Canola Disease Update. Ralph Lange Alberta Innovates Technology Futures Red Deer, AB 18 January, 2012

Transcription

1 Canola Disease Update Ralph Lange Alberta Innovates Technology Futures Red Deer, AB 18 January, 2012

2 Outline The survey Blackleg Resistance breakdown Sclerotinia Minor diseases Strategies

3 The survey Agriculture Minister Gerry Minister Ritz working to resolve restrictions on Canadian canola exports to China. Canola Council of Canada (CCC) investing funding from the Agri- Flexibility Program Field demonstrations and surveys Canola-meal feed trials in Chinese dairies Canola disease surveys in Alberta sporadic in AB, regular in SK and MB. Consistent protocols nationwide Surveys in 2010, 2011, 2012 planned. Alberta collaborators: AAFC, AARD, AITF, Birch Hills, BRRG, Canola Council, CARA, LARA, PARDA, SARA, SARDA, U of A Municipalities: Grande Prairie, Warner, Kneehill, Newell, Northern Lights, Rockyview

4 The survey Targeted 161 fields Got data for 148 (blackleg basal stem canker) Random survey 100 plants per field Survey for blackleg plus other diseases of canola Samples retained for PCR confirmation of blackleg by CFIA Disease % Incidence (% plants with symptoms) Sclerotinia stem rot 8.7 Blackleg 8.5 Alternaria pod spot 6.8 Blackleg (basal stem canker) 5.4 Blackleg (upper stem lesion) 4.0 Brown Girdling Root Rot 1.7 Club root 1.3 Downey mildew 1.0 Foot rot 0.3 Aster yellows 0.2 Fusarium wilt 0.1

5 Typical blackleg symptoms lesion with dark border, light center pepper spots - pycnidia canker base of plant - stem breaks lesions of weakly virulent strain higher on stem

6 Harder to recognize in the field

7 Diffuse symptoms Pycnidia present Stem weakened, but no distinct lesion Can occupy the entire main stem Symptom of resistance breakdown (unsure) Weakly-virulent strain (L. biglobosa)

8 Internal blackening

9 Leaf symptoms Noticeable before bolting present on resistant varieties Means blackleg present Not predictive of stem lesions or yield losses

10 Seed infection Few seeds infected Usually can t diagnose visually, so a lab test is required Resistant varieties can produce infected seed

11 Blackleg What is it? Fungal disease caused by two species: Leptosphaeria maculans Causes severe lodging, premature dessication Formerly virulent strain Leptosphaeria biglobosa Mild symptoms only Formerly weakly virulent strain Why does this matter?

12 Matters because both species are not found everywhere

13 Virulent blackleg endemic in Canada

14 Blackleg Survey % Prevalence of Blackleg stem canker Infected Fields 100% 90% 80% 70% 60% 50% 40% MB SK AB 30% 20% 10% 0%

15 Blackleg Survey % Incidence of Blackleg stem canker Infected Plants % plants infected with blackeg Manitoba Saskatchew an Alberta

16 Blackleg prevalence % fields with symptoms Blackleg widespread in Alberta Blackleg found in % of fields in eastcentral and Peace regions Least-affected areas in southern AB No regions can be considered blackleg free

17 Change in prevalence 2010 vs Increases in Peace region due to moisture (dry in 2010) Significant increases in scattered areas in rest of province

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19 Blackleg incidence % symptomatic plants 2011 Greatest incidence in areas where blackleg has been established the longest east central Significant blackleg in Peace this year Even though disease occurs throughout AB, the no. diseased plants/per field low in some areas (southern AB)

20 Change in blackleg incidence 2010 to 2011 Percentage of plants affected per field same as last year in most areas Peace River region increased incidence around Grande Prairie moisture related

21 Blackleg Severity 2011 Overall, Blackleg most severe in east-central and Peace regions BUT, severely affected fields interspersed with lightly or unaffected fields

22 Change in severity 2010 vs Substantial increase in severity in many regions compared to 2011 Related to local microclimate or seeding date? Localized breakdown in resistance may also be a factor

23 Resistant vs. susceptible cultivars Hyola50 BravoTT

24 Loss of resistance to blackleg

25 500 Canola Cropping Frequency Black DG East soil zone Based on AFSC data canola on canola 1 year break 2 year 3 year 4+ on fallow Records

26 Blackleg on a Resistant B. napus cultivar 14 September, 2010 Cougar CL Resistant Westar Susceptible

27 Rated vs. actual performance under blackleg disease pressure R Registration Vegreville 2010 Severity rating MR MS S Westar AC Excel RR Defender DS Roughrider SP Admirable 46A73 SP Banner H21 45H25 46A76 Conquest Cougar CL Q2 Rugby 3465 Nexera 824CL

28 Managing blackleg and resistance breakdown Crop rotation or ROTATE GENETICS Disease free seed, seed treatments Effective resistant cultivars Foliar fungicides Effective resistant cultivars Effective resistant cultivars

29 Ensuring Disease Resistance Durability high high Gene flow R genes & quant. resist. in multi-lines or regional deployment Pathogenic Diversity low Use quantitative resistance Gene flow high low Pyramid R genes low Use R gene McDonald BA. and Linde C. Euphytica 124 (2): , 2002.

30 Cultivar rotation: Blackleg can be reduced by not over-using the same resistance % blackleg infection Y77 % blackleg infection ATR-Beacon 0 45Y77 ATR-Beacon AV-Garnet Dune 2007 stubble type 0 45Y77 ATR-Beacon AV-Garnet Dune 2007 stubble type % blackleg infection AV-Garnet 45Y77 ATR-Beacon AV-Garnet Dune 2007 stubble type % blackleg infection Hyola50 45Y77 ATR-Beacon AV-Garnet Dune 2007 stubble type

31 Sclerotinia stem rot petals crucial

32 Sclerotinia stem rot vs. blackleg Sclerotinia stem rot Very substantial effect of weather on disease occurrence and severity High gene flow (sexual recombination) Resistance quantitative Unlikely to break down Control relies on fungicides Short survival time short rotations effective No evidence of pathogenic adaptation Resistance equally effective anywhere Blackleg Weather important High gene flow (sexual recombination) Resistance qualitative and quantitative Resistance breakdown Increasing importance of quantitative resistance and fungicides? Pathogenic adaptation widespread and rapid Gene deployment and gene stewardship necessary

33 Stem rot incidence % symptomatic plants 2011 Moderate (central) to low (south) stem rot incidence Some regions skewed upwards due to individual heavilyaffected fields.

34 Change in stem rot incidence 2010 to 2011 Percentage of plants affected per field same as last year in most areas Peace River region increased incidence around Grande Prairie moisture related

35 Club root Region Nr. Fields Incidence (%) A B All

36 Root rot complex Incidence (%) Region Nr. Fields Foot rot BGRR A B All

37 Strategies for control Blackleg: Disease widespread, resistance breakdown ubiquitous, long rotation unlikely New resistance(s): e.g. quantitative, resistance, exotic resistance Most important: adopt practices to slow resistance breakdown: Gene deployment, fungicides, rotation of cultivars

38 Strategies for control Sclerotinia: Severity, incidence is weather dependent Resistance useful addition Fungicides will continue to be important