Mealy Cabbage Aphid
Peach -Potato Aphid
Flea Beetles
Caterpillar
Cutworms
Cabbage Root Fly
Diamond back Moth
Slugs
Downy mildew
Dark Leaf Spot
Light leaf spot
Phoma Leaf
Spot/canker
Powdery Mildew
Ring spot
White blister
Area affected (ha)
4,008
2,672
5,344
8,016
1,336
4,008
1,336
24,047
10,688
10,688
5,344
18,703
2,672
18,703
4,008
18,703
21,375
Yield Loss (t)
5,635
00
00
00
00
00
00
00
017,528
Cost to the industry (£K)
-3,126
0-80
-120
-20
-60
00
-160
00
-187
-27
-187
-40
-187
-8,611
Cost per affected hectare (£K)
-0.8
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
-0.4
Percent reduction in
production (%)
1.2
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
3.7
Table 8.
Impact of weeds, pests and diseases on brassicas as a result of the potential pesticide losses caused by the restrictions put in
place by the current water quality requirements – whilst using sensible m
itigation, e.g. biological controls.
Water Quality
Broad-leaved weeds
Volunteer potatoes
Mealy Cabbage
Aphid
Peach -Potato Aphid
Flea Beetles
Caterpillar
Cutworms
Cabbage Root Fly
Diamond back Moth
Slugs
Downy mildew
Dark Leaf Spot
Light leaf spot
Phoma Leaf
Spot/canker
Powdery Mildew
Ring spot
White blister
Area affected (ha)
4,008
2,672
5,344
8,016
1,336
4,008
1,336
24,047
10,688
10,688
5,344
18,703
2,672
18,703
4,008
18,703
21,375
Yield Loss (t)
4,813
1,095
00
00
00
00
470
00
00
00
Cost to the industry (£K)
-2,457
-719
00
00
0-2,405
00
-276
00
00
00
Cost per affected hectare (£K)
-0.6
-0.3
0.0
0.0
0.0
0.0
0.0
-0.1
0.0
0.0
-0.1
0.0
0.0
0.0
0.0
0.0
0.0
Percent reduction in
production (%)
1.0
0.2
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.1
0.0
0.0
0.0
0.0
0.0
0.0
* Cost to the industry assumes that the active substances are lost to the whole industry; however a complete revocation of the active substance is a last resort. Instead specific catchments may be
affected, if this is the case the cost per hectare can be used to apply to the area within a catchment that is affected.
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Weeds
Currently, the programme of pendimethalin plus clomazone mentioned in ’business as usual’, plus mechanical hoeing, provides the control required. However, there is acceptance that crops may start to get weedier and this is already noticeable where trifluralin is no longer used, with more fat hen and redshank present. Both of these weeds could lead to contamination of harvested crops.
HDC trials have demonstrated the efficacy of at least two new herbicides for brassica crops but, where data is not available, residue trials will be required before submission of an application for Specific Off-label Approval. The industry hopes that these materials will be available by 2013. In spite of a reduction in herbicide choice, the threat with regard to loss of weed control is considered to be low.
Pests
The only loss due changing approvals legislation is bifenthrin, which was lost due to failure to gain Annex 1 approval under 91/414/EEC and this is of concern as it used in programmes for both aphid and caterpillar control, although there are alternative pyrethroids available.
Diseases
The only expected loss due to changing approvals legislation is tebuconazole which is widely used either alone or with trifloxystrobin. A lack of effective fungicides is potentially the greatest threat to UK brassica production. However, the further development of disease forecasting incorporating spore trapping should provide greater confidence in the timing of fungicides and the possibility of reducing the number of applications of those products that are available. There is also the possibility for ‘organic’ fungicide use i.e. foliar phosphites or biopesticides, though the latter would require UK approval.
5.1.3 Water Quality
The active substances that are currently available on brassicas that are at risk from restrictions due to Water quality requirements are:
• Carbetamide (herbicide)
• Chlorpyrifos (insecticide)
• Chlorothalonil (fungicide)
• Clopyralid (herbicide)
• Cypermethrin (insecticide)
• Glyphosate (herbicide)
• Iprodione (fungicide)
• Metaldehyde (molluscicide) The impact of these potential restrictions is shown in Table 8. The largest impact in terms of both cost and lost production would come from the potentially reduced ability to control broad-leaved weeds, this equates to a £2.5M cost (in increased cultivations and weeding and reduced yields), a 1% reduction in production, or a £600 reduction in gross margin per affected hectare. The cost of replacing chlorpyrifos with more expensive alternatives for
Page 29
the control of cabbage root fly would cost the industry £2.4M, or about £100 per affected hectare. The potential loss of chlorothalonil could make control of diseases such as downy mildew, more difficult with alternative active substances costing £10 ha more and being slightly less effective.
Weeds
Glyphosate is used pre-cropping to burn off germinated weeds as a more cost effective treatment than the alternatives of flame weeding or additional cultivation. Carbetamide is only used to a limited extent in spring cabbage and greens for annual grasses and some broad-leaved weeds. Volunteer potatoes (Solanum tuberosum): Control of volunteer potatoes would be a greater challenge with the loss of both clopyralid (e.g. Dow Shield) and glyphosate. More effort would be required in minimising the number of tubers left after harvesting as well as tackling volunteers in strongly competitive crops in the rotation. The last resort would be the expensive option of hand-weeding.
Pests
Although the loss of chlorpyrifos is assessed here under water quality issues there are a number of other issues associated with chlorpyrifos that could result in it being withdrawn from the market. Cabbage aphid (Brevicoryne brassicae) and peach-potato aphid (Myzus persicae): Cypermethrin and chlorpyrifos would not be available but there are alternatives.
Cabbage root fly (Delia radicum): Of major concern is the loss of chlorpyrifos, for application during plant propagation, for cabbage root fly control, though this material will be replaced by spinosad, at an appreciable extra cost. Cutworms (e.g. Agrotis segetum): Cypermethrin would be missed for cutworm control but there are alternative insecticides, including other pyrethroids, and also the option of timely irrigation to minimise attacks. For the latter, use should be made of the cutworm prediction service available from HDC or ADAS. Slugs (Deroceras reticulatum and others): An integrated approach should be used including the decision support method which has been developed for Brussels sprouts. Methiocarb and ferric phosphate are available as replacements for the widely used molluscicide metaldehyde.
Diseases No immediate impact
5.1.4 Other reasons for pesticide losses
Weeds
Trifluralin has had its approval revoked (2009) and it is no longer legal to apply it to crops in the UK. One of the main reasons for its approval being revoked was related to its appearance in water. In addition propachlor and chlorthal-dimethyl both failed to gain annex 1 approval and have therefore be removed from the market.
Page 30
Pests
Dimethoate is a useful part of the insecticidal programme mix but there are alternatives available. Slugs (Deroceras reticulatum and others): Loss of metaldehyde as an active substance in slug baits may put greater pressure on the continued use of slug pellets based on methiocarb. Methiocarb if increased use of methiocarb occurred it could lead to it being detected in water in the future. Slug pellets based on ferric phosphate are also available and may be as effective as either metaldehyde or methiocarb. Additionally, biological control options exist, such as nematodes. However, both ferric phosphate pellets and nematodes are more expensive control options.
Diseases
The impact of the possible loss of chlorothalonil, due to UK Specific Pollutant (there has been no decision yet on whether or not chlorothalonil will be included as a UK Specific Pollutant) concern, would be appreciable as it is often used in programmes for its long-lasting broad-spectrum protectant properties as well as being a component of Folio Gold (chlorothalonil +metalaxyl-M) used for white blister control (£27M) in Brussels sprouts and cauliflower.
5.2 Carrots By value (£129M) carrots are the most important vegetable crop in the UK, grown on some 11,000 ha 11, which has not varied much in recent years. Production is virtually all year round with early crops grown under plastic film to advance the start of harvesting to June. Later crops are over-wintered in the soil, covered with straw to provide insulation and black plastic to keep light out, so preventing re-growth. These crops are harvested from January to May but quality can deteriorate and there is interest in cold storage as an alternative option. If there is a shortage of UK production in May to early June then imports from Spain and France fill the gap. Specialist carrot crops such as Chantenay and bunched crops are also grown. The average gross margin assumptions for carrots used in this assessment are in Table 9 Table 9. Carrot gross margin
Crop Carrots
Crop area* ha 11,028
Yield* t/ha 68
Value* £/t 180
Seed cost £/ha 650
Fertiliser cost £/ha 160
Spray cost £/ha 520
Bio-control cost £/ha
Cultivation costs £/ha 455
Other costs £/ha 2,895
Total value £/ha 12,222
Total costs £/ha 4,680
Gross margin £/ha 7,542
11 Basic Horticultural Statistics 2008
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5.2.1 Business as usual and untreated scenarios
Under ‘business as usual’ the largest potential gains could come from improved control of aphids (£14M), sclerotinia (£8M) and potato volunteers (£7M) ( Tabe 10). The figures in brackets are the potential increase in value to the industry that could occur if 100% control was achievable. In the absence of pesticides, major losses in carrots when using sensible non-pesticide mitigation measures are caused by broad-leaved weeds (28% reduction in production), volunteer potatoes (19% reduction in production), annual meadow grass (18% reduction in production), sclerotinia (16% reduction in production) and aphids (14% reduction in production). The additional cost of cultivation and weeding operations to control problem weeds, combined with the yield losses, could cost £3-5K per hectare if there were no chemical control measures (Table 11). Tabe 10. Impact of weeds, pests and diseases on carrots under business as usual (potential yield and gross margin increases if better control was possible - despite use of available pesticides)
Business as usual
Annual meadow grass
Broad-leaved weeds
Potato volunteers
Aphids
Cutworm
Fly (Carrot)
Alternaria leaf blight
Cavity spot
Powdery mildew
Sclerotinia
Area af fected (ha) 11,028 11,028 9,925 6,617 5,514 5,514 8,822 2,206 4,411 8,822
Potential increase in yield if
100% control possible (t)
17,645 25,133 39,701 75,398 16,310 23,798 21,174 16,310 10,587 45,135
Potential increase in value to
industry if 100% control
possible (£K)
3,176 4,524 7,146 13,572 2,936 4,284 3,811 2,936 1,906 8,124
Increased value per affected
hectare (£K)
0 0 1 2 1 1 0 1 0 1
Table 11. Impact of weeds, pests and diseases on carrots in the absence of pesticide applications – whilst using sensible mitigation, e.g. biological controls. (Worst case scenario)
Untreated
Annual meadow grass
Broad-leaved weeds
Potato volunteers
Aphids
Cutworm
Fly (Carrot)
Alternaria leaf blight
Cavity spot
Powdery mildew
Sclerotinia
Area af fected (ha) 11,028 11,028 9,925 6,617 5,514 5,514 8,822 2,206 4,411 8,822
Yield Loss (t) 132,336 198,912 139,320 97,862 22,056 80,626 127,043 32,621 42,348 116,367
Cost to the industry (£K) -45,391 -58,478 -32,462 -19,375 -2,956 -25,559 -21,350 -6,866 -6,864 -19,429
Cost per affected hectare (£K) -4 -5 -3 -3 -1 -5 -2 -3 -2 -2
Percentage reduction in
production (%)
18.4 27.7 19.4 13.6 3.1 11.2 17.7 4.5 5.9 16.2
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Weeds
The policy is zero tolerance of weeds with all species being a target for control. Keeping the crop weed free for the first 6 weeks from emergence is the key to maximising yield and reducing effects of competition for nutrients and moisture. Weed competition makes machine harvesting difficult, particularly if large weeds are present in summer and autumn crops. Creeping weeds e.g. bindweed and knotgrass can be troublesome if they become wrapped in toppers during harvesting. Weeds can act as a reservoir for pest and disease e.g. increase in disease risk for sclerotinia. Current practice for weed control relies not only on herbicides but increasingly on vision guidance inter-row hoeing. However, this technique does not control weeds in the row. Broad-leaved weeds: The loss of two key herbicides and the reduction in the rates and increase in harvest interval for linuron have caused challenges only partially solved by the approval of clomazone, prosulfocarb and flumioxazine. Linuron and pendimethalin continue to be the basis for weed control, though strategies have changed with the lower maximum dose rates of both now allowed. Post-emergence linuron with prosulfocarb controls a wide spectrum of weeds including fumitory, thistles, cleavers and even knotgrass; however the 12 week harvest interval for prosulfocarb is an area of difficulty for early crops. In many circumstances, only the addition of metribuzin at early post-emergence for mayweeds and mignonette is required to achieve good control. Flumioxazine is also used for the control of broad-leaved weeds but some crop accumulation of herbicide has been reported with consequent stunting and twisting of foliage and disappointing weed control. Precision hoes are now an established part of control strategies when weather permits. The technique has proved to be particularly effective for the control of fool's parsley and mignonette and weeds closely related to carrots such as hemlock and wild carrot, although fields with these weeds are best avoided. Volunteer potatoes (Solanum tuberosum): Control is a particular challenge for many carrot growers now that the widely used metoxuron is no longer available. However, there are alternatives of prosulfocarb + linuron, flumioxazin and spot treatment with glyphosate using a weed wiper where there is sufficient height differential between weed and crop. Strategies should also be in place to limit the number of tubers left at harvest and to tackle the problem elsewhere in the rotation. However, carrots are often grown on rented land and the full history or potential extent of a potato volunteer problem may not be known. In the absence of herbicides, the stale seedbed technique can be employed as practised by producers of organic carrots. It requires the making of beds six to eight weeks in advance of drilling to provide the opportunity of achieving two passes with a propane weed burner. Growers of non-organic crops could use a contact herbicide such as glyphosate as an alternative to kill emerged weeds. Brush weeding, precision hoeing and hand weeding can also be used, but these techniques would require additional land and labour to mitigate the reduction in availability of herbicides.
Pests
Whilst a low level of foliar pests can be tolerated, those which eat or mine the saleable parts of the carrot crop cause direct reduction in yield and increased costs of hand sorting. The policy is therefore zero tolerance of root pests as damaged and infested roots cannot be marketed other than as stock feed.
Page 33
Willow-carrot aphid (Cavariella aegopodii): This aphid is a major pest as it often causes loss of yield in carrot crops sown in April/May, but those sown in June may escape attack. When many aphids are present, the leaves may be discoloured, distorted and sometimes shiny from honeydew excretion. This aphid is the most important vector for spreading two increasingly important virus diseases, parsnip yellow fleck (PYFV) and carrot motley dwarf complex (CMD). Yellow water traps should be used to give information on the movement of aphid populations as they happen. The Rothamsted Insect Survey operates a national network for monitoring insect populations in the UK including willow-carrot aphid and peach-potato aphid. Pirimicarb (e.g. Aphox) is still effective against this species Carrot fly (Psila rosae): The most important pest of carrots, which has been well controlled for over 10 years by pyrethroid insecticides, particularly lambda-cyhalothrin. There is concern about the continued use of only one group of insecticides but to date there is no evidence of insecticide resistance. The Warwick-HRI/HDC forecast is widely used to ensure timely application of insecticide. Tefluthin seed treatment is also used on some crops and has the added benefit of aiding establishment, with seedling counts up to 20% greater where it has been used. The HDC pest bulletin provides predicted dates for fly emergence and egg laying. In the absence of insecticides, alternative strategies are available or are being developed. On a small scale, net covers as used by organic growers are a possibility but experience in their use by turnip/swede growers (who have no insecticide alternative) shows they are both unpopular and expensive. There is a possibility of vertical net fences and this work has been completed but commercial scale implementation would again be expensive and require a very disciplined approach with a high likelihood of failure. With both techniques, there is a disposal issue. Cutworms (e.g. Agrotis segetum): The need for control should be based on the prediction model run by both ADAS and HDC/Warwick-HRI as the system is well established and reliable. Insecticides are available but timely rainfall or irrigation is very effective in controlling feeding caterpillars and in some years no insecticides are required.
Diseases
There are some 10 fungal, bacterial and viral diseases which could have an impact on carrot crops. The crop is vulnerable to root diseases from an early stage onwards, to foliage diseases and to those pathogens which affect the crop during long-term field storage. Much of the recent progress in crop yield, quality and season extension is directly due to an improved understanding of disease control and the use of fungicides. Their use has enabled the carrot crop to retain a healthy canopy for longer and as a consequence marketed yields have improved to keep pace with falling prices. Cavity spot (Pythium violae): This unpredictable disease causes blemishes on carrot roots and is a major concern. The fungicide metalaxyl-M is available but the disease is only now being fully understood. HDC-funded research suggests that cavity spot is highly dependent on environmental conditions during the season, and that disease prediction based on Pythium levels in the soil pre-planting is of limited use, as levels of P. violae could be low at this time and may not correlate well with cavity spot incidence. Alternaria blight (Alternaria dauci): The disease is favoured by warm and wet conditions and can be seed-borne. Early epidemics reduce yield. Disease forecasting systems are available but have not been validated under UK conditions. Tebuconazole is widely used in fungicide programmes.
Page 34
Powdery mildew (Erysiphe heraclei): It is often found with alternaria blight despite its preference for drier conditions. As an alternative to fungicides sulphur, applied as a foliar feed, provides some control. Sclerotinia (Sclerotinia sclerotiorum): Symptoms on foliage can be obvious from mid-August and subsequently the disease can cause rotting of roots in the field. Fungicide applications commence just prior to canopy closure, often based on information from commercially-funded Sclerotinia apothecial germination monitoring sites. There is some interest in using sprays at planting of the biological control agent Coniothyrium minitans (Contans WG) for control of sclerotia in the soil, but the treatment is expensive. In general, foliar diseases (alternaria, cercospora spot and powdery mildew) continue to be well controlled by the fungicide programmes put in place for sclerotinia control. Devising fungicide programmes that reduce the risk of resistance development (by alternating strobilurin with non-strobilurin products) is increasingly problematic because of the availability of four strobilurin products (some in formulated mixtures with non-strobulirun fungicides). Current practice is to use boscalid + pyraclostrobin early in the disease control program as this minimises the detectable residues at harvest. Effective control of the main carrot diseases would be impossible without the use of the current range of fungicides and in particular the cost effective use of tebuconazole.
5.2.2 Changing approvals legislation
Under the changing approvals legislation scenario the following active substances that are currently used on carrots could be lost:
• Flumioxazin (herbicide)
• Linuron (herbicide)
• Pendimethalin (herbicide)
• Tebuconazole (fungicide) The impact of these losses on weeds pests and diseases is identified in Table 12. The most significant impact is on broad-leaved weed control. Weeds would not only cost more to control but would still cause significant yield losses (17% reduction in yield, £1-2K cost per hectare). Loss of tebuconazole would make alternaria leaf blight more difficult to control, resulting in yield losses and increased fungicide costs (3% reduction in production, £4M cost to the industry).
Page 35
Table 12. Impact of weeds, pests and diseases on carrots as a result of the pesticide losses caused by the changing approvals legislation scenario– whilst using sensible mitigation, e.g. biological controls. Cost to the industry is the additional cost
Changing approvals
legislation
Annual meadow grass
Broad-leaved weeds
Potato volunteers
Aphids
Cutworm
Fly (Carrot)
Alternaria leaf blight
Cavity spot
Powdery mildew
Sclerotinia
Area af fected (ha) 11,028 11,028 9,925 6,617 5,514 5,514 8,822 2,206 4,411 8,822
Yield Loss (t) 70,579 122,179 69,060 0 0 0 21,174 0 7,058 5,990
Cost to the industry (£K) -15,285 -25,852 -14,455 0 -551 0 -4,049 0 -1,390 -1,316
Cost per affected hectare (£K) -1 -2 -1 0 0 0 0 0 0 0
Percentage reduction in
production (%)
9.8 17.0 9.6 0.0 0.0 0.0 2.9 0.0 1.0 0.8
Weeds
Broad leaved weeds: In the absence of the herbicides linuron, pendimethalin and flumioxazin, techniques used by organic growers would need to be adopted such as the use of stale seedbeds, brush weeding and other mechanical controls as well as hand weeding. The implications for carrot production would be an increase in cost and also a requirement for about 10% more land. There would be the cost of propane gas for flame burners (partially balanced by saving on herbicide costs), the cost of additional contractor services for brush weeding and other mechanical controls plus hand weeding. Additional mechanical and hand weeding could result in up to 15% reduction in plant stand. Volunteer potatoes (Solanum tuberosum): Control of volunteer potatoes would be a major challenge with the loss of both linuron and flumioxazin
Pests
There are no implications for pest control.
Diseases
The cost implication of the loss of tebuconazole and to a lesser extent tebuconazole + trifloxystrobin could be substantial as both are important fungicides in control programmes. Approval of alternatives or new actives would be required otherwise there would be too much reliance on those left. However if this fails, an overall reduction in productivity from the loss of tebuconazole could be up to 10% in marketable yield. The implication is that either a greater area would need to be grown or quality standards relaxed.
5.2.3 Water Quality
The active substances that are currently available on carrots that are at risk from restrictions due to water quality requirements are:
• Cypermethrin (insecticide)
• Glyphosate (herbicide) The impact of these restrictions is shown in Table 13. The main impact of water quality requirements could be on the control of volunteer potatoes with yield losses and increased costs (7% reduction in production, £12M cost in reduced yields & increased hand weeding) likely if the approval for glyphosate was removed.
Page 36
Table 13. Impact of weeds, pests and diseases on carrots as a result of the potential pesticide losses caused by the restrictions put in place by the current water quality requirements – whilst using sensible mitigation, e.g. biological controls.
Water Quality
Annual meadow grass
Broad-leaved weeds
Potato volunteers
Aphids
Cutworm
Fly (Carrot)
Alternaria leaf blight
Cavity spot
Powdery mildew
Sclerotinia
Area af fected (ha) 11,028 11,028 9,925 6,617 5,514 5,514 8,822 2,206 4,411 8,822
Yield Loss (t) 0 0 53,179 0 0 0 0 0 0 0
Cost to the industry (£K) 0 0 -11,458 0 0 0 0 0 0 0
Cost per affected hectare (£K) 0 0 -1 0 0 0 0 0 0 0
Percentage reduction in
production (%)
0.0 0.0 7.4 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Cost to the industry assumes that the active substances are lost to the whole industry; however a complete revocation of the active substance is a last resort. Instead specific catchments may be affected, if this is the case the cost per hectare can be used to apply to the area within a catchment that is affected.
Weeds
Volunteer potatoes (Solanum tuberosum): The last remaining (after losses to changing approvals legislation) herbicide option for control of volunteer potatoes, i.e. the use of glyphosate, could be lost due to water quality requirements concerns. More effort would be required in minimising the number of tubers left after harvesting, as well as tackling volunteers in strongly competitive crops. The last resort would be the expensive option of hand weeding.
Pests
Cutworms (e.g. Agrotis segetum): Cypermethrin would not be available, but there are other pesticide options. The alternative strategy of using a prediction model for timely application of irrigation, in the absence of rainfall, can achieve effective control.
Diseases
There are no implications for disease control.
5.2.4 Other reasons for losses
Weeds
Broad-leaved weeds: Though included in Annex 1 all plant protection products containing only chlorpropham are subject to phased revocation with all stocks to be used by 31 July 2010. However, it is possible that this active may become available again.
5.3 Leeks The leek crop is established either from direct drilling or, to a far lesser extent, by transplanting and is valued at £35M grown on 1,647 ha.12 The area of the crop has been static for a number of years. The main production areas are Lincolnshire and the north west of England. UK leeks are available nearly year-round (except June) with seasonal peaks in the autumn and again in the spring. Early crops are covered with fleece to create
12 Basic Horticultural Statistics 2008
Page 37
a warm ‘micro-climate’ to advance the start of harvesting. There is a high requirement for labour for both growing the crop e.g. hand weeding and market preparation. The average gross margin assumptions for leeks used in this assessment are in Table 14. Table 14. Leeks gross margin
Crop Leeks
Crop area* ha 1,647
Yield* t/ha 26
Value* £/t 825
Seed cost £/ha 625
Fertiliser cost £/ha 267
Spray cost £/ha 489
Bio-control cost £/ha
Cultivation costs £/ha 230
Other costs £/ha 7,670
Total value £/ha 21,450
Total costs £/ha 9,281
Gross margin £/ha 12,169
5.3.1 Business as usual and untreated scenarios
Under ‘business as usual’ the largest potential gains could come from improved control of annual meadow grass (£2.6M), rust (£2.6M), bean seed fly (£1.5M), and broad-leaved weeds (£1.1M) (Table 15). The figures in brackets are the potential increase in value to the industry that could occur if 100% control was achievable. In the absence of pesticides, major losses in leeks when using sensible non-pesticide mitigation measures are caused by annual meadow grass (65% reduction in production), broad-leaved weeds (50% reduction in production), bean seed fly (26% reduction in production) and rust (17% reduction in production). (Table 16). Table 15. Impact of weeds, pests and diseases on leeks under business as usual (potential yield and gross margin increases if better control was possible - despite use of available pesticides)
Business as usual
Annual meadow grass
Broadleaved weeds
Potato volunteers
Volunteer barley
Bean seed fly
Onion fly
Thrips
Phytophthora - white tip
Rust
Area af fected (ha) 1,647 1,647 659 1,400 1,400 824 206 659 988
Potential increase in yield if 100%
control possible (t)
2,569 1,285 856 1,092 1,820 1,071 375 1,542 2,569
Potential increase in value to
industry if 100% control possible
(£K)
2,120 1,060 707 901 1,501 883 309 1,272 2,120
Increased value per affected
hectare (£K)
1 1 1 1 1 1 2 2 2
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Table 16. Impact of weeds, pests and diseases on leeks in the absence of pesticide applications – whilst using sensible mitigation, e.g. biological controls. (Worst case scenario)
Untreated
Annual meadow grass
Broadleaved weeds
Potato volunteers
Volunteer barley
Bean seed fly
Onion fly
Thrips
Phytophthora - white tip
Rust
Area af fected (ha) 1,647 1,647 659 1,400 1,400 824 206 659 988
Yield Loss (t) 27,834 21,411 5,995 9,100 10,920 5,353 803 3,426 7,066
Cost to the industry (£K) -27,847 -22,959 -5,486 -8,417 -8,862 -4,330 -641 -3,131 -6,232
Cost per affected hectare (£K) -17 -14 -8 -6 -6 -5 -3 -5 -6
Percentage reduction in
production (%)
65.0 50.0 14.0 21.3 25.5 12.5 1.9 8.0 16.5
Weeds
For direct drilled crops, weeds compete strongly with the crop and the policy is zero tolerance. Yield and quality can be reduced and there is the risk of crop rejection when retailer/processor size grade specifications are not met. Leeks are undercut at harvesting and the presence of weeds can result in harvesting problems and damage to the crop. The presence of weeds can lead to increased problems with pest and disease due to a changed microclimate within crop. Broad-leaved weeds: Programmes are often based on diquat or glyphosate to clean up a stale seedbed pre-drilling and then pendimethalin with ioxynil or chloridazon at repeat low dose rates for annual weeds, with fluroxypyr being used for redshank. Use of inter-row weeding using precision hoeing has increased, as it provides an effective method of control of seedling weeds, although the opportunities to use the technique depend on suitable weather. Some hand pulling of larger weeds such as small nettle is often necessary because herbicide choice has been reduced in recent years. Volunteer potatoes (Solanum tuberosum): Herbicide options available are fluroxypyr, prosulfocarb + linuron or clopyralid, though hand weeding is often the only effective means of control.
In the absence of herbicides the stale seedbed would continue to be used but with pre-emergence flaming to control emerged weeds, although this is an expensive technique. Subsequently brush weeding could be used as well as 2-3 passes of intra-row mechanical control (hoeing, rotary cultivation, finger weeding). Hand weeding would also be required. Compared with the herbicide option (with some hand weeding) the cost of control would increase from £200-300/ha to £1000-£3000/ha for the no herbicide scenario.
Pests
Bean seed flies (Delia platura, D. florilega) and onion fly (Delia antiqua): The larvae attack seedlings and often cause the plant to collapse, leading to total loss in whole areas of crop. This results in increased size and thickness of the surviving leeks due to the plant population being too low. The soil-acting pyrethroid seed treatment tefluthrin is available.
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Onion thrips (Thrips tabaci): The most important pest of leek as large populations can develop, causing blemishes on the leaves, which results in increased market preparation costs, reduced quality and, on occasions, may make the crop unmarketable. Deltamethrin has been widely used for control but there is now resistance to it and the other pyrethroid lambda-cyhalothrin. Alternatives include chlorpyrifos and the newer insecticide spinosad. Spray treatments are applied when thrips numbers are increasing (as indicated by sticky traps or plant samples). An integrated programme for thrips control on leek is being developed at Rothamsted Research. In the absence of insecticides there is the option of using crop covers or fleece, which are already used for early crops, but the technique is expensive and for later crops the covers cannot be left on until harvest. In addition, there are disposal costs with the overall cost from £1000-£2500/ha against an insecticidal option of £100. Irrigation has also been used but with only limited effect, as have physically-acting insecticides such as Majestik, again with limited effectiveness. Biological control agents, biopesticides, crop fences and companion plants are all options which are currently being researched, some of these may provide alternatives in the future.
Diseases
The policy is zero tolerance of disease because of risk of reduced quality leading to additional market preparation costs and the possibility of crop rejection where retailer/processor size grade specifications are not met. White tip (Phytophthora porri): A soil-borne disease favoured by wet weather in late summer and autumn, leading to water-soaked lesions and dieback which requires increased stripping costs to meet market specifications. Key products available for white tip control on leek are chlorothalonil + metalaxyl-M and dimethomorph + mancozeb. Rust (Puccinia allii): The most important disease of leeks and can be found from July onwards, although in cold frosty weather plants usually grow away from the disease. Leek rust results in yield loss and appreciable extra stripping costs to obtain a marketable product. A range of active substances are available for control, including both strobilurins and conazole products. There are no alternatives at present to fungicides, though biopesticides could be an option in the longer term. Plant breeding for tolerance to disease is actively being pursued by the major leek breeding company Nunhems but varieties are still a few years from being commercially available.
5.3.2 Changing approvals legislation scenario
Under the changing approvals legislation scenario the following active substances that are currently used on leeks could be lost:
• Linuron (herbicide)
• Ioxynil (herbicide)
• Pendimethalin (herbicide)
• Tebuconazole (fungicide) The impact of these losses on weeds pests and diseases is identified in Table 17. The most significant impacts would come from annual meadow grass (56% reduction in production) as a result of increased costs and reduced yields, other weeds would have
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similar impacts with significant reductions in yields caused by broadleaved weeds and volunteer potatoes. The increased cost of control would be split across all weeds as the mechanical and hand weeding systems would control multiple weed species in a single pass. There would also be increased costs associated with the control of rust and white tip (£1.1M and £0.6M respectively in cost to the industry). Table 17. Impact of weeds, pests and diseases on leeks as a result of the pesticide losses caused by the changing approvals legislation scenario– whilst using sensible mitigation, e.g. biological controls. Cost to the industry is the additional cost Changing approvals legislation
Annual meadow grass
Broadleaved weeds
Potato volunteers
Volunteer barley
Bean seed fly
Onion fly
Thrips
Phytophthora - white tip
Rust
Area af fected (ha) 1,647 1,647 659 1,400 1,400 824 206 659 988
Yield Loss (t) 13,275 10,277 2,055 4,368 0 0 0 0 0
Cost to the industry (£K) -12,633 -10,160 -1,814 -3,603 -630 -371 0 -7 -10
Cost per affected hectare (£K) -8 -6 -3 -3 0 0 0 0 0
Percentage reduction in
production (%)
31.0 24.0 4.8 10.2 0.0 0.0 0.0 0.0 0.0
Weeds
Broad-leaved weeds: The loss of propachlor and chlorthal dimethyl in March 2010 followed subsequently by ioxynil, linuron, pendimethalin will leave only chloridazon, metazachlor, pyridate and possibly bentazone in the armoury. The challenge to control broad-leaved weeds will be considerably increased, necessitating further recourse to precision hoeing and hand weeding at an additional cost of at least £110/ha.
Volunteer potatoes (Solanum tuberosum): The options for the control will be reduced with the loss of ioxynil and linuron (with prosulfocarb). As a result of changing approvals legislation, the threat to UK leek production due to the lack of herbicide choice will be high as the additional costs of controlling weeds are unlikely to be recouped in increased market prices.
Pests
There are no implications for pest control resulting from the changing pesticides legislation.
Diseases
White tip (Phytophthora porri) Tebuconazole and tebuconazole + trifloxystrobin could be lost. Other products are available. Rust (Puccinia allii) Tebuconazole and tebuconazole + trifloxystrobin could be lost. Other products are available.
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5.3.3 Water Quality
The active substances that are currently available on leeks that are at risk from restrictions due to water quality requirements are:
• Bentazone (herbicide)
• Chlorpyrifos (insecticide)
• Clopyralid (herbicide)
• Fluroxypyr (herbicide)
• Glyphosate (herbicide) The impact of these restrictions is shown in Table 18. The impact of water quality requirements on its own would be less than the changing approvals legislation. There would be moderate yield losses caused by weed competition from a variety of weed species (1-2% reduction in production). The impact of these potential losses on top of those expected for the changing approvals legislation scenario would be greater, with weed control options severely limited. Table 18. Impact of weeds, pests and diseases on leeks as a result of the potential pesticide losses caused by the restrictions put in place by the current water quality requirements – whilst using sensible mitigation, e.g. biological controls.
Water Quality
Annual meadow grass
Broadleaved weeds
Potato volunteers
Volunteer barley
Bean seed fly
Onion fly
Thrips
Phytophthora - white tip
Rust
Area af fected (ha) 1,647 1,647 659 1,400 1,400 824 206 659 988
Yield Loss (t) 428 428 514 0 0 0 0 0 0
Cost to the industry (£K) -353 -505 -424 0 0 0 0 0 0
Cost per affected hectare (£K) 0 0 -1 0 0 0 0 0 0
Percentage reduction in
production (%)
1.0 1.0 1.2 0.0 0.0 0.0 0.0 0.0 0.0
* Cost to the industry assumes that the active substances are lost to the whole industry; however a complete revocation of the active substance is a last resort. Instead specific catchments may be affected, if this is the case the cost per hectare can be used to apply to the area within a catchment that is affected.
Weeds
Broad leaved weeds: Further losses could be bentazone, a useful contact herbicide applied before 3 true leaves for control of many annual broad-leaved weeds including fools parsley and common stocksbill, and metazachlor a residual herbicide. Volunteer potatoes (Solanum tuberosum): Control of volunteer potatoes would be a major challenge with the loss of prosulfocarb + linuron due to changing approvals legislation scenario and then the clopyralid, fluroxypyr and glyphosate options due to water quality requirements. More effort would be required in minimising the number of tubers left after harvesting and as well as tackling volunteers in strongly competitive crops. The last resort would be the expensive option of hand weeding.
Pests
Onion thrips (Thrips tabaci): Chlorpyrifos, one of the controls for thrips, would be at risk but there are alternatives available including spinosad but at an additional cost.
Diseases
There are no implications for disease control.
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5.3.4 Other reasons for pesticide losses
Diseases
White tip (Phytophthora porri): One of the key products for control is Fubol Gold, which could be at risk because one of the components is chlorothalonil, which is on the watch list as a UK Specific Pollutant. The combination of losses of herbicides, insecticides and fungicides due changing approvals legislation and water quality requirements could affect the viability of UK leek production and lead to production and harvesting costs exceeding market returns.
5.4 Onions Bulb onions are grown on 8,575 ha. The value of crop is £46M13. The main onion crop is drilled in March and April, harvested in late August and September, and can be sold out of ambient, cold stores and controlled atmosphere stores until the following July. A significant proportion of the crop is grown from sets or modules in order to advance the start of harvesting to early August and provide a more certain cropping outcome for some locations and soils. There is a small area of crop grown from autumn planting or drilling to mature in July to further extend the season of home production. The production cycle after growing the crop is to remove foliage in the field at harvest time with the bulbs immediately transported to specialist stores to minimise any weather risks. Blowing high volumes of air, at a predetermined temperature, through the crop then dries the onions. After this initial drying, the warm air is re-circulated through the onions at a carefully controlled humidity to complete the drying process, and produce a golden brown colour on the outer skins.
The average gross margin assumptions for onions used in this assessment are in Table 19. Table 19. Onion gross margin
Crop Onion
Crop area ha 8,575
Yield t/ha 41
Value £/t 132
Seed cost £/ha 640
Fertiliser cost £/ha 375
Spray cost £/ha 499
Bio-control cost £/ha
Cultivation costs £/ha 215
Other costs £/ha 2,211
Total value £/ha 5,412
Total costs £/ha 3,940
Gross margin £/ha 1,472
13 Basic Horticultural Statistics 2008
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5.4.1 Business as usual and untreated scenarios
Under ‘business as usual’, the largest potential gains could come from improved control of downy mildew (£3.5M), botrytis neck rot (£2.5M) and annual meadow grass (£2M) ( Table 20). The figures in brackets are the potential increase in value to the industry that could occur if 100% control was achievable. In the absence of pesticides, major losses in onions when using sensible non-pesticide mitigation measures are caused by downy mildew (59% reduction in production), broad-leaved weeds 34% reduction in production), botrytis neck rot (27% reduction in production) and annual meadow grass (24% reduction in production) (Table 21). Table 20. Impact of weeds, pests and diseases on onions under business as usual (potential yield and gross margin increases if better control was possible - despite use of available pesticides)
Business as usualAnnual m
eadow grass
Broad-leaved weeds
Volunteer potatoes
Bean seed fly
Thrips
Botrytis leaf spot
Botrytis neck rot
Downy mildew
Leaf blotch
White rot
Area af fected (ha) 5,574 6,860 1,286 3,430 2,573 8,575 5,574 8,575 2,573 1,715
Potential increase in yield if
100% control possible (t )
14,380 6,037 1,698 7,546 3,396 7,546 18,951 26,411 2,264 2,916
Potential increase in value to
industry if 100% control
possible (£K)
1,898 797 224 996 448 996 2,501 3,486 299 385
Increased value per affected
hectare (£K)
0 0 0 0 0 0 0 0 0 0
Table 21. Impact of weeds, pests and diseases on onions in the absence of pesticide applications – whilst using sensible mitigation, e.g. biological controls. (Worst case scenario)
Untreated
Annual m
eadow grass
Broad-leaved weeds
Volunteer potatoes
Bean seed fly
Thrips
Botrytis leaf spot
Botrytis neck rot
Downy mildew
Leaf blotch
White rot
Area af fected (ha) 5,574 6,860 1,286 3,430 2,573 8,575 5,574 8,575 2,573 1,715
Yield Loss (t) 85,000 120,736 12,824 45,276 16,979 37,730 96,426 207,515 11,319 11,062
Cost to the industry (£K) -19,719 -39,545 -3,377 -5,911 -2,192 -2,751 -11,279 -25,162 -825 -1,491
Cost per affected hectare (£K) -4 -6 -3 -2 -1 0 -2 -3 0 -1
Percentage reduction in
production (%)
24.2 34.3 3.6 12.9 4.8 10.7 27.4 59.0 3.2 3.1
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Weeds
The weed policy is zero tolerance, as bulb onions compete very poorly with weeds, leading to loss of yield and uneven maturity. The market for onions is closely size-related with larger bulbs (typically 60-80 mm diameter) often valued at an additional £80-100/tonne over smaller sized bulbs (40-60 mm diameter), so freedom of weed competition from the start is essential. The operation of machinery for undercutting and harvesting, the drying/curing process and storage can all be hindered or compromised by the presence of weeds. In addition, pests and disease can be encouraged by weedy crops, hindering effective spray application, modifying the microclimate or by the weeds directly acting as hosts. The current practice for weed control relies not only on herbicides but increasingly on vision guidance inter-row hoeing. However, this technique does not control weeds in the row. Annual meadow grass (Poa annua): Tepraloxydim continues to be used successfully for annual meadow grass as is the newer addition of prosulfocarb. Broad leaved weeds: The main competitive weeds are knotgrass, fat hen, small nettle, pansy and speedwells and programmes continue to be based on pendimethalin and repeat applications of ioxynil. Prosulfocarb is being used for fumitory, cleavers and ploygonums as a tank-mix with linuron. Fluroxypyr is used for annual weeds including black bindweed, chickweed, cleavers and forget-me-knot. Flumioxazin is also used post–emergence for annual weeds, but there is a risk of crop spotting/damage. Good wax levels on the crop foliage are crucial, as is avoiding application if the foliage is wet, as this can lead to increased crop damage. The reintroduction of pyridate provides control of black nightshade, cleavers, corn marigold, fat hen, fumitory, groundsel and speedwells. Precision hoes are now an established part of weed control strategies when weather conditions permit. Volunteer potatoes (Solanum tuberosum): Currently there are a number of herbicide options available. The strategies of using either two applications of fluroxypyr or prosulfocarb + linuron or the newer SLOA for flumioxazin are all available, and also give control of broad leaved weeds. Spot treatment with glyphosate using a weed wiper is also possible, as is hand weeding. However, strategies should also be in place to limit the number of tubers left at harvest and to tackle the problem elsewhere in the rotation with a strongly competitive crop. There are alternative techniques with the potential for adoption in the absence of herbicides. Stale seedbeds could be used, particularly for overwinter crops in combination with pre-emergence flame weeding. Crop inter-row hoeing from 2-5 true leaf with a vision guided precision hoe is increasingly used, with the cost comparing favourably with a herbicide application. Hand weeding is always an option, but expensive starting at about £700/ha.
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Pests
The control of insect pests in bulb onions is extremely important to maximise both yield and quality and to ensure that crops meet specifications. Bean seed flies (Delia platura, D. florilega), onion fly (Delia antiqua): The larvae attack seedlings and feed within damaged tissue or bulbs leading to an uneven plant stand, which can have implications for bulb size, shape and firmness and reduce storage potential. The soil acting pyrethroid seed treatment tefluthrin is available. Onion thrips (Thrips tabaci): On occasions an important pest of bulb onions, as large populations can feed on the onion scales underneath the skin and reduce quality and storage potential. Deltamethrin has been widely used for control, but there is now resistance to it and to the other pyrethroid lambda-cyhalothrin. Alternatives include chlorpyrifos and spinosad. Spray treatments should be applied when thrips numbers are increasing (as indicated by sticky traps or plant sampling). An integrated programme for thrips control is being developed at Rothamsted Research. In the absence of insecticides there is the option of crop covers or fleece but this technique would be prohibitively expensive, with an overall cost including disposal to land fill of £1000-£2500/ha against an insecticidal option of as little £10. Irrigation has also been used but with only limited effect. Biological control agents, biopesticides and companion planting are options which have yet to be taken up by the industry but they could have a place
Diseases
The control of both foliar and soil-borne diseases in bulb onions is extremely important for a number of reasons. Onion bulbs with high levels of foliar disease are more susceptible to fungal and bacterial storage pathogens and are also less able to take up any sprout suppressant which is used to prolong the storage period. Skin retention can be affected, which may result in downgrading from pre-packing to processing with a consequent drop in value of circa £100/tonne. Crops with internal disease problems in excess of 2% after grading may be unmarketable Botrytis leaf spot (Botrytis squamosa): Small white circular or elliptical white spots with water-soaked margins appear on the leaves, particularly during wet or humid periods, and can spread rapidly causing collapse of foliage. Several chlorothalonil products are approved and also iprodione. Disease forecasting systems are under development. Botrytis neck rot (Botrytis allii): Severe losses can occur in store with affected bulbs becoming soft with a brownish rot of the scales. The fungus is carried in the seed and attacks seedlings at emergence though symptoms are difficult to detect. A seed treatment is available.
Downy mildew (Peronospora destructor): A major disease of the crop with affected plants developing pale oval areas on the leaves, which then die from the leaf tip backwards resulting in soft, immature bulbs. Spores spread very rapidly especially during cool wet weather i.e. potato blight conditions. Fungicides may need to be applied frequently, with dimethomorph + mancozeb and benthiavalicarb-isopropyl + mancozeb forming the mainstay of many programmes.
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Leaf blotch (Cladosporium allii-cepae): An important disease with the first symptoms elliptical white or pale brown spots which darken with age. A heavily-infected crop may look as if it has been sprayed with a contact herbicide. Triazole fungicides and chlorothalonil are approved. White rot (Sclerotium cepivorum): The disease causes severe losses and is soil-borne, with resting bodies (sclerotia) persisting for many years. Affected plants show yellow leaves and wilting followed by root rotting, and the base of the bulb becomes covered with white or grey fungus which produces new sclerotia. The problem is often patchy but can spread gradually with successive cultivations and repeated allium cropping. Tebuconazole and boscalid + pyraclostrobin provide control. Alternatives using green compost enhanced with a specific strain of Trichoderma viride are under investigation and show promise.
5.4.2 Changing approvals legislation scenario
Under the changing approvals legislation, the following active substances that are currently used on onions could be lost:
• Flumioxazin (herbicide)
• Linuron (herbicide)
• Mancozeb (fungicide)
• Pendimethalin (herbicide)
• Tebuconazole (fungicide) The impact of these losses on weeds pests and diseases is identified in Table 22. The most significant impacts of the changing approvals legislation scenario would be on downy mildew control (46% reduction in production) as a result of the lost of mancozeb, with weeds also becoming difficult to control, resulting in reduced yields (11-15% reduction in production) and increased costs. Table 22. Impact of weeds, pests and diseases on onions as a result of the pesticide losses caused by the changing approvals legislation scenario– whilst using sensible mitigation, e.g. biological controls. Cost to the industry is the additional cost
Changing approvals
legislation
Annual m
eadow grass
Broad-leaved weeds
Volunteer potatoes
Bean seed fly
Thrips
Botrytis leaf spot
Botrytis neck rot
Downy mildew
Leaf blotch
White rot
Area af fected (ha) 5,574 6,860 1,286 3,430 2,573 8,575 5,574 8,575 2,573 1,715
Yield Loss (t) 41,524 54,331 2,264 0 0 0 0 162,239 11,319 755
Cost to the industry (£K) -10,880 -13,745 -1,784 0 0 0 0 -26,338 -1,983 -125
Cost per affected hectare (£K) -2 -2 -1 0 0 0 0 -3 -1 0
Percentage reduction in
production (%)
11.8 15.5 0.6 0.0 0.0 0.0 0.0 46.1 3.2 0.2
Weeds
Broad-leaved weeds The impending loss of propachlor and chlorthal-in March 2010 (due to failure to achieve annex 1 listing), and the likely loss of pendimethalin, linuron, flumioxazin will leave only chloridazon and prosulfocarb as residual herbicides and pyridate, bentazone and clopyralid remaining as contact broad leaf herbicides. Effective weed control will be
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extremely difficult, particularly for drilled crops on sands. More precision hoeing will be required and hand weeding at additional cost.
Pests
There are no implications for pest control resulting from the changing approvals legislation.
Diseases
Downy mildew (Peronospora destructor): The loss of mancozeb would severely restrict the options available for downy mildew control with products such as dimethomorph + mancozeb, benthiavalicarb-isopropyl + mancozeb also being lost, as would the newer approval for mancozeb + metalaxyl-M. The remaining downy mildew products: chlorothalonil, chlorothalonil + metalaxyl-M and azoxystrobin would be insufficient for effective disease control. Leaf blotch (Cladosporium allii-cepae) and white rot (Sclerotium cepivorum): The loss of tebuconazole would reduce the options available for control of both white rot and cladosporium leaf blotch.
5.4.3 Water Quality
The active substances that are currently available on onions that are at risk from restrictions due to water quality requirements are:
• Bentazone (herbicide)
• Clopyralid (herbicide)
• Fluroxypyr (herbicide)
• Iprodione (fungicide) The impact of these restrictions is shown in Table 23. The potential loss of iprodione as a result of water quality legislation could result in botrytis becoming more difficult to control, resulting in yield losses (5% reduction in production) and increased costs. There could also be a small impact on weed control of broad-leaved weeds and volunteer potatoes.
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Table 23. Impact of weeds, pests and diseases on onions as a result of the potential pesticide losses caused by the restrictions put in place by the current water quality requirements – whilst using sensible mitigation, e.g. biological controls.
Water Quality
Annual m
eadow grass
Broad-leaved weeds
Volunteer potatoes
Bean seed fly
Thrips
Botrytis leaf spot
Botrytis neck rot
Downy mildew
Leaf blotch
White rot
Area af fected (ha) 5,574 6,860 1,286 3,430 2,573 8,575 5,574 8,575 2,573 1,715
Yield Loss (t) 0 3,018 1,698 0 0 7,546 18,951 0 0 0
Cost to the industry (£K) 0 -577 -346 0 0 -1,854 -3,059 0 0 0
Cost per affected hectare (£K) 0 0 0 0 0 0 -1 0 0 0
Percentage reduction in
production (%)
0.0 0.9 0.5 0.0 0.0 2.1 5.4 0.0 0.0 0.0
* Cost to the industry assumes that the active substances are lost to the whole industry; however a complete revocation of
the active substance is a last resort. Instead specific catchments may be affected, if this is the case the cost per hectare can be used to apply to the area within a catchment that is affected.
Weeds
Clopyralid, bentazone and fluroxypyr could all be lost as a result of the water quality requirements, leaving only chloridazon and prosulfocarb as residual herbicides and pyridate as a contact broad leaf herbicide.
Pests
There are no implications for pest control.
Diseases
Botrytis spp.: Loss of iprodione will reduce the options for control of botrytis.
5.4.4 Other reasons for pesticide losses
Diseases
White tip (Phytophthora porri): One of the key products for control is chlorothalonil + metalaxyl-m, which could be at risk because one of the components is chlorothalonil, on the watch list as a UK Specific Pollutant.
Downy mildew (Peronospora destructor): Two of the remaining downy mildew products, chlorothalonil and chlorothalonil + metalaxyl-M could be lost due to chlorothalonil being on the watch list as a UK Specific Pollutant. The combined impact of changing approvals legislation and water quality requirements could be potentially catastrophic for bulb onion production in the UK. Severe restrictions of both herbicide and fungicide choice would result in the yields of conventionally-grown crops being reduced by up to 50% of those currently achieved, with quality not guaranteed and with production costs potentially increased by £500-700/ha.
5.5 Outdoor Lettuce Lettuces are grown as wholehead and also as leaves for bagged salads. The main types grown in the UK are iceberg, cos/romaine, roundhead, gem, batavia and speciality lettuce. Pest control is primarily by use of insecticides or molluscicides and resistant varieties.
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Disease control is achieved by the use of fungicide programmes, together with the use of varieties that are resistant to downy mildew (Bremia lactucae) The average gross margin assumptions for lettuce used in this assessment are in Table 24. Table 24. Outdoor Lettuce gross margin
Crop Outdoor
Lettuce
Crop area ha 5,592
Yield t/ha 21
Value £/t 839
Modules / blocks £/ha 1,995
Fertiliser cost £/ha 267
Spray cost £/ha 348
Bio-control cost £/ha
Cultivation costs £/ha 220
Other costs £/ha 3,225
Total value £/ha 17,451
Total costs £/ha 6,055
Gross margin £/ha 11,396
5.5.1 Business as usual and untreated scenarios
Under ‘business as usual’ the largest potential gains could come from improved control of downy mildew (£10M), broad-leaved weeds (£9.5M), currant-lettuce aphids, peach-potato aphids (£7.7M) and sclerotinia (£5.4M) (Table 25). The figures in brackets are the potential increase in value to the industry that could occur if 100% control was achievable. In the absence of pesticides, major losses in outdoor lettuce, when using sensible non-pesticide mitigation measures, are caused by broad-leaved weeds (55% reduction in production), downy mildew (40% reduction in production) and currant-lettuce aphids and peach-potato aphid (38% reduction in production) ( Table 26).
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Table 25.
Impact of weeds, pests and diseases on outdoor lettuce under business as usual (potential yield and gross m
argin increases if
better control was possible - despite use of available pesticides)
Business as usual
Broadleaved weeds
Currant lettuce aphid
lettuce root aphid
Peach-potato aphid
Cutworms
Slugs
Silver Y moth
Botrytis
Downy mildew
Ring spot
Sclerotinia
Lettuce Mosaic Virus
Cucumber mosaic virus
Beet western Yellows Virus
Area affected (ha)
5,592
4,194
3,355
4,194
1,678
3,355
1,118
5,592
5,592
1,398
5,592
4,194
4,194
4,194
Potential increase in yield if 100%
control possible (t)
11,329
9,185
5,603
9,185
3,674
7,348
3,674
5,939
11,877
1,454
6,431
1,837
1,837
1,837
Potential increase in value to
industry if 100% control possible
(£K)
9,505
7,706
4,701
7,706
3,082
6,165
3,082
4,983
9,965
1,220
5,395
1,541
1,541
1,541
Increased value per affected
hectare (£K)
22
12
22
31
21
10
00
Table 26.
Impact of weeds, pests and diseases on outdoor lettuce in the absence of pesticide applications – whilst using sensible m
itigation,
e.g. biological controls. (Worst case scenario)
Untreated
Broadleaved weeds
Currant lettuce aphid
lettuce root aphid
Peach-potato aphid
Cutworms
Slugs
Silver Y moth
Botrytis
Downy mildew
Ring spot
Sclerotinia
Lettuce Mosaic Virus
Cucumber mosaic virus
Beet western Yellows Virus
Area affected (ha)
5,592
4,194
3,355
4,194
1,678
3,355
1,118
5,592
5,592
1,398
5,592
4,194
4,194
4,194
Yield Loss (t)
63,693
44,540
28,653
44,540
22,044
39,491
14,696
23,878
47,141
3,551
25,723
9,185
9,185
9,185
Cost to the industry (£K)
-63,649
-42,398
-28,063
-42,398
-18,579
-33,505
-12,386
-19,485
-39,003
-2,842
-21,034
-7,387
-7,387
-7,387
Cost per affected hectare (£K)
-11
-10
-8-10
-11
-10
-11
-3-7
-2-4
-2-2
-2
Percentage reduction in
production (%)
54.8
38.3
24.6
38.3
19.0
34.0
12.6
20.5
40.5
3.1
22.1
7.9
7.9
7.9
Page 51
Weeds
Poor weed control can result in a reduction in yield and quality of transplanted lettuce. Weeds can shade or compete with lettuce, resulting in small and misshapen heads. Product quality can also be reduced by contamination with weed seeds such as groundsel and sow thistle from within the crop or by aerial dispersal from surrounding land. Hand harvesting can be hindered by the presence of nettles and thistles. Weeds can provide a microclimate favourable for disease and they can act as hosts for lettuce mosaic virus and beet western yellows virus. Broad-leaved weeds Historically few herbicides were ever approved for lettuce and only two will remain in 2010: propyzamide and pendimethalin. Furthermore, only a narrow range of weeds are susceptible to propyzamide. Troublesome weeds in lettuce crops include, redshank, black bindweed, groundsel, field speedwell, knotgrass, fat-hen, mayweeds and annual meadow-grass.
Pests
Currant-lettuce aphid (Nasonovia ribis-nigri): The most important pest of lettuce foliage in the UK. Winged aphids are produced on currant bushes in May and fly to lettuce on which successive generations are produced until September/October. Resistance has been found to several groups of insecticide including carbamates, pyrethroids and organophosphates. However, effective insecticide controls remain e.g. spirotetramat, pymetrozine and acetamiprid. Field and garden slugs (Derocerus reticulatum and Arion distinctus): Potentially very damaging pests, affecting crop quality through feeding as well as capable of contaminating the harvested crop. Key to effective control of slugs is monitoring activity within the crop. Cultural control measures include removal of weeds and repeated cultivation. Biological control through the use of nematodes can be effective under suitable conditions. Slug pellets are the most widely used slug control and are based on metaldehyde, methiocarb or ferric phosphate. Equally good results can be achieved regardless of the active substance on which the pellet formulation is based. Lettuce root aphid (Pemphigus bursarius): A potentially important pest of outdoor lettuce crops, particularly if the crop is under drought stress. As with currant-lettuce aphid, cultural methods, including use of resistant varieties, are important considerations for control of this pest. Again, spirotetramat may provide effective insecticide control. Peach-potato aphid (Myzus persicae): Another potentially important aphid pest of lettuce, which like the currant-lettuce aphid has developed resistance to carbamates, pyrethroids and organophosphates. Effective insecticides include neonicotinoids e.g. acetamiprid, as well as spirotetramat. Silver Y moth (Autographa gamma): Does not survive UK winters, but immigrants are found each year and can occur in high numbers under ideal conditions. Although initially found towards the coast this pest readily spreads across the country. A second generation in the UK further increases numbers. Several control options exist, such as diflubenzuron, spinosad and deltamethrin, although the last is harmful to natural enemies. Cutworms (Agriotes segetum): Feeding on the stem or roots, including the tap root, cutworms (also called turnip moth caterpillars) may cut off a series of plants, hence their name. Close-planted crops are at most risk from attack. Control of this pest is based on
Page 52
computer predictions of the vulnerable early instar caterpillars, which may be targeted with pyrethroid insecticides or irrigation, if natural rainfall at the critical period is insufficient.
Diseases
Downy mildew (Bremia lactucae): The most important disease, which can attack all lettuce types. Severe downy mildew causes lowered yield and quality, with diseased leaves needing to be trimmed from the harvested produce. Control of this disease depends on the use of resistant varieties, together with fungicides appropriate for control of oomycetes, such as metalaxyl-M and dimethomorph. Resistant cultivars are continually challenged and overcome by evolving strains of B. lactucae. In addition, isolates of B. lactucae from several countries including the UK, have developed insensitivity to metalaxyl. Resistance management requires that site-specific fungicides such as metalaxyl and dimethomorph are partnered with active substances from other chemical groups, e.g. mancozeb. Sclerotinia (Sclerotinia sclerotiorum, S. minor): An economically important problem on lettuce in the UK. Due to long-term survival of sclerotia in soil, it is difficult to control this disease by rotation. Azoxystrobin and boscalid + pyraclostrobin are both effective against this disease, and research efforts are focussing on improving spray timing by forecasting. Contans (Coniothyrium minitans), a biological fungicide, is also available for soil incorporation prior to planting, although it is not used extensively at present. Grey mould (Botrytis cinerea): A ubiquitous disease which can occur under a wide range of conditions but is particularly favoured by high relative humidity. B. cinerea is a weak pathogen, so the disease is most common on damaged or senescing tissue, or following infection by another pest or pathogen. Control typically involves use of iprodione, although resistance to this fungicide can occur. Products such as fenhexamid and cyprodonil + fludioxonil are also available for botrytis control on lettuce. Ringspot (Microdochium panattoniatum): Most prevalent on cos / romaine lettuce types, causing loss of quality. Spores are spread by water-splash, so the disease is particularly severe in wet seasons. Azoxystrobin), Boscalid + pyraclostrobin and thiram are effective against this disease. Viruses: The main viruses on lettuce are Beet Western Yellows, Lettuce Mosaic Virus (LMV) and Cucumber Mosaic Virus. Each of these is aphid-borne so control depends largely on the use of aphicides. LMV can also be seed-borne.
5.5.2 Changing approvals legislation scenario
Under the changing approvals legislation scenario the following active substances that are currently used on outdoor lettuce could be lost:
• Mancozeb (fungicide)
• Pendimethalin (herbicide) The impact of these losses on weeds pests and diseases is identified in Table 27. The largest impacts of the changing approvals legislation are likely to occur as a result of poor control of downy mildew (30% reduction in production) and poor weed control (9% reduction in production. There will be additional costs associated with cultivations and hand weeding, and a decrease in crop value due to reduction in head size (total cost to the industry from broad-leaved weeds about £12M).
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Table 27.
Impact of weeds, pests and diseases on outdoor lettuce as a result of the pesticide losses caused by the changing approvals
legislation scenario– whilst using sensible m
itigation, e.g. biological controls. Cost to the industry is the additional cost
Changing approvals legislation
Broadleaved weeds
Currant lettuce aphid
lettuce root aphid
Peach-potato aphid
Cutworms
Slugs
Silver Y moth
Botrytis
Downy mildew
Ring spot
Sclerotinia
Lettuce Mosaic Virus
Cucumber mosaic virus
Beet western Yellows Virus
Area affected (ha)
5,592
4,194
3,355
4,194
1,678
3,355
1,118
5,592
5,592
1,398
5,592
4,194
4,194
4,194
Yield Loss (t)
10,166
00
00
00
035,263
00
00
0
Cost to the industry (£K)
-11,952
00
00
00
0-29,289
00
00
0
Cost per affected hectare (£K)
-20
00
00
00
-50
00
00
Percentage reduction in
production (%)
8.7
0.0
0.0
0.0
0.0
0.0
0.0
0.0
30.3
0.0
0.0
0.0
0.0
0.0
Table 28.
Impact of weeds, pests and diseases on outdoor lettuce as a result of the potential pesticide losses caused by the restrictions put
in place by the current water quality requirements – whilst using sensible m
itigation, e.g. biological controls.
Water Quality
Broadleaved weeds
Currant lettuce aphid
lettuce root aphid
Peach-potato aphid
Cutworms
Slugs
Silver Y moth
Botrytis
Downy mildew
Ring spot
Sclerotinia
Lettuce Mosaic Virus
Cucumber mosaic virus
Beet western Yellows Virus
Area affected (ha)
5,592
4,194
3,355
4,194
1,678
3,355
1,118
5,592
5,592
1,398
5,592
4,194
4,194
4,194
Yield Loss (t)
13,902
00
00
00
00
00
00
0
Cost to the industry (£K)
-51,446
00
00
-17
0-84
00
00
00
Cost per affected hectare (£K)
-90
00
00
00
00
00
00
Percentage reduction in
production (%)
12.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Cost to the industry assumes that the active substances are lost to the whole industry; however a complete revocation of the active substance is a last resort. Instead specific catchments may be
affected, if this is the case the cost per hectare can be used to apply to the area within a catchment that is affected.
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Weeds
Broad-leaved weeds: The impending loss of propachlor (due to failure to achieve annex 1 listing) and the likely loss of pendimethalin will leave propyzamide as the only herbicide available. Propachlor was used on most lettuce crops (with propyzamide) for safe and effective control of most annual weeds, and was vital post-planting for the large area of the crop grown on highly organic soils, where the activity of residual soil-acting herbicides is reduced.
Pests
No insecticides currently used for the control of lettuce pests are predicted to be lost.
Diseases
Downy mildew: The possible loss of mancozeb under changing approvals legislation, could impact significantly on control of downy mildew. While this product is not the most effective against the disease, it is currently an important partner product to actives such as metalaxyl and dimethomorph, to which there is a high risk of developing fungal resistance.
5.5.3 Water Quality The active substances that are currently available on outdoor lettuce that are at risk from restrictions due to water quality requirements are:
• Cypermethrin (insecticide)
• Glyphosate (herbicide)
• Iprodione (fungicide)
• Mancozeb (fungicide)
• Metaldehyde (molluscicide)
• Propyzamide (herbicide) The impact of these restrictions is shown in Table 28. The main impact is on weed control with be yield losses from broad-leaved weeds (12% reduction in production) and increased costs associated with their control (£51M, cost to the industry).
Weeds
Broad-leaved weeds: The only remaining herbicide for lettuce (after the potential losses to the changing approvals legislation) would be propyzamide.. This could be at risk from water quality requirements, leaving the possibility that there will be no chemical options for weed control. To mitigate the loss of lettuce herbicides it will be increasingly important to locate lettuce crops in fields with low weed pressure. A previous crop that has had excellent weed control generates fewer weed seeds that then germinate in a subsequent lettuce crop. The stale seedbed technique will continue to be important to reduce weed pressure before planting with shallow cultivations, flaming or contact herbicide (glyphosate or diquat) used to kill emerged weeds. Also, there will need to be more use of precision guidance systems such as the Garford Robocrop and finger weeders. These techniques will not remove all weeds but rather they will make subsequent hand weeding operations more efficient but even so there could be 10-15% losses due to hoeing and hand weeding. In HDC trials three herbicides, BUK 9900H (code name), S-metolachlor and ethametsulfuron, all show potential for weed control in outdoor transplanted lettuce in the
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future, but as yet, none are registered in the UK. Residue data for SOLAs for lettuce will be required for BUK 9900H and ethametsulfuron and possibly S-metolachlor.
Pests
Only one insecticide, cypermethrin, that is currently used on outdoor lettuce crops, is thought to be at risk from water quality requirements. The impact of the loss of this active substance would be slight as other pyrethroid insecticides are available to growers for control of caterpillar pests and for some aphid pests. There is already resistance to this group of compounds in some aphids. The molluscicide, metaldehyde, is also at risk from water quality requirements and is widely used for the control of slugs. However, again effective alternatives exist including pellets based on methiocarb or ferric phosophate. Therefore, the effect of losing metaldehyde would be slight, although crop protection costs may increase.
Diseases
If mancozeb were to be with drawn as a result of water quality requirements it could impact on downy mildew control as described under 5.5.2. In addition, the loss of iprodione would remove a fungicide that is routinely used for botrytis control. However, there are other products such as cyprodinil + fludioxonil that could replace iprodione, although at a slightly higher cost. The loss of cypermethrin would not necessarily impact on virus control, since there would be other equivalent aphicides available.
5.5.4 Other reasons for pesticide losses Propachlor failed to achieve annex 1 listing and therefore will have its approval revoked in the next year. This will make
Weeds
Propachlor failed to achieve annex 1 listing and therefore will have its approval revoked in the next year. Broad-leaved weeds: Though included in Annex 1, all plant protection products containing only chlorpropham are subject to phased revocation, with all stocks to be used by 31 July 2010. Chlorpropham is an important soil-acting herbicide for lettuce grown on organic soils, though it gives no control of troublesome weeds such as groundsel and mayweed. However, it is possible that this active may become available again.
Pests
Currant-lettuce aphid (Nasonovia ribis-nigri) and peach-potato aphid (Myzus persicae): Use of neonicotinoids e.g. acetamiprid on outdoor lettuce may be limited as proscribed by retailers due to concern over a possible negative impact of this group of insecticides on bees. If this were the case, spirotetramat or pymetrozine would be used likely replacements. Field and garden slugs (Derocerus reticulatum and Arion distinctus): Loss of metaldehyde may put greater pressure on the continued use of slug pellets based on methiocarb. Methiocarb is already listed as a Potential Future Priority Substance and UK Specific Pollutant. However, slug pellets based on ferric phosphate are also available for use and may be as effective as either metaldehyde or methiocarb. Additionally, biological control options exist, such as nematodes. However, both ferric phosphate pellets and nematodes are more expensive control options.
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Diseases
Downy mildew: Continued development of resistance to metalaxyl over time could potentially lead to reduced ability to control downy mildew on lettuce.
5.6 Apple The majority of UK apple orchards are in England. Although the overall area of apples has continued to decline over the last 2 decades an increasing area of new orchards is now being planted. The difficult years have seen smaller older businesses close and others rationalise, but in all of the main areas key growers are investing in new orchards. The new plantings are often Gala, Braeburn and the new club varieties such as Jazz and Kanzi. In the past there was a fashion for planting in multiple rows but in recent years most new plantations have been intensive single row systems. There have been some new orchards planted which are being run to organic standards, but production is still at a low level. The majority of the dessert apples are marketed via packers through supermarkets, with a small proportion sold through wholesale markets and direct sales. Culinary varieties are also grown. Bramley is the main culinary variety, with about one third of production sent to the fresh market and the remainder destined for processing as juice, cider and in pies, crumbles etc. Table 29. Apple gross margin
Crop ApplesCrop area ha 8,741
Yield t/ha 28
Value £/t 495
Establisment costs £/ha 3,600
Fertiliser cost £/ha 150
Spray cost £/ha 1,055
Bio-control cost £/ha
Cultivation costs £/ha
Other costs £/ha
Total value £/ha 13,761
Total costs £/ha 4,805
Gross margin £/ha 8,956
5.6.1 Business as usual & untreated
Under ‘business as usual’, it be seen that the potential of apple orchards is largely met already (Table 30) with few losses to weeds and pests and just small yield losses occurring due to disease. In the absence of pesticides, major losses in apples when using sensible non-pesticide mitigation measures are caused by scab (10% reduction in production), broad-leaved weeds and codling moth (5% reduction in production), phytophthora (2.5% reduction in production) and powdery mildew (2% reduction in production) (Table 31).
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Table 30.
Impact of weeds, pests and diseases on apples under business as usual (potential yield and gross m
argin increases if better
control was possible - despite use of available pesticides)
Business as usual
Annual Meadow Grass
Annual Mercury
Broadleaved weeds
Couch
Docks
Nettle
Thistles
Aphids
Capsid
Leaf Hopper
Two-spotted spider mite
Codling moth
Tortrix & winter moths
Sawfly
Blossom weevils
Blossom Wilt
Brown Rot
Canker
Phytophthora - crown rot
Phytophthora - fruit rot
Powdery Mildew
Scab
Area affected (ha)
5,245
437
8,741
87
874
44
874
3,496
2,622
2,622
98,741
8,741
6,556
4,371
2,622
8,741
3,496
1,748
4,371
8,741
8,741
Potential increase in yield if 100%
control possible (t)
00
00
00
00
00
00
00
00
243
97
0121
0243
Potential increase in value to
industry if 100% control possible
(£K)
00
00
00
00
00
00
00
00
120
48
060
0120
Increased value per affected
hectare (£K)
00
00
00
00
00
00
00
00
00
00
00
Table 31.
Impact of weeds, pests and diseases on apples in the absence of pesticide applications – whilst using sensible m
itigation, e.g.
biological controls. (Worst case scenario)
Untreated
Annual Meadow Grass
Annual Mercury
Broadleaved weeds
Couch
Docks
Nettle
Thistles
Aphids
Capsid
Leaf Hopper
Two-spotted spider mite
Codling moth
Tortrix & winter moths
Sawfly
Blossom weevils
Blossom Wilt
Brown Rot
Canker
Phytophthora - crown rot
Phytophthora - fruit rot
Powdery Mildew
Scab
Area affected (ha)
5,245
437
8,741
87
874
44
874
3,496
2,622
2,622
98,741
8,741
6,556
4,371
2,622
8,741
3,496
1,748
4,371
8,741
8,741
Yield Loss (t)
1,458
012,150
24
00
24
972
00
012,150
01,822
00
1,458
583
06,075
4,860
24,300
Cost to the industry (£K)
65
66-17,815
1131
7119
-481
0865
0-3,130
2,885
1,261
1,442
1,508
4,304
848
1,005
-1,368
-1,750-11,373
Cost per affected hectare (£K)
00
-20
00
00
00
00
00
01
00
10
0-1
Percentage reduction in
production (%)
0.6
0.0
5.0
0.0
0.0
0.0
0.0
0.4
0.0
0.0
0.0
5.0
0.0
0.8
0.0
0.0
0.6
0.2
0.0
2.5
2.0
10.0
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Weeds
Apples are generally grown in a weed free strip with a zero tolerance for weeds between budburst and harvest. All weed species are targets for control, because of the risk of:
• reduced fruit size and the possibility of crop rejection where retailer/processor size grade specifications not met.
• lower yields, both in the year of weed competition and the subsequent year, due to reduced fruit bud development. In most years there is insufficient rainfall to supply the fruits’ requirements in July and August. The competition for this water from weeds has a serious impact on fruit size and overall yield.
• Increased problems with pest and disease, due to the microclimate around the trunk and their effect on shielding pesticide sprays.
All weed groups: Most growers apply a tank mix of herbicides a number of times during the year to the herbicide strip to control all the weeds that may be present. Control is not always complete but it is usually adequate to prevent yield reduction from weed competition, whilst keeping herbicide costs to a minimum. Most growers continue to rely upon 2 or 3 applications of glyphosate because of its relatively low cost and effective control of a wide range of weeds. The applications are timed to remove over-wintered, spring and summer germinated weed, and to check (rather than kill) any perennial weeds that may be present at those times. In addition, growers use hormone-type herbicides in orchards, either as spot treatments or as carefully-directed applications under trees, to control perennial broad-leaved weeds. Mixtures containing 2,4-D, dicamba, MCPA and/or mecoprop-P are the most popular. They are used in preference to the more expensive and composite-weed specific clopyralid. In some orchards growers occasionally make spot applications of triclopyr for the control of perennial nettle, field horsetail and rosebay and great willowherbs. In the ‘untreated’ situation, where no herbicides were available, all weeds would be a severe problem and yields would be reduced substantially as weeds competed for water and nutrients. The options for mitigation are limited. Cultivation would be difficult in intensive orchards and would damage the important surface roots. Flame burning and hand weeding would not be practical. The use of compost mulches derived from green waste is possible, but NVZ regulations restrict the amount that can be applied to an insufficient depth to achieve weed control. Potentially the most effective option for mitigation would be plastic mulches. New orchards could be established through woven plastic ground cover (e.g. Mypex™). The total cost could be reduced by just covering the herbicide strip with the mulch and continuing to mow the grass alleyway. In established plantations, although difficult, it would be possible to lay mulch along the herbicide strips and fit it around trees. Some weeds would grow through the holes and joins so there would be a need for some hand weeding and strimming. There would be some reduction in yield due to competition from problem weeds in some orchards.
Pests
Aphids - Rosy apple aphid (Dysaphis plantaginea): Various species affect apples and most are well controlled. Thiacloprid and flonicamid are the basis of the control programme and are applied pre-blossom and in many places post-blossom as well. In an untreated situation natural predators would build up and once stabilised there would only be a small reduction in yield. Capsids (Plesiocoris rugicollis): Currently a problem in some orchards causing minor damage to some leaves and cosmetic damage to some fruit. In an untreated situation, the
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level of damage to fruits would rise as the pest has few natural predators, but the damage would only be cosmetic and the fruit would still be suitable for processing. Fruit tree red spider mite (Panonychus ulmi): Appears in ‘hot spots’ in some young orchards in June for no obvious reason, but is easily controlled with tebufenpyrad or fenpyroximate. It is also a problem in some newly planted orchards. In untreated orchards it would be well controlled by natural predators. Codling moth (Cydia pomonella): Numbers are monitored with pheromone traps and usually exceed the threshold by the end of May/early June, which would trigger a spray application. Methoxyfenozide works well and is now the preferred insecticide. Indoxacarb is not used very often because it is expensive. Spinosad is used later in the season because it has a shorter harvest interval. Control with insecticides is good; in an untreated situation the pest would cause considerable losses as a result of larvae boring into the fruit. Natural predators and parasites would build up, when yield losses would be around 5%. Tortrix and Winter moths (Tortricidae): Tortrix moths are monitored and successfully controlled in the same way as codling moth. In an unsprayed situation, damage would occur in the form of raised “stings” on the fruit, but the damage is only superficial and the affected fruit could be used for processing. Natural predators and parasites would build up and would achieve a level of control in the same way as they would for codling moth. Apple sawfly (Hoplocampa testudinea): A potential problem on some sites and varieties such as Discovery and Worcester are highly susceptible. Usually good control is achieved with thiacloprid. In the untreated situation, the larvae would burrow into the small fruitlets and cause them to fall off. At the fruitlet stage, the tree can often lose significant numbers of fruitlets without markedly affecting the final yield. A small yield reduction would be expected in an untreated orchard. Apple blossom weevil (Anthonomus pomorum): Another potential problem in some orchards, particularly when there are warm days in May, when eggs may be laid in many blossoms. These blossoms are subsequently grazed by the larvae and do not develop. When fruit set is good the final yield is not affected. In an untreated orchard, this would also generally be the situation.
Diseases
Brown rot (Sclerotinia fructigena): Usually well controlled, but can be a problem in some Cox, Discovery and Cameo orchards, particularly after initial damage from birds. Boscalid + pyraclostrobin is used very effectively when applied during the period full bloom to petal fall, and cyprodinil + fludioxonil has also been effective. In an untreated orchard, entry points for the disease could increase so that the level of diseased fruit in the orchard and in store from contact spread would cause a yield reduction. Apple canker (Nectria galligena): Under control in most orchards unless there are triggers such as late October frosts. The only exceptions are old orchards with ongoing problems and most heritage varieties where disease levels can be high. The increased use of copper oxychloride sprays at bud burst for scab and sprays of tebuconazole and now thiophanate–methyl at harvest are thought to be achieving better control. A very low level of rots usually shows up in store. In an untreated situation, the level of rotted fruit in the orchard and in store would be expected to rise. Fastidious pruning out and disposal of cankered wood during the summer and winter would mitigate the losses but would increase costs. Planting and maintaining healthy trees would also keep levels low.
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Phytophthora fruit rot (Phytophthora syringae): Not usually a problem in orchards or in stored fruit when the weather is dry during harvest. In wet seasons mancozeb + metalaxyl-M and captan are applied during the two weeks before harvest and give good control. Even so, a background level of rots can still appear in store. In an untreated orchard discipline would need to be exercised at harvest, so that apples were only harvested and stored during dry weather. In problem orchards the removal of lower branches and application of mulches would have to be considered as a way of preventing fruit becoming infected via soil splash. Powdery mildew (Podosphaera leucotricha): Generally well controlled in most orchards, but there has been an ongoing severe problem in some Cox orchards. A range of fungicides such as myclobutanil is used successfully and also in recent years potassium bicarbonate and sulphur have had a beneficial effect. In an untreated orchard if potassium bicarbonate and sulphur could still be used and additional pruning out of the primary mildewed shoots was carried out (at extra cost) the yield losses could be maintained at low levels. Apple scab (Venturia inaequalis): Usually well controlled in most varieties, particularly in dry springs. The only exception is the variety Gala, which has seen a persistent problem in some orchards in recent years. Many growers now apply a wider range of protectant and eradicant fungicides than in the past, often applied as mixtures. The new fungicide fenbuconazole has been effective. Dithianon + pyraclostrobin and boscalid + pyraclostrobin are also used successfully in mixes. In an untreated orchard yield loss due to scab would be expected both in the orchard and after storage. The losses could be mitigated at extra cost by sweeping leaf debris from the orchard and also additional pruning to remove infected wood. If allowed, sulphur sprays would also have a beneficial effect.
5.6.2 Changing approvals legislation
Under the changing approvals legislation scenario the following active substances that are currently used on apples could be lost:
• Amitrole (herbicide)
• Bifenthrin (insecticide)
• Glufosinate ammonium (herbicide)
• Fenbuconazole (fungicide)
• Mancozeb (fungicide)
• Pendimethalin (herbicide)
• Tebuconazole (fungicide) The impact of these losses on weeds, pests and diseases is identified in Table 32. Calculations show that the scale of these potential losses, arising from the changing approvals legislation, are relatively minor in apples, with just a slight reduction in canker control, but with some increased costs from the use of alternative fungicides.
Page 61
Table 32.
Impact of weeds, pests and diseases on apples as a result of the pesticide losses caused by the changing approvals legislation
scenario– whilst using sensible m
itigation, e.g. biological controls. Cost to the industry is the additional cost
Changing approvals legislation
Annual Meadow Grass
Annual Mercury
Broadleaved weeds
Couch
Docks
Nettle
Thistles
Aphids
Capsid
Leaf Hopper
Two-spotted spider mite
Codling moth
Tortrix & winter moths
Sawfly
Blossom weevils
Blossom Wilt
Brown Rot
Canker
Phytophthora - crown rot
Phytophthora - fruit rot
Powdery Mildew
Scab
Area affected (ha)
5,245
437
8,741
87
874
44
03,496
2,622
2,622
98,741
8,741
6,556
4,371
2,622
8,741
3,496
1,748
4,371
8,741
8,741
Yield Loss (t)
00
00
00
00
00
00
00
00
097
00
00
Cost to the industry (£K)
00
00
00
00
00
00
00
00
0-310
00
00
Cost per affected hectare (£K)
00
00
00
00
00
00
00
00
00
00
00
Percentage reduction in
production (%)
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Table 33.
Impact of weeds, pests and diseases on apples as a result of the potential pesticide losses caused by the restrictions put in place
by the current water quality requirements – whilst using sensible m
itigation, e.g. biological controls.
Water Quality
Annual Meadow Grass
Annual Mercury
Broadleaved weeds
Couch
Docks
Nettle
Thistles
Aphids
Capsid
Leaf Hopper
Two-spotted spider mite
Codling moth
Tortrix & winter moths
Sawfly
Blossom weevils
Blossom Wilt
Brown Rot
Canker
Phytophthora - crown rot
Phytophthora - fruit rot
Powdery Mildew
Scab
Area affected (ha)
5,245
437
8,741
87
874
44
874
3,496
2,622
2,622
98,741
8,741
6,556
4,371
2,622
8,741
3,496
1,748
4,371
8,741
8,741
Yield Loss (t)
1,458
121
12,150
24
24
1243
00
00
00
00
00
00
00
0
Cost to the industry (£K)
-722
-60-19,126
-12
-12
-1-120
00
00
00
00
00
00
00
-437
Cost per affected hectare (£K)
00
-20
00
00
00
00
00
00
00
00
00
Percentage reduction in
production (%)
0.6
0.1
5.0
0.0
0.0
0.0
0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
* Cost to the industry assumes that the active substances are lost to the whole industry; however a complete revocation of the active substance is a last resort. Instead specific catchments may be
affected, if this is the case the cost per hectare can be used to apply to the area within a catchment that is affected.
Page 62
Weeds
The herbicides that would be lost which could be used in orchards are glufosinate ammonium, pendimethalin and amitrole. These herbicides are used infrequently at present. While glyphosate and the hormone herbicides are available for the bulk of the herbicide programme [meaning unclear], the loss of these herbicides will not have a significant impact on apple production.
Pests
The only insecticide likely to be lost which could be used in orchards is bifenthrin. This would have minimal impact; it is not widely used, due to its low compatibility with IPM programmes and also because there are effective alternatives.
Diseases
The fungicides that will be lost with approved uses on apples are fenbuconazole, tebuconazole and mancozeb. Even though fenbuconazole and tebuconazole have been used increasingly since their recent approvals, there are effective alternatives and their removal from the market should not have a significant impact.
5.6.3 Water Quality
The active substances that are currently available on apples that are at risk from restrictions due to water quality requirements are:
• Captan (fungicide)
• Chlorpyrifos (insecticide)
• 2,4-D (herbicide)
• Glyphosate (herbicide)
• MCPA (herbicides) The impact of these restrictions is shown in Table 33. The most significant of the potential losses due to water quality requirements would be the potential losses of herbicides, resulting in reduced control of broad–leaved weeds (5% reduction in production) and annual meadow grass (0.6% reduction in production).
Weeds
The herbicides that will be lost which are used in orchards are glyphosate, MCPA and 2,4-D. As these herbicides presently form the bulk of the herbicide programme for apples, the effect of their loss would be very significant. Contact herbicides such as diquat applied frequently would give some control of weeds, but it would be insufficient for satisfactory results. Unless new full approvals or SOLAs were obtained, fruit growers would have to resort to the mitigation measures detailed above (Section 5.6.1), such as the use of polythene mulches.
Pests
The single insecticide that could be lost which is used in orchards is chlorpyrifos. Although still used by many growers, its use is currently declining. Its loss would not have a major effect as there are other alternative insecticides now available.
Diseases
The fungicide that could be lost for apples is captan. It is currently widely used, although its loss from a disease control point of view would not have a major impact, as there are a number of suitable alternative fungicides available.
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5.7 Pear Most UK pear orchards are in England, with production concentrated in the South-East and East Anglia, with a small area in the West Midlands. Although the area of pears declined in the early part of the last decade, it is now relatively static at around 1,500 hectares. Production is now mainly in the hands of specialist growers, who usually grow apples as well. Most orchards are planted as single rows in a herbicide strip with grass alleyways. The variety Conference accounts for 81% of the national pear orchard. Comice and to a lesser extent Concorde are the other main varieties grown. The majority of the dessert pears are marketed through supermarkets, with a small amount through wholesale markets and direct sales. A small but increasing tonnage of pears is processed into juice and pear cider. Table 34. Pear gross margin
Crop PearsCrop area ha 1,472
Yield t/ha 14
Value £/t 503
Establishment cost £/ha 4,400
Fertiliser cost £/ha 200
Spray cost £/ha 795
Bio-control cost £/ha
Cultivation costs £/ha
Other costs £/ha
Total value £/ha 6,791
Total costs £/ha 5,395
Gross margin £/ha 1,396
5.7.1 Business as usual & untreated scenarios
Under ‘business as usual’, weeds, pests and diseases are generally well controlled (Table 35). In the absence of pesticides, major losses in pears when using sensible non-pesticide mitigation measures are caused by brown rot (15% reduction in production), scab (12% reduction), pear sucker (10% reduction) and broad-leaved weeds (5% reduction) (Table 36).
Page 64
Table 35.
Impact of weeds, pests and diseases on pear under business as usual (potential yield and gross m
argin increases if better control
was possible - despite use of available pesticides)
Business as usual
Annual meadow
grass
Annual Mercury
Broadleaved weeds
Couch
Docks
Nettle
Thistles
Willowherb
Aphids
two-spotted spider
mite
Codling moth
Tortrix and winter
moths
Pear sucker
Blossom weevil
Botrytis
Brown Rot
Canker
Fireblight
Powdery Mildew
Scab
Area affected (ha)
883
74
1,472
15
147
7147
736
589
0736
736
1,472
74
147
1,472
589
0589
1,472
Potential increase in yield if 100%
control possible (t)
00
00
00
00
00
00
20
04
40
00
020
Potential increase in value to
industry if 100% control possible
(£K)
00
00
00
00
00
00
10
02
20
00
010
Increased value per affected
hectare (£K)
00
00
00
00
00
00
00
00
00
00
Table 36.
Impact of weeds, pests and diseases on pear in the absence of pesticide applications – whilst using sensible m
itigation, e.g.
biological controls. (Worst case scenario)
Untreated
Annual meadow
grass
Annual Mercury
Broadleaved weeds
Couch
Docks
Nettle
Thistles
Willowherb
Aphids
two-spotted spider
mite
Codling moth
Tortrix and winter
moths
Pear sucker
Blossom weevil
Botrytis
Brown Rot
Canker
Fireblight
Powdery Mildew
Scab
Area affected (ha)
883
74
1,472
15
147
7147
736
589
0736
736
1,472
74
147
1,472
589
0589
1,472
Yield Loss (t)
596
0994
20
02
99
80
497
497
1,987
0199
2,981
397
00
2,385
Cost to the industry (£K)
-167
11
-2,487
122
121
60
105
0-114
-114
-727
14
-32
-822
27
094
-1,258
Cost per affected hectare (£K)
00
-20
00
00
00
00
00
0-1
00
0-1
Percentage reduction in
production (%)
3.0
0.0
5.0
0.0
0.0
0.0
0.0
0.5
0.0
0.0
2.5
2.5
10.0
0.0
1.0
15.0
2.0
0.0
0.0
12.0
Page 65
Weeds
Pears are generally grown in a weed-free strip, with a zero tolerance for weeds between bud burst and harvest. All species are targets for control, because of the risk of:
• reduced size and the possibility of crop rejection where retailer/processor size grade specifications not met.
• lower yields, both in the year of weed competition and the subsequent year due to reduced fruit bud development. In most years there is insufficient rainfall to supply total fruit requirements in July and August. Increased competition for water from weeds has a serious impact on fruit size and overall yield. Pears are particularly sensitive to sub-optimal water supply during August.
• Increased problems with pest and disease, due to the amended microclimate around the trunk and their shielding effect on sprays.
All weed groups: Most growers apply a tank mix of herbicides a number of times during the year to the herbicide strip, to control all the weeds that may be present. Control is not always complete but it is normally sufficient to prevent yield reduction as a result of weed competition, whilst keeping herbicide costs low. Most growers continue to rely upon 2 or 3 applications of glyphosate because of its relatively low cost and effective control of a wide range of weeds. The applications are timed to remove over-wintered, spring and summer germinated weeds, and will check (rather than kill) any perennial weeds that may be present at the time. In addition, growers use hormone-type herbicides in orchards, either as spot treatments or as carefully-directed applications under the trees, to control perennial broad-leaved weeds. Mixtures containing 2,4-D, dicamba, MCPA and/or mecoprop-P are most commonly used. They are preferred to the more expensive and composite-weed specific clopyralid (e.g. Dow Shield). Spot applications of triclopyr are occasionally made for the control of perennial nettle, field horsetail and rosebay- and great willowherbs In some orchards. In the untreated situation where no herbicides are available, all weeds would pose a severe problem and yields would be reduced substantially as weeds competed for water and nutrients. The options for mitigation are limited see apples section 5.6.1 for details.
Pests
Aphids esp pear-bedstraw aphid (Dysaphis pyri): Various aphid species affect pears and most are well controlled by predators,, but in some years the pest appears in pockets at levels that need treatment. Pirimicarb is effective. In an untreated situation, natural predators would build up. Once populations had stabilised, there would a small reduction in yield. Fruit tree red spider mite (Panonychus ulmi): Often appears in ‘hot spots’ in some young orchards, but is easily controlled with tebufenpyrad or fenpyroximate. It is also a problem in some newly planted orchards. In untreated orchards it would be well controlled by natural predators. Codling Moth (Cydia pomonella): Numbers are monitored with pheromone traps, usually exceeding the threshold by the end of May or early June, after which a spray is applied. Methoxyfenozide works well and is now the preferred insecticide. Control with insecticides is good, but given an untreated situation, the pest would cause considerable losses consequent on the larvae boring into the fruit, which subsequently turn yellow on the tree. Natural predators and parasites would build up and mitigate some of the yield losses, which would be around 5%, but additional costs for picking/ grading /sorting would be incurred.
Page 66
Tortrix and Winter moths (Tortricidae): Tortrix moths are monitored and successfully controlled in a similar way to codling moth. In the unsprayed situation, damage would only be superficial and the affected fruit could still be used for processing. Natural predators and parasites would build up and would achieve control in the same way as they would for codling moth. Pear sucker (Psylla pyricola): A serious problem in pear orchards in hot dry summers. Sprays of mancozeb, sulphur and spirodiclofen are used for control. Heavy rain in June and July and low temperatures can successfully suppress the pest in some seasons. In an untreated situation, the pest would cause considerable losses, with the leaves and fruit being covered in honeydew and subsequently sooty mould. Natural predators and parasites would build up, but net yield losses would be around 5%.
Diseases
Botrytis fruit rot (Botrytis cinerea): Usually present at very low levels in an orchard and in most cases only develops where fruit has been damaged. Currently some pears are drenched at harvest with iprodione, which suppresses the botrytis infection in store. In an untreated situation there would be some infection occurring in the orchard, especially if fruit was damaged by wind or pests and also in store. Brown rot (Sclerotinia fructigena): Not generally a problem in orchards in most years, perhaps due to increased use of captan for scab control. Brown rot does develop where fruit has suffered physical damage during gales or where it has insect damage or bird pecks in late August. In the untreated situation there could be significant infection in the orchard, especially if fruit was damaged by wind or pests and also in store if it was not possible to drench the fruit. Pear canker (Nectria galligena): Usually under control in most orchards. The increased use of copper oxychloride sprays at bud burst for scab is thought to be achieving better control. Canker is a problem on the tree as it invades and kills shoots and branches, but there is usually only a very low level of rots in store. In the untreated situation, the main problem would be an increase in the amount of wood canker. This could reach levels where the loss of fruiting wood could cause a reduction in potential yield. Fastidious pruning out and disposal of cankered wood during the summer and winter would mitigate the losses, but would increase costs. Planting and maintaining healthy trees would also keep levels low. Powdery mildew (Podosphaera leucotricha): Generally well controlled in most orchards. A range of fungicides such as myclobutanil is used successfully. In an untreated orchard, if potassium bicarbonate and sulphur could still be used and additional pruning out of the primary mildewed shoots was carried out at extra cost, the yield losses could be maintained at low levels. Any affected fruit would still be suitable for processing. Pear scab (Venturia pirina): This is an ongoing problem in pears, across all varieties, particularly Comice, especially where there are wood scab infections. Repeated captan + myclobutanil applications are used in an attempt to achieve control. In an untreated orchard, yield loss due to scab would be expected both in the orchard and after storage. The losses could be mitigated at extra cost by sweeping leaf debris from the orchard and also additional pruning to remove infected wood. If allowed, sulphur sprays would also have a beneficial effect. Fruit infected early in the season would be lost altogether or would be very deformed and only suitable for processing. Fruit affected later in the season would not be suitable for the fresh market under EU Grading Regulations and would only be suitable for the processing market which is limited at the moment. [The EU Grading regulations specify what constitutes Class 1 and Class 2 produce. It is policed by the
Page 67
Horticultural Marketing Inspectorate. Supermarkets have their own specifications which incorporate these regulations. Any Pears or apples covered with Scab lesions would be classed as out of grade and would not be able to be sold on the fresh market].. Potentially significant yield reductions could occur, particularly in wet years.
5.7.2 Changing approvals legislation scenario
Under the changing approvals legislation scenario the following active substances that are currently used on pears could be lost:
• Amitrole (herbicide)
• Bifenthrin (insecticide)
• Glufosinate-ammonium (herbicide)
• Fenbuconazole (fungicide)
• Mancozeb (fungicide)
• Pendimethalin (herbicide)
• Tebuconazole (fungicide) The impact of these losses on weeds, pests and diseases is identified in Table 37. These would be relatively minor in pears, with just slight increases in costs of alternative fungicide regimes.
Page 68
Table 37.
Impact of weeds, pests and diseases on pear as a result of the pesticide losses caused by the Changing approvals legislation
scenario– whilst using sensible m
itigation, e.g. biological controls. Cost to the industry is the additional cost
Changing approvals legislation
Annual meadow
grass
Annual Mercury
Broadleaved weeds
Couch
Docks
Nettle
Thistles
Willowherb
Aphids
two-spotted spider
mite
Codling moth
Tortrix and winter
moths
Pear sucker
Blossom weevil
Botrytis
Brown Rot
Canker
Fireblight
Powdery Mildew
Scab
Area affected (ha)
883
74
1,472
15
147
7147
736
589
0736
736
1,472
74
147
1,472
589
0589
1,472
Yield Loss (t)
00
00
00
00
00
00
00
00
00
00
Cost to the industry (£K)
00
00
00
00
00
00
00
00
-44
0-59
0
Cost per affected hectare (£K)
00
00
00
00
00
00
00
00
00
00
Percentage reduction in
production (%)
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Table 38.
Impact of weeds, pests and diseases on pear as a result of the potential pesticide losses caused by the restrictions put in place by
the current water quality requirements – whilst using sensible m
itigation, e.g. biological controls.
Water Quality
Annual meadow
grass
Annual Mercury
Broadleaved weeds
Couch
Docks
Nettle
Thistles
Willowherb
Aphids
two-spotted spider
mite
Codling moth
Tortrix and winter
moths
Pear sucker
Blossom weevil
Botrytis
Brown Rot
Canker
Fireblight
Powdery Mildew
Scab
Area affected (ha)
883
74
1,472
15
147
7147
736
589
0736
736
1,472
74
147
1,472
589
0589
1,472
Yield Loss (t)
119
10
994
22
020
99
00
00
00
00
00
00
Cost to the industry (£K)
-60
-5-2,708
-1-1
0-10
-50
00
00
00
00
00
00
Cost per affected hectare (£K)
00
-20
00
00
00
00
00
00
00
00
Percentage reduction in
production (%)
0.6
0.1
5.0
0.0
0.0
0.0
0.1
0.5
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
* Cost to the industry assumes that the active substances are lost to the whole industry; however a complete revocation of the active substance is a last resort. Instead specific catchments may be
affected, if this is the case the cost per hectare can be used to apply to the area within a catchment that is affected.
Page 69
Weeds
As with apples, the herbicides that will be lost under this scenario are glufosinate-ammonium, pendimethalin and amitrole. These herbicides are used infrequently at the moment. As long as glyphosate and the hormone herbicides remain available for the bulk of the herbicide programme, their loss would not impact significantly on pear production.
Pests
The sole insecticide expected to be lost which could be used on pears is bifenthrin. Its current usage is limited, due to its relatively poor compatibility with IPM programmes and the availability of effective alternatives. There would be little impact from its loss.
Diseases
The fungicides fenbuconazole, tebuconazole and mancozeb would be expected to be lost to pear growers under changing approvals legislation. Even though fenbuconazole and tebuconazole have been used a little since their recent approvals, and mancozeb is widely used, their loss will not have a notable impact because there are effective alternatives.
5.7.3 Water Quality
The active substances that are currently available on pear that are at risk from restrictions due to water quality requirements are:
• 2,4-D (herbicide)
• Captan (fungicide)
• Chlorpyrifos (insecticide)
• Glyphosate (herbicide)
• MCPA (herbicide) The impact of these restrictions is shown in Table 38. The potential loss of actives to water quality requirements could result in reduced weed control with a reduction in yield expected, as a result of poor broad-leaved weed control (5% reduction in production). The combination of yield reductions and increased costs of mitigation could cost growers about £2K per affected hectare, making pear production unviable.
Weeds
The herbicides approved for use in pears that will be lost are glyphosate, MCPA and 2,4-D. As with apples, these herbicides presently form the bulk of the herbicide programme for pears and the effect of their loss would be very significant. Contact herbicides such as diquat applied frequently could be used, but control would be insufficient. Unless new full approvals or SOLAs were obtained, fruit growers would have to resort to the mitigation measures detailed above, such as the use of polythene mulches.
Pests
Under this scenario, the insecticide chlorpyrifos could be lost. Although still widely employed, its use is currently declining and other alternative insecticides are available. Its loss would not have a major effect.
Diseases
The fungicide approved for pears that could be lost is captan. Although currently used on many farms, its loss would not have a major impact as there are alternative fungicides available.
Page 70
5.8 Plum (stone fruit) There has been a steady decline in the plum area over the last 20 years. Initially this was due to old unproductive orchards were grubbed, but more recently, growers have become disillusioned by poor returns from the markets, so that grubbing is expected to continue to exceed new plantings. Erratic cropping and cheap imports are the main problems. Victoria is the main variety, accounting for 46% of the area, with the remainder devoted to a wide range of varieties, such as Marjorie’s Seedling and more recent introductions, such as Opal. The majority of dessert plums are marketed through supermarkets, with a small amount sold through wholesale markets and direct sales. A very small tonnage is used for processing. Table 39. Plum gross margin
Crop PlumCrop area ha 880
Yield t/ha 13
Value £/t 1,472
Seed cost £/ha 2,200
Fertiliser cost £/ha 100
Spray cost £/ha 455
Bio-control cost £/ha
Cultivation costs £/ha
Other costs £/ha
Total value £/ha 19,136
Total costs £/ha 2,755
Gross margin £/ha 16,381
5.8.1 Business as usual and untreated scenarios
Under ‘business as usual’, the majority of weeds, pests and diseases are well controlled (Table 40). In the absence of pesticides, major losses in plums when using sensible non-pesticide mitigation measures are caused by brown rot (17% reduction in production), broad-leaved weeds (5.5% reduction in production), plum fruit moth and botrytis (5.3% reduction in production each) (Table 41).
Page 71
Table 40.
Impact of weeds, pests and diseases on plum under business as usual (potential yield and gross m
argin increases if better control
was possible - despite use of available pesticides)
Business as usual
Annual Meadow Grass
Annual Mercury
Broadleaved weeds
Couch
Docks
Nettle
Thistles
Willowherb
Hop damson aphid
Leaf curling plum aphid
Mealy plum aphid
two-spotted spider mite
Two-spotted spider mite
Plum fruit moth
Bacterial canker
Botrytis
Blossom wilt
Brown rot
Plum rust
Area affected (ha)
528
44
880
988
488
440
528
704
440
44
9836
144
528
704
176
Potential increase in yield if 100%
control possible (t)
00
00
00
00
010
00
012
00
859
0
Potential increase in value to
industry if 100% control possible
(£K)
00
00
00
00
015
00
018
00
11
88
0
Increased value per affected
hectare (£K)
00
00
00
00
00
00
00
00
00
0
Table 41.
Impact of weeds, pests and diseases on plum in the absence of pesticide applications – whilst using sensible m
itigation, e.g.
biological controls. (Worst case scenario)
Untreated
Annual Meadow Grass
Annual Mercury
Broadleaved weeds
Couch
Docks
Nettle
Thistles
Willowherb
Hop damson aphid
Leaf curling plum aphid
Mealy plum aphid
two-spotted spider mite
Two-spotted spider mite
Plum fruit moth
Bacterial canker
Botrytis
Blossom wilt
Brown rot
Plum rust
Area affected (ha)
704
44
880
988
488
440
704
704
440
44
9836
1440
704
704
176
Yield Loss (t)
503
0629
10
01
63
10
503
63
00
609
0601
503
1,922
13
Cost to the industry (£K)
-635
7-2,114
-113
111
-27
70
-656
-40
00
-796
0-803
-1,174
-4,107
-74
Cost per affected hectare (£K)
-10
-20
00
00
0-1
00
0-1
0-2
-2-6
0
Percentage reduction in
production (%)
4.4
0.0
5.5
0.0
0.0
0.0
0.0
0.6
0.1
4.4
0.6
0.0
0.0
5.3
0.0
5.3
4.4
16.8
0.1
Page 72
Weeds
Plums are usually grown in a weed-free strip with a zero tolerance for weeds between bud burst and harvest; all species are targets for control, because of the risk of:
• reduced size/quality and the possibility of crop rejection where retailer/processor size grade specifications are not met.
• reduced yield, both in the year of weed competition and the subsequent year, due to reduced fruit bud development. The competition for water from weeds has a serious impact on fruit size and overall yield.
• Increased problems with pest and disease, due to the altered microclimate around the trunk and their shielding effect from sprays
All weed groups: Most growers apply a tank mix of herbicides a number of times during the year to the herbicide strip to control all the weeds that may be present. Control is not always complete, but it is usually adequate to prevent yield reduction from weed competition, whilst keeping herbicide costs to a minimum. Most growers continue to rely upon 2 or 3 applications of glyphosate because of its relatively low cost and effective control of a wide range of weeds. The applications are timed to remove over-wintered, spring and summer germinated weed and to check (rather than kill) any perennial weeds that may be present at those times. Where overwinter-germinated cleavers and American willowherb have been inadequately controlled by glyphosate, growers often use glufosinate-ammonium or diquat in February or March (pre-bud burst) and some growers have used carfentrazone-ethyl on its own or in combination with glyphosate or diquat to clear these weeds. The range of residual pre-emergence herbicides available to plum growers remains very limited, to the extent that many weeds, such as redshank, groundsel (Senecio vulgaris), black nightshade, black bindweed, common orache, Canary grass and cockspur grass are no longer adequately controlled, not only in the planting year, but in established cropping orchards. In an untreated situation where no herbicides are available, all weeds would be a severe problem and yields would be reduced substantially as weeds competed for water and nutrients. The options for mitigation are limited. Cultivations would be difficult in intensive orchards and likely to damage the important surface roots. Flame or hand weeding would not be practical. The use of mulches using green composted is possible, but NVZ regulations restrict the amount that can be applied to a depth that is insufficient to achieve weed control. Potentially the most effective option for mitigation would be woven plastic mulches, such as Mypex™. New orchards could be established through woven plastic ground cover laid in the tree rows. Costs could be reduced by restricting the mulches to the tree rows and continuing to establish and mow the grass alleyway. In established plantations, although difficult, it would be possible to lay mulch along the herbicide strips and fit it around trees. Weeds growing through the holes and joins would need some hand weeding and strimming. There would be some reduction in yield due to competition from problem weeds in some orchards.
Pests
Plums have the ability to produce a colossal overset and this attribute has the potential to offset losses from pest damage in many years. Aphids: Various species affect plums. Damson-hop aphid (Phorodon humuli) has not been a problem for most growers for some years now. Its incidence has declined significantly, perhaps because very few hops are now grown near plum orchards. Leaf-curling plum aphid (Brachycaudus helichrysi) is now the main aphid problem in most years. The aphid causes newly opening leaves to curl up, preventing flowers from developing and results in a potential small loss of yield on some sites. Growers used to
Page 73
find that one application of chlorpyrifos (many products) was inadequate, but now find that thiacloprid is effective if it is applied early enough. Mealy plum aphid (Hyalopterus pruni) has only been seen at low levels in recent years and like leaf-curling plum aphid usually shows up in the same place each year. In the untreated situation, natural predators would build up. Once established, there would be a small reduction in yield resulting from damson-hop aphid and mealy plum aphid, but a more significant potential loss from leaf-curling plum aphid. Mesh netting would not be a feasible way of mitigating the losses because it would be prohibitively expensive and in any case would not adequately control the aphids. Fruit tree red spider mite (Panonychus ulmi): Often appears in ‘hot spots’ in some young orchards, but it is easily controlled with tebufenpyrad or fenpyroximate. It is also a problem in some newly planted orchards. In untreated orchards, it would be well controlled by natural predators. Plum fruit moth (Cydia funebrana): Numbers are monitored with pheromone traps and are regularly above threshold during June and July, giving growers a control problem. Many growers apply more than two sprays of thiacloprid or chlorpyrifos, as control is very important for crops destined for supermarkets. Overall control with insecticides is good, but in an untreated situation the pest would cause considerable losses as a result of the larvae boring into the fruit, rendering it unmarketable. Natural predators and parasites would build up and projected yield losses would be around 5%.
Diseases
Blossom wilt (Sclerotinia laxa): A problem in some years when the weather is wet during blossom. Growers use cyprodinil + fludioxonil and boscalid + pyraclostrobin successfully. In an untreated situation, there would be some potential loss of yield. Infected blossoms could be removed by hand at extra cost to mitigate the problem, but there would still be some potential loss of yield. Botrytis fruit rot (Botrytis cinerea): Is at very low levels in most years and is only usually seen where fruit has been damaged or is already infected with brown rot. Fungicides applied for blossom wilt and brown rot usually achieve good control. In an untreated situation, there would be some potential loss of yield, particularly in wet summers. Brown rot (Sclerotinia fructigena & S. laxa): A potential problem most years in many orchards, particularly when the weather is wet during ripening. Spray programmes using fenbuconazole and fenhexamid have achieved good control. In the untreated situation, there would be substantial loss of yield in the orchard and later, if fruit was stored. The losses would be greater in summers where the weather was wet during the fruit ripening period and also if there had been blossom wilt present in the orchard. The only mitigation would be to remove infected fruit from the trees by hand at extra cost so that infection did not spread to adjoining fruit or become mummified on the tree later in the year and carry the infection over to the following year. Plum rust (Tranzschelia pruni-spinosae var. discolor): Only usually a problem late in the season, particularly in some Victoria orchards. Growers have been able to achieve reasonable control with myclobutanil or boscalid + pyraclostrobin. In the untreated situation, there could be some very small loss of potential yield; this could be mitigated to some extent by sweeping up infected leaves in the autumn.
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5.8.2 Changing approvals legislation scenario
Under the changing approvals legislation, the following active substances that are currently used on plum could be lost:
• Amitrole (herbicide)
• Glufosinate-ammonium (herbicide)
• Fenbuconazole (fungicide)
• Pendimethalin (herbicide)
• Tebuconazole (fungicide) The impact of these losses on weeds pests and diseases is identified in Table 42. The most significant impacts of the changing approvals legislation will be on brown rot control (2% reduction in production) and blossom wilt (0.6% reduction in production). The loss of these herbicides would not necessarily result in a decrease in yield as a result of weed competition as alternative methods of weed control, such as increased cultivations and hand weeding could be used along side remaining herbicides to maintain yield. However these alternative weeding methods are costly, estimated to be £225 per ha more than herbicide control. This has an effect on the gross margin, resulting in a potential loss to the industry of £198K from broad-leaved weeds and £191K from grass weeds.
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Table 42.
Impact of weeds, pests and diseases on plum as a result of the pesticide losses caused by the changing approvals legislation
scenario– whilst using sensible m
itigation, e.g. biological controls. Cost to the industry is the additional cost
Changing approvals legislation
Annual Meadow Grass
Annual Mercury
Broadleaved weeds
Couch
Docks
Nettle
Thistles
Willowherb
Hop damson aphid
Leaf curling plum aphid
Mealy plum aphid
two-spotted spider mite
Two-spotted spider mite
Plum fruit moth
Bacterial canker
Botrytis
Blossom wilt
Brown rot
Plum rust
Area affected (ha)
528
44
880
988
488
440
528
704
440
44
9836
144
528
704
176
Yield Loss (t)
00
00
00
00
00
00
00
00
68
233
3
Cost to the industry (£K)
-119
-10
-198
-2-20
-1-20
-99
00
00
00
00
-84
-322
-4
Cost per affected hectare (£K)
00
00
00
00
00
00
00
00
00
0
Percentage reduction in
production (%)
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.6
2.0
0.0
Table 43.
Impact of weeds, pests and diseases on plum as a result of the potential pesticide losses caused by the restrictions put in place by
the current water quality requirements – whilst using sensible m
itigation, e.g. biological controls.
Water Quality
Annual Meadow Grass
Annual Mercury
Broadleaved weeds
Couch
Docks
Nettle
Thistles
Willowherb
Hop damson aphid
Leaf curling plum aphid
Mealy plum aphid
two-spotted spider mite
Two-spotted spider mite
Plum fruit moth
Bacterial canker
Botrytis
Blossom wilt
Brown rot
Plum rust
Area affected (ha)
528
44
880
988
488
440
528
704
440
44
9836
144
528
704
176
Yield Loss (t)
76
62,517
11
013
63
00
00
00
00
00
0
Cost to the industry (£K)
-111
-9-5,025
-2-2
0-19
-93
00
00
00
00
00
0
Cost per affected hectare (£K)
00
-60
00
00
00
00
00
00
00
0
Percentage reduction in
production (%)
0.7
0.1
22.0
0.0
0.0
0.0
0.1
0.6
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
* Cost to the industry assumes that the active substances are lost to the whole industry; however a complete revocation of the active substance is a last resort. Instead specific catchments may be
affected, if this is the case the cost per hectare can be used to apply to the area within a catchment that is affected.
Page 76
Weeds
The herbicides that could be lost which are available for use in plums are glufosinate ammonium, pendimethalin and amitrole. These herbicides are used infrequently at the moment. While glyphosate and diquat remain available for the bulk of the herbicide programme, the loss of the above herbicides will not have an impact on plum production.
Pests
No insecticides which could be used in plum orchards will be lost.
Diseases
The fungicides that could be lost which are available for use on plums, are fenbuconazole and tebuconazole. Even though fenbuconazole has become widely used, its loss will not have a significant impact because there are effective alternatives. Tebuconazole is used very little, so its loss will not have an impact.
5.8.3 Water Quality
The active substances that are currently available on plum that are at risk from restrictions due to water quality requirements are:
• Chlorpyrifos (insecticide)
• Glyphosate (herbicide) The impact of these restrictions is shown in Table 43. The potential loss of actives to water quality requirements could result in reduced control of broad-leaved weeds (22% reduction in production). There would be additional costs associated with their control, amounting to £1.5k per hectare; with the associated yield losses, this could cost growers in the region of £6K per hectare.
Weeds
The herbicide that could be lost which is used in plum orchards is glyphosate. As this herbicide presently forms the main constituent of the herbicide programme for the crop, the effect of its loss would be very significant. Contact herbicides such as diquat applied frequently would give some control of weeds, but would be insufficient. Unless new approvals were obtained, growers would have to resort to the mitigation measures described above, such as the use of woven polythene mulches.
Pests
The insecticide used in plum orchards which could be lost with this scenario is chlorpyrifos. Although still used by many growers, its use is currently declining. Its loss would not have a major effect as there are other alternative insecticides available.
Diseases
No fungicides are due be lost which are used in plum orchards.
5.9 Blackcurrants Blackcurrants in the UK are grown principally for processing into juice with over 95% of the area grown on contract to GlaxoSmithKline for Ribena™. The remaining non-contracted area is also grown for processing; as juice for other manufacturers or as IQF fruit used in a range of fruit products. A very limited area of blackcurrants is grown for the fresh market, mainly for PYO sales.
Page 77
Blackcurrants are unusual for a fruit crop in that virtually all harvesting and pruning is done by machine. The labour input is therefore much lower than for other fruit crops and blackcurrants are often grown on mixed arable farms where they are the only fruit crop. Gross margin details used in this assessment are in Table 44. Crop area and yield are from Defra Horticultural Statitics, gross margin information is based on data from Nix 2009, modified by expert opinion. Table 44. Blackcurrant gross margin
Crop Blackcurrant
Crop area ha 2,250
Yield t/ha 6
Value £/t 610
Plants £/ha 300
Fertiliser cost £/ha 150
Spray cost £/ha 870
Bio-control cost £/ha
Cultivation costs £/ha
Other costs £/ha
Total value £/ha 3,782
Total costs £/ha 1,320
Gross margin £/ha 2,462
Page 78
5.9.1 Business as usual and untreated scenarios
Under ‘business as usual’, the largest potential gains would come from improved control of leaf midge (£425K), broad-leaved weeds (£170K), grass weeds (£85K) and sawfly (£85K) (Table 45). The figures in brackets are the potential increase in value to the industry that could occur if 100% control was achievable. In the absence of pesticides, major losses in blackcurrants when using sensible non-pesticide mitigation measures are caused by grass weeds (80% reduction in production), broad-leaved weeds (70% reduction in production) and fungal leaf spot (45% reduction in production) (Table 46). Table 45. Impact of weeds, pests and diseases on blackcurrants under business as usual (potential yield and gross margin increases if better control was possible - despite use of available pesticides)
Business as usualBroadleaved weeds
Chickweed
Cleavers
Grass weeds
Leaf midge
Sawfly
Slugs and snails
Fungal leaf spot
Area af fected (ha) 2,250 450 450 2,250 2,250 2,250 1,800 1,800
Potential increase in yield if 100%
control possible (t)
279 0 28 140 698 140 0 112
Potential increase in value to
industry if 100% control possible
(£K)
170 0 17 85 425 85 0 68
Increased value per affected
hectare (£K)
0 0 0 0 0 0 0 0
Table 46. Impact of weeds, pests and diseases on blackcurrants in the absence of pesticide applications – whilst using sensible mitigation, e.g. biological controls. (Worst case scenario)
Untreated
Broadleaved weeds
Chickweed
Cleavers
Grass weeds
Leaf midge
Sawfly
Slugs and snails
Fungal leaf spot
Area af fected (ha) 2,250 450 450 2,250 2,250 2,250 1,800 2,025
Yield Loss (t) 9,765 558 2,232 11,160 2,790 4,185 1,116 6,278
Cost to the industry (£K) -11,897 -516 -1,537 -12,748 -1,567 -2,418 -652 -2,918
Cost per affected hectare (£K) -5 -1 -3 -6 -1 -1 0 -1
Percentage reduction in
production (%)
70.0 4.0 16.0 80.0 20.0 30.0 8.0 45.0
Weeds
Blackcurrants are normally planted in rows 3 metres apart with either:
• A 1 metre strip along the row kept weed-free with herbicides and the alleyway grassed down or weeds allowed to develop, in either case maintained by mowing
• Overall herbicide; both the row and alleyways kept weed-free with herbicides At present the UK area is split approximately 60:40 between the two options but the trend is for more plantations to have grassed alleyways. Whilst vegetation cover can be tolerated in the alleyways, the policy has to be for zero-tolerance of weeds within the row. The reasons for this are:
Page 79
• Reduced quality and the possibility of crop rejection where processor specifications are not met or potentially toxic contaminants are present e.g. nightshade berries, ragwort flower heads
• Reduced yield due to weed competition
• Machine harvesting difficulties – especially due to cleavers or bindweed overgrowth
• Increased problems with pest contamination – e.g. snails
• Increased problems with disease – e.g. Botrytis due to damp microclimate within crop
Broad-leaved weeds: The most problematical broad-leaved weeds are the perennials such as creeping thistle (Cirsium arvense), perennial nettle (Urtica dioica), field bindweed (Convolvulus arvensis) and docks (Rumex spp.). These are all currently controlled by dichlobenil applied to the crop row and by mowing or glyphosate or MCPB applied to the alleyway. The withdrawal of dichlobenil in March 2010 will make control of these weeds much more difficult, as there is no alternative selective treatment that can be applied to the crop row. In the immediate future growers are likely to invest in hooded sprayers that will allow applications of glyphosate to be made closer to the crop row. However for younger plantations where there is less crop canopy to shade out the weeds, there is likely to be some weed growth remaining in the centre of the row. If no herbicides were available, perennial broad-leaved weeds would be a severe problem for all of the reasons listed above and yield would be reduced by 70% in the absence of other measures. The options for mitigation are limited. New plantings could be established through woven plastic ground cover (e.g. Mypex™) but trials have shown this is not a complete answer as weed growth through planting holes and along bed edges remains problematic, and needs to be accompanied by hand weeding. Plastic ground cover mulches can also exacerbate problems with vine weevil infestation. In established plantations, Mypex is not an option as the bushes are already in place, and the average plantation life is 10-12 years. Flame weeding has not been successful in blackcurrants as the heat damages the lower buds and young shoots on the bushes. Apart from perennials, a wide range of common annual weeds can establish in plantations. These are currently well controlled with residual herbicides such as dichlobenil, pendimethalin, oxadiazon and propyzamide, with flufenacet + metribuzin possibly being used more in the future following a recent SOLA. For control of existing annual weed growth, dichlobenil and the contact herbicides glufosinate ammonium or glyphosate are widely used. In the absence of herbicides, annual broad-leaved weeds would compete strongly with the crop and yields would be limited, as indicated above, for perennial weeds. The options for mitigation are few, as described previously. Chickweeds (Cerastium spp.): Chickweeds are currently well controlled with dichlobenil. Its loss will place more reliance on pendimethalin, propyzamide, napropamide and isoxaben herbicides for residual control. For contact control of existing infestations dichlobenil is widely used, but in future there will be more reliance on propyzamide or directed sprays of glufosinate-ammonium or glyphosate. The latter two options can be less effective as it is not possible to treat the middle of the bush with them. In the absence of herbicides, chickweeds would compete strongly with the crop and yields would be limited as indicated above for perennial weeds. Cleavers (Galium aparine): Cleavers are currently controlled by combinations of dichlobenil and propyzamide. The loss of dichlobenil will place more reliance on
Page 80
pendimethalin, propyzamide, napropamide and oxadiazon herbicides for residual control. For contact control of existing infestations dichlobenil is widely used, but in future there will be more reliance on propyzamide or directed sprays of glufosinate-ammonium or glyphosate. The latter two options can be less effective as it is not possible to treat the middle of the bush. A SOLA for use of carfentrazone-ethyl would make cleavers control easier. In the absence of herbicides, cleavers would compete strongly with the crop and yields would be limited as indicated above for perennial weeds. Cleavers in particular make mechanical harvesting very difficult. Grass weeds (e.g. Elytrigia repens): Perennial grasses such as couch, ryegrass and fescues are the most problematical. These are all currently controlled by dichlobenil and/or propyzamide applied to the crop row in the winter and fluazifop-p-butyl applied as a selective treatment pre-flowering. Grasses in the alleyways are controlled by mowing, or applications of glyphosate or glufosinate ammonium. The withdrawal of dichlobenil in March 2010 and later withdrawal of fluazifop-p-butyl, due to failure to make annex 1 inclusion, will make control of these weeds much more difficult, as there will be no selective treatments that can be applied to the crop row. In the immediate future growers are likely to invest in hooded sprayers that will allow applications of glyphosate to be made closer to the crop row. However, for younger plantations where there is a reduced crop canopy to shade out the weeds, there is likely to be some weed growth remaining in the centre of the row. If no herbicides were available, perennial grass weeds would be a severe problem for all of the reasons listed above and yield would be reduced by 80% in the absence of other measures. The options for mitigation are limited, as discussed above for broad-leaved weeds. Apart from perennials, a wide range of common annual grasses, in particular annual meadow grass, can establish in plantations. These are currently well controlled with residual herbicides such as dichlobenil, pendimethalin, oxadiazon and propyzamide; flufenacet + metribuzin may be used more in the future following a recent SOLA. For control of existing annual weed growth, dichlobenil and the contact herbicides glufosinate-ammonium or glyphosate are widely used. In the absence of herbicides, annual broad-leaved weeds would compete strongly with the crop and yields would be limited as indicated above for perennial weeds. The options for mitigation are restricted as discussed earlier for this crop.
Pests
Blackcurrant leaf midge (Dasineura tetensi): Blackcurrant leaf midge is a ubiquitous pest, whose larvae cause distortion of growing points, the impact of which is particularly severe in young plantations. Infestation limits extension growth which, in turn, reduces yield in the following season. In the absence of control measures, young plantations would suffer yield reductions estimated to be 30%. Mature plantations would suffer yield reductions estimated to be 10%. Leaf midge was well controlled by fenpropathrin, which failed Annex 1 listing and has been withdrawn. Bifenthrin is now the only remaining treatment and even that is not fully effective; currently yield losses are estimated at 5%, due to reduction in growth in younger plantations. Bifenthrin has also failed Annex 1 listing so will be withdrawn by 2011. Remaining insecticides such as lambda-cyhalothrin and thiacloprid offer very limited control. Blackcurrant sawfly (Nematus olfaciens): Blackcurrant sawfly is a sporadic pest, whose larvae can cause near complete defoliation of affected bushes. This results in yield reductions and the risk of rejection of harvested fruit due to caterpillar contamination. Currently fully effective control options are chlorpyrifos and thiacloprid. It is possible to
Page 81
achieve very good control with these insecticides, so at present crop rejections are very rare and yield losses only occur when an infestation is not noticed soon enough. In the absence of insecticides, yield losses and crop rejection would occur, as there are no other measures that can be taken
Alternative solutions and potential for uptake: lambda-cyhalothrin is partially effective and is full approved. Bifenthrin is partially effective, but has failed Annex 1 listing, so will be withdrawn by 2011. Spinosad is very effective and work is underway to generate the necessary residue data to support a SOLA application. Work to determine the structure of the sawfly pheromone, with a view to exploiting it in control strategies, is proposed in a recently submitted HortLINK application. Snails (Helix aspersa and others): Snails are very widely distributed in blackcurrant plantations. The feeding damage to the foliage is insignificant; the main problem is crop contamination. At present control is achieved by applying metaldehyde bait to the crop prior to harvest. The fruit is also checked during harvest and snails removed by hand. If there were no control measures available, very high levels of infestation would occur on some sites and it would be impractical to remove sufficient by hand during the harvesting operation.
Diseases
Leaf spot (Drepanopeziza ribis): Leaf spot is likely to occur in most years. At present good control can be achieved with a wide range of available fungicides, particularly mancozeb, chlorothalonil, cyprodinil + fludioxonil, pyraclostrobin + boscalid, kresoxim-methyl and mycobutanil. If there were no fungicides available, leaf spot would not be controlled. Under wet conditions, bushes would become defoliated before harvest, leading to total crop loss and significantly reduced yield potential for the following year. At present none of the available cultivars have resistance to leaf spot and this has not been a priority in breeding programmes. For currants, the immediate impact for leaf spot control is likely to be slight – alternative materials are available, but the ability to maintain a robust anti-resistance strategy will be compromised. Of particular concern is over-reliance on the QoI group of fungicides, that has rapidly led to the occurrence of resistance and loss of control in other crops and diseases.
5.9.2 Changing approvals legislation
Under the changing approvals legislation scenario, the following active substances that are currently used on blackcurrants could be lost:
• Bifenthrin (insecticide)
• Glufosinate-ammonium (herbicide)
• Mancozeb (fungicide)
• Pendimethalin (herbicide) The impact of these losses on weeds pests and diseases is identified in Table 47. The most significant impact of changing pesticide legislation is the failure of bifenthrin to gain Annex 1 listing. This means that there is no effective control measure for leaf midge resulting in yield losses (15% reduction in production).
82
Table 47. Impact of weeds, pests and diseases on blackcurrants as a result of the pesticide losses caused by the changing approvals legislation scenario– whilst using sensible mitigation, e.g. biological controls. Cost to the industry is the additional cost Changing approvals legislation
Broadleaved weeds
Chickweed
Cleavers
Grass weeds
Leaf midge
Sawfly
Slugs and snails
Fungal leaf spot
Area af fected (ha) 450 450 2,250 1,800 2,250 2,250 2,250 1,800
Yield Loss (t) 0 0 112 0 2,093 0 0 0
Cost to the industry (£K) -214 -16 -111 -79 -1,231 45 0 -81
Cost per affected hectare (£K) 0 0 0 0 -1 0 0 0
Percentage reduction in
production (%)
0.0 0.0 0.8 0.0 15.0 0.0 0.0 0.0
Weeds
Broad leaved weeds: Whilst glyphosate or diquat continue to be available, the loss of glufosinate-ammonium will not have a significant impact as glyphosate is an acceptable substitute for most situations and £55/ha cheaper. The loss of pendimethalin need not compromise weed control, but the alternatives such as oxadiazon are more expensive (£150/ha more than pendimethalin). Flufenacet + metribuzin has recently been approved (SOLA) but was found to be most effective when used with pendimethalin. Oxadiazon may prove to be an equally effective tank mix partner, but at increased cost. Chickweeds (Cerastium spp): Glyphosate is an acceptable substitute for contact weed control and propyzamide or flufenacet + metribuzin for residual weed control. The difference in cost for a glyphosate and propyzamide programme is £35/ha. Cleavers (Galium aparine): Glyphosate is an acceptable substitute for contact weed control and oxadiazon for residual weed control. The difference in cost for a glyphosate and oxadiazon programme is £95/ha. Grass weeds (e.g. Elytrigia repens) Glyphosate is an acceptable substitute for contact weed control and propyzamide or flufenacet + metribuzin for residual weed control. The difference in cost for a glyphosate and propyzamide programme is £35/ha.
Pests
Leaf midge (Dasineura tetensi): The pesticide lost is bifenthrin which is the only effective treatment. Remaining insecticides such as lambda-cyhalothrin and thiacloprid offer very limited control, so the loss of bifenthrin will cause yield reductions as discussed above for untreated crops. For the future, the structure of the leaf midge pheromone is now understood. Research to exploit the use of the pheromone in control strategies, based on trapping, confusion or improved application timing, is proposed in a recently submitted HortLINK project application. A near-market insecticide (spirotetramat) being developed by Bayer is said to be effective against midge species. It is expected to be available for top fruit by 2011, but would require a SOLA for use in blackcurrants.
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Diseases
Leaf spot (Drepanopeziza ribis): Mancozeb is very widely used in leaf spot control programmes. In the short term, other fungicides such as chlorothalonil, cyprodinil + fludioxonil, pyraclostrobin + boscalid or kresoxim-methyl could be used to substitute without affecting control. However some of these fungicides are more expensive and two of the four are strobilurins. There is a significant risk of overuse of Qol mode of action fungicides which would lead to resistance. There are no other mitigation measures that could be used, although in the very long term disease resistance cultivars might be bred.
5.9.3 Water Quality
The active substances that are currently available on blackcurrants that are at risk from restrictions due to water quality requirements are:
• Asulam (herbicide)
• Chlorpyrifos (insecticide)
• Glyphosate (herbicide)
• MCPB (herbicide)
• Metaldehyde (molluscicide)
• Propyzamide (herbicide) The impact of these restrictions is shown in Table 48. The most significant impacts would occur if the range of herbicides were to have their approvals revoked. This would result in a reduction in grass weed control causing yield losses (39% reduction in production) and increased costs. Broad-leaved weeds will also cause increased yield losses (33% reduction in production) and increased costs. The potential loss of metaldehyde would result in more costly alternatives having to be used to control slugs and snails (£650K, cost to the industry). Table 48. Impact of weeds, pests and diseases on blackcurrants as a result of the potential pesticide losses caused by the restrictions put in place by the current water quality requirements – whilst using sensible mitigation, e.g. biological controls.
Water Quality
Broadleaved weeds
Chickweed
Cleavers
Grass weeds
Leaf midge
Sawfly
Slugs and snails
Fungal leaf spot
Area af fected (ha) 450 450 2,250 1,800 2,250 2,250 2,250 1,800
Yield Loss (t) 4,604 0 251 5,441 0 837 558 0
Cost to the industry (£K) -6,318 -29 -205 -10,114 0 -578 -646 0
Cost per affected hectare (£K) -14 0 0 -6 0 0 0 0
Percentage reduction in
production (%)
33.0 0.0 1.8 39.0 0.0 6.0 4.0 0.0
* Cost to the industry assumes that the active substances are lost to the whole industry; however a complete revocation of the active substance is a last resort. Instead specific catchments may be affected, if this is the case the cost per hectare can be used to apply to the area within a catchment that is affected.
Weeds
Broad-leaved weeds: The herbicides that might be affected by water quality requirements are the contact herbicides glyphosate, asulam, MCPB and residual herbicide propyzamide. After dichlobenil has been withdrawn in March 2010, these herbicides when used as directed sprays will form the main control measures against broad leaved perennial weeds. The loss of these herbicides would inevitably mean a substantial loss of yield due to increased weed competition, as well as the additional cost in hand weeding.
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Whilst glufosinate-ammonium continues to be available, a measure of control could be achieved but glufosinate-ammonium is not as effective long term as glyphosate and is more expensive. Repeat treatments would be required, yet only 2 applications are permitted per year. If glufosinate-ammonium was also lost under the changing approvals legislation, then there would be no control measures for perennial broad-leaved weeds in this crop. The possibility of SOLAs for carfentrazone-ethyl and fluazasulfuron are under discussion and would help the situation. The alternatives such as mulching are discussed above, but are only appropriate for new plantations. Control of annual broad-leaved weeds will be easier with a range of herbicides available, such as napropamide for residual control, although contact control of existing weeds will be difficult with diquat offering only moderate control. Chickweeds (Cerastium spp.): The herbicides that might be lost are the contact herbicide glyphosate and residual herbicide propyzamide. Glufosinate-ammonium is an acceptable substitute for contact weed control and pendimethalin or flufenacet + metribuzin for residual weed control. However if glufosinate-ammonium was also lost under the changing approvals legislation, then there would be no contact control measures for chickweed. If pendimethalin was also lost under the changing approvals legislation, then other herbicides, such as napropamide, could be used for residual control. Cleavers (Galium aparine): The herbicides that might be lost are the contact herbicide glyphosate and residual herbicide propyzamide. Glufosinate-ammonium is an acceptable substitute for contact weed control and pendimethalin or flufenacet + metribuzin for residual weed control. However if glufosinate-ammonium was also lost under the changing approvals legislation, then there would be no contact control measures for chickweed. A SOLA for carfentrazone-ethyl would be particularly useful for contact control of cleavers. Grass weeds (Elytrigia repens): The herbicides that might be lost are the contact herbicide glyphosate, and residual herbicide propyzamide. After dichlobenil has been withdrawn in March 2010, these herbicides when used as directed sprays will form the main control measure against perennial grass weeds. The loss of these herbicides inevitably means a substantial loss of yield due to weed competition, as well as increased cost in hand weeding. Whilst glufosinate-ammonium continues to be available, a measure of control could be achieved but glufosinate-ammonium is not as effective long term as glyphosate and is more expensive. Repeat treatments would be required yet only 2 applications are permitted per year. If glufosinate-ammonium was also lost under the changing approvals legislation, then there would be no control measures for perennial grass weeds. The possibility of a SOLA for flazasulfuron is under discussion and would help the situation. Alternatives such as mulching are discussed above, but are only appropriate for new plantations. Control of annual grasses will be easier, with a range of herbicides available such as napropamide for residual control, although contact control of existing weed will be difficult, with diquat offering very poor control.
Pests
Snails (Helix aspersa and others): The molluscicide that might be lost is metaldehyde, which is the main control measure currently used. If this were not available, ferric phosphate would be used instead but is much more expensive (£145/ha more) and less effective. Whilst direct crop damage is insignificant, it is thought that very high levels of infestation could occur on some sites that would be impractical to remove sufficiently by
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hand during the harvesting operation. This could result in an average of 5% crop rejections due to contamination. No other mitigation measures are available, although copper fungicides (cost £25/ha) applied after harvest can reduce the problem. Blackcurrant sawfly (Nematus olfaciens): The relevant pesticide lost is chlorpyrifos. Thiacloprid and chlorpyrifos are the main control measures for this pest. If chlorpyrifos was lost thiacloprid would be used instead. Although it is more expensive (£30/ha more), a similar level of control would be achieved. However, if thiacloprid was also lost under the changing approvals legislation, then there would be no fully effective control measures for sawfly. In the absence of insecticides, yield losses and crop rejection would occur, as there are no other measures that can be taken
Other insecticide options are limited; lambda-cyhalothrin is partially effective and is full approved. Bifenthrin is partially effective, but has failed Annex 1 listing so will be withdrawn by 2011. Spinosad is very effective and work is underway to generate the necessary residue data to support a SOLA application. Research work to determine the structure of the sawfly pheromone, with a view to exploiting it in control strategies, is proposed in a recently submitted HortLINK application.
5.10 Raspberry At least 70% of the area currently used for raspberry production in the UK is protected for at least part of its growing season by polythene clad tunnels e.g. Spanish tunnels. In the case of fruit produced for fresh fruit sales via the major multiples, at least 90% of the cropped area is protected in this way. The tunnel legs and hoops of these structures are placed in position either prior to or just after planting the crop and, depending upon the type of raspberry (i.e. summer or primocane (autumn) fruiting) and the nature of the planting material (i.e. standard bare root, long cane, module raised plants or roots planted), the tunnels are clad with polythene either soon after or 3-15 months after planting. The date when the polythene is pulled over the tunnels can also depend upon the harvest schedule e.g. for early cropping of summer fruiting raspberries, the tunnels may be clad as early as late February, so that harvesting from mid to late June and into July is achieved. Where late or normal season cropping is required, then covering of the tunnels will not usually take place until just prior to the start of flowering or at late green fruit i.e. about a week before harvest commences. As the protection of the raspberry crop in this way is now widespread, it has been assumed for this study that the raspberry crop is of a summer fruiting cultivar, protected by tunnels from just prior to flowering through until the end of harvest, when the tunnel cladding is removed. For the rest of the growing and dormant period of each year, the plants are in the open i.e. fully exposed to the weather. An increasing area of raspberries is grown in soil-less substrate consisting of peat, peat: bark or peat:coir mixes. The raspberry plants are planted into pots, troughs or bags. Although some of the substrate crop is grown under all-year-round glasshouse protection, most, like the soil planted crop, is cultivated outside and protected for part of each growing season by polythene-clad tunnels. For this study, a soil-grown crop has been modelled.
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Table 49. Raspberry gross margin
Crop RaspberryCrop area* ha 1,634
Yield* t/ha 9
Value* £/t 6,677
Plants planting & soil
sterilisation
£/ha 2,393
Fertiliser cost £/ha 300
Spray cost £/ha 992
Bio-control cost £/ha 162
Cultivation costs** £/ha 3,618
Other costs (w/o over
10 years)***
£/ha 2,150
Total value £/ha 58,090
Total costs £/ha 9,615
Gross margin £/ha 48,475 *Defra horticulture statistics ** Bio-control, weeding, primocane and floricane management, pruning and tying to crop support trellis *** Spanish tunnels, polythene cladding and crop support trellis
5.10.1 Business as usual and untreated scenarios
Under ‘business as usual’, the largest potential gains could come from improved control of primocanes (£14M), broad-leaved weeds (£9.5M), raspberry beetle, capsid and plant bugs, botrytis and grass weeds (£4.7M) (Table 50). The figures in brackets are the potential increase in value to the industry that could occur if 100% control was achievable. In the absence of pesticides, major losses in raspberries, when using sensible non-pesticide mitigation measures, are caused by grass weeds and broad-leaved weeds (40% reduction in production for each), botrytis, capsid and plant bugs (30% reduction in production each) and raspberry beetle and powdery mildew (20% reduction in production each) (Table 51).
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Table 50.
Impact of weeds, pests and diseases on raspberry under business as usual (potential yield and gross m
argin increases if better
control was possible - despite use of available pesticides)
Business as usual
Broadleaved
weeds
Creeping bitter
yellow cress
Grass weeds
Horsetails
Perennial
bindweeds
Primocane
control
Aphids
Raspberry beetle
Brown scale
Capsid and plant
bugs
Caterpillars
Raspberry cane
midge
Two spotted
spider mite
Pre-planting soil
pests
Sawfly
Slugs & snails
Weevils
Whitefly
Cane spot
Botrytis (canes &
fruit)
Cane blight
Powdery mildew
Raspberry yellow
rust
Pre-planting soil
diseases
Area affected (ha)
1,634
163
1,634
82
245
1,634
1,144
1,634
82
1,634
163
1,634
817
409
245
409
327
163
817
1,634
817
817
817
817
Potential increase in
yield if 100% control
possible (t)
1,422
28
711
14
43
2,132
199
711
0711
28
426
142
178
036
142
28
355
711
355
355
71
711
Potential increase in
value to industry if 100%
control possible (£K)
9,492
190
4,746
95
285
14,238
1,329
4,746
04,746
190
2,848
949
1,186
0237
949
190
2,373
4,746
2,373
2,373
475
0
Increased value per
affected hectare (£K)
61
31
19
13
03
12
13
01
31
33
33
10
Table 51.
Impact of weeds, pests and diseases on raspberry in the absence of pesticide applications – whilst using sensible m
itigation, e.g.
biological controls. (Worst case scenario)
Untreated
Broadleaved
weeds
Creeping bitter
yellow cress
Grass weeds
Horsetails
Perennial
bindweeds
Primocane
control
Aphids
Raspberry beetle
Brown scale
Capsid and plant
bugs
Caterpillars
Raspberry cane
midge
Two spotted
spider mite
Pre-planting soil
pests
Sawfly
Slugs & snails
Weevils
Whitefly
Cane spot
Botrytis (canes &
fruit)
Cane blight
Powdery mildew
Raspberry yellow
rust
Pre-planting soil
diseases
Area affected (ha)
1,634
245
1,634
82
327
1,634
1,144
1,634
82
1,634
163
1,634
817
409
245
490
327
163
817
1,634
817
817
817
817
Yield Loss (t)
5,686
43
5,686
71
284
2,843
1,990
2,843
43
4,265
100
20
86
188
43
256
057
2,132
4,265
1,422
2,843
853
2,132
Cost to the industry (£K)-40,631
-273-37,886
-471-1,882-20,765-13,103
-19,345
-272-28,211
-638
131
-687
-518
-245-94,987
-497
-592-13,895-27,791
-9,150-18,641
-5,353-12,767
Cost per affected
hectare (£K)
-25
-1-23
-6-6
-13
-11
-12
-3-17
-40
-1-1
-1-194
-2-4
-17
-17
-11
-23
-7-16
Percentage reduction in
production (%)
40.0
0.3
40.0
0.5
2.0
20.0
14.0
20.0
0.3
30.0
0.7
0.1
0.6
1.3
0.3
1.8
0.0
0.4
15.0
30.0
10.0
20.0
6.0
15.0
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Weeds
For this study, it has been assumed that the soil surface in raspberry plantations is maintained weed free using a range of residual and contact herbicides. Broad-leaved weed control pre- and post-planting: Creeping thistle, perennial nettle, perennial bindweeds, horsetail and creeping buttercup along with a wide range of annual broad-leaved weeds are the main targets for control pre-planting, usually by the use of one or two applications of glyphosate or amitrole during the 12 months prior to planting. Glyphosate, carfentrazone-ethyl or diquat are applied just prior to planting to clear any remaining just-germinated weeds. Post-planting weed control is more difficult, as there are at present a relatively small number of pre-emergence products with approval for application immediately post-planting (or in the planting year). As a result, black nightshade, redshank, cleavers and knotgrass can often become problem weeds and require hand removal in order to prevent the crop plants from suffering a severe check to their growth. In established crops, there is currently a reasonable but diminishing range of actives for pre-emergence annual broad-leaved weed control. However, cleavers, groundsel and knotgrass control can at times be difficult to achieve. In addition, clover, amphibious bistort, perennial nettle, silverweed, creeping buttercup, perennial bindweeds, dandelion, creeping bitter cress and creeping thistle are difficult to control and, with the loss of dichlobenil, some e.g. perennial nettle are now impossible to control legally. The range of actives for post-emergence broad-leaved weed control is very limited. The options are propyzamide for chickweed control over winter when applied in the period November – January and directed applications of MCPB for post-harvest use only, for suppression of creeping thistle and perennial bindweeds and to kill several species of annual broad-leaved weeds. Directed or shielded sprays of carfentrazone-ethyl or glufosinate-ammonium are used in the crop rows in the winter or early spring months to clear some over wintered weed, the carfentrazone-ethyl being particularly useful against cleavers, American willowherb and clover. These products are also used in the spring and summer months as shielded directed sprays in the alleys to clear or check the growth of broad-leaved weeds but, with the exception of carfentrazone-ethyl (when applied in the crop rows for removal of unwanted primocane), are not applied into or around the bases of the canes in the crop rows. Grass weeds: Pre-planting glyphosate or amitrole are used to clear couch and other perennial and annual grass weeds. Some growers have returned to the use of amitrole as they have found in recent years that glyphosate no longer provides effective control of couch grass. With the notable exception of isoxaben, most of the current residual herbicides approved for use in raspberries will provide control of annual meadow grass, provided that application of a suitable product is made in October each year. Post-emergence control of this weed is now reliant upon the use of glufosinate-ammonium and propyzamide, with the former applied in the crop rows in March (use limited to March – October), pre-emergence of primocanes in the crop rows and the latter applied during the winter months (Nov-January).
Pests
The main pests of outdoor and protected raspberry crops are raspberry beetle (Byturus tomentosus), aphids (mainly large raspberry aphid, (Amphorophora idaei), small raspberry
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aphid (Aphis idaei) and potato aphid (Macrosiphum euphorbiae)), raspberry cane midge (Resseliella theobaldi), capsids (common green capsid (Lygocoris pabulinus) and tarnished plant bug (Lygus lineolaris)), two-spotted spider mite (Tetranychus urticae) and wingless weevils (vine weevil (Otiorhynchus sulcatus) and clay coloured weevil (O. singularis)). Small raspberry sawfly (Prioporus morio), brown scale (Parthenolecanium corni), various Lepidopteran caterpillars (e.g. Cacoecimorpha pronubana, Archips podana, Epidlema uddmanniana), raspberry leaf and bud mite (Phyllocoptes gracilis), blackberry leaf midge (Dasineura plicatrix) and snails and slugs are also commonly found, and in some cases are an increasing problem in raspberries. Insect control is currently achieved either by the routine application of insecticides in the case of raspberry beetle and raspberry cane midge or, for the other major and minor pests, when their presence is detected and where applicable thresholds for damage have been reached. Control of mite pests is achieved by the introduction of predatory mites and midges and the use of specific acaricides. Aphids (Amphorophora idaei, Aphis idaei, Myzus persicae, Macrosiphium euphorbiae): Amphorophora idaei and Aphis idaei are primarily of importance as potential vectors of virus in the raspberry crop. Cultivars are available with resistance to the feeding of one, two or four strains of Amphorophora idaei, the most useful being the latter gene (A10) resistance. There is currently no source of resistance to Aphis idaei and in recent years a fifth strain of Amphorophora idaei has appeared in English raspberry plantations which is capable of colonising plants of A10 cultivars e.g. Leo, Autumn Bliss and Octavia. In addition, aphids with populations which have resistance to groups of pesticides i.e. peach-potato aphid (Myzus persicae) are often being found, especially in protected crops of raspberries where the climatic conditions permit numbers to increase rapidly. Currently both the large and small raspberry aphids are susceptible to thiacloprid, pirimicarb and pymetrozine, the main insecticides used for the control of aphids in both outdoor and protected raspberry. However, there are application problems when these products are used in the protected tunnel crop. They are also often used when temperatures are low in the early spring months, when the first adult aphids are seen feeding on the unfolding foliage of the crop, resulting in their failure to achieve effective control. Bifenthrin, lambda-cyhalothrin and deltamethrin are rarely used specifically for aphid control, in part because their use is detrimental to the majority of the indigenous and introduced predatory mites and midges used to control two-spotted spider mite in this crop. Some of the current most important commercial raspberry cultivars are particularly susceptible to aphid-borne virus, for example large areas of infested Glen Ample plantations have succumbed to mosaic virus within 4 years of planting. The protection of crops with tunnels exacerbates this situation, creating conditions for rapid build up in aphid numbers and the easy movement of the large raspberry aphid within crops. A recent HortLINK project has shown that the application of an insecticide active against aphids in early October can substantially reduce the over-wintering population of the large raspberry aphid, thereby reducing the number of sprays required to control this pest the following spring and early summer. Chlorpyrifos is often used for the control of aphids in the early spring or autumn when spraying is required during periods when the temperature is low. Some growers use pyrethrins for aphid control with reasonable success, but this active has on occasions caused damage to the foliage of protected crops.
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Aphids in raspberries can also cause crop rejection due to their presence in product after picking and the contamination of the fruit surface with honeydew and sooty mould. Biological control of the large raspberry aphid has to date proved impossible using the predatory midges used for the control of other aphid species e.g. Aphis ervi used to control Macrosiphium euphorbiae. Other materials that offer control i.e. dodecyl phenol ethoxylate and natural plant extracts are only used during harvest and are best suited to use with AYR protected crops. Raspberry beetle (Byturus tomentosus): Adult beetles feed upon the flowers of several hedgerow rosaceous trees and shrubs before entering into raspberry plantations to lay their eggs on the flowers of this crop. The adults can cause some damage to young raspberry foliage and the petals, stamens and anthers of flowers, but the damage caused by the larvae of this pest burrowing into the drupelets of the ripening fruit is the primary cause of crop rejection. There is a nil tolerance for the presence of this pest or fruit damaged by it in a consignment of fresh fruit or fruit that is to be processed for all major sales outlets for this crop. Routine spraying of crops with an insecticide either just prior to the opening of the first flower, during flowering and/or at late green fruit/first pink fruit has been the norm for many years, as growers felt that it was impossible to take the risk of fruit contamination and market rejection. Chlorpyrifos, bifenthrin, deltamethrin, thiacloprid and lambda-cyhalothrin will provide effective control of this pest, but most growers of summer fruiting raspberries use either chlorpyrifos or thiacloprid just prior to the first flower opening followed, in the case of primocane-fruiting raspberries, by the use of bifenthrin, thiacloprid or deltamethrin at first pink fruit i.e. within 3-4 days of the start of picking. Deltamethrin is the most popular product for use at this stage of crop development as it has a nil day harvest interval and there is little or no risk of residues being present in fruit at harvest.
For some years researchers at SCRI have been developing UV Light-reflecting white sticky traps for detecting the presence, and thereafter monitoring the numbers of adult raspberry beetles in raspberry and other Rubus crop plantations. These have been used by growers as a means of deciding the optimum time to apply a control spray i.e. when the catch in the traps is 5 or more adult beetles. More recent work as part of a HortLINK project has led to the development of a cross-vane funnel trap, containing lures of flower volatiles. This can be used, not only to detect the time when adult beetles migration into plantations occurs (in both outdoor and protected crops) and the threshold when spraying should be carried out, but also offers the possibility of developing a ‘lure, trap and kill’ means of controlling this pest. Potentially this could, where it is established that beetle numbers are very low, enable growers to dispense with pesticide use against this pest. Trials work in Norway, Switzerland and the UK has established that around 50 traps would be required for an individual plantation to develop a barrier ‘to lure and trap’ sufficient numbers of adult beetles as they migrate from hedgerow plants into adjacent raspberry plantations pre-flowering. This technique is unlikely, with the exception of crops that are being grown organically, to provide the required 100% beetle control required for most outlets for this crop. However, if accompanied by careful picking to remove any remaining damaged fruit where beetle numbers are low to moderate, (or coupled with a pre-flowering insecticide application timed by trap catches where beetle numbers are high), the use of, this technique could offer the possibility of effective control and nil or minimal insecticide use.
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Raspberry cane midge (Resseliella theobaldi): Female midges lay their eggs under the epidermis of the rind of primocane, the larval feeding causing an accentuation of the natural splitting of the rind of the cane and damage to underlying cortical tissue. The occurrence of at least three, (and in the case of tunnel and AYR protected raspberry crops four or even five), midge generations per year, can leave canes very badly damaged at the end of the season. This damage reduces the canes’ ability to withstand the winter, so that in the spring they are left dead or dying or, having provided sites for infection by cane blight (Leptosphaeria coniothyrium), the cane succumbs to this disease. Control is achieved by one or two applications of chlorpyrifos. Treatment may not be necessary if midge numbers are small or the primocane rind of the raspberry cultivar involved does not readily split or if the first flush of primocane has been removed from the plantation, so again there are no egg laying sites present. Trials continue to be carried out to identify a replacement for chlorpyrifos for the control of this pest. The use of midge sex pheromones is being investigated for mating disruption or ‘lure and kill’ of this pest in protected crops, but so far this method of control has not been successful. Work is now underway to identify the volatiles that attract adult female raspberry cane midge to egg laying sites of primocanes, with the possibility that they might be used in the 'lure and kill’ technique.
Capsids (Lygocoris pabulinus, Lygus rugulipennis): Currently the main capsid causing damage to raspberry foliage, shoot tips, fruiting laterals, flowers and fruits is the common green capsid (Lygocoris pabulinus), but tarnished plant bug (Lygus rugulipennis) in recent years has been observed causing damage to the fruit of later, predominantly protected primocane fruiting raspberry crops. Control is achieved by applying chlorpyrifos, deltamethrin, thiacloprid, bifenthrin, lambda-cyhalothrin or pyrethrins, with the majority of growers using chlorpyrifos, thiacloprid or lambda-cyhalothrin if common green capsid is found feeding on plants pre-flowering. Closer to harvest thiacloprid, bifenthrin or deltamethrin may be used. Levels of control with both pyrethrins and thiacloprid can be variable at times. In addition to direct damage to harvestable fruit, common green capsid, if not effectively controlled, can cause considerable damage to primocane, killing growing points, stimulating branching and leaving it unsuitable for retention to crop the following year. Where tarnished plant bug numbers are high, appreciable malformation of fruit may occur. Selecting and discarding this unmarketable fruit during picking or packing can substantially increase the cost of harvest. The protection of crops with polythene clad tunnels has created ideal conditions for both capsid species. Plantations where weed control, especially of perennials such as perennial nettle and amphibious bistort or the annuals black nightshade and redshank, is poor are also more susceptible to attack by common green capsid. Weevils (Otiorhynchus sulcatus, O. singularis): Vine weevil (Otiorhynchus sulcatus) is now a widespread problem in cane fruit and especially raspberry crops. Clay-coloured weevil (O. singularis) in contrast is a more localised problem, with the damage primarily being caused to the fruit laterals, leaves, flowers and developing fruits by the adult weevils, whereas vine weevil larvae cause the most serious damage by feeding upon the crop’s root system. Adult vine weevil also causes damage to the foliage of plants; usually this is how their presence is first noted, but in the main they are potential post-harvest crop contaminants, rather than causing direct damage to the fruit.
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In the late spring or early summer months, the majority of growers currently apply bifenthrin in the evening for the control of adult weevils, as soon as appreciable numbers of these pests are seen feeding in the crop canopy. Sprays of thiacloprid, chlorpyrifos, deltamethrin or lambda-cyhalothrin are occasionally used but in the main have been found to be less effective than bifenthrin in controlling this pest, cannot be used close to or during harvest (bifenthrin has a 2 day harvest interval) and/or have an unacceptable and long term impact upon predatory mites or midges used in the crop to control two-spotted spider mite.
For substrate-grown crops, growers increasingly use applications of insect pathogenic nematodes i.e. Steinernema kraussei or Heterorhabditis sp) in the late summer/early autumn or late winter/early spring periods for the control of the weevil larvae. However, this technique is at present very expensive and, for soil grown crops, far less reliable.
Work is currently underway to identify new insecticides with activity against this pest and other biological agents for larval control Two spotted spider mite (Tetranychus urticae): Occasionally a problem in early summer fruiting raspberry crops, but a more serious and widespread problem in protected primocane-fruiting raspberry crops where products such as deltamethrin are used for raspberry beetle control.
Bifenthrin, chlorpyrifos, clofentezine, dodecyl phenol ethoxylate, natural plant extracts and tebufenpyrad, can currently be used for the control of this pest in both outdoor and protected crops; abamectin can only be used in the protected crop. Resistance to chlorpyrifos and bifenthrin is widespread and these products are now rarely used specifically for the control of two-spotted spider mite. Reliance is therefore now placed upon clofentezine and tebufenpyrad for the outdoor crop and clofentezine and abamectin in the protected crop. Resistance to tebufenpyrad is suspected, as this has been used in several soft fruit crops for a number of years. Greater reliance is therefore placed by growers on the introduction of the predatory mites Phytoseiulus persimilis, Amblyseius andersoni and Amblyseius californicus. Although Amblyseius californicus can only be introduced into AYR protected crops, its presence has been recorded in many outdoor and tunnel-protected plantations where it successfully over-winters. In protected crops, Feltiella acarisuga is often introduced into pest hot spots to aid control. Naturally- occurring populations of predators are often present i.e. of Orius and Anthocoris nemoralis, especially in summer-fruiting raspberry plantations, which aid two-spotted spider mite control later in the summer.
Biological control of two-spotted spider mite is possible in both outdoor and protected crops. It is expensive both as regards the predators that are used and the monitoring that this technique demands, so most growers tend to use a acaricide at least once per season to reduce the number of over-wintered eggs or to control the first generation of adult summer mites and then to use predators as soon as the daily temperatures permit. This practice is accompanied by the spraying of hot spots of mites in the crop if they occur. Caterpillars (various including Cacoecimorpha pronubana, Archips podana, Epidlema uddmanniana): More common in AYR protected crops, where species such as vapourer and carnation tortrix moth are now more often seen, causing damage to foliage, flowers and fruits. They are potential crop contaminants. For outdoor and tunnel-protected crops, various tortrix moth caterpillars including winter tortrix, strawberry tortrix and carnation tortrix moth are more likely to be seen, along with those of raspberry bud moth (Scotland only) and bramble shoot moth.
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Control is achieved using chlorpyrifos, deltamethrin, bifenthrin or, more recently, spinosad. Bacillus thuringiensis var. kurstaki is also used, but in the majority of cases fails to give sufficient control. Small raspberry sawfly (Prioporus morio): In some seasons, damage to foliage and crop contamination by the larvae of this pest, especially in AYR protected raspberry crops, can be serious. Chlorpyrifos, thiacloprid, pyrethrins, deltamethrin, bifenthrin and lambda-cyhalothrin are available, but by far the most effective material is thiacloprid, one application of this active per cropping season usually being sufficient to achieve effective control. Whitefly (Trialeurodes vaporariorum): Predominantly a pest of AYR protected raspberry crops. Bifenthrin, thiacloprid, dodecyl phenol ethoxylate, natural plant extracts and pyrethrins can be used in the raspberry crop for this pest’s control, but unfortunately resistance to most of these actives is widespread, so growers resort to repeated spray applications of dodecyl phenol ethoxylate, natural plant extracts, or use of sticky traps and crop hygiene, especially with regard to weed control and removal of all spent crop foliage and other crop debris that could act as over-wintering sites for this pest. Encarsia formosa is used, but does not work well in raspberries for the control of this pest Slugs and snails (various species): Both cause damage to the rind of primocane in the early spring months, enhancing the splitting of rind and providing egg laying sites for raspberry cane midge. They also cause damage to fruiting laterals, flowers and fruit, and are potential crop contaminants (snails). Metaldehyde is used for control, usually one application per year into the bases of canes in crop rows when damage is seen to the rind of primocane, or the pest is observed feeding in the crop canopy. Ferric phosphate not used, as it is expensive and primarily provides control of slugs, not snails.
Disease
Cane spot (Elsinoe veneta): Some cultivars such as Leo, Glen Clova and Tulameen are particularly susceptible to infection by this disease. Cane spot is active during periods of cool wet weather in the spring and early summer, when infection takes place from the canes of current season floricane across to primocane, the leaves of primocane and floricane, flowers, pedicels (fruit stalks) and developing fruits. This renders infected fruit unmarketable and reduces the winter hardiness and cropping ability of current season primocane in the following season. The only products with on label approval currently recognised as having activity against cane spot contain copper oxychloride and ammonium carbonate. Use of these actives is limited to two or three applications per year; application with other pesticides, notably insecticides, is not recommended and some growers are not keen on their use due to the presence of high levels of copper in the soil of their plantations. Products containing chlorothalonil, thiram, dichlofluanid and tolyfluanid were used in the past for the control of cane spot. More recently tebuconazole and boscalid + pyraclostrobin have been identified as having potential for the control of this disease. Two, or in some seasons three, fungicide applications are applied for the control of this disease; the first in the early spring as the first leaves of the floricane start to unfold (or first primocane emerges from the soil), the last at the onset of flowering. The avoidance of resistance is becoming very difficult, due to the lack of alternative actives for control of cane spot.
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Cane and fruit botrytis (Botrytis cinerea): Serious fruit loss can be experienced with outdoor crops and in the leg rows of Spanish tunnel-protected crops during wet springs and summers. In addition, yield loss can occur due to the infection of the nodal buds of primocanes, which may die or become weakened at an early stage of their development or die later in the following spring/early summer when the primocane becomes floricane. Cultivars vary greatly in their susceptibility to cane botrytis e.g. Glen Ample and Tulameen are particularly susceptible, whilst Malling Juno and Leo are tolerant or resistant to infection. Most growers however continue to apply routinely a programme of fungicides with activity against this fungus from the early spring, as the first leaves of the floricane start to unfold (or first primocane emerges from the soil), up until the onset of (and many during) flowering of the crop. Currently growers have a wide range of products to choose from i.e. azoxystrobin, Bacillus subtilis strain QST 713, boscalid + pyraclostrobin, cyprodinil + fludioxonil, fenhexamid, iprodione, pyrimethanil and tebuconazole. All, with the exceptions of iprodione and boscalid + pyraclostrobin (outdoor crop use only), are approved (on label or SOLA) for use in both outdoor and protected crops. Spur blight (Didymella applanata): Currently there are no products with approval for the control of this disease: and although boscalid + pyraclostrobin and tebuconazole are thought to have activity against this disease, this is not proven. Infection takes place primarily during and after harvest from current season floricane to primocane. Cultivars vary greatly in their susceptibility to this disease with unfortunately two of the three most important summer fruiting cultivars, i.e. Glen Ample and Tulameen, being highly susceptible to infection and Octavia moderately so. Infection of the nodal buds of primocane leads to their weakening, delay or failure to break in the spring with consequent crop loss. Cane blight (Leptosphaeria coniothyrium): An opportunist infection, which is most probably always present in established raspberry plantations. Infection of damaged primocane by various means, e.g. enhanced splitting of primocane rind and underlying cortical damage produced by the feeding of raspberry cane midge larvae, mechanical or frost damage to primocane or damage to cane tissue produced by cane botrytis or spur blight, can permit infection. This disease damages xylem tissue, preventing movement of water from roots through floricane in the spring and early summer months, resulting in infected canes wilting or dying above the point at which infection has occurred. In some seasons this can cause high levels of crop loss. A programme of sprays using tebuconazole alternated with boscalid + pyraclostrobin is currently applied post-harvest until the early autumn for the control of this disease in plantations where infection has occurred. No other fungicides currently approved for use in this crop have shown activity against this disease. Good crop hygiene, including removal of old floricane stubs (that can act as sources of infection and cause damage to new primocane, creating points of entry for this disease) and effective control of raspberry cane midge can help to reduce the incidence. However, there is some evidence that the now-widespread practice of removing the first flush of primocane in the crop row and protection of the crop by polythene clad tunnels may produce primocane that, because of its juvenility, is more susceptible to infection by this disease when the tunnel cladding is removed in late July-early August. Canes continue to be susceptible to infection well into the late autumn or even early winter months. The conversion of plantations to biennial cropping, so that floricane and primocane are no longer present together in the crop row, can also be used as a means of reducing the risk of infection, but this will inevitably lead to some reduction in cropping.
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Powdery mildew (Sphaerotheca macularis): Infects foliage, the tips of primocane and fruit. Most crop loss is from the latter, fruit infected with powdery mildew being unmarketable. Currently there are a reasonable number of fungicides available for the control of this disease on the outdoor crop, namely azoxystrobin, boscalid + pyraclo- strobin, bupirimate, cyprodinil + fludioxonil, fenpropimorph, myclobutanil, potassium hydrogen carbonate and tebuconazole. Azoxystrobin, cyprodinil + fludioxonil, myclobutanil, potassium hydrogen carbonate and tebuconazole can also be used in protected crops, but of these only myclobutanil, with a 3 day harvest interval, and potassium hydrogen carbonate, with a nil harvest interval, are used close to, or during, the harvest of protected raspberry crops. The disease is most prevalent in hot dry summers, particularly when the temperature and relative humidity overnight are high, infection being most common and often serious in polythene clad tunnel-protected crops. Some cultivars of summer fruiting raspberries and primocane fruiting raspberries are very susceptible to infection. A routine programme of fungicides is usually applied where susceptible cultivars are being grown in, and protected by, tunnels, commencing at the first signs of infection on primocane shoot tips or foliage in the spring or just prior to the onset of flowering. Primocane-fruiting crops are usually also sprayed during flowering and harvest to provide control of this disease. Raspberry rust (Phragmidium rubi-idaei): This disease has increased in importance in recent years. The foliage, sepals and pedicels of flowers and occasionally the individual drupelets of fruit can be infected. Picking of fruit in crops of autumn-fruiting raspberries when there is widespread foliage infection present can be unpleasant and can leave some fruits unsaleable, due to contamination with spores. The principal impact of infection is the reduction of photosynthetic area of leaves during the infected crop’s growing season and premature leaf drop, the latter potentially reducing the winter hardiness of summer-fruiting raspberry canes. Most current commercial raspberry cultivars are susceptible or highly susceptible to infection, notably Glen Ample, Tulameen and Polka, so most growers now routinely apply fungicides for the control of this disease pre- or post-harvest, as soon as infection is noted. Several fungicides have activity against raspberry rust i.e. azoxystrobin, boscalid + pyraclostrobin, fenpropimorph, myclobutanil, and tebuconazole. Myclobutanil is particularly useful where infection is first identified just prior to or during harvest. Many growers are now routinely applying tebuconazole in outdoor and protected raspberry crops in order to reduce the risk of infection occurring during harvest.
5.10.2 Changing approvals legislation scenario
Under the changing approvals legislation scenario, the following active substances that are currently used on raspberries could be lost:
• Bifenthrin (insecticide)
• Glufosinate-ammonium (herbicide)
• Iprodione (fungicide)
• Pendimethalin (herbicide)
• Tebuconazole (fungicide) The impact of these losses on weeds pests and diseases is identified in Table 52.
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Table 52.
Impact of weeds, pests and diseases on raspberry as a result of the pesticide losses caused by the changing approvals legislation
scenario– whilst using sensible m
itigation, e.g. biological controls. Cost to the industry is the additional cost
Changing approvals
legislation
Broadleaved
weeds
Creeping bitter
yellow cress
Grass weeds
Horsetails
Perennial
bindweeds
Primocane
control
Aphids
Raspberry beetle
Brown scale
Capsid and plant
bugs
Caterpillars
Raspberry cane
midge
Two spotted
spider mite
Pre-planting soil
pests
Sawfly
Slugs & snails
Weevils
Whitefly
Cane spot
Botrytis (canes &
fruit)
Cane blight
Powdery mildew
Raspberry yellow
rust
Pre-planting soil
diseases
Area affected (ha)
1,634
163
1,634
8163
1,634
1,144
1,634
82
1,634
163
1,634
817
1,634
245
409
817
163
817
1,634
817
817
817
817
Yield Loss (t)
5,255
6,649
5,966
6,663
6,634
4,545
2,488
5,966
6,677
5,966
6,649
6,251
6,535
6,499
6,677
6,641
6,535
6,649
6,322
5,966
6,322
6,322
6,606
5,966
Cost to the industry (£K)
-6,311-1,278-10,998
22-1,227
-5,837-15,234
-20,075
-472-18,921
-280
12
-311
#####
-277
0-12,635
-753
-7,085
0-14,204-11,847
-8,999
-3,112
Cost per affected
hectare (£K)
-4-8
-73
-8-4
-13
-12
-6-12
-20
0-7
-10
-15
-5-9
0-17
-15
-11
-4
Percentage reduction in
production (%)
37.0
46.8
42.0
46.9
46.7
32.0
17.5
42.0
47.0
42.0
46.8
44.0
46.0
45.7
47.0
46.7
46.0
46.8
44.5
42.0
44.5
44.5
46.5
42.0
Table 53.
Impact of weeds, pests and diseases on raspberry as a result of the potential pesticide losses caused by the restrictions put in
place by the current water quality requirements – whilst using sensible m
itigation, e.g. biological controls.
Water Quality
Broadleaved
weeds
Creeping bitter
yellow cress
Grass weeds
Horsetails
Perennial
bindweeds
Primocane control
Aphids
Raspberry beetle
Brown scale
Capsid and plant
bugs
Caterpillars
Raspberry cane
midge
Two spotted
spider mite
Pre-planting soil
pests
Sawfly
Slugs & snails
Weevils
Whitefly
Cane spot
Botrytis (canes &
fruit)
Cane blight
Powdery mildew
Raspberry yellow
rust
Pre-planting soil
diseases
Area affected (ha)
1,634
163
1,634
82
245
1,634
1,144
1,634
82
1,634
163
1,634
817
409
245
490
327
163
817
1,634
817
817
817
817
Yield Loss (t)
5,255
6,649
5,966
6,663
6,634
4,545
6,478
5,966
6,677
5,966
6,649
6,251
6,535
6,499
6,677
6,641
6,535
6,649
6,322
5,966
6,322
6,322
6,606
5,966
Cost to the industry (£K)-11,189
0-11,273
0-2,121
00
00
0-285######
00
0-2,041
00
00
00
0-4,746
Cost per affected
hectare (£K)
-70
-70
-90
00
00
-2-7
00
0-4
00
00
00
0-6
Percentage reduction in
production (%)
37.0
46.8
42.0
46.9
46.7
32.0
45.6
42.0
47.0
42.0
46.8
44.0
46.0
45.7
47.0
46.7
46.0
46.8
44.5
42.0
44.5
44.5
46.5
42.0
* Cost to the industry assumes that the active substances are lost to the whole industry; however a complete revocation of the active substance is a last resort. Instead specific catchments may be
affected, if this is the case the cost per hectare can be used to apply to the area within a catchment that is affected.
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Weeds
The loss of amitrole is of most importance, although glyphosate remains an effective active substance for the control of perennial or annual broad-leaved or grass weeds prior to planting raspberries. In contrast, the loss of pendimethalin would not cause great problems, especially now that its usefulness for long term control against several weed species is impaired, following a reduction in the maximum individual rate of use from 5 to 3.3L/ha. The loss of glufosinate-ammonium would affect the post-emergence control of many broad-leaved and grass weeds e.g. annual meadow grass growing in the crop rows, which would be difficult if not impossible to control. The wide spectrum of activity of this herbicide, (including unwanted raspberry primocane removal from plantation alleys), means that it is widely and regularly used by growers to clear the plantation’s soil surface of over-winter germinated weed in March and to keep the alleys or edges of raised beds free of weed until and after harvest. Some growers also use this product for unwanted primocane removal in the crop rows, although carfentrazone-ethyl has been found to be a more effective and safer product to repeatedly use in plantations for this purpose. It offers good control of annual broad-leaved weeds such as cleavers and American willowherb, but has no activity against grasses.
Pests
Aphids (Amphorophora idaei, Aphis idaei, Myzus persicae, Macrosiphium euphorbiae): A serious effect as loss of bifenthrin, on top of losses that have already occurred due to failure to achive Annex 1 inclusion, will leave only pymetrozine and pyrethrins for the control of these pests and no strategy to prevent resistance. The loss of these pesticides and resultant failure to control especially the large raspberry aphid, will also lead to an increased risk of aphid-borne virus incidence in the majority of raspberry crops, including those which currently have A10 resistance. As a result, the lifespan of commercial plantations is expected to be substantially reduced. Raspberry beetle (Byturus tomentosus): The loss of bifenthrin, and other active substances lost due to failure to gain Annex 1 inclusion, will leave growers with few options for raspberry beetle control close to or during harvest especially in primocane (autumn) fruiting raspberry plantations where adult beetles numbers and hence the risk of crop damage and fruit contamination are high. The use of funnel traps with flower volatile lures will take some time to establish and be accepted by commercial growers as a safe, viable means of controlling this pest. Currently the cost of this method of control is also substantially greater that that for chemical control. Capsids (Lygocoris pabulinus, Lygus rugulipennis): The loss of insecticides to changing pesticide legislation, on top of those that have failed to achieve Annex 1 listing would result in the effective control of common green capsid becoming more or less impossible, as will also be the case with tarnished plant bug. Crop losses as a result of the increased presence in crops of these pests could be expected to be substantial. Weevils (Otiorhynchus sulcatus, O. singularis): Control of both vine weevil and clay coloured weevil would become impossible, unless a replacements for bifenthrin is found. The loss of bifenthrin is of significance, as this was the only really effective active against adult weevils.
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Two-spotted spider mite (Tetranychus urticae): No real change would result, as bifenthrin is no longer used primarily for control of this pest. Biological control is improving and several newer acaricides which may eventually achieve approval for use in cane fruit crops e.g. bifenazate, spirodiclofen are appearing.
Diseases
Cane spot (Elsinoe veneta): Potentially a serious impact, as the changes would remove tebuconazole, which is one of only four products with any activity against this disease. Spur blight (Didymella applanata): Potentially a serious impact, as tebuconazole could be lost, one of only two products with any activity against this disease. Cane blight (Leptosphaeria coniothyrium): Again a potentially a serious impact, as the changes would remove tebuconazole, one of only two products with any activity against this disease. Also, this loss will mean that there is no strategy available for preventing fungicide resistance. Powdery mildew (Sphaeratheca macularis): Impact would be the greatest on the protected crop, as this is the most susceptible to infection. Loss tebuconazole would mean that effective control of this disease, especially in susceptible cultivars of long cropping season autumn- and late spring-early summer- fruiting plantations would be very difficult and, in some seasons, impossible to achieve.
5.10.3 Water Quality
The active substances that are currently available on raspberry that are at risk from restrictions due to water quality requirements are:
• Asulam (herbicide)
• Chlorpyrifos (insecticide)
• Glyphosate (herbicide)
• Iprodione (fungicide)
• MCPB (herbicide)
• Metaldehyde (molluscicide)
• Propyzamide (herbicide) The impact of these restrictions is shown in Table 48.
Weeds
The loss of glyphosate is of most importance in this scenario, especially if amitrole is lost to changing approvals legislation, as there are currently no other effective actives for the control of perennial or annual broad-leaved or grass weeds prior to planting the raspberry crop. The loss of asulam would mean that growers have no pre- or (most importantly) post-planting treatment for the control of docks, a weed that in recent years has become increasingly significant in all soft fruit crops, particularly strawberries and cane fruit. The loss of propyzamide would mean that the control of many over-winter germinated and established grass weeds would be completely compromised in this crop, especially if the approval for fluazifop-P-butyl is, as expected, also lost. In recent years perennial grass weeds have become an increasing problem in raspberries. With the revocation of the approval for the use of dichlobenil in all crops including raspberry, the above products remain as the only options for the control of these weeds.
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The loss of MCPB would remove the only remaining legal active for the control or suppression of perennial broad-leaved weeds including creeping thistle and perennial bindweeds in this crop. This would substantially increase crop loss due to reduction of crop vigour and the inability of pickers to harvest crop in infested areas of plantations. Costs of production due to the additional hand weeding that would be required to achieve at least some control of these weeds, even if black polymulch or woven plastic mulches were used to cover the soil surface in the crop rows, would also increase.
Pests
Raspberry cane midge (Resseliella theobaldi): The loss of chlorpyrifos would mean that control of this pest would no longer be possible in commercial raspberry crops. Pheromone use for ‘lure, trap and kill’ or mating disruption is not proven and currently looks unlikely to offer reliable techniques for the control of this pest. Cane losses and hence reductions in yield could be expected as a result of the inability to control this pest. Caterpillars (various including Cacoecimorpha pronubana, Archips podana, Epidlema uddmanniana): The loss of chlorpyrifos would be important on sites where caterpillars e.g. bramble shoot moth are present on crops early in the year in cold weather, when the activity of alternative insecticides is likely to be impaired. Spinosad is expected to be used for caterpillar control in cane fruit crops as a replacement for chlorpyrifos but at present only has use on the outdoor crop. Its use for caterpillar control is however likely to result in the resistance of western flower thrips to this active. This thrips species is expected to become an increasingly important pest of raspberries and other cane fruits over the next few years. The loss of metaldehyde for slug and snail control would create difficulties as regards the control of these pests, as although ferric phosphate could be used for slug control it has little if any activity against snails which are potentially the more serious of the two in raspberries. As a crop contaminant at harvest, the presence of snails leads to crop rejection (a single consignment or even a whole season’s produce).
Disease
Water quality requirements will have no additional impact upon the industry as far as disease control is concerned, as iprodione is now rarely used for fruit or cane Botrytis control in raspberry crops.
5.10.4 Other reasons for pesticide losses
These have mainly occurred due to the regular presence of residues in fruit at harvest (buyer and consumer pressure) or lack of supporting data for re-registration of approval for use in a minor crop. For example a Standing Committee decision in July 2007 to reduce the MRL for chlorothalonil in raspberries to the limit of determination resulted in the revocation of approval for use of chlorothalonil in raspberry.
5.11 Strawberry At least 70% of the area currently used for strawberry production in the UK is protected for at least part of its growing season by polythene clad tunnels e.g. Spanish tunnels. For fruit produced for fresh market sales via the major multiples, at least 90% of the cropped area is protected in this way. The tunnel legs and hoops of these structures are placed in
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position either prior to or just after planting the crop. Depending upon the type of strawberry i.e. June-bearing or everbearer, the planting and the type of material being used (i.e. fresh dug, cold stored runners, tray or misted tip plants), the tunnels are clad with polythene either within one or two days or weeks or 7-8 months after planting. For this study an in-soil grown crop is used. Table 54. Strawberry gross margin
Crop Strawberry
Crop area* ha 4,770
Yield* t/ha 21
Value* £/t 1,921
Plants / planting &
sterilisation
£/ha 3,464
Fertiliser cost £/ha 900
Spray cost £/ha 1,707
Bio-control cost £/ha
Cultivation costs** £/ha 1,120
Other costs*** £/ha 4,687
Total value £/ha 41,109
Total costs £/ha 11,878
Gross margin £/ha 29,231 *Defra horticulture statistics ** Basic cultivations pre-planting, bio-control, weeding *** Spanish tunnels, polythene cladding and trickle irrigation
5.11.1 Business as usual and untreated scenarios
Under ‘business as usual’ the largest potential gains could come from improved control of grass weeds (£37M), botrytis (£33M), broad-leaved weeds, strawberry runners and blossom weevils (£29M) (Table 55). The figures in brackets are the potential increase in value to the industry that could occur if 100% control was achievable. In the absence of pesticides, major losses in strawberries when using sensible non-pesticide mitigation measures are caused by blossom weevils (52% reduction in production), powdery mildew (39% reduction in production) and botrytis (25% reduction in production). Reduced control of weeds would also result in yield losses (Table 56).
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Table 55.
Impact of weeds, pests and diseases on strawberry under business as usual (potential yield and gross m
argin increases if better
control was possible - despite use of available pesticides)
Business as usual
Broadleaved weeds
Grass weeds
Horsetails
Strawberry runners
Capsid and plant bugs
Tortrix caterpillars various
Two spotted spider mites
Blossom Weevil
Vine weevil
Whitefly
Slugs & snails
Botrytis
Powdery mildew
Area affected (ha)
4,770
4,770
24
4,770
2,385
1,193
3,339
3,578
2,385
48
3,816
4,770
3,339
Potential increase in yield if 100%
control possible (t)
15,312
19,395
77
15,312
7,145
766
4,287
15,312
7,656
82
10,616
17,353
12,862
Potential increase in value to
industry if 100% control possible
(£K)
29,414
37,257
147
29,414
13,726
1,471
8,236
29,414
14,707
157
20,394
33,336
24,708
Increased value per affected
hectare (£K)
68
66
61
28
63
57
7
Table 56.
Impact of weeds, pests and diseases on strawberry in the absence of pesticide applications – whilst using sensible m
itigation, e.g.
biological controls. (Worst case scenario)
Untreated
Broadleaved weeds
Grass weeds
Horsetails
Strawberry runners
Capsid and plant bugs
Tortrix caterpillars various
Two spotted spider mites
Blossom Weevil
Vine weevil
Whitefly
Slugs & snails
Botrytis
Powdery mildew
Area affected (ha)
4,770
4,770
24
4,770
2,385
1,431
3,339
3,578
2,385
48
3,816
4,770
3,339
Yield Loss (t)
20,416
20,416
77
20,416
12,760
6,125
12,862
53,591
20,416
102
16,332
25,520
39,300
Cost to the industry (£K)
-36,781
-36,781
-135
-36,781
-23,942
-11,424
-25,832
-102,094
-38,649
-185
-31,307
-45,521
-73,044
Cost per affected hectare (£K)
-8-8
-6-8
-10
-8-8
-29
-16
-4-8
-10
-22
Percentage reduction in
production (%)
20.0
20.0
0.1
20.0
12.5
6.0
12.6
52.5
20.0
0.1
16.0
25.0
38.5
I
102
Weeds
Broad-leaved weeds: Even with planting through polythene mulch covering the soil surface in the crop rows, both annual and perennial weeds can be difficult to control in both outdoor and protected strawberry crops. As a consequence, most growers take some time to rid the site to be planted of pernicious perennial weeds e.g. creeping thistle, clover, perennial nettle, dandelion etc. Post-planting, and thereafter, pre-emergence residual and translocated herbicides are applied routinely over the plantations of raised beds to reduce the numbers of weeds that can germinate and emerge around each plant in the planting holes or through tears or splits that have inadvertently been created in the mulch. Contact and contact/translocated herbicides are also used (mostly as carefully directed/shielded applications) in the wheelings between the raised beds to remove weeds and strawberry runners post-planting onwards, along with one or two applications of residual herbicides to minimise the germination of annual weeds. Currently there is a reasonable range of herbicides available to the industry for use before and after planting which will provide, if applied at the correct time, control of most arable annual weeds. However, the approvals of some actives have recently been revoked e.g. chlorthal–dimethyl and propachlor. As a result some weeds, notably mallow, cleavers, groundsel, cranesbills, black nightshade and redshank, still prove difficult to control on some sites. HDC is currently funding trials to identify new residual, contact and contact/translocated actives that might be safely used in strawberries. As in the model adopted for this study, the soil surface of the raised beds is covered with black polythene mulch and the wheelings between the beds maintained weed free using a range of residual and contact herbicides. Unwanted runners growing on the beds are removed by a topper post-harvest and, in the late winter/early spring, runner removal in the wheelings and sides of the raised beds is achieved through the shielded application of contact herbicides. Grass weeds: Prior to the crop being planted, glyphosate or amitrole are used to clear couch and other perennial and annual grass weeds. Some growers have returned to the use of amitrole as they have found in recent years that glyphosate no longer provides effective control of couch grass. With the notable exception of isoxaben, most of the current residual herbicides approved for use in strawberries will provide control of annual meadow grass, provided that application of a suitable product is made in the late autumn i.e. October each year. Control of grass weeds post-emergence is now reliant upon the use of glufosinate-ammonium and propyzamide, the former applied in the wheelings between the raised beds containing the crop in March (use limited to March – October) and the latter applied during the winter months (Nov-January). Currently two ACCase inhibitor herbicides, cycloxydim and fluazifop-P-butyl, are approved for application in strawberries for the post-emergence control of grass weeds including couch grass and volunteer cereals. However, the incidence of grass weeds which are not always susceptible to this group of herbicides, e.g. canary grass and barren (sterile) brome, is increasing in some areas of the UK (notably the south and south-east of England), so grass weeds in the strawberry crop are an increasing problem. Horsetails (Equisetum sp.): Currently there are no products which can provide effective control or growth suppression of horsetails in strawberry crops. Some growers in desperation use 2,4-D post-harvest in order to lessen the impact of this weed in their
103
crops. Glufosinate-ammonium is also applied pre- and post-harvest in the wheelings as a carefully directed shield spray in order to check the weed. Strawberry runner control: At least two and sometimes three applications of either glufosinate-ammonium (with or without the addition of a wetter), diquat or diquat + glufosinate-ammonium are applied each growing season. This can be as shielded or directed sprays down the wheelings of plantations where the crop is grown in poly-mulched covered raised beds or, where there is no poly-mulch laid on the soil surface of the beds, down the wheelings and between the rows of strawberries in the beds to remove unwanted strawberry runners. Without runner removal, competition for light, nutrients and water between the strawberry plants within a plantation would inhibit flower initiation, flower set and substantially reduce flower set, fruit size and hence also yield. Plants would be more prone to pathogens, especially Botrytis and powdery mildew infection, and effective control of these diseases would be impaired. Harvesting a crop without adequate runner control would also be very difficult and costly. In the case of weeds, around 15% loss of potential yield is the norm as a result of inadequate broad-leaved, grass weed and strawberry runner control. If no herbicides were available for their control then the loss of yield could be expected to rise to 20%. Without the current range of herbicides control of broad leaved weeds before and particularly after planting would be very difficult in the crop rows and bed wheelings. Radical changes to the methods of alleyway weed control would be required, involving the covering of the soil surface in this area of the plantation with a woven plastic mulch in order to exclude weeds; weed control in the crop rows would need to be carried out by hand and runner removal partly by hand and partly (as now) by the use of a tractor- mounted topper run over the tops of the beds.
Pests
Capsids: Common green capsid (Lygocoris pabulinus) and tarnished plant bug (Lygus rugulipennis; Common green capsid attacks foliage, flowers and fruits predominantly during the early summer, whilst the tarnished plant bug targets flowers and fruit during the summer and early autumn. Late June-bearing and everbearer crops are the most seriously damaged by these pests. Currently there is a very limited range of products available for the control of capsids. In most cases either thiacloprid or (predominately) bifenthrin is applied to achieve control. Bifenthrin is particularly useful as it has a nil day harvest period, so use is possible during the harvest of everbearer varieties when tarnished plant bug levels may be such that, without control, a high proportion of fruit will be so badly damaged that it will be unmarketable. Growers however endeavour to avoid pesticide use against this pest during harvest as all the products involved are potentially injurious to beneficials, be they pollinating insects or predatory mites or insects introduced into the crop to control pests such as two-spotted spider mite, tarsonemid mite or aphids. Funnel traps containing pheromones are under development for detecting the presence and for monitoring the population of these pests. They are not likely to be suitable for ‘lure and kill’ application to control either of these capsids in the near future. Caterpillars - carnation tortrix moth (Cacoecimorpha pronubana), straw coloured tortrix moth (Clepsis spectrana), flax moth (Cnephasia interjectana) and strawberry tortrix moth (Acleris comariana): The caterpillars of several tortrix moths are pests of both outdoor and protected strawberry where serious damage to the foliage, flowers and fruits can occur.
104
Currently there are a reasonable number of actives available for the control of these pests, although use of spinosad is restricted to the protected crop and unless caterpillars are very small at the time of application, Bacillus thuringiensis often proves to be ineffective against them. Chlorpyrifos is primarily used for tortrix moth caterpillar control pre-flowering or post- harvest and bifenthrin when control is required closer to or actually during harvest. Two-spotted spider mite (Tetranychus urticae): These mites cause damage to foliage, flowers and fruits, reducing plant vigour and yield. There is currently a reasonable range of acaricides for use on both outdoor and protected crops. Integrated pest management (IPM) is widely practised with regards to the control of this pest, with Phytoseiulus persimilis, Amblyseius californicus, Amblyseius andersoni and Feltiella acarisuga introduced into crops routinely for its control.
Conditions in tunnel-grown and other protected crops favour this pest, so growers regularly monitor for its presence from the onset of plant growth. In the absence of pesticides greater reliance will have to be made by growers on the introduction of predatory mites Phytoseiulus persimilis, Amblyseius andersoni and Amblyseius californicus for the control of this pest. Although the latter can only be introduced into AYR protected crops, its presence has been recorded in many outdoor and tunnel protected plantations, where it successfully overwinters. In protected crops, Feltiella acarisuga is often introduced into pest hot spots to aid control. Biological control of two-spotted spider mite is possible in both outdoor and protected crops, but can be expensive both as regards the cost of predators used and the monitoring that this technique demands.
Currently there are no other non-pesticidal, practicable or economically viable options available to growers for the control of strawberry blossom weevil, capsids, whitefly or slugs and snails. Strawberry blossom weevil (Anthonomus rubi): A very serious pest of strawberry; adult female blossom weevils bite part way through the pedicels of flower buds in which they have laid an egg. The affected flower buds fail to open, detach from the flower truss and fall to the ground. The eggs hatch and the resultant beetle larvae feed within the flower bud, pupate and emerge as adult weevils later in the summer. These adult weevils feed on the petals and youngest foliage of several rosaceous crops and hedgerow plants including strawberry, causing some damage to everbearer strawberry crops that are flowering through the summer into the autumn. In the early autumn, the adult weevils hide in the crop debris around the plants they have been feeding upon and may hibernate there. They emerge in May or June of the following year. The latest flowers of early-fruiting and potentially all of the flowers of mid- and late June-bearing cultivars are susceptible to attack where the pest remains uncontrolled. Some plantations of late-fruiting June-bearing cultivars, e.g. Florence, have lost 60 - 70% of their flowers to this pest. On many sites therefore, routine applications of chlorpyrifos, bifenthrin or thiacloprid are being applied as soon as the first signs of damage to the flower buds are noted. This is usually as the flower trusses start to elongate out of the centre of the plants crowns. Late-flowering cultivars and those with few flowers per flower truss are the most liable to attack and to suffer serious economic loss. Chlorpyrifos has been found to provide the most effective control of this pest, but only when applied at the maximum rate of use and at high volume, so that effective coverage of the crop canopy and underlying leaf stalks and crop debris is achieved.
105
Cross-vaned funnel traps containing flower volatile lures are currently under development, initially to identify the presence of, and monitor the population of, strawberry blossom weevil in crops. It is hoped that at some stage that these traps might also be employed to ‘lure and kill’ this pest. Wingless weevils i.e. vine weevil (Otiorhynchus sulcatus) and clay coloured weevil (O. singularis): Vine weevil is now a widespread problem in strawberries. Clay coloured weevil in contrast is a more localised problem. Adult vine weevil causes damage to the plant foliage and usually this is how their presence is first noted. Adults are potential post-harvest crop contaminants, but it is the larvae of these pests that cause the most serious damage to crops by feeding during the late summer, autumn and early spring. In some cases, larvae almost completely destroy the root systems of large numbers of plants. The collapse or actual death of plants damaged in this way regularly occurs during the period between flowering and picking, as a result of the increasing demand upon the plant roots as the foliar canopy expands and fruits develop, but cannot be sustained. The majority of growers currently apply sprays of bifenthrin in the evening for the control of adult weevils, as soon as appreciable numbers of these pests are seen feeding in the crop canopy. Sprays of thiacloprid or chlorpyrifos are also occasionally used, but experience is that they are usually less effective in controlling this pest and/or cannot be used close to or during harvest (bifenthrin has a nil harvest interval). Some of the alternatives also have an unacceptable and long term impact upon predatory mites or midges used in the crop to control two-spotted spider mite. A soil drench of chlorpyrifos is also often used in crops where this pest has been found. This provides control of weevil larvae and is usually applied when the soil conditions are suitable after harvest in either September or October, depending on the harvest period of the crop involved. For substrate-grown crops, growers increasingly use applications of insect pathogenic nematodes i.e. Steinernema kraussei or Heterorhabditis sp.) in the late summer-early autumn or late winter-early spring periods for the control of the weevil larvae. However, this technique is at present very expensive and far less reliable when applied to soil-grown crops. Work is currently underway to identify new insecticides with activity against this pest and other biological agents for larval control. In the absence of pesticides more reliance would have to be made on the use of insect pathogenic nematodes i.e. Steinernema kraussei or Heterorhabditis spp.) applied to the soil or substrate in the late summer-early autumn or late winter- early spring for the control of these pests. However this technique is at present very expensive when used and far less reliable if applied to soil-grown crops. Whitefly (Trialeurodes vaporariorum): Predominantly seen as a pest of AYR protected strawberry crops. Bifenthrin, thiacloprid, dodecyl phenol ethoxylate, natural plant extracts, pyrethrins and spiromesifen (in substrate-grown crops only) can be used in the strawberry crop to control whitefly, but unfortunately resistance to most of these actives is widespread. Growers are resorting to repeated applications of dodecyl phenol ethoxylate, natural plant extracts and sticky traps. Crop hygiene is important, especially with regards to weed control and removal of all spent crop foliage and other crop debris that could act as over-wintering sites for this pest. Encarsia formosa is used but does not work well in
106
strawberries for the control of whitefly. The recent approval of a product containing the pathogenic fungus Beauveria bassiana strain ATCC 74040 will be helpful to growers who have problems with the control of whitefly in protected crops. Slugs and snails: Both of these pests cause damage to strawberry crops, including those under tunnel protection. In wet seasons losses of fruit, particularly in raised beds running adjacent to the tunnel legs where water from the roofs falls to the ground, tend to be the most damaged. Growers routinely use bait boxes, or in some cases overall applications, of metaldehyde- based slug pellets through the crop. These are usually used at the onset of flowering. Some growers use ferric phosphate instead of metaldehyde-based products, but only if the main pest is slugs not snails. The cost of these products is far greater than those containing metaldehyde. Methiocarb-based pellets are still permitted for use in strawberries but only in outdoor crops, so use of these is far less than in the past.
Diseases
Botrytis (Botrytis cinerea): One of the most important diseases of strawberries, causing losses before and especially after harvest of fruit. Post-harvest losses are the result of fruit collapsing and developing spore bodies on their surface within a few hours or days of picking, during their distribution or sale. Currently there is a wide range of fungicides available for the control of this disease, some with short harvest intervals, that enable them to be used in everbearer cultivars close too, or actually during, harvest. The rapid cooling of fruit to 2-4ºC within a few hours of harvest and thereafter during storage, packing, distribution and sale at temperatures between 4-6ºC can substantially reduce the risk of fruit developing this disease. A high proportion of fruit is recognised to carry latent infection, even where routine application of fungicides for its control has been made during flowering. The protection of crops with polythene-clad tunnels during their flowering and harvest period reduces the levels of fruit found infected with Botrytis during picking; however a high proportion of the fruit will still carry latent infection and so be liable to develop the disease if the fruit is not handled appropriately up until the point of sale or consumption. Established plantations of June-cropping and everbearer strawberries are usually topped in the late winter-early spring to remove as much dead or decaying crop debris (leaf litter etc) as possible. This may be followed by a drench of a suitable fungicide just prior to, or soon after, the onset of crop growth to reduce over-winter inoculum of Botrytis and powdery mildew. Powdery mildew (Sphaerotheca macularis): This disease is of considerable and increasing importance as it infects foliage, stolons, flowers and fruits. This inhibits the photosynthetic ability of the plant, reducing growth and cropping potential. Mildew-infected fruits are unmarketable. Unfortunately most of the current major commercial June- and everbearer strawberry cultivars are either susceptible or very susceptible to infection by this disease, with newly planted plantations becoming rapidly infected with the disease if established adjacent to infected plantations. The increased day and night temperatures and the high relative humidity often experienced by the crop during the period July –October favours the development and spread of powdery mildew. Even where tunnel management is good enough (appropriately ventilated) to achieve temperatures and relative humidity less
107
conducive to this disease, routine application of fungicides is the norm, especially for crops which are being harvested during the period July – September. Currently there is a wide range of actives available for the control of powdery mildew, although the majority are protective rather than curative in action. However, application close to and during harvest creates problems as regards residues in crops at harvest.
5.11.2 Changing approvals legislation
Under the changing approvals legislation scenario, the following active substances that are currently used on strawberry could be lost:
• Amitrole (herbicide)
• Bifenthrin (insecticide – failure to gain Annex 1 inclusion)
• Glufosinate-ammonium (herbicide)
• Pendimethalin (herbicide)
• Quinoxyfen (fungicide) The impact of these potential losses is shown in Table 57. The most significant impact is the failure of bifenthrin to gain Annex 1 inclusion. This will result in reduced control of blossom weevil (15% reduction in production) and capsid and plant bugs (11% reduction in production). The reduced availability of herbicides will also cause some yield losses from broad leaved weeds and reduced strawberry runner control (5% loss of production).
108
Table 57.
Impact of weeds, pests and diseases on strawberry as a result of the pesticide losses caused by the changing approvals legislation
scenario– whilst using sensible m
itigation, e.g. biological controls. Cost to the industry is the additional cost
Changing approvals legislation
Broadleaved weeds
Grass weeds
Horsetails
Strawberry runners
Capsid and plant bugs
Tortrix caterpillars various
Two spotted spider mites
Blossom Weevil
Vine weevil
Whitefly
Slugs & snails
Botrytis
Powdery mildew
Area affected (ha)
4,770
4,770
24
4,770
3,339
1,193
3,339
3,578
2,385
48
3,816
4,770
3,339
Yield Loss (t)
5,104
1,021
05,104
10,718
510
015,312
5,104
00
00
Cost to the industry (£K)
-23,716
-15,992
-18
-23,836
-20,526
-958
-270
-29,345
-11,340
00
0-668
Cost per affected hectare (£K)
-5-3
-1-5
-6-1
0-8
-50
00
0
Percentage reduction in
production (%)
5.0
1.0
0.0
5.0
10.5
0.5
0.0
15.0
5.0
0.0
0.0
0.0
0.0
Table 58.
Impact of weeds, pests and diseases on strawberry as a result of the potential pesticide losses caused by the restrictions put in
place by the current water quality requirements – whilst using sensible m
itigation, e.g. biological controls.
Water Quality
Broadleaved weeds
Grass weeds
Horsetails
Strawberry runners
Capsid and plant bugs
Tortrix caterpillars various
Two spotted spider mites
Blossom Weevil
Vine weevil
Whitefly
Slugs & snails
Botrytis
Powdery mildew
Area affected (ha)
4,770
4,770
24
4,770
3,339
03,339
3,578
2,385
48
3,816
4,770
3,339
Yield Loss (t)
10,208
6,125
05,104
10,718
3,828
022,968
5,104
05,716
00
Cost to the industry (£K)
-33,362
-25,816
-18
-24,344
-20,526
-7,326
0-44,121
-11,087
0-10,914
00
Cost per affected hectare (£K)
-7-5
-1-5
-60
0-12
-50
-30
0
Percentage reduction in
production (%)
10.0
6.0
0.0
5.0
10.5
3.8
0.0
22.5
5.0
0.0
5.6
0.0
0.0
* Cost to the industry assumes that the active substances are lost to the whole industry; however a complete revocation of the active substance is a last resort. Instead specific catchments may be
affected, if this is the case the cost per hectare can be used to apply to the area within a catchment that is affected.
109
Weeds
The loss of amitrole is of most importance, as this would leave only one active for the control of perennial or annual broad-leaved or grass weeds for use prior to planting of the strawberry crop. In contrast, the loss of pendimethalin would not cause great problems, especially now that its usefulness for long term control of several weed species is impaired, following the reduction in the maximum individual rate of use from 5 to 3.3L/ha. The loss of glufosinate-ammonium would cause difficulty as regards the post-emergence control of many broad-leaved and grass weeds. For example, annual meadow grass growing in the wheelings or between the crop rows would become difficult if not impossible to control. The wide spectrum of activity for this herbicide, (including the removal of unwanted strawberry runners growing in the wheelings or between the crop rows of plantations) means that it is widely and regularly used by growers to clear the soil surface of over-winter germinated weed in March and to keep alleys or edges of raised beds free of weed and unwanted runners until after harvest.
Pests
The loss of bifenthrin will cause the industry great problems as regards the control of capsids, strawberry blossom weevil and adult wingless weevil, as there are few if any alternatives for the control of these pests. Losses of harvestable yield could therefore increase appreciably, to 40% for strawberry blossom weevil and capsids and 25% in the case of wingless weevils. The loss of this synthetic pyrethroid would also impact upon the control of tortrix moth caterpillars in protected and particularly outdoor strawberry crops, with the reduction in harvestable yield due to damage caused by these pests increased from 3 to 5%. There would be little or no effect on any yield loss incurred as regards two-spotted spider mite or whitefly control. Likewise the loss of the above actives would not affect the control of slugs and snails.
Diseases
Quinoxyfen is widely used by growers for powdery mildew control in the late spring in both June-bearing and everbearer strawberry crops. Despite its loss, the industry would still currently have access to a reasonably wide range of actives for the control of this disease.
5.11.3 Water Quality
The active substances that are currently available on strawberry that are at risk from restrictions due to water quality requirements are:
• Asulam (herbicide)
• Chlorpyrifos (insecticide)
• Glyphosate (herbicide)
• Iprodione (fungicide)
• Metaldehyde (molluscicide)
• Propyzamide (herbicide) The impact of these potential restrictions is shown in Table 58. The most significant impact would be on the level of blossom weevil control achieved (22% reduction in yield) and on broad-leaved weed control (10% reduction in production).
110
Weeds
The loss of glyphosate would leave growers with no herbicides for the effective control of perennial broad-leaved or grass weeds before planting strawberries. To continue to grow crops successfully in the soil, the use of a 12- or 18-month bare fallow pre-planting, in order to provide some control of perennial grass and some broad-leaved weeds, would have to be considered. This would require the foregoing of income from a site for longer between the grubbing of one strawberry crop and planting of the next. The loss of asulam would mean that growers have no pre- or, most importantly, post-planting treatment for the control of docks, a weed that in recent years has become increasingly important in all soft fruit crops, particularly strawberry. Loss of propyzamide would mean that the control of many over-winter germinated and established grass weeds would be completely compromised in this crop, especially where grass weeds have already developed, or are likely to develop, resistance to ACCase inhibitor herbicides.
Pests
The loss of chlorpyrifos would leave growers with no effective pesticides for the control of strawberry blossom weevil or capsids. Although thiacloprid has some activity against these pests, it cannot be relied upon to provide satisfactory control. The loss of chlorpyrifos would increase the area affected by tortrix moth caterpillar damage from 25 to 30% and the loss of harvestable yield from 5 to 15%, as there would no longer be any effective control measures available for use on outdoor crops and a very limited range of actives for use on the protected strawberry crop. The loss of metaldehyde for slug and snail control would create difficulties as regards the control of these pests. Although ferric phosphate could be used for slug control, it has little if any activity against snails, which are potentially the more serious of the two pests. They are a crop contaminant at harvest and their presence can lead to crop rejection (single consignment or even a whole season’s produce) by sales outlets.
Disease
This will have no additional impact upon the industry as far as disease control is concerned, as iprodione is now rarely used for fruit botrytis control in the strawberry crop.
5.11.4 Other reasons for pesticide losses
These have mainly occurred due to the presence of residues in fruit at harvest (buyer and consumer pressure) or lack of supporting data for re-registration of approval for use in strawberry, which is viewed as a minor crop.
5.12 Cucumber Cucumbers are grown only under protection, usually in heated glasshouses. Most crops are grown in bags of substrate (e.g. rockwool, coir or foam), with only a small area grown in the soil. Crops are usually replanted once or twice each year, normally onto the used substrate, to maintain production of high quality fruit. Inevitably there is greater disease pressure in the replanted crops, this sometimes applies to pests as well. Weeds are not a problem as the soil is covered with polythene. Pest control is primarily by use of biological control, with only occasional use of insecticides or acaricides. Disease control is achieved by a combination of tolerant varieties (where available), fungicides, glasshouse and environment control (esp. humidity control), good hygiene and crop management.
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Table 59. Cucumber gross margin
Crop CucumberCrop area* ha 105
Yield t/ha 557
Value £/t 675
Eastablishment costs £/ha 39,750
Fertiliser cost £/ha 11,000
Spray cost £/ha 7,000
Bio-control cost £/ha 5,000
Cultivation costs £/ha
Other costs £/ha
Total Value £/ha 375,975
Total costs** £/ha 62,750
Gross margin £/ha 313,225 *Defra horticulture statistics ** Input costs and yield average of 20 growers in 2009. (for seed cost read plant costs – up to three crops)
5.12.1 Business as usual and untreated scenarios
Under ‘business as usual’, the major causes of loss are gummy stem blight (Mycosphaerella) (£2.9M), powdery mildew (£2M) and pythium root rot (£2M) (Table 4). The major pest problem is two-spotted spider mite, accounting for £0.5M. If no pesticides were used, the major problem would be pythium root rot (£24,M) and gummy stem blight (£9.9M). Lack of any insecticides would have little effect on pest control due to the widespread adoption of biological pest control and its continuing successful development to counter emerging pest threats. Losses due to pythium are calculated at a price of £1/plant and a population of 15,000 plants/ha. Control of pythium is very dependent on hygiene and preventative treatment with propamocarb hydrochloride.
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Table 60.
Impact of pests and diseases on cucumber under business as usual (potential yield increases if better control was possible -
despite use of available pesticides)
Business as usual
Black root rot
Bacterial stem rot
Botrytis
Downy mildew
Fusarium wilt
Gummy stem blight
Penicillium stem rot
Powdery Mildew
Pythium root rot
Sclerotinia stem rot
Verticillium Wilt
Aphids
Capsid (tarnished
plant bug)
Caterpillars
Broad mite
Two-spotted spider
mite
Western flower
thrips
Whitefly
Leaf hopper
Area affected (ha)
00
11
132
0105
50
02
00
016
37
11
0
Potential increase in yield if 100%
control possible (t)
88
58
146
15
292
4,386
58
2,924
2,924
29
88
117
01
1877
409
585
1
Potential increase in value to
industry if 100% control possible
(£K)
59
39
99
10
197
2,961
39
1,974
1,974
20
59
79
01
1592
276
395
1
Increased value per affected
hectare (£K)
376
376
188
19
376
94
376
19
376
188
376
38
08
938
838
6
Table 61.
Impact of pests and diseases on cucumber in the absence of pesticide applications – whilst using sensible m
itigation, e.g.
biological controls. (Worst case scenario)
Untreated
Black root rot
Bacterial stem rot
Botrytis
Downy mildew
Fusarium wilt
Gummy stem
blight
Penicillium stem
rot
Powdery Mildew
Pythium root rot
Sclerotinia stem
rot
Verticillium Wilt
Aphids
Capsid (tarnished
plant bug)
Caterpillars
Broad mite
Two-spotted
spider mite
Western flower
thrips
Whitefly
Leaf hopper
Area affected (ha)
00
11
11
53
0105
63
00
50
20
16
37
11
0
Yield Loss (t)
88
58
2,924
15
292
14,621
58
11,697
35,091
29
88
292
058
1439
409
585
1
Cost to the industry (£K)
-59
-39
-1,937
-8-196
-9,686
-39
-7,528
-23,466
-19
-59
-180
0-21
-1-280
-148
-358
0
Cost per affected hectare (£K)
-372
-372
-184
-15
-372
-184
-372
-72
-372
-184
-372
-34
3-11
-6-18
-4-34
-2
Percentage reduction in
production (%)
0.2
0.1
5.0
0.0
0.5
25.0
0.1
20.0
60.0
0.1
0.2
0.5
0.0
0.1
0.0
0.8
0.7
1.0
0.0
113
Weeds
Weeds are not generally a problem within glasshouse cucumbers as they are planted into slabs of rockwool or other substrate. Bindweed (Fallopia convolvulus) Removed by hand between crops. White/black plastic over the soil surface is used to control weeds during cropping.
Pests
Aphids (Aphis gossypii, Aulacorthum solani, Macrosiphum euphorbiae and Myzus persicae ): Aphis gossypii is most damaging, usually infesting only summer-replanted crops. Other species occur throughout the year. Spraying with pymetrozine at first sign is usually effective. Biological control is possible, but more expensive (£250/ha). Low levels of aphids can be damaging, due to transmission of Cucumber Mosaic Virus. Tarnished plant bug (Lygus rugulipennis): Capsids affect crops during establishment. Yield losses are typically small – pymetrozine is used to reduce feeding damage to nil. Caterpillars: Tortrix moths (various species) cause damage. Indoxacarb works well to control them. Deltamethrin is used at the end of the season to reduce winter carry-over. Recently, problems have reduced compared with previous years. Caterpillars can also be removed by hand and this adds little time to regular crop work. Bacillus thuringiensis gives a good level of control of early-instar larvae. Broad mite (Polyphagotarsonemus latus): Controlled with biological control agents. Two-spotted spider mite (Tetranychus urticae): Abamectin resistance is increasing. Spiromezifen is reasonably effective, but has negative effects on biocontrol. Bifenzate (not yet approved) is less damaging to biocontrol and very effective. Biocontrol is expensive and needs skilled operators. Western flower thrips (Frankliniella occidentalis): Abamectin is relatively ineffective, due to resistance problems. Spinosad (Conserve) works to some extent in the north, but has little effect in the south, again due to resistance. Control is now achieved predominantly by biocontrol. Whitefly (Trialeurodes vaporariorum): Generally controlled by biocontrol, which can be very effective. Low levels of the whitefly can be very damaging, due to transmission of Beet Pseudo Yellows Virus.
Diseases
Black root rot (Phomopsis sclerotioides): Carbendazim was recently lost due to removal of its approval. The area affected by this disease was kept low due to its use. Levels may increase without identification of a suitable alternative. Thiophanate-methyl would be suitable if cleared for use. Bacterial stem rot (Pectobacterium carotovorum): This stem base rot is rare, confined largely to soil crops. Cupric ammonium carbonate can be used to aid control of the disease. Botrytis (Botrytis cinerea): Existing growing practices are keeping the problem under control, probably due to use of cyprodinil + fludioxonil.
114
Downy mildew (Pseudoperonospora cubensis): This non-indigenous disease tends to occur in a few crops each year, especially on the outside row of heated crops or in unheated crops. Although fungicides for control of the disease are available (e.g. azoxystrobin and metalaxyl-M), control is generally achieved through use of heat and ventilation. Fusarium wilt (Fusarium oxysporum f. sp. cucumerinum): An occasional but very damaging disease that tends to occur on certain nurseries each year. Drenching roots with carbendazim provided control until this chemical was withdrawn for commercial reasons. Currently it is controlled by removal of plants and replanting. With no effective fungicides available, this disease could become a significant problem over time, especially if infection occurred on a propagation nursery. Thiophanate-methyl would be suitable if cleared for use. Gummy stem blight (Didymella bryoniae ): This common and widespread disease, also known as Mycosphaerella, affects leaves, stems and fruit and is currently the major disease problem in cucumber. Fungicides used to reduce the disease are cyprodinil+fludioxonil and imazalil; iprodione is no longer available, having been withdrawn for commercial reasons. There is potential to improve on ‘business as usual’. Fungaflor is no longer available after 30 June 2010 (expected to be re-introduced). Penicillium stem rot (Penicillium oxalicum): Occasionally this disease occurs and can be very damaging, spreading rapidly at high humidity, but is usually only seen on a small number of isolated plants. It is controlled by prompt removal of affected plants and reduction of humidity. Iprodione was used as a HV spray to control the disease, but the approval was recently withdrawn for commercial reasons. There is a lack of known effective alternative fungicides if this disease were to re-appear as a major problem. Powdery mildew (Golvinomyces orontii and Sphaerotheca fusca): Control is dependent on myclobutanil. Tolerant varieties have reduced severity of this disease, but it remains a common problem. Bupirimate is available but harms biological pest control. Imazalil is available until 30 June 2010 and a new registration is expected from that date. Pythium root and stem base rot (Pythium aphanidermatum and other Pythium species): This is the major disease of cucumber and affects plants in all substrates. Crops re-planted in summer when root temperatures may be high due to lack of crop shading are particularly susceptible. Infection on re-plants from Holland is quite common. Preventative treatment with propamocarb hydrochloride is widely (almost exclusively) used; there are no alternative fungicides approved for control of pythium on the crop. Plants affected by pythium usually die, so they are removed and replaced with new plants, either at a different position on the slab or on a new slab. Plants cost £1/plant and the standard population is 15,000/ha. Sclerotinia stem rot (Sclerotinia sclerotiorum): This disease is most commonly found on shoots in the upper canopy, although it can affect fruit and stems. Control is by removal of affected plants or plant parts. Fungicides are rarely used to control the problem. Verticillium wilt (V. albo-atrum): This disease affects both soil-grown and substrate-grown crops. Affected plants invariably die. Control is by removal and replanting. Carbendazim drenches were used to provide some control until approval for this fungicide on cucumber was withdrawn for commercial reasons. The problem tends to persist on a nursery and can increase over a number of seasons. There is potential to improve over ‘business as usual’. Thiophanate-methyl would be suitable if cleared for use.
115
5.12.2 Changing approvals legislation scenario
Under the changing approvals legislation scenario, no active substances are expected to be affected that are used on cucumber. The impact of this potential loss is shown in Table 62).
5.12.3 Water Quality
No pesticides currently used on cucumber are expected to be affected by water quality requirements (Table 63). Iprodione could potentially be affected, but use of this fungicide on cucumber was recently withdrawn for commercial reasons.
5.12.4 Other reasons for pesticide losses
Pests
Aphids (Aphis gossypii, Aulacorthum solani, Macrosiphum euphorbiae and Myzus persicae ): Use of thiacloprid on cucumber may be prohibited due to retailer/consumer concern over a possible link between this type of insecticide and bee death. If this were the case, pymetrozine (e.g. Chess WG) would likely be used instead, but this would then become the only product for this use and could lead to resistance. Thiacloprid is cheaper and acts faster.
Diseases
No problem issues at present although iprodione has been lost due to the withdrawal of approval for use on cucumber. This was for commercial reasons.
116
Table 62.
Impact of pests and diseases on cucumber as a result of the pesticide losses caused by the changing approvals legislation
scenario– whilst using sensible m
itigation, e.g. biological controls. Cost to the industry is the additional cost
Changing approvals legislation
Black root rot
Bacterial stem rot
Botrytis
Downy mildew
Fusarium wilt
Gummy stem blight
Penicillium stem rot
Powdery Mildew
Pythium root rot
Sclerotinia stem rot
Verticillium Wilt
Aphids
Capsid (tarnished
plant bug)
Caterpillars
Broad mite
Two-spotted spider
mite
Western flower
thrips
Whitefly
Leaf hopper
Area affected (ha)
00
11
132
0105
50
02
00
016
37
11
0
Yield Loss (t)
00
00
00
00
00
00
00
00
00
0
Cost to the industry (£K)
00
00
00
00
00
00
00
00
00
0
Cost per affected hectare (£K)
00
00
00
00
00
00
00
00
00
0
Percentage reduction in
production (%)
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Table 63.
Impact of pests and diseases on cucumber as a result of the potential pesticide losses caused by the restrictions put in place by
the current water quality requirements – whilst using sensible m
itigation, e.g. biological controls
Water Quality
Black root rot
Bacterial stem rot
Botrytis
Downy mildew
Fusarium wilt
Gummy stem blight
Penicillium stem rot
Powdery Mildew
Pythium root rot
Sclerotinia stem rot
Verticillium Wilt
Aphids
Capsid (tarnished
plant bug)
Caterpillars
Broad mite
Two-spotted spider
mite
Western flower
thrips
Whitefly
Leaf hopper
Area affected (ha)
00
11
132
0105
50
02
00
016
37
11
0
Yield Loss (t)
00
00
00
00
00
00
00
00
00
0
Cost to the industry (£K)
00
00
00
00
00
00
00
00
00
0
Cost per affected hectare (£K)
00
00
00
00
00
00
00
00
00
0
Percentage reduction in
production (%)
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
*Cost to the industry assumes that the active substances are lost to the whole industry, however a complete revocation of the active substance is a last resort. Instead specific catchments may be
affected, if this is the case the cost per hectare can be used to apply to the area within a catchment that is affected.
Page 117
5.13 Tomatoes Most tomatoes are produced in heated glasshouses usually on plants grown for a 9-11 month period. Young plants raised by specialist propagators are planted in bags of substrate (rockwool, coir or woodfibre), in the soil, or are grown by Nutrient Film Technique (NFT). A wide range of types and varieties are grown. The greater use of ‘heritage’ varieties in recent years, with less resistance to diseases than modern varieties, has led to the reappearance of previously uncommon problems. Pest control is achieved predominantly by biological control, using an increasing range of predators and parasites, while disease control is achieved through a combination of genetic resistance (where available), management of the crop and glasshouse environment to minimise conditions favourable to infection, and occasional use of fungicides. The main targets for fungicide treatment are botrytis and powdery mildew. Table 64. Tomato gross margin
Crop TomatoesCrop area ha 212
Yield t/ha 416
Value £/t 1,249
Seed cost £/ha 6,000
Fertiliser cost £/ha 9,000
Spray cost £/ha 1,500
Bio-control cost £/ha
Cultivation costs £/ha
Other costs £/ha
Total value £/ha 519,584
Total costs £/ha 16,500
Gross margin £/ha 503,084 *Defra horticulture statistics ** Input costs and yield average of 20 growers in 2009. (for seed costs read plant costs)
5.13.1 Business as usual and untreated scenarios
Under ‘business as usual’, the largest potential gains could come from improved control of botrytis (£5.5M), fusarium diseases (£2.5M), verticillium wilt (£1.4M), pepino mosaic virus (not controlled by pesticides), beneficial insects (Macrolophus and Nesidiocoris) (£1.7M) and moths (£1.2M) (Table 65) In the absence of pesticides, major losses in tomato when using sensible non-pesticide mitigation measures are caused by botrytis (£22M), powdery mildew (£11M) and Pythium root rot (£5.5M) (Table 66).
Page 118
Table 65.
Impact of pests and diseases on tomatoes under business as usual (potential yield increases if better control was possible -
despite use of available pesticides)
Business as usual
Black root rot
Botrytis
Fusarium wilt
Late blight
Leaf mould
Powdery mildew
Phytophthora root rot
Pythium root rot
Stem rot (Didymella)
Verticillium wilt
Aphids
Beneficals -
Macrolophus,
nesidocoris
Carmine spider mite
Leaf miners - various
Moths Tuta, Turkey
moth, tomato moth
Two-spotted spider
mite
White Fly
Area affected (ha)
21
53
64
6106
221
011
421
221
15
21
11
Potential increase in yield if 100%
control possible (t)
441
4,410
1,984
176
529
3,087
353
441
31
1,102
88
1,323
220
88
926
441
441
Potential increase in value to
industry if 100% control possible
(£K)
551
5,508
2,478
220
661
3,855
441
551
39
1,377
110
1,652
275
110
1,157
551
551
Increased value per affected
hectare (£K)
26
104
390
52
104
36
208
26
182
130
26
78
130
578
26
52
Table 66.
Impact of pests and diseases on tomatoes in the absence of pesticide applications – whilst using sensible m
itigation, e.g.
biological controls. (Worst case scenario)
Untreated
Black root rot
Botrytis
Fusarium wilt
Late blight
Leaf mould
Powdery mildew
Phytophthora root rot
Pythium root rot
Stem rot (Didymella)
Verticillium wilt
Aphids
Beneficals -
Macrolophus,
nesidocoris
Carmine spider mite
Leaf miners - various
Moths Tuta, Turkey
moth, tomato moth
Two-spotted spider
mite
White Fly
Area affected (ha)
21
106
64
6138
621
032
621
221
15
25
15
Yield Loss (t)
661
17,638
1,984
176
926
8,599
1,058
4,410
44
3,307
529
2,205
220
88
926
529
617
Cost to the industry (£K)
-794
-21,871
-2,469
-214
-1,147
-10,533
-1,312
-5,476
-55
-4,083
-651
-2,722
-272
-78
-1,140
-623
-749
Cost per affected hectare (£K)
-37
-206
-388
-50
-180
-76
-206
-258
-258
-128
-102
-128
-128
-4-77
-24
-50
Percentage reduction in
production (%)
0.8
20.0
2.3
0.2
1.1
9.8
1.2
5.0
0.1
3.8
0.6
2.5
0.3
0.1
1.1
0.6
0.7
Page 119
Weeds
Weeds are not generally a problem, as the soil is covered by polythene or a woven material. In areas around stanchions and pathways where the soil is uncovered, volunteer tomato seedlings are killed by application of salt or removed by hand. Herbicides are not used.
Pests
Aphids (Aulacorthum solani, Myzus persicae, Marcosiphum euphorbiae): Occasional pests on tomato. Control is by spraying with pymetrozine at first sign of infestation. Biological control is possible but more expensive. Beneficial insects (Macrolophus and Nesidiocoris): Macrolophus is an occasional problem, especially on cherry types and fruit sold on the vine. Currently controlled by buprofezin, although this product is being withdrawn for commercial reasons on 31 March 2010. Alternative insecticides are available (e.g. pymetrozine ). Nesidiocoris has been reported on the Isle of Wight, but not as yet on the mainland. Carmine spider mite (Tetranychus cinnabarinus): Control is more difficult than for two-spotted mite. Usually controlled by biological predators. If necessary, the acaricides abamectin or etoxazole can be used. Leafhopper (Hauptidia maroccana): An increasing pest, associated with reduced use of pesticides. Controlled by biological predators. If necessary, indoxacarb (Steward) can be used and is relatively safe with biological control agents. Leaf miners (Liriomyza bryoniae and other species): A common pest. Biological control employed. Moths (Lacanobia oleracea) and others: Green or brown caterpillars of the tomato moth cause holes in the leaves and can also feed on fruits and stems. Control is by HV sprays of Bacillus thuringiensis. The turkey moth (Chrysodexis chalcites) has recently become a problem in some crops in northern England and causes considerably more damage to fruit than Lacanobia. Control is by Dipel or, at greater cost, Macrolophus. The non-indigenous Tuta absoluta moth, which causes blotch mines on tomato leaves and also damages fruit, was intercepted in 2009 and could become a serious problem in UK crops. Macrolophus is hoped to be effective by egg predation. Two-spotted spider mite (Tetranychus urticae): A serious pest of tomato. Biological control can be successful, but is expensive and requires skilled staff. Acaricides are also available (e.g. spiromesifen, abamectin and etoxazole), though with negative effects on biocontrol. A new predator from Syngenta looks promising. Western flower thrips (Frankliniella occidentalis): WFT is seldom a problem in tomato. Control is by biologicals or spinosad (Conserve). Whitefly (Trialeurodes vaporariorum) Biological agents generally provide good control. Pymetrozine is sometimes used to control patches of whitefly infestation. This insecticide can now be used through the drip irrigation system.
Diseases
Black root rot (Thielaviopsis basicola) A common disease in NFT crops and occasionally found in crops grown in soil or on substrates. NFT crops appear to tolerate
Page 120
infection to some extent. Carbendazim was widely used in NFT crops to control the disease until this fungicide was withdrawn for commercial reasons. A SOLA for thiophanate methyl was approved in 2009 (SOLA1969/09) and is likely to provide some control. Botrytis (Botrytis cinerea): A wide range of fungicides is currently available and used on tomato for control of botrytis. Key products are iprodione, pyrimethanil and cyprodinil+fludioxonil. It would be useful if the harvest interval for cyprodinil+fludioxonil could be reduced from 7 to 3 days. Fusarium wilt (F. oxysporum f. sp. lycopersici) and fusarium crown and root rot (F. oxysporum f. sp. radicis-lycopersici): Fusarium wilt is generally controlled by use of resistant varieties, but several recent outbreaks in varieties listed as resistant to fusarium wilt indicate a new race is present in the UK. Fusarium crown and root rot is controlled very effectively by resistant varieties, but outbreaks continue in ‘heritage’ varieties. Thiophanate methyl is used to provide some control. There is room for improvement in the control of fusarium diseases of tomato. Late blight (Phytophthora infestans): An occasional problem in unheated or poorly heated glasshouses. Difficult to control with fungicides, more readily controlled by use of heat, ventilation and removal of affected tissues. Control will be unaffected by loss of any currently available fungicides. Leaf mould (Fulvia fulva): An occasional problem, especially on older varieties with incomplete resistance. The disease is controlled by HV sprays of azoxystrobin or chlorothalonil (partial control). Azoxystrobin can cause crop damage. Thiophanate methyl applied for root diseases may give some control. Powdery mildew (Golvinomyces orontii): A widespread and common disease. Partially controlled by use of tolerant varieties. HV sprays of sulphur provide effective control if applied at an early stage of infection. Myclobutanil is also available and sometimes used. There is potential for more effective and economic control if sulphur vapourisers were to be permitted. Phytophthora foot rot and stem rot (e.g. Phytophthora cryptogea): Primarily a problem of soil-grown crops, but can be severe in NFT or hydroponic crops where the irrigation waste solution is recycled. Etridiazole provided effective control but this product was recently withdrawn for commercial reasons. Propamocarb hydrochloride may give some control. This disease could become increasingly important if growers are required to recycle irrigation solution in substrate crops, though losses can be mitigated by an effective solution disinfestation treatment (e.g. heat, UV light, slow sand filter). Pythium root rot (Pythium spp.): Pythium root rots can be troublesome in hydroponic systems, especially where drainage is poor and at the plant establishment stage. Propamocarb hydrochloride provides some control. Stem rot (Didymella lycopersici): A rare but potentially devastating disease due to its high infectivity. Controlled by hygiene and high volume sprays of iprodione or maneb. Efficacy of newer fungicides permitted on tomato against this fungus is unknown (e.g. pyrimethanil, cyprodinil+fludioxonil). Identification of alternative fungicides effective against D. lycopersici is required as an insurance against the reappearance of stem blight. Verticillium wilt (V. albo-atrum and V. dahliae): Isolates of V. albo-atrum able to overcome host resistance are increasingly common on UK nurseries. Control is currently achieved by use of grafted plants to increase root vigour (though there are disbenefits with
Page 121
increased botrytis if plant vigour is too high) and drench treatments with carbendazim, until it was recently withdrawn, or thiophanate-methyl. The efficacy of thiophanate-methyl treatment is unproven. There is room for improvement in the control of verticillium wilt in tomato. Switching from own-roots to grafted plants increases costs from 80p to £1.20/plant.
5.13.2 Changing approvals legislation
Under the changing approvals legislation scenario, the following active substance that is currently used on tomato could be lost:
• Maneb (fungicide) The impact of this loss on diseases is identified in Table 67.
Diseases
Stem rot (Didymella lycopersici) Maneb would potentially be used if outbreaks of stem rot occurred. It is not known if any of the remaining fungicides permitted on tomato would give effective control of stem rot. The only known effective alternative, iprodione, is at risk from water quality requirements.
5.13.3 Water Quality
The active substances that are currently available on tomatoes that are at risk from restrictions due to water quality requirements are:
• Iprodione (fungicide) The impact of this loss is shown in Table 68.
Diseases
Botrytis (B. cinerea) Loss of iprodione will reduce control of botrytis. The alternative fungicides are unlikely to provide sufficient control due to a long harvest interval (cyprodinil+fludioxonil) or resistant strains (pyrimethanil). Stem rot (Didymella lycopersici) Iprodione is the main fungicide available for use if stem rot were to re-appear.
5.13.4 Other reasons for pesticide losses
Carbendazim has been withdrawn from sale as a result of commercial reasons.
Page 122
Table 67.
Impact of pests and diseases on tomato as a result of the pesticide losses caused by the changing approvals legislation scenario–
whilst using sensible m
itigation, e.g. biological controls. Cost to the industry is the additional cost
Changing approvals legislation
Black root rot
Botrytis
Fusarium wilt
Late blight
Leaf mould
Powdery mildew
Phytophthora root rot
Pythium root rot
Stem rot (Didymella)
Verticillium wilt
Aphids
Beneficals -
Macrolophus,
nesidocoris
Carmine spider mite
Leaf miners - various
Moths Tuta, Turkey
moth, tomato moth
Two-spotted spider
mite
White Fly
Area affected (ha)
21
53
64
6106
221
011
421
221
15
21
11
Yield Loss (t)
00
00
00
00
00
00
00
00
0
Cost to the industry (£K)
00
00
00
00
00
00
00
00
0
Cost per affected hectare (£K)
00
00
00
00
00
00
00
00
0
Percentage reduction in
production (%)
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Table 68.
Impact of pests and diseases on tomato as a result of the potential pesticide losses caused by the restrictions put in place by the
current water quality requirements – whilst using sensible m
itigation, e.g. biological controls. Cost to the industry assumes that the active
substances are lost to the whole industry; however a complete revocation of the active substance is a last resort. Instead specific catchments
may be affected, if this is the case the cost per hectare can be used to apply to the area within a catchment that is affected.
Water Quality
Black root rot
Botrytis
Fusarium wilt
Late blight
Leaf mould
Powdery mildew
Phytophthora root rot
Pythium root rot
Stem rot (Didymella)
Verticillium wilt
Aphids
Beneficals -
Macrolophus,
nesidocoris
Carmine spider mite
Leaf miners - various
Moths Tuta, Turkey
moth, tomato moth
Two-spotted spider
mite
White Fly
Area affected (ha)
21
74
64
6106
221
011
421
221
15
21
11
Yield Loss (t)
01,764
00
00
00
13
00
00
00
00
Cost to the industry (£K)
0-2,203
00
00
00
-17
00
00
00
00
Cost per affected hectare (£K)
0-30
00
00
00
-78
00
00
00
00
Percentage reduction in
production (%)
0.0
2.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
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5.14 Hardy Nursery Stock As the most recently published Defra statistics do not contain numbers of field grown stock produced, it has not been possible to include this portion of the hardy ornamentals industry in the assessment. The calculations only include the area attributed to container grown stock (2,380 hectares). The impacts of the changing approvals legislation and Water Quality scenarios upon field-grown stock (7,139 hectares) are discussed, although calculations are not available. Hardy ornamental nursery stock is one of the most diverse sectors of the UK horticultural industry, growing a wide range of different plant species. Stock is produced for use within the industry (e.g. young plants as plugs, rooted cuttings or liners), as finished stock for retail sale (e.g. garden centres), and for landscapers and other planting schemes in various sizes and forms (bare root, containerised and container grown). The principal production systems are:
• Field grown, where stock is grown in the field, lifted and sold bare root.
• Containerised, where stock is initially grown in the field and is containerised prior to sale.
• Container grown, where stock is produced in peat-based growing media for all of the production cycle. Most growers are now using growing media containing at least 20% peat alternatives.
Table 69. Hardy nursery stock gross margin
Crop Hardy
nursery stock
Crop area ha 2,380
Yield plants per ha 106,535
Value £/plant 3
Liners £/ha 112,143
Growing media £/ha 10,830
Spray cost £/ha 3,205
Pots £/ha 6,392
Labour £/ha 103,872
Other costs £/ha
Total value £/ha 346,239
Total costs £/ha 236,442
Gross margin £/ha 109,797
5.14.1 Business as usual and untreated scenarios
Under ‘business as usual’ the largest potential gains could come from improved control of vine weevil (£6.5M), two-spotted spider mite, capsids, botrytis and powdery mildew (£4.3M each) (Table 70). The figures in brackets are the potential increase in value to the industry that could occur if 100% control was achievable. In the absence of pesticides, major losses in hardy nursery stock when using sensible non-pesticide mitigation measures would be caused by grass and broad-leaved weeds due predominantly to increased costs associated with controlling weeds (£128M each), aphids (£108M) and powdery mildew (£86M).
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Customers and consequently retailers demand plants that are free of pests and diseases, therefore growers manage pests, diseases and weeds to meet this requirement. The weather has a huge influence over the demand for hardy ornamental stock. Inclement weather is often the main reason why stock is not sold at key times (e.g. poor spring weather will impact upon the sales of spring-flowering shrubs) leading at times to significant wastage. Weeds are controlled with a combination of residual herbicides, some post-emergence herbicides and hand weeding. Hand weeding is costly and is minimised by most producers by having a good herbicide programme in place. A range of pests feed on hardy nursery stock subjects. Integrated crop management (ICM) including the use of biological control is used on some nurseries. Biological controls currently cost approximately 20 - 25% more than conventional chemical programmes, (costs vary according to each crop type & input/application method). Temperatures are not sufficiently high within protected structures to utilise biological controls to their full potential. Most protected ornamental crops are grown with minimal heat (i.e. frost protection), indeed not all subjects require frost protection. It would not be economic to raise temperatures to make more use of biological controls (aphid and whitefly predators require a minimum temperature of 18ºC to be effective). Putting mesh over vents and doors is not likely to be a practical or successful approach as key pests are often brought in on plant material when dormant or in low numbers, making them difficult to detect. Wider use could be made of bio-pesticides in the future for both pest and disease control. Major pesticide losses are likely to lead to higher levels of plant damage and failure, not only through the direct loss of the active substance, but also as a result of more widespread resistance to pesticides, caused by reliance on a fewer key active substances.
Weeds – Container production
Following potting, container-grown crops are normally treated with a residual herbicide. The granular formulation of oxadiazon is used on most subjects (providing crop safety is not an issue), as this is easy to apply to relatively small batches of stock. Other residual herbicides are also used at various stages of the production cycle to control those weeds that are not controlled by isoxaben and to extend the duration of residual weed control as residual herbicides have to be re-applied to maintain their effectiveness. The most problematic weeds include: Annual meadow grass (Poa annua), Bittercress (Cardamine spp.), Chickweeds (Stellaria media & Cerastium fontanum Baumg. spp. trivale), Groundsel (Senecio vulgaris), Sow thistle (Sonchus oleraceus) and Willowherbs (Epilobium spp.) These weed species are all controlled using a combination of the aforementioned herbicides. Other herbicides are also used, primarily where crop damage is caused by the use of isoxaben and/or oxadiazon. Residual herbicides are also used in non-cropped areas and the withdrawal of dichlobenil in March 2010 will place more reliance on pendimethalin, propyzamide, napropamide, isoxaben and oxadiazon, and contact herbicides. Contact herbicides such as glufosinate-ammonium are essential to control flushes of weed growth, (particularly willowherb, which glyphosate does not effectively control), and to prevent weeds seeding and contaminating adjacent crops.
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Table 70.
Impact of weeds, pests and diseases on hardy nursery stock (container production only) under business as usual (potential yield
and gross m
argin increases if better control was possible - despite use of available pesticides)
Business as usual
Broadleaved weeds
Grass weeds
Aphids
Capsid and plant bugs
Caterpillars
Leaf miner
Mealybug
Two-spotted sider mite
Scale insects
Sciarid fly
Slugs / Snails
Thrips
Vine weevil
Whitefly
Black root rot
Botrytis
Downy mildew
Leaf spot (Bacterial)
Leaf spot (Fungal)
Powdery Mildew
Rhizoctonia
Rust
Verticillium Wilt
Area affected (ha)
119
119
286
238
179
119
119
238
119
119
119
179
357
179
71
238
238
0119
238
238
167
119
Potential increase in
yield if 100% control
possible (1000 plants)
667
667
961
1,335
601
133
133
1,335
133
267
400
1,001
2,002
400
160
1,335
534
133
133
1,335
534
187
267
Potential increase in
value to industry if
100% control possible
(£K)
2,169
2,169
3,123
4,337
1,952
434
434
4,337
434
867
1,301
3,253
6,506
1,301
520
4,337
1,735
434
434
4,337
1,735
607
867
Increased value per
affected hectare (£K)
18
18
11
18
11
44
18
47
11
18
18
77
18
70
418
74
7
Table 71.
Impact of weeds, pests and diseases on hardy nursery stock (container production only) in the absence of pesticide applications –
whilst using sensible m
itigation, e.g. biological controls. (Worst case scenario)
Untreated
Broadleaved weeds
Grass weeds
Aphids
Capsid and plant bugs
Caterpillars
Leaf miner
Mealybug
Two-spotted sider mite
Scale insects
Sciarid fly
Slugs / Snails
Thrips
Vine weevil
Whitefly
Black root rot
Botrytis
Downy mildew
Leaf spot (Bacterial)
Leaf spot (Fungal)
Powdery Mildew
Rhizoctonia
Rust
Verticillium Wilt
Area affected (ha)
1,190
1,190
1,190
357
595
119
119
714
119
119
357
357
357
179
476
714
714
48
714
833
238
238
119
Yield Loss (1000 plants)
33,363
33,363
33,363
4,004
6,673
667
667
16,014
667
667
2,002
4,004
2,002
1,001
8,007
16,014
16,014
107
16,014
23,354
1,335
2,135
667
Cost to the industry
(£K)
-127,264
-128,792
-108,278
-13,010
-21,602
-2,167
-2,168
-51,995
-2,168
-2,168
-6,506
-12,934
-6,506
-3,238
-26,023
-59,218
-56,799
0-59,433
-85,841
-5,159
-7,758
-2,375
Cost per affected
hectare (£K)
-107
-108
-91
-36
-36
-18
-18
-73
-18
-18
-18
-36
-18
-18
-55
-83
-80
0-83
-103
-22
-33
-20
Percentage reduction in
production (%)
13.2
13.2
13.2
1.6
2.6
0.3
0.3
6.3
0.3
0.3
0.8
1.6
0.8
0.4
3.2
6.3
6.3
0.0
6.3
9.2
0.5
0.8
0.3
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If no herbicides were available, production and labour costs would rise dramatically due to increased amounts of time spent hand weeding crops. ‘Pot toppers’ could be used as mitigation measures, but they are not very effective in most situations. The increase in costs would significantly reduce the competiveness of UK growers. Weeds in non-cropped areas could be flamed to achieve control; however this task would have to be repeated throughout the growing season. Flaming weeds could not be carried out right up to the edge of beds (as with herbicides) as woven plastic membranes would be damaged, so some hand weeding of these areas would be unavoidable .
Weeds – Field production
Perennial weeds are controlled on land the season before it is brought into production. This is because it can be difficult to achieve perennial weed control after planting the crop without causing crop damage. Active substances such as glyphosate that are translocated to the roots play an important role in achieving control of perennial weeds. Problematic perennial broad-leaved weeds are controlled by specific herbicides, such as: docks (Rumex spp.) and bracken (Pteridium aquilinum) by 2,4-D perennial nettle (Urtica dioica) by MCPA, thistles (Cirsium arvense) by clopyralid. Perennial grasses e.g. Couch (Elytrigia repens) may be controlled with glyphosate or glufosinate-ammonium during the summer. Post planting, residual herbicides are used to control annual weeds and are generally applied in late winter/spring and may be topped up in late summer. Post-emergence herbicides are also used to control flushes of weed growth. The type of residual herbicide used depends on crop safety (particularly when applied over the crop), soil type and the weed species present. Alternatively, some growers apply residual herbicides and then carry out inter-row spraying with contact herbicides such as glufosinate-ammonium. If no herbicides were available, weed control would become the biggest challenge for field production of nursery stock. The loss of residual herbicides would remove grower’s flexibility to control weed growth. This would leave them with two main options - flaming and cultivations. Flaming would not be suitable for hedging crops grown in beds, as the rows are so close that it would be difficult to achieve weed control without inflicting crop damage. There is more potential for the use of flaming in the production of field-grown trees, however young crops where the bark is not fully lignified are likely to be damaged. Cultivations only contribute to weed control when soil conditions are dry, causing uprooted weeds to desiccate. In the last three wet summers, cultivations alone would have added little to weed control, particularly on heavier soils.
Pests (container–grown and field)
The loss of any insecticide increases the challenge for growers of achieving pest control whilst managing insecticide resistance. This has the greatest impact when controlling key pests where resistance is already prevalent, such as with some aphid and thrips species, two-spotted spider mite and whitefly populations. Aphids (Various species) can be problematic; feeding damage and the secretion of honeydew which is colonised by black sooty moulds can render stock unmarketable. In addition, aphids may carry and transmit viruses which can also have a negative effect on marketability. Insecticide resistance is a factor when controlling Myzus persicae (pyrethroids and pirimicarb are ineffective) and Aphis gossypii (pirimicarb ineffective). Products with short persistence such as primicarb, pymethrozine and pyrethrins are used within Integrated Pest Management (IPM) systems to reduce pest numbers prior to the introduction of biological controls. Neonicotinoids such as thiacloprid and acetamiprid are used in non-IPM systems (where biological controls are not used) to control species where
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resistance is an problem during the growing season. During the winter, when temperatures are low, physical insecticides or pyrethroids are relied upon. Biological control is not currently an effective option on outdoor crops. Naturally occurring predators do not generally build up quickly enough to reduce pest numbers before crop damage is inflicted. Capsid (Lygus rugulipennis): The feeding activities of capsid bugs affect crops during establishment, resulting in puckered/distorted foliage, making stock unmarketable. Residual pyrethroids offer the best control, but pymetrozine is also effective and is applied where IPM is used. Caterpillars: Carnation tortrix moth (Cacoecimorpha pronubana) and light brown apple moth, (Epiphyas postvittana) are responsible for the majority of damage on evergreen nursery stock subjects. Species such as Silver Y (Autographa gamma) can also cause damage on other subjects. Established tortrix caterpillars could be removed by hand as their presence is made evident as leaves and growing points are bound together in a web. However, this would increase labour costs and delay marketability. In addition, growers aim to control caterpillars whilst small, before they cause too much damage and when they are easier to kill with IPM-compatible pesticides. Bacillus thuringiensis, spinosad or indoxacarb give a good level of control at this stage. Pyrethroids, such as deltamethrin, or nicotine are effective on larger caterpillars. Two-spotted spider mite (Tetranychus urticae): Spider mites in modest quantities can cause leaf speckling or silvering but, if left unchecked, higher numbers can bring about leaf yellowing and drop, with webbing being produced around the growing points when populations are large. Bifenthrin is effective and controls all stages of the life cycle. The other approved product, fenpyroximate, which also controls all stages of the pest, can only be used once per year. Dimethoate is an organophosphate, so resistance may be encountered; this active substance has not been widely used in recent years due to the availability of more selective acaricides such as abamectin and bifenazate. Resistance to abamectin is increasing in some crops. Spiromesifen is reasonably effective, but has negative effects on bio-control and some plant species. Little crop safety information is known for products with SOLAs, so growers have to test spray subjects prior to widespread use. Bio-control is expensive and needs skilled operators who understand how the various predators react to different temperatures. An understanding of desirable pest to predator ratios is also beneficial. The requirement for skilled operators increases the potential cost of IPM. In non-IPM systems, dimethoate may have a place where resistance to other acaricides is becoming problematic. Thrips (Frankliniella occidentalis and Thrips tabaci) Thrips can cause leaf silvering; in higher numbers they can be very damaging, affecting the growing points of crops and distorting flowers. In addition, western flower thrips have the potential to transmit viruses such as tomato spotted wilt virus, which can render stock unmarketable. Resistance to insecticides is a huge problem in thrips populations, particularly for Western Flower Thrips (WFT) control. Tolerance to key pesticides is suspected in hardy ornamentals. The effectiveness of pyrethroids, abamectin and spinosad are variable, depending on how much exposure pest populations have had to these active substances. Alternatively, thiacloprid is effective and teflubenzuron controls immature thrips. Biological controls can be effective, however, most flowering ornamentals are marketed just before flowering, when there is rarely a source of pollen on which predators can establish. The other pests noted within the assessment (leaf miner, mealybug, sciarid fly, scale insect, slugs/snails) are of less significance or of major significance on fewer plant species.
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Diseases (container–grown and field)
Botrytis (Botrytis cinerea): Botrytis can potentially infect most plants as a true pathogen or as a secondary pathogen, establishing on dead or dying tissue and then infecting healthy tissue. Botrytis spores require moisture to penetrate plant tissue, therefore the disease is more problematic when humidity is high or growing conditions are damp. Cultural measures and manipulation of the growing environment are employed where feasible to limit the severity of this and other foliar pathogens that require these conditions. Such measures include ensuring adequate plant spacing, good air movement and the avoidance of watering late in the day. However protectant (azoxystrobin, chlorothalonil etc) and eradicant (cyprodinil + fludioxonil, iprodione and prochloraz etc.) fungicides are still relied upon. Downy mildew (Various species): The cultural and environmental controls described above for Botrytis are also employed for downy mildew. In addition disease control is currently achieved by using protectant sprays of azoxystrobin and chlorothalonil, combined with fungicides mostly based on metalaxyl-M. Powdery Mildew (Various species): Cultural measures that maintain dry foliage and minimise humidity within crops, principally under protection, are again important in the control of powdery mildew. Fungicide programmes are based around protectant and eradicant fungicides from different fungicidal groups, as this pathogen is capable of producing mutant, resistant strains if constantly targeted with the same chemistry. Fungicides with protectant action that are commonly used include azoxystrobin, chlorothalonil and sulphur. Sulphur is however rarely used on container-grown stock due to undesirable spray deposits that reduce marketability. Eradicants include boscalid and pyraclostrobin, bupirimate, myclobutanil and potassium bicarbonate (potassium bicarbonate currently has commodity substance approval).
5.14.2 Changing approvals legislation scenario
Under the changing approvals legislation the following active substances that are currently used on hardy nursery stock could be lost:
• Bifenthrin (insecticide)
• Flumioxazin (herbicide)
• Glufosinate-ammonium (herbicide)
• Mancozeb (fungicide)
• Pendimethalin (herbicide) The impact of these losses on weeds, pests and diseases (in containerised nursery stock) is identified in Table 72. The most significant impacts of the changing approvals legislation scenario will be on vine weevil control (£6.5M), with weeds also becoming difficult to control resulting in reduced yields and increased costs (£8.6M). However the impacts on weed control in field grown crops could be even larger.
Weeds – Container production
The loss of the above herbicides will have a negligible effect on weed control within container production. The only potential loss of significance is flumioxazin (winter use only, SOLA), which has a broad weed spectrum and will kill weed seedlings up to four true leaves. The full potential of this active substance may not have been fully explored as some crop safety problems exist. However, the loss of glufosinate-ammonium for weed control in non-cropped areas around production nurseries would be a significant loss. This active substance has replaced paraquat following that herbicide’s revocation; glufosinate-ammonium provides good
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control of nursery weeds, including some that are difficult to control, such as willowherb. Other options include glyphosate (which is cheaper, but not particularly effective on willowherb) or non-translocated herbicides, such as diquat or carfentrazone-ethyl. The relatively low rates of diquat permitted mean that this active substance is only completely effective on weed seedlings. Best results are achieved with carfentrazone-ethyl when small, actively growing weeds are sprayed.
Weeds – Field production
The loss of pendimethalin and flumioxazin would severely impact on residual weed control in field production. Most field nurseries are on light soils to facilitate easy lifting of plants for marketing when stock is dormant; production on such soils minimises damage to soil structure. In such situations flumioxazin, pendimethalin and propyzamide may be applied in late winter to provide residual weed control. Few residual herbicides, which are crop safe, are approved for use on sandy soils and the loss of pendimethalin and flumioxazin would make residual weed control difficult. The contact herbicide glufosinate-ammonium is used as an inter-row spray on tree seedling nurseries, where lower rates of residual herbicides are generally employed. Glufosinate-ammonium is the safest active substance for use as an inter-row treatment. In its absence, treatment using glyphosate would be too risky to consider as a replacement, as the slightest bit of drift could result in crop damage. In addition, species belonging to the Rosaceae family (important in nursery stock) are sensitive to glyphosate. Non-translocated herbicides, such as diquat and carfentrazone-ethyl, are not as effective as glufosinate-ammonium on grasses or established weeds. Glufosinate-ammonium is also used to control seedling weeds prior to planting, where soil conditions are unsuitable for cultivations. In addition, it may be used to control annual weed growth on non-cropped land before the land is brought back into production. This active substance is particularly effective on willowherb and grass weeds. Alternatives include glyphosate (which is cheaper, but not particularly effective on willowherb) or non-translocated herbicides such as diquat or carfentrazone-ethyl. The relatively low rate for diquat means that this active substance is only fully effective on seedling weeds. Best results are achieved with carfentrazone-ethyl, when small actively growing weeds are sprayed. Neither diquat nor carfentrazone-ethyl control grass weeds well.
Pests
The loss of bifenthrin only has a minor impact on the control of many nursery stock pests, as other pyrethroids can, in most cases, be used in its place. There are also sufficient alternative active substances to achieve control of most pests. The impact of losing bifenthrin is likely to be greatest on the control of two-spotted spider mite, as remaining pyrethroids do not have acaricidal effects. Bifenthrin is also particularly effective against populations of this pest as it is active against all stages of the pest (eggs, nymphs, larvae and adults). Other acaricides have limitations on their use, as mentioned in Section 5.14.1, “Business as usual”. Using these actives, growers have to repeat spray to control mites or tank mix products at their own risk. Information relating to the compatibility of active substances marketed by different companies is rarely available. Tank mixing also increases the risk of crop damage.
Diseases
The main impact is the loss of mancozeb for downy mildew control as a protectant, or within mixtures with metalaxyl-M. Its loss would increase the potential for disease resistance amongst the remaining eradicant fungicides.
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Table 72.
Impact of weeds, pests and diseases on hardy nursery stock (containerised stock only) as a result of the pesticide losses caused
by the changing approvals legislation scenario– whilst using sensible m
itigation, e.g. biological controls. Cost to the industry is the additional
cost
Changing approvals
legislation
Broadleaved weeds
Grass weeds
Aphids
Capsid and plant bugs
Caterpillars
Leaf miner
Mealybug
Two-spotted sider mite
Scale insects
Sciarid fly
Slugs / Snails
Thrips
Vine weevil
Whitefly
Black root rot
Botrytis
Downy mildew
Leaf spot (Bacterial)
Leaf spot (Fungal)
Powdery Mildew
Rhizoctonia
Rust
Verticillium Wilt
Area affected (ha)
119
119
286
238
179
119
119
238
119
119
119
179
357
179
71
238
238
119
119
238
238
167
119
Yield Loss (1000 plants)
2,669
2,669
0801
00
133
0133
133
0400
2,002
601
00
801
0534
0801
0400
Cost to the industry
(£K)
-8,674
-8,674
-62
-2,602
-39
-26
-459
-51
-459
-459
0-1,340
-6,583
-1,990
00
-2,602
434
-1,735
0-2,602
0-1,301
Cost per affected
hectare (£K)
-73
-73
0-11
00
-40
-4-4
0-8
-18
-11
00
-11
4-15
0-11
0-11
Percentage reduction in
production (%)
1.1
1.1
0.0
0.3
0.0
0.0
0.1
0.0
0.1
0.1
0.0
0.2
0.8
0.2
0.0
0.0
0.3
0.0
0.2
0.0
0.3
0.0
0.2
Table 73.
Impact of weeds, pests and diseases on hardy nursery stock as a result of the potential pesticide losses caused by the restrictions
put in place by the current water quality requirements – whilst using sensible m
itigation, e.g. biological controls.
Water Quality
Broadleaved weeds
Grass weeds
Aphids
Capsid and plant bugs
Caterpillars
Leaf miner
Mealybug
Two-spotted sider mite
Scale insects
Sciarid fly
Slugs / Snails
Thrips
Vine weevil
Whitefly
Black root rot
Botrytis
Downy mildew
Leaf spot (Bacterial)
Leaf spot (Fungal)
Powdery Mildew
Rhizoctonia
Rust
Verticillium Wilt
Area affected (ha)
119
119
286
238
179
119
119
238
119
119
119
179
357
179
71
238
238
119
119
238
238
167
119
Yield Loss (1000 plants)
133
133
320
801
200
13
13
013
133
267
20
4,004
200
01,068
00
00
1,335
00
Cost to the industry
(£K)
-434
-434
-1,041
-2,602
-651
-43
-43
0-43
-434
-898
-65
-13,011
-651
0-3,501
00
00
-4,362
00
Cost per affected
hectare (£K)
-4-4
-4-11
-40
00
0-4
-80
-36
-40
-15
00
00
-18
00
Percentage reduction in
production (%)
0.1
0.1
0.1
0.3
0.1
0.0
0.0
0.0
0.0
0.1
0.1
0.0
1.6
0.1
0.0
0.4
0.0
0.0
0.0
0.0
0.5
0.0
0.0
* Cost to the industry assumes that the active substances are lost to the whole industry; however a complete revocation of the active substance is a last resort. Instead specific catchments may be
affeted, if this is the case the cost per hectare can be used to apply to the area within a catchment that is affected.
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5.14.3 Water Quality
The active substances that are currently available on hardy nursery stock that are at risk from restrictions due to water quality requirements are:
• Asulam (herbicide)
• Chlorphyifos (insecticide)
• Clopyradlid (herbicide)
• Cypermethrin (insecticide)
• 2,4-D (herbicide)
• Glyphosate (herbicide)
• Iprodione (fungicide)
• Metaldehyde (molluscicide)
• Metazachlor (herbicide) The impact of these restrictions on containerised production is shown in Table 73. The most significant impact of pesticide losses due to water quality requirements could arise if insecticides such as chlorpyrifos and cypermethrin lost their approval. This could result in poor control of vine weevils, with a potential cost to the industry of £13M. The potential loss of actives to water quality requirements could result in botrytis (£3.5M) becoming more difficult to control, resulting in yield losses and increased costs. There would also be an impact on weed control which although relatively small in containerised stock, could be even greater in field grown stock.
Weeds – Container production
Amongst a number of herbicides in the list above,the main impact as far as container production of nursery stock is concerned relates to the loss of the residual herbicide metazachlor. Alternatives to metazachlor include flumioxazine (SOLA), isoxaben, lenacil, napropamide and oxadiazon. Crop safety is a crucial factor when selecting a particular herbicide, so not all active substances listed here are available for all crops. The possibility of a SOLA for isoxaben + terbuthylazine is under discussion and would help the situation. Since propyzamide has been re-registered, uses of this active substance are restricted to forest nurseries. The post-emergence graminicide tepraloxydim/fluazipop-P-butyl can be used (SOLA) at grower’s own risk. Annual meadow grass (Poa annua) is not however controlled by fluazipop-P-butyl; this can be the predominant grass weed on some nurseries. Weed control in adjacent non-cropped areas is an important element of keeping container nursery stock weed-free. The loss of glyphosate, when combined with the loss of glufosinate-ammonium under the changing approvals legislation (which would be the main alternative), would lead to an increased reliance on residual herbicides, combined with more regular spraying with diquat and/or carfentrazone-ethyl. Weeds – Field production The loss of propyzamide would have the most severe impact, especially if combined with the loss of flumioxazin and pendimethalin (to changing approvals legislation). As a result, residual weed control on sandy soils would be extremely difficult. The potential loss of glyphosate and propyzamide could mean that no effective contact herbicides for grass control would be left, which could be potentially devastating. The loss of metazachlor as a winter residual herbicide would be a further gap in the armoury. The remaining residual
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herbicides would not adequately control the weed spectrums that are problematic with this production method. Growers would have to resort to more inter-row spraying (requiring more investment in sprayers), costly hand weeding and inter-row cultivations, with their potential for increased soil erosion on sloping sites. The loss of 2,4-D for horsetail and bindweed control, asulam, a relatively safe spot treatment for docks and bracken within crops, clopyralid for thistle and other composite weed control, and MCPA for perennial nettles on top of the loss of glyphosate would make perennial weed control really very difficult. Potential replacement active substances for broadleaf, perennial weed control include fluroxypyr, dicamba (which is only available in mixtures) and triclopyr. A SOLA would be required for the use of triclopyr in ornamental plant production and forest nurseries. It is too early to determine which mixture containing dicamba would be most appropriate for use in forest nurseries and ornamental plant production as the full extent of herbicide losses is not yet known. It is however highly likely that a SOLA would be required for the use of this mixture. SOLAs are currently in place for the use of fluroxypyr. The loss of the herbicides described above would result in an increase in competition from weeds. This would undoubtedly affect crop growth and development, reducing air movement within crop canopies. This is likely to increase the severity of the foliar diseases. Weed growth would also intercept the fungicide applications, shielding the target, and reducing further the efficacy of remaining treatments. Hand weeding would be necessary, but it would not be cost- effective to keep crops as clear of weeds as is current practice. This would result in an increase in the length of production cycles, reducing throughput, profit and the competiveness of the UK industry. As with container-grown production, the loss of glyphosate combined with the loss of glufosinate-ammonium (which would have been the main alternative) would lead to an increased reliance on remaining residual herbicides for weed control in non-cropped areas. This would be necessary to prevent perennial weeds establishing, as their control would be more difficult. On sites where topsoil erosion is unlikely,, increased cultivations (with associated increases in carbon emissions) could be carried out to prevent weed establishment. In addition, more regular spraying with non-translocated herbicides such diquat or carfentrazone-ethyl would be likely to become common practice. As mentioned, however, carfentrazone-ethyl does not control grass weeds well. Given the number of and uses of the herbicides which could be lost under water quality requirements, weed control in field-grown stock would be the most severely affected area of hardy ornamental nursery stock production. Pests The loss of cypermethrin has a minor impact on the control of many pests. There are however sufficient active substances remaining for adequate control of aphids, capsid bugs, caterpillars, leaf miner, mealybug, scale insects, sciarid fly, thrips, two-spotted spider mite and whitefly. Slugs and snails (Various spp.) Slugs and snails can cause unacceptable damage to a range of crops e.g. Choisya, Hosta and Ligularia. They tend to be more problematic on some sites, particularly in container production, where conditions are generally moister than in the field. The loss of metaldehyde would leave a gap as methiocarb is not currently approved for use under protection. Nematodes are only effective against slugs and are time consuming to apply, resulting in increased costs. This would leave growers needing to control slugs and snails under protection with one main formulation of slug
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pellets based on ferric phosphate, which is not as cost effective as metaldehyde and is three times more expensive. Vine weevil (Otiorhynchus spp.) The recent loss of fipronil has led to an increased reliance on chlorpyrifos (SuSCon Green Soil Insecticide) for vine weevil control over the past two growing seasons. However, the active substance in the SuSCon Green formulation is due to change within the next six months, although it has not yet been disclosed what the replacement will be. Without this change, the loss of chlorpyrifos would have had a more severe impact (assuming that its efficacy is maintained by its successor).
Diseases
Iprodione is the only anticipated fungicide loss. This active is mainly used for Botrytis control, but is also provides effective control of rhizoctonia. In addition, this fungicide controls sclerotinia, although this is not a major problem in hardy ornamental plant production. Iprodione is perhaps less effective than it once was, but still has useful eradicant properties and a place within spray programmes. Botrytis control could be enhanced by using cyprodinil + fludioxonil following the loss of iprodione; however only two applications can be applied per crop. Hardy ornamentals are normally produced over at least two seasons, so cyprodinil + fludioxonil will only be part of the solution for Botrytis control. Fewer alternative control options exist for rhizoctonia/sclerotinia control.
5.14.4 Other reasons for pesticide losses
Transfer from the Long Term Arrangements for Extension of Use (LTAEU) to Specific Off Label Approvals (SOLAs) The availability of pesticides to growers in the hardy ornamentals sector has already been affected by the transfer from the Long Term Arrangements for Extension of Use (LTAEU) to Specific Off Label Approvals (SOLAs), where no label approval was in place. This has resulted in the loss of key acaricides such as bifenazate and fungicides such as imazalil, mepanipyrim, proquinazid and fenhexamid. Some of these products have had SOLAs issued for use on forest nurseries; overall this sector of the ornamental industry seems to be less severely affected. The transfer from the LTAEU to SOLAs is not expected to be completed until 2013, so the full impact of these changes in legislation is not yet known. Chlorothalonil is being considered as a UK specific pollutant The use of chlorothalonil is important in the control of a range of diseases. The product is a multi-site inhibitor so the risk of resistant pathogens developing is low. This factor, combined with its broad disease control spectrum is the reason why this active substance is widely used in a range of fungicide programmes. The loss of such fungicides places increased reliance on other active substances, increasing the risk of pathogen resistance to other fungicides developing. This active substance is going into a voluntary stewardship programme and growers of crops other than wheat and barley will lose uses of this active substance by 2011. The implementation of staff re-entry periods into crops for new or re-registered products is likely to have an impact on which products may be used close to marketing stock. Long re-entry periods would also mean that crop workers would have to wear protective clothing when working within crops. This would make working within protected environments unbearable during the heat of summer (staff commonly wear shorts and t-shirts). It would also be difficult to enforce, as the industry relies on foreign labour and language barriers can be a problem in some businesses.
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5.15 Protected Ornamentals For the purpose of this project, the term ‘protected ornamental crops’ was used to cover container-grown pot plants and bedding plants; protected cut flowers were not included. The pot plant sector covers a wide range of indoor plant species including both foliage and flowering plants, together with a small number of hardy nursery stock species (e.g. azalea, hydrangea). The bedding plant sector covers an even greater number of species, many of them annuals, produced all year round in a range of pot and pack sizes, hanging baskets, troughs and containers. Most pot plant crops are grown within glasshouses; bedding plant production occurs within a combination of glasshouses and polythene tunnels. The intensity of production varies by crop and business, with some enterprises being capital-intensive (e.g. using thermal screens, supplementary lighting, mobile benching, gantry irrigation etc. in the production process) whilst others are much less so. Many of the crops (especially the bedding plant species) are short term and in excess of 3 crops can be produced during the year. Most crops are still grown in peat-based substrates, although a greater percentage of alternative materials are now included. Integrated pest management is becoming more widespread within the industry, especially on pot plants and bedding plant crops which require a heat input. A number of basic environmental, cultural and hygiene practices are used to minimise disease development, but control is still very much based on the use of a range of fungicides. Herbicides are not used over or immediately around crops for weed control, due to crop sensitivity and the likelihood of damage. Weed control around the nursery site still however needs to be maintained. Gross margin figures in the calculations are for production of a double 6 pack of seed raised bedding plants, but the returns are based on an average price for the entire industry (bedding and pot plants) therefore the two do not necessarily tie up. Table 74. Ornamentals gross margin (based on the production of a double 6 pack of seed raised bedding plants)
Crop Ornamentals
Crop area ha 939
Yield plants/ha 539,992
Value* £ per plant 0.43
Seed cost £/ha 12,122
Growing media £/ha 4,821
Spray cost £/ha 718
Bio-control cost £/ha
Casual labour £/ha 6,658
Pack, label & heating
costs
£/ha 21,350
Total value £/ha 232,196
Total costs £/ha 45,669
Gross margin £/ha 186,527 *Returns are based on average price for entire industry (bedding & pot plants)
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5.15.1 Business as usual and untreated scenarios Under Business as usual, the largest potential gains could come from improved control of Botrytis (£1.1M). The figures in brackets are the potential increase in value to the industry that could occur if 100% control was achievable. In the absence of pesticides, major losses in ornamentals when using sensible non-pesticide mitigation measures are caused by botrytis (£15M), downy mildew (£5.1M), caterpillars and aphids (£5M each) and thrips (£4.7M) (
Table 76). Any sign of pest or disease often results in the whole consignment of plants being rejected by retailers and garden centres at delivery; therefore high levels of pest and disease control are important to maintain plant quality and customer satisfaction. Direct losses from pests and diseases are generally well minimised within the industry, the main influence on wastage being fluctuations in customer demand due to changes in the prevailing weather conditions. However, high plant losses can occur when weather conditions are particularly conducive to any specific disease or pest. The main challenge for the sector is botrytis, which attacks a wide range of plant species and a range of fungicides is required to supplement cultural and environmental measures to keep the disease in check. Downy mildew can be a widespread problem as it attacks the two main bedding plant species produced – pansies and impatiens. A wide range of pests attacks bedding and pot plant crops, but the three of most importance are aphids, caterpillars and thrips. Without the option of fungicides, disease control would be very difficult in the case of botrytis, downy mildew and root rots. The industry could invest in more fans per structure to improve air circulation and reduce the incidence of foliar diseases. Physical or biological additives to growing media could be used to help control root diseases. However, an increase in the labour input per hectare would inevitably be required to permit more extensive hand cleaning of crops prior to marketing. Where growing temperatures permit (i.e. are sufficiently high), biological control agents could be used in place of some pesticides, but their use would not give all year round pest control for many crops. Placing mesh over vents to prevent pest access is not seen as a very practical option and it would not prevent pests entering production structures on bought-in plant material. Wider use of bio-pesticides, for both pest and disease control, could be made in the future to address the loss of synthetic pesticides. However, ultimately any major pesticide losses would lead to higher levels of losses and wastage for many crops. (The up and coming loss of nicotine, as a spray and smoke treatment, is an important loss to the industry as it was the last remaining volume treatment available for the control of a number of pests, specifically whitefly).
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Table 75.
Impact of weeds, pests and diseases on ornamentals under business as usual (potential yield and gross m
argin increases if better
control was possible - despite use of available pesticides)
Business as usual
Aphids
Caterpillars
Leaf miner
Two-spotted sider
mite
Sciarid fly
Slugs and snails
Thrips
Vine weevil
Whitefly
Black root rot
Botrytis
Downy mildew
Leaf spot (Fungal)
Leaf spots
(Bacterial)
Powdery mildew
Pythium and
Phytophthora root
rots
Rhizoctonia
Rust
Sclerotinia
Area affected (ha)
47
47
919
28
28
47
128
19
141
94
95
28
47
919
9
Potential increase in yield if 100%
control possible (1000 plants)
284
284
521
46
31
413
131
52
2,480
568
53
78
309
521
5
Potential increase in value to
industry if 100% control possible
(£K)
122
122
29
20
13
178
013
22
1,067
244
21
33
133
29
2
Increased value per affected
hectare (£K)
33
00
10
40
01
83
00
13
00
0
Table 76.
Impact of weeds, pests and diseases on ornamentals in the absence of pesticide applications – whilst using sensible m
itigation,
e.g. biological controls. (Worst case scenario)
Untreated
Aphids
Caterpillars
Leaf miner
Two-spotted
sider mite
Sciarid fly
Slugs and
snails
Thrips
Vine weevil
Whitefly
Black root rot
Botrytis
Downy mildew
Leaf spot
(Fungal)
Leaf spots
(Bacterial)
Powdery mildew
Pythium and
Phytophthora
root rots
Rhizoctonia
Rust
Sclerotinia
Area affected (ha)
188
188
28
47
47
47
188
294
47
282
188
19
547
94
928
9
Yield Loss (1000 plants)
10,551
10,551
78
517
1,344
1,294
10,551
51,035
517
31,805
10,551
52
5776
5,428
26
310
26
Cost to the industry (£K)
-5,047
-5,051
-50
-260
-641
0-4,685
0-518
-231
-14,854
-5,088
-36
-5-373
-2,502
-11
-154
-10
Cost per affected hectare (£K)
-27
-27
-2-6
-14
0-25
0-6
-5-53
-27
-2-1
-8-27
-1-5
-1
Percentage reduction in
production (%)
2.1
2.1
0.0
0.1
0.3
0.3
2.1
0.0
0.2
0.1
6.3
2.1
0.0
0.0
0.2
1.1
0.0
0.1
0.0
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Pests
Aphids (Aphis gossypii, Aulacorthum solani, Macrosiphum euphorbiae and Myzus persicae). A range of aphid species attack bedding and pot plant crops, but the two which cause most problems are A. gossypii and M. persicae as they are resistant / tolerant to a number of insecticides. All species cause direct damage by their feeding, but they can also transmit a number of viruses. There is a wide reliance on neonicotinoids (especially imidacloprid and thiacloprid), pyrethroids and pymetrozine for control of these pests. In the absence of pesticides, biological pest control agents (Aphidius and Aphidoletes species) are available, but complete control throughout the year on all crops is impossible to achieve and costly relative to pesticides. Caterpillars (Autographa gamma, Lacanobia oleracea, Cacoecimorpha pronubana etc.). Caterpillars can be problematic for much of the year on many crops. Outside of IPM schemes, pyrethroids are used to achieve rapid control, although recently more use is being made of spinosad and indoxacarb, following HDC-funded trial results. There are no effective biological control agents as such for caterpillars; instead regular applications of the bio-pesticide of Bacillus thuringiensis (Dipel DF) are used. Thrips (Frankliniella occidentalis, Thrips tabaci etc.). Western flower thrips (WFT) is not the problem it was on bedding plants, although it is still a major headache on pot- grown chrysanthemums, causing damage to flowers and leaves and potentially transmitting a number of important viruses. Biological control, specifically in the form of the predatory mite Amblyseius cucumeris, is used quite often for many heated crops. Chemical control is based around neonicotinoids, spinosad and abamectin, and tolerance has been noted in WFT to most of these active substances. The other pests noted in the assessment (leaf miner, two spotted spider mite, sciarid fly, slugs / snails, vine weevil and whitefly) are of less significance or of major significance on fewer plant species.
Diseases
Grey mould (Botrytis cinerea). Grey mould is a potential disease of many plant species throughout the year, but especially during humid or wet weather. The disease can cause losses both during the production stage and through the supply chain, attacking flowers, foliage and stems of plants. A wide range of cultural and environmental measures are employed to control this and other foliar diseases (such as downy mildew and leaf spot diseases), including ensuring adequate plant spacing and air movement, ‘heat boosts’ during periods of high humidity, avoidance of watering during late evening etc. Even with these measures in place, there is still great reliance on a range of protectant (azoxystrobin, chlorothalonil etc.) and eradicant (cyprodinil + fludioxonil, iprodione, prochloraz etc.) fungicides to achieve control. Downy mildew (Peronospora violae, Plasmopara obducens, Bremia lactucae etc.). As for botrytis, a number of cultural and environmental measures are employed to minimise disease risk. However, disease control is currently achieved by a few fungicide products, many of them based on metalaxyl-M. Access to some of the new potato blight fungicides is currently limited, due to the need for a specific protected use recommendation to be added to the label. Root rots (Pythium species and Phytophthora species). For susceptible plant species, fungicide drenches (fosetyl-aluminim, metalaxyl-M or propamocarb-hydrochloride) are commonly used to protect crops. There is a need for further work to explore the potential
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of physical (green compost, bark etc) and biological (Bacillus subtilis etc.) additives to control these diseases.
5.15.2 Changing approvals legislation scenario
Under the changing approvals legislation scenario, the following active substances that are currently used on protected ornamentals could be lost:
• Bifenthrin (insecticide)
• Mancozeb (fungicide) The impact of these losses on weeds pests and diseases is identified in Table 77. The most significant impacts of the changing approvals legislation scenario will be on downy mildew control (£487K).
Weeds
Weeds should not be a particular problem within crops and as such have not been included within this assessment. However, weed control is required over the nursery site itself and the loss of key contact and systemic herbicides such as glufosinate-ammonium will impact on general weed control. This could result in weed control within crops becoming more difficult, due to increased weed pressure from surrounding areas.
Pests
The loss of bifenthrin has a minor impact on the control of many pests, including aphids, caterpillars, two spotted spider mite, sciarid fly and whitefly. In most cases, there are still sufficient alternative active substances available (either other pyrethroids or other active substances) to compensate for the loss of bifenthrin, with only a small impact on some crops.
Diseases
The main impact is the loss of mancozeb on downy mildew control, either as a stand alone protectant fungicide or in mixtures with metalaxyl-M. The loss of protectant fungicides such as mancozeb will increase the potential for disease resistance amongst the range of eradicants used. Carbendazim is on the list of active substances expected to be lost due to the revision of EU Directive 91/414/EEC. This chemical was widely used within the industry for the control of black root rot and leaf spot diseases, but its approval was revoked around 2 years ago and hence it has not been included in this assessment.
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Table 77.
Impact of weeds, pests and diseases on ornamentals as a result of the pesticide losses caused by the changing approvals
legislation scenario– whilst using sensible m
itigation, e.g. biological controls. Cost to the industry is the additional cost
Changing approvals legislation
Aphids
Caterpillars
Leaf miner
Two-spotted
sider mite
Sciarid fly
Slugs and
snails
Thrips
Vine weevil
Whitefly
Black root rot
Botrytis
Downy mildew
Leaf spot
(Fungal)
Leaf spots
(Bacterial)
Powdery
mildew
Pythium and
Phytophthora
root rots
Rhizoctonia
Rust
Sclerotinia
Area affected (ha)
66
75
919
28
28
47
128
19
141
94
95
28
47
919
9
Yield Loss (1000 plants)
476
998
031
00
00
00
01,035
00
00
00
0
Cost to the industry (£K)
-252
-455
0-14
00
00
00
0-487
00
00
00
0
Cost per affected hectare (£K)
-4-6
0-1
00
00
00
0-5
00
00
00
0
Percentage reduction in
production (%)
0.1
0.2
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.2
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Table 78.
Impact of weeds, pests and diseases on ornamentals as a result of the potential pesticide losses caused by the restrictions put in
place by the current water quality requirements – whilst using sensible m
itigation, e.g. biological controls.
Water Quality
Aphids
Caterpillars
Leaf miner
Two-spotted
sider mite
Sciarid fly
Slugs and
snails
Thrips
Vine weevil
Whitefly
Black root rot
Botrytis
Downy mildew
Leaf spot
(Fungal)
Leaf spots
(Bacterial)
Powdery
mildew
Pythium and
Phytophthora
root rots
Rhizoctonia
Rust
Sclerotinia
Area affected (ha)
47
47
919
28
47
47
128
19
141
94
95
28
47
919
9
Yield Loss (1000 plants)
259
517
00
01,262
00
00
1,552
00
00
010
010
Cost to the industry (£K)
-119
-238
00
0-607
00
00
-720
00
00
0-6
0-6
Cost per affected hectare (£K)
-3-5
00
0-13
00
00
-50
00
00
-10
-1
Percentage reduction in
production (%)
0.1
0.1
0.0
0.0
0.0
0.2
0.0
0.0
0.0
0.0
0.3
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
* Cost to the industry assumes that the active substances are lost to the whole industry; however a complete revocation of the active substance is a last resort. Instead specific catchments may be
affected, if this is the case the cost per hectare can be used to apply to the area within a catchment that is affected.
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5.15.3 Water Quality The active substances that are currently available for protected ornamentals that are at risk from restrictions due to water quality requirements are:
• Chorpyrifos (insecticide)
• Cypermethrin (insecticide)
• Iprodione (fungicide)
• Metaldehyde (molluscicide) The impact of these restrictions is shown in Table 78. The potential loss of actives to water quality requirements could result in botrytis (£0.7M) becoming more difficult to control, resulting in yield losses and increased costs there would also be increased cost associated with the control of slugs and snails (£0.6M).
Weeds
As mentioned previously, weed incidence within these crops is not of importance and, as such, has not been included within this assessment. However, adequate weed control is important over the nursery site itself and the loss of key contact and systemic herbicides such as glyphosate would impact on general weed control. This could make weed control within crops more difficult, due to increased weed pressure from surrounding areas particularly if combined with losses expected under the changing approvals legislation scenario.
Pests
The loss of cypermethrin has a minor impact on the control of many pests, including aphids, caterpillars, leaf miner, sciarid fly, thrips and whitefly. In most cases, there are still sufficient alternative active substances available (either other pyrethroids, although with the planned loss of bifenthrin, the choice is limited to deltamethrin, or other active substances from other chemical groups) to compensate for the loss of cypermethrin, with only a small impact on some crops. Although slugs and snails are not a major problem for the crops being considered, they can be damaging on certain nurseries. The loss of metaldehyde could be a significant problem, as, of the alternative moluscicides, methiocarb cannot be used under protection and ferric phosphate or nematodes are either unsuitable or not cost-effective over large areas. The loss of chlorpyrifos (specifically within SuSCon Green) may have an impact on a small number of longer-term crops (for example cyclamen) for vine weevil control, however the main active, chlorpyrifos is due to be replaced, see hardy nursery stock. Other active substances and parasitic nematodes are available for use to control this pest.
Diseases
The potential loss of iprodione would impact mainly on botrytis control, but also on the control of rhizoctonia and sclerotinia. The active substance appears to be less effective nowadays, but is still a useful eradicant product to use within spray programmes. In the case of Botrytis control, the product is being superseded by cyprodinil + fludioxonil, but beyond further reliance on strobilurin-type fungicides, there are fewer alternative fungicides for the control of rhizoctonia and sclerotinia.
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5.15.4 Other reasons for pesticide losses Chlorothalonil being considered as a candidate UK specific pollutant. If it were to be lost it would have a large impact on general disease control, as the active substance is widely used as a protectant fungicide within spray programmes to achieve control of a number of significant diseases. As mentioned previously, the loss of useful protectant fungicides increases the risk of disease resistance to other remaining fungicides. Other pesticide issues specific to ornamental crops which could impact on the future range of available pesticides include: 1. The move from Long Term Arrangements for Extension of Use (LTAEU) on ornamental crops to Specific Off Label Approval (SOLA), with the loss of pesticides to the sector which do not gain a SOLA. 2. The implementation of staff re-entry periods into crops on labels for new products / re-registered products. Many bedding plant crops and some pot plant crops are short term, and a long re-entry period (where protective clothing would be needed to go into the crop) of 14-21 days would mean that the product could not be used in the spring /summer (as it would entail retailers and customers wearing protective clothing to purchase plants).
5.16 Appendix 1 Crop Experts Crop Expert Brassicas Don Tiffin (ADAS) Carrots Don Tiffin (ADAS) Leeks Don Tiffin (ADAS) Onions Don Tiffin (ADAS) Outdoor Lettuce Don Tiffin – weeds (ADAS)
Tom Pope – pests (ADAS) Kim Green - disease (ADAS)
Apple Chris Nicholson (ADAS) Pear Chris Nicholson (ADAS) Plum Chris Nicholson (ADAS) Blackcurrant John Atwood (ADAS) Raspberry Janet Allen (ADAS) Strawberry Janet Allen (ADAS) Cucumber Tim O’Neill (ADAS)
Derek Hargreaves (independent consultant) Tomato Tim O’Neill (ADAS)
Derek Hargreaves (independent consultant) Hardy nursery stock David Talbot (ADAS)
John Atwood (ADAS) combined with the expert opinion of Andrew Hewson, ADAS and economic data from William George, ADAS associate, including data from the Nursery Business Improvement Scheme (NBIS), run on behalf of the Horticultural Trades Association (HTA).
Ornamentals and bedding plants Wayne Brough (ADAS) Tim O’Neill (ADAS) John Buxton (ADAS) Andrew Hewston (ADAS)
