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A comprehensive canola disease management strategy includes considering past disease outcomes and planning to reduce future disease impacts. This blog reviews the 2024 canola disease survey outcomes from Manitoba, Saskatchewan and Alberta to help growers and agronomists better inform their canola disease management strategies for 2025.
A plant disease occurs when all three components of the disease triangle are present: the host, pathogen and suitable environment. If canola is the host, and environmental conditions are conducive, then management related to the pathogen (such as actions to minimize disease spore loads in a field) can impact the resulting disease occurrence.
When reviewing the following survey information, recall the meaning of these terms that describe the disease presence and impact:
- Prevalence is the percentage of fields surveyed that have infection in them.
- Incidence is the percentage of plants surveyed within a field that have disease symptoms.
- Severity is the degree of infection in a plant, often rated with a scale, if available (ex. 0-5 scale for blackleg).
Results from all three provincial disease surveys were generated using proper scouting methods (including the random selection of at least 100 plants from a “W” pattern in a field), which are essential to the quality of data. Further specifics on the methods followed are described in the Western Forum on Pest Management (WFPM) 2024 oilseed disease report.
Apply this research on your farm
- Review 2024 canola disease prevalence, incidence and severity in Manitoba, Saskatchewan and Alberta.
- Make a disease management plan for each field, using agronomy guides that support effective scouting, accurate identification and good records.
- Work with an agronomist to help ensure timely assessments and decision-making for each field.
- Support provincial disease survey efforts, where possible.
- Subscribe to Canola Watch and the PCDMN for seasonal updates.
The complete plant disease situation from the 2024 growing season from all three Prairie provinces, will be posted by the Canadian Phytopathological Society (CPS) in the Canadian Journal of Plant Pathology once finalized.
Manitoba
The 2024 Manitoba Canola Disease Survey data, which will be published by CPS in the Canadian Journal of Plant Pathology, included 138 fields in the major canola growing regions of the province that Manitoba Agriculture and supporting agronomists surveyed between August 5 – October 2. The majority of the crops were surveyed before swathing, as noted in the WFPM 2024 oilseed disease report. Disease assessments were made on 100 plants in each field (20 plants from five sites at least 20 metres from the edge of the field and at least 20 metres from each other). Fields were assessed for the prevalence and incidence of sclerotinia, blackleg, aster yellows, foot rot, verticillium stripe and clubroot and sclerotinia and blackleg severity were rated according to their respective 0-5 rating scales.
| Canola disease | Prevalence | Incidence | Severity |
| Alternaria | 38% | 23%* | <1% |
| Aster yellows | 28% | 2%* | |
| Blackleg** | 76% | 12% | 1.2 |
| Foot rot | Not observed | ||
| Sclerotinia stem rot | 57% | 5% | 1.7 |
| Verticillium stripe | 60% | 32%* |
Manitoba reported two new symptomatic cases of clubroot in two different RMs, outside of the 138 canola fields surveyed in 2024. One positive case was also documented outside of the survey (in a different RM), detected through soil samples.
Manitoba Agriculture’s Season Summary Crop Report explained that high moisture and humidity in Manitoba’s 2024 growing season created conditions conducive to disease development. In canola crops, verticillium stripe was most prevalent disease (especially in the northwest region of the province), followed by sclerotinia and blackleg. In addition to highlighting verticillium stripe, the last 2024 issue of weekly Crop Pest Updates that Manitoba Agriculture released (on August 22) also mentioned the Bird’s-nest Fungus, which can be mistaken for apothecia (sclerotinia spore-producing structure).
Saskatchewan
The general 2024 Saskatchewan Canola Disease Survey involved the surveying of 208 fields (across the major canola growing regions of Saskatchewan) by the Saskatchewan Ministry of Agriculture and supporting agronomists. These results, along with the methods used in the survey are available in the WFPM 2024 oilseed disease report and will be available in the Canadian Journal of Plant Pathology.
Crops were surveyed between August 5 and September 26, before swathing. Disease assessments were made on 100 plants in each field (20 plants from five sites that were at least 30 metres from the field edge and at least 20 metres from each other. The diseases assessed include: sclerotinia stem rot. blackleg, aster yellows, foot rot, alternaria black spot, fusarium wilt, verticillium stripe, powdery mildew, downy mildew, white rust, grey stem, bacterial pod spot, and clubroot.
Symptoms of powdery mildew were observed in two of the surveyed fields. Symptoms suggesting foot rot, downy mildew, white rust, and bacterial pod spot were not found in any of the surveyed fields assessed.
Similar to the previous year, the Saskatchewan Ministry of Agriculture conducted a post-harvest verticillium-specific survey in 2024 (in addition to the general canola disease survey). It targeted 100 fields across Saskatchewan to assess the prevalence and incidence of the disease and help evaluate the risk this disease poses to canola production in Saskatchewan. The results are in the provided table.
The higher average sclerotinia incidence rates in 2024 mentioned in the SK Disease Pest Survey Results webinar (compared to the last two growing seasons) were attributed to more favorable weather conditions during the growing season.
| Canola disease | Prevalence | Incidence | Severity |
| Alternaria | 69% | ||
| Aster yellows* | 25% | 0.6% | |
| Blackleg** | 92% | 23% | 0.39 |
| Foot rot | Not observed | ||
| Sclerotinia stem rot | 56% | 9% | 0.24 |
| Verticillium stripe | 32% |
**Values based on blackleg through basal stem cross-section analysis.
The Clubroot monitoring program in Saskatchewan, which is a collaboration between the Saskatchewan Ministry of Agriculture, SARM plant health technical advisors, Saskatchewan Crop Insurance Corp and SaskOilseeds, is 100% permission-based survey. The 2024 program surveyed 181 commercial fields in high-risk areas (not just randomly selected fields). Results from this, share in the Saskatchewan Disease Pest Survey Results webinar included:
- No new commercial fields with visible clubroot symptoms, leaving 82 as the total number of commercial fields with visible symptoms found by these annual surveys between 2017-2024).
- Two new commercial fields with clubroot were identified by DNA test, bringing the total up to 45 commercial fields with positive DNA tests but no visible symptoms of clubroot found by these annual surveys between 2017-2024.
Alberta
Between July 26 and October 18 Alberta Agriculture surveyed 401 Alberta canola fields. Canola plants were rated at ten sample points in each field along a W-shaped transect that was more than 20 metres away from other locations and from the field margin. One hundred plants were rated for clubroot at the field entrance and then 10 plants at each of the other nine locations. The lower six to twelve inches of ten stems were collected at each of the ten sample points (100 stems/field) and rated for blackleg, sclerotinia stem rot and verticillium stripe.
Survey results are in the table below (and will be in the Canadian Journal of Plant Pathology). Blackleg was again the most prevalent disease, followed by sclerotinia stem rot and clubroot. Prevalence of all measured canola diseases was slightly higher in 2024 compared to the previous year, except for sclerotinia.
| Canola disease | Prevalence | Incidence | Severity |
| Blackleg | 96.5% | 31.8% | 0.6 |
| Clubroot | 6.8% | 0.7% | 0.01 |
| Sclerotinia stem rot | 14.5% | 0.9% | Not collected |
| Verticillium stripe | 6.2% |
In an additional monitoring effort described in the WFPM 2024 oilseed disease report, 36 canola fields across central and southern Alberta were surveyed for verticillium stripe between October 1-10, 2024, with 100 plants examined in each field. An additional 22 symptomatic samples were provided by agronomists for disease rating and further testing. While symptoms were only observed in ~10% of fields, 74% of survey samples and 44% of samples submitted by agronomists were identified by laboratory analyses as blackleg, 1% were confirmed as sclerotinia and only 8% were confirmed as verticillium stripe. The simultaneous occurrence of blackleg and verticillium stripe was also noted in some fields. These findings suggest verticillium stripe could be a risk to canola production in Alberta, despite lower prevalence compared Manitoba.
Support future disease survey efforts
Manitoba
- To support the survey effort in Manitoba, contact Sonia Wilson, Provincial Oilseed Specialist if you are willing to participate in the 2025 crop survey (again or for the first time).
- Submit free canola samples to the PSI lab through the #GetTested program for clubroot, blackleg presence and race identification and verticillium stripe testing, if you are a member of the Manitoba Canola Growers qualify. Additional testing offered at a fee include glyphosate resistance kochia and Amarnath species identification.
Saskatchewan
- Participate in the valuable disease monitoring program offered by SaskOilseeds, in partnership with the Saskatchewan Ministry of Agriculture, for to find out if verticillium stipe, clubroot and/or blackleg are on your fields.
- Support the crop disease surveying efforts by getting involved. To participate, just fill out the Pest Monitoring Sign-up Form and/or sign up to become a Volunteer Crop Reporter for the coming growing season.
Alberta
- Check the Prairie Crop Disease Monitoring Network for in-season updates and scouting tips and protocols.
- Continue to support the crop disease monitoring efforts on commercial fields in Alberta.
Management
In addition to assessing your canola disease risk, consider options to manage each disease if it occurs and future planning and tracking for a long term strategy.
- Blackleg: Follow the recommendations in the Blackleg Management Guide and use the Blackleg yield loss Calculator to assess damage after each season.
- The Blackleg disease cycle can help ensure proper disease identification and recommended timing (related to plant growth stage) of disease events and management options (such as the early critical window of infection to protect crops from, ideal scouting timing, and crop rotation timing for residue decomposition) that align with Keep it Clean.
- Clubroot: Use the Clubroot management info to keep spores low and local and how to understand and use clubroot resistance as part of an integrated clubroot management plan.
- Watch this descriptive clubroot video (on Clubroot.ca) to understand why certain management strategies are effective or not, and the scouting video to watch for it in fields.
- Sclerotinia: Use the sclerotinia risk assessment tool to calculate disease risk, inform your spray decision at flowering and evaluate it after with disease severity estimation.
- The sclerotinia stem rot disease cycle can add context to maximize management choices, and the Sclerotinia resources can prepare you for proper identification, choose the ideal sclerotinia fungicide timing for a spray decision and support your late season disease rating technique.
- Verticillium stripe: use the Verticillium stripe field scouting guide to identify it and differentiate it from blackleg and research into yield impact and resistance options.
- Also review the disease cycle infographic check out the verticillium stripe in canola video for a better overall understanding of this disease and factors impacting it.
- Other canola diseases: Differentiate between root rots with this infographic, learn about aster yellows with this infographic and check the Canola Disease Scouting Guide to help identify and understand less common canola diseases, in addition to those mentioned above.
- Use the CCC’s phenology sheet to keep good records and track disease throughout the season for maximum value from post-season reviews and assessments.
Published March 31, 2025
