Canola School: Weather shift increases sclerotinia risk

It may have been a dry start to the year, with little to name of seedling diseases, but that doesn’t mean canola producers are off the disease-scouting hook this summer.

According to Clint Jurke, agronomy director with the Canola Council of Canada, due to the last four weeks of higher precipitation levels over the Prairies, “the potential for those diseases to start manifesting themselves is certainly increasing.”

Jurke recommends producers start to consider sclerotinia risks early on. In order for sclerotia to germinate, and produce apothecia (which in turn release ascospores), they require at least 10 days of moist soil conditions, and temperatures of 15 to 25°C.

“The question is really whether or not those ascospores are going to happen to coincide in that 20 to 50 per cent flowering stage in an individual field,” says Jurke. “If they do, we have wet crop canopies that are really good for the disease…”

In addition to visually scouting fields, producers also have the option of petal testing.

“There are genetic tests that are available, where you can take canola flower petals, and send them to a lab and they’ll run a DNA test to determine whether or not the fungus is actually on those petals,” says Jurke, adding if there is, and the canopy is wet, producers may consider remedial action.

Closer to swathing, crop scouting can provide an indication of the presence of clubroot, blackleg, or unmanaged sclerotinia.

And the more disease you have, the more variability you’ll have, says Jurke, adding disease levels can have an impact even as far as how the crop flows through the combine, and how much seed is retained.