Blackleg
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The risks from high canola frequency
Blackleg
Scientific research in Western Canada has identified three factors that increase the risk of canola yield loss in short rotations. They are blackleg, clubroot and cabbage root maggot. Clubroot will drive the need for longer breaks between canola crops on more and more farms.
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Interpreting blackleg race ID test results
Blackleg
Step 1. Sample Collection The ideal time to pull and assess plants for blackleg infection is at 60% seed colour change, which is around swath timing. Plants should still be green. Cut just below the crown of the plant into the root material to assess. “Look for black discolouration within the hypocotyl tissue, often appearing […]
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When is ‘too late’ to assess stubble for blackleg?
Blackleg
Field observations suggest that blackleg may be increasing in some areas. Official disease survey results for 2018 will be announced at Western Forum October 17-19. In the meantime, farmers and agronomist may still have time to count the percentage of plants that are diseased.
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Test blackleg races in a field; make better seed decisions
Blackleg
New tests allow farmers to identify the blackleg races in their fields. With this information, farmers can choose canola varieties with resistance to those races.
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What’s going on with the roots?
Blackleg
Take a random look at a few canola roots in each field to see what’s going on. Also dig up the root area for plants that look less than healthy for no apparent reason. This plant has foot rot.
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After the hail
Blackleg
How many plants recovered? Are they at early stages and at risk of heavy blackleg infection? What is the crop nutrition situation?
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Blackleg decision: When does a fungicide pay?
Blackleg
Blackleg infection at or just after the cotyledon stage is the mostly likely to cause any significant yield loss. If fungicide to control blackleg is to provide any economic benefit, it has to be applied very early in the season and the crop has to be at risk of early and fairly widespread infection. With good management, including a two-year break between canola crops, growing blackleg resistant varieties and rotation of R genes, fungicide is not necessary. In that situation, fungicide to reduce blackleg losses does not usually provide an economic return.
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Quick comparison: Blackleg, clubroot, sclerotinia stem rot
Blackleg
Use this quick-reference table to compare key distinguishing features, mechanisms for spread, and management options for blackleg, clubroot and sclerotinia stem rot.
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Blackleg video quiz for CCA credit
Blackleg
Watch the video. Take the quiz.
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Blackleg: New stubble test from Discovery Seed Labs
Blackleg
Discovery Seed Labs in Saskatoon is the first to offer a test of canola stubble to determine (1) if blackleg is present and (2) what race of blackleg it is. This can help farmers and agronomists make proper use of the new blackleg resistance-gene (R-gene) classification system when making seed decisions.
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Blackleg scouting in the fall
Blackleg
If you missed the swath-timing window to check canola stems for blackleg, you still have lots of time to look for blackleg pseudothecia on old canola stem pieces in fields that will go into canola next year. This can help with seed decisions.
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Seed: How much blackleg before I rotate resistance?
Blackleg
If one in 10 plants has a blackleg rating of 2 or worse, this is a clear sign that the blackleg pathotypes in a field do not align with the blackleg resistance (R) package in the particular hybrid grown. While yield loss in this situation may not be significant (each affected plant will have at […]
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Blackleg, foot rot or cutworms?
Blackleg
These can be hard to tell apart sometimes. Pinched or otherwise damaged-looking stems can occur with all three. The photo shows blackleg infection. Here’s how to tell them apart…
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Blackleg: Early scouting and fungicide
Blackleg
For fungicide to provide an economic level of blackleg suppression, the crop has to be susceptible to the disease, blackleg incidence and severity must be high (usually due to short canola rotations) and the fungicide has to go on early – cotyledon to 4-leaf stage – before visible symptoms appear.
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What’s new in blackleg management?
Blackleg
Using the same disease resistance genetics over and over causes a shift in pathogen population, which can then overcome the resistance in our varieties – similar to herbicide resistance in weeds. Knowing the resistance genetics used in previous years will allow growers to rotate to a different resistance gene and reduce the blackleg infection within a field. As many as 10 new blackleg resistance labels will be applied to varieties in the coming years. They will use these letters A, B, C, D, E₁, E₂, F, G, H, X to identify major resistance genes present.