Manitoba canola fields recorded six new cases of clubroot in 2026, some with unusually severe symptoms, provincial plant pathologist Simon Huang told a Manitoba Agriculture Crop Talk webinar on 7 October, Don Norman reports for the Manitoba Co-operator. It is the most new cases since 2018, when 15 fields were confirmed.
A seventh case was found in mustard grown as a biofumigant for potatoes in the RM of Cornwallis. The canola cases were in the rural municipalities of Lorne and Louise, one each, and Pembina and Swan River West, two each, all confirmed by Stephen Strelkov's lab at the University of Alberta.
The soil-borne disease forms galls on canola roots, limiting water and nutrient uptake and causing wilting, early ripening and yield loss. Clubroot has been less common in Manitoba than in Alberta, but this year's fields showed extensive galling, wilting patches, discolouration and premature death. "This would be more typical of symptoms in Alberta because they have more pathotypes and more inoculum load," Huang said.
The affected fields were sown with first-generation clubroot-resistant varieties, Huang confirmed, but he said it would be premature to conclude that resistance has been overcome. Tests to identify the pathotypes, which could show whether new ones have reached Manitoba, are due in early 2027. Few Manitoba samples have been characterised before, so known pathotypes, including 5L, 2C, 8A and 3H, may not show the full picture. Oilseeds specialist Sonia Wilson said broader second-generation resistance is available in some varieties.
Wilson advised a two- or three-year break between canola crops, preferably three where clubroot has been seen, along with resistant varieties and limiting the movement of contaminated soil, since the pathogen's resting spores can build up before symptoms appear. Manitoba Canola Growers offers one free clubroot soil test per field, best taken at field entrances or around suspect patches, with the GPS location recorded.
Photo: Leafhopper65 / Wikimedia Commons (public domain)
Source: Manitoba Co-operator
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