Upload
kaya-crofford
View
218
Download
0
Tags:
Embed Size (px)
Citation preview
Disease Control Products for Stored Potatoes
Jill Thomson and
Doug Waterer
Dept of Plant Sciences, University of Saskatchewan
Control of Storage Diseases
• Challenge - need dependable control of various diseases during storage/handling
• Challenge - need safe, affordable products
• Challenge - products must be readily applied with available equipment
Control of Storage Diseases
• Traditional options
– Mertec (TBZ)• spray applied during load-in• good coverage critical• not effective against bacteria• not effective against Late Blight• extensive resistance in Dry Rot
and Silver scurf• $ 6.40/tonne at CDN label rate
Control of Storage Diseases
• Available options
– Dithane (Mancozeb)• spray applied during load-in• good coverage critical• not effective against bacteria• effective against Dry Rot and
Silver scurf• $ 11.06/tonne• only registered for use on seed
Control of Storage Diseases
• Purogene (Anthium) – UAP– Sodium chlorite + acid = Chlorine dioxide
(gas) + other Cl species – applied as spray to potatoes going into
storage and/or– added to ventilation air
Control of Storage Diseases
• Purogene– works by oxidation reactions
– label indicates effective against L. blight, Silver Scurf, Dry Rot and Bacterial Soft rot
– inactivated by soil
– no residual activity
– repeated or continuous treatment recommended
Control of Storage Diseases
• Purogene - Status– Researched by MSU, NDSU, Idaho, MB
and AB.– 5th year of Class 18 Exemption in U.S.– Emergency use in Canada in 1999,
2000 and 2001 but not in 2002
Control of Storage Diseases
• Purogene Efficacy against Soft rot– MB data– some control
020406080
100
% Soft Rot
0 50 100 400
PPM Purogene
Soft Rot Control with Purogene
Russets Shepody 1 Shepody 2
Control of Storage Diseases
Effect of Purogene on the amount of rot found on tubers (MANITOBA)
Cultivar Concentration Avg Rot per Tuber (%)
Russet B. 0 23.5
50 3.8
200 1.1
400 2.2
Shepody 0 9.1
50 5.8
400 3.2
Shepody 0 1.1
50 2.4
200 0.2
400 0.3
Control of Storage Diseases
• Purogene vs Late Blight– MB data– Tubers treated immediately after inoculation – some control
020406080
100
Trial 1 Trial 2 Trial 3 Trial 4
Control Purogene
Control of Storage Diseases
• Purogene vs Rhizoctonia, Silver Scurf, Soft Rot and Dry Rot– AB data– Tubers sprayed at load in– Tubers treated in storage (weekly)– minimal control
Control of Storage Diseases
• Purogene - Safety– mixing step requires safety equipment (ClO2
vapors) – ventilate storage for 2 h prior to re-entry– potatoes must be washed prior to
consumption– slowly corrodes copper, brass, aluminum
Control of Storage Diseases
• Purogene - Economics– 16-32 ml/ton applied at load-in– max rate of 16 ml/ton/month applied during
storage humidifaction– $25/L– $ 2.50/ton for pre-treatment + continuous
application over 5 months
Control of Storage Diseases
• Purogene Conclusions– variable results– problems getting full activation– problems with inactivation by soil– problems with uniformity of
distribution of effective dosages– problems with adding humidity to
problem storages– relatively safe and affordable
Control of Storage Diseases
• Oxidate– BioSafe– Hydrogen Peroxide + acetic acid – applied as spray to potatoes going
into storage and/or– added to ventilation air
Control of Storage Diseases
• Oxidate – works by oxidation reactions– label indicates effective against L. blight,
Silver Scurf, Dry Rot and Bacterial Soft rot– inactivated by soil– no residual activity – continuous treatment recommended
Control of Storage Diseases
• Oxidate - Status – approved in U.S. for use in wide range
crops in field and storage– approved as an “organic” pesticide– “Emergency Use” in BC and AB in 2002– full registration anticipated for April 2003– NB has done some testing in potatoes
Control of Storage Diseases
• Oxidate - Efficacy
0
5
10
15
20
25
Ave
rage
% d
ry
rot
0 1% 2%
Oxidate treatment
FDR development after Oxidate treatment for 16 weeks
ShepodyNorland
Control of Storage Diseases
• Oxidate - Efficacy
0
20
40
60
80
100
Inci
den
ce s
ilver
sc
urf
(av.
%)
0 1% 2%
Oxidate treatment
Silver scurf development after Oxidate treatment for 16 weeks
ShepodyNorland
Control of Storage Diseases
• Oxidate - Efficacy
0
1
2
3
4
5
Sof
t ro
t (
%)
0 1% 2%
Oxidate treatment
Soft rot development after Oxidate treatment for 16 weeks
ShepodyNorland
Control of Storage Diseases
• Oxidate - Safety– no mixing step – concentrated product is corrosive – no re-entry restriction – no limit to amount applied – no requirement to wash prior to consumption– slowly corrodes copper, brass, aluminum
Control of Storage Diseases
• Oxidate - Economics– 1-2% solution applied to wetness at load-in– 1:100 to 1:300 applied during storage humidifaction– $17.78/L– pre-treatment = $ 0.71-1.42/tonne– 1% in humidification system = $1.78 per injection– How many injections into system over 5 month
period?
Control of Storage Diseases
• Oxidate – Conclusions– potential to reduce disease
levels– high dosages and continuous
application most effective– safe and affordable– need uniform delivery of
effective dosages– adding humidity to problem
potatoes ?
– Impact on sprouting ??
Control of Storage Diseases
• Ozone – various manufacturers– O2 + high energy = O3 (gas) – applied at high levels to potatoes
going into storage and/or– added to ventilation air
Control of Storage Diseases
• Ozone – works by oxidation reactions– lab studies indicates effective against range of
bacteria and fungi– inactivated by soil– no residual activity – continuous treatment recommended
Control of Storage Diseases
• Monitoring equipment mounted above conveyor. Injection of O3 into conveyor system, removal of excess O3.
Control of Storage Diseases
• Ozone - Status– well established in other food areas– data for storage use is limited– advantage = does not depend on
water for delivery (spray or humidity)
Control of Storage Diseases
• Ozone – Efficacy
01020304050607080
% I
ncid
ence
1 day 1 wk 3 wks
Exposure time
FDR on surface-inoculated tubers
OZONEControl
Control of Storage Diseases
• Ozone – Efficacy
05
1015202530
% I
ncid
ence
1 day 1 wk 3 wks
Exposure time
Silver scurf after ozone treatment
OzoneControl
Control of Storage Diseases
• Ozone – Efficacy– O3 applied loading into storage
0
5
10
15
20
Ext
ent
of F
DR
d
amag
e (s
q.c
m)FDR development in wounded,
inoculated tubers
NorlandYukon Gold
Control of Storage Diseases
• Ozone - Safety– widely used to sanitize food and buildings – corrosive at high concentrations – exposure levels well established – no limit to amount applied – no requirement to wash prior to consumption
Control of Storage Diseases
• Ozone - Economics– generators + power
– 500 ppm during loading
– 2 ppm during storage ventilation
– $ ?
Control of Storage Diseases
• Ozone - Conclusions– primarily provides contact control– most effective against surface problems (scurf
and bacteria)– ineffective against aggressive or well
established infections– economics ?– Impact on product/facilities ?
Control of Storage Diseases
• Conclusions– Purogene and Oxidate demonstrated to
provide some control under certain conditions– Ozone also shows potential– Most effective against new, surface problems – Supplement to good harvest and storage
management practices