It’s been six years since the disease we now call verticillium stripe was discovered in canola in North America.
First identified on a research farm in Manitoba in 2014, a Canadian Food Inspection Agency (CFIA) survey the next year found the pathogen, which can cause striping symptoms on canola stems, in six provinces — from B.C. to Quebec.
And yet, most of the reports of the disease have been limited to Manitoba, explains Justine Cornelsen, agronomy specialist with the Canola Council of Canada, based in western Manitoba.
“We’re only really seeing reports of it within the canola disease survey in Manitoba so far,” she says.
The key distinguishing feature is microsclerotia that appear as small black specks when you peel back the outer layer of the stem, says Cornelsen.
In Europe, the same pathogen is known to cause yield losses in oilseed rape crops ranging from 10 to 50 percent. Cornelsen says the yield impact doesn’t appear to be that significant in Canada — possibly due to different growing conditions, including the fact Canadian farmers grow spring-seeded canola varieties.
That verticillium stripe hasn’t been more widespread or damaging is great news for canola growers, but it’s also made it more difficult to get a handle on understanding the disease.
Recommendations for best management practices — mainly practicing good soil sanitation on equipment and extending crop rotations — are largely based off of Europe’s experience, and are similar to recommended practices for clubroot disease. To date, no fungicides or soil amendments have been found to be effective at killing the pathogen that causes verticillium stripe, says Cornelsen. On the genetics front, she says she has seen noticeable differences among varieties in field plots, but that research is still in the early stages.
She encourages growers to scout proactively, looking for the small microsclerotia bodies in the stem later in the growing season and after harvest. Since it can be tough to distinguish, she suggests sending samples to your provincial lab to determine whether your plants have verticillium stripe.
Justine Cornelsen joined RealAgriculture’s Kara Oosterhuis to discuss the latest on verticillium stripe for this episode of Canola School: