Canola acres in western Canada have been increasing due to the strong returns generated by growing canola. This has resulted in shortened crop rotations between canola crops, and increased grower and industry concern regarding Blackleg.
Current Blackleg Knowledge
Blackleg pressure has increased in areas of western Canada, as evidenced by the number of reported grower and industry concerns. New canola varieties are assigned their Blackleg rating by the Western Canada Canola/Rapeseed Recommendation Committee (WCC/RRC) based on data generated during the final two years before variety registration; this rating applies to the variety for its lifespan.
The current Blackleg ratings as per the 2010 WCC/RRC regulations are as follows: R = <30% infection vs. Check (Westar which is 100% susceptible) MR = 30 – 49% infection vs. Check MS = 50 – 69% infection vs. Check S = 70 – 100% infection vs. Check There are currently four different virulent strains of Blackleg that have been identified in western Canada, with PG2 the most common strain in most areas. Recently the new strains PG3, PG4, and PGT have been detected in western Canada. Dow AgroSciences and the canola industry have been working to understand these new strains, their geographic presence, their impact on canola production, and how to develop varieties with improved overall Blackleg resistance. While in the past there have been many varieties with an R rating for Blackleg, some new varieties are being rated MR for Blackleg due to the increased number of PG groups and their differing levels of virulence.