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What Lurks in Your Canola Field:Disease Surveys of 2009
Debra McLaren & Anastasia KubinecAAFC-Brandon and MAFRI-Carman
D. McLaren, A. Kubinec, R. Kutcher, S. Strelkov, F. Dokken, P. Northover, S-F. Hwang, R. Howard
and K. Turkington
Studies / Collaborators
Survey of Canola Diseases in ManitobaSurveillance and dispersal of Plasmodiophora
brassicae in western Canada
Manitoba Team for Canola Survey
• Manitoba Canola Growers Association• AAFC
– Deb McLaren, Tom Henderson, Danny Hausermann and Teri Kerley
• MAFRI– Anastasia Kubinec, Brian Jack, Stephanie Jersak,
Hilmar Johnson, Lionel Kaskiw, Ingrid Kristjanson and Kristen Phillips
• Canola Council of Canada– Derwyn Hammond
• 140 canola fields in Manitoba
• 60 of these fields = soil samples for clubroot
Canola Fields for Survey in Manitoba
Bruce Barker Bruce Barker
Sanitation Practices for Canola Survey
• Wear disposable booties and disposable rubber gloves
• Sterilize soil sampling equipment in bleach after leaving field but before entering vehicle
• Eliminate transport of infected soil outside of the sealed soil sample.
• Do not drive into the field
Soil Collection for Clubroot Assessment
• Collect 1 L soil from all 5 points of W combined
• If entrance to field is obvious, collect soil from 5 points in area limited to the vicinity of this approach.
• To collect soil, clear away crop residue and scoop approx. 1 cup soil from top 5-10 cm
• Place in paper bags to air-dry.
Canola Diseases
Sclerotinia Stem RotBlackleg
Alternaria Black SpotAster YellowsFusarium Wilt
Foot RotClubroot
Rating for Sclerotinia Stem Rot
• Main stem lesions that affected the entire plant were recorded separately from any lesion in the upper branches or pods
Sclerotinia Stem Rot in Manitoba (2009)
Crop RegionNo. of Crops Prevalence (%) Incidence
Central 49 96 19
East./Interlake 20 100 37
Northwest 23 96 20
Southwest 48 81 7
Province 140 91 18
Canola Council
Sclerotinia in Canola: Previous Years
Year No. of Crops Prevalence (%) Incidence
2008 54 94 23
2007 40 80 5
2006 33 39 3
2005 81 40 3
2004 68 72 9
Blackleg: Leptosphaeria maculans
Whitish, round to irregular lesions on leaves dotted with pycnidiaLesions on leaves become papery and dryBrown to greyish black lesions, become sunken cankers , girdling the stemBlack lines inside base of stemPremature plant death
Blackleg Rating System
• Main stem lesions that affected the entire plant were recorded separately from any lesion(s) in the upper branches or pods
• Cankers formed early in the season may girdle the stem (virulent strain – L. maculans)
• Weakly virulent strain (L. biglobosa) also causes stem lesions but superficial, non-girdling and occur late in the season so don’t affect yield
Blackleg in Manitoba Canola Fields (2009)CCC
Basal Cankers Upper Stem Lesions
Crop Region
PercentPrevalence Incidence
PercentPrevalence Incidence
Central 76 8 76 5
East./Inter. 75 4 60 2
Northwest 22 2 43 7
Southwest 44 2 40 1
Province 56 4 56 4
Blackleg in Canola: Previous YearsCCC
Basal Cankers Upper Stem Lesions
Crop Region
PercentPrevalence Incidence
PercentPrevalence Incidence
2008 17 3 54 7
2007 52 2 65 7
2006 39 7 61 5
2005 60 4 65 6
2004 32 6 35 5
Alternaria Black Spot
Canola Council of Canada
Canola Council of Canada
•Brown to black small, round spots onpods and stems•As disease progresses, spots become black to gray with black border •Leaves die and drop off•Pods become dry and sunken and split prematurely
Alternaria Black Spot
Crop RegionNo. of Crops Prevalence (%)
Disease Severity
Central 49 47 <1
East./Interlake 20 85 <1
Northwest 23 22 <1
Southwest 48 23 <1
Province 140 40 <1
* Generally a 1% infection of pods or stems translates into a 1% yield loss.
• In some plants, yellowing & necrosis affects one side of stem, or individual branches
Distinct colour: grey-green with a red-pink cast
Healthy
Fusarium Wilt
Crop RegionNo. of Crops Prevalence (%) Incidence
Central 49 2 <1
East./Interlake 20 10 <1
Northwest 23 0 0
Southwest 48 4 <1
Province 140 4 <1
Fusarium Wilt : Previous Years
Crop RegionNo. of Crops Prevalence (%) Incidence
2008 54 9 1
2007 40 15 <1
2006 33 18 1
2005 81 21 1
2004 68 0 0
Aster Yellows
•Transmitted by asterleafhoppers
•Malformation of the floral parts•Round to oval blue-greenish,hollow bladder like formations
Aster Yellows
Crop RegionNo. of Crops Prevalence (%) Incidence
Central 49 14 <1
East./Interlake 20 20 <1
Northwest 23 13 <1
Southwest 48 15 <1
Province 140 15 <1
Foot RotDiseases of Field Crops in Canada
• Early symptoms of light brown lesions on roots(taproot and/or mainlateral roots) below soilline
• Lesions enlarge, leavinga “stubby root
• Plants ripen prematurely
Foot Rot
• Foot rot was observedin 2% of canola fields
• Disease incidence was<1% in Central, E/I andNW regions.
• No foot rot observed inSW region.
Why is Clubroot of Concern?
• Serious disease of canola, mustard and other crops in the cabbage family
• Spreads through resting spores in soil• Resting spores are extremely long lived• This can be problematic under tight rotations• Infestations near 20% cause yield loss of
10%• Yield and quality (oil content) of the seed are
reduced
Clubroot Status (Oct. 2009)
• Clubroot confirmed in 454 fields since 2003
• 224 fields visited & 49 new cases identified in 2009
• 17 municipalities & City of Edmonton– Additional cases suspected
but not confirmed• Presence of P. brassicae
inoculum also confirmed in Saskatchewan (1 field in 2008)
• Presence in Manitoba in one canola field in 2005.
What is being done about Clubroot?
• April 2007 – clubroot added as a declared pest to Alberta’s Agricultural Pest Act.
• June 2009 – clubroot declared a pest in SK under The Pest Control Act.
• Not a legislated pest in Manitoba yet but this is in progress
• Required to take steps to destroy, control and prevent spread of clubroot.
Clubroot – Management Strategies
• Use long rotations between crops – 4 yrs or more• Practice good sanitation to restrict movement of
contaminated soil• Soil conservation practices to reduce erosion• Scout regularly to ID causes of wilting, stunting,
yellowing and premature ripening• Avoid common untreated seed because ‘earth tag’
on seed from infested fields could introduce resting spores to clean fields.
• Risk of spreading clubroot through contaminated seed is much less than through transporting contaminated soil on field equipment.
Summary
• Clubroot– Alberta: New cases of clubroot continue to be identified– Saskatchewan: One case of clubroot 2008; no symptoms in 2009; soil
sample results pending– Manitoba: No clubroot symptoms in 2009; soil samples
• Sclerotinia:– Similar levels in past few years
• Blackleg:– prevalence of basal cankers increased; that of stem cankers relatively the
same. • Fusarium wilt:
– prevalence reduced over years
• Survey of Manitoba canola fields:– will continue as a collaboration between AAFC, MAFRI, MCGA, and CCC