Growers who seeded clubroot-resistant hybrids should know that low-level infection — up to 8% of plants — is normal for these hybrids. These off-types will be scattered uniformly through the stand.
If resistant hybrids have levels higher than this, a patch of susceptible volunteers is the most likely reason. Volunteer canola densities can easily exceed 10 plants per square foot in canola-on-canola rotations, and will be part of the current crop unless a different herbicide-tolerant system was used. With canola-wheat-canola rotations, volunteer canola in the next canola crop may persist at levels of about one plant per square foot in certain situations.
If volunteers cannot explain high infection rates in resistant varieties, then growers should contact their seed rep for further diagnosis.
Click here for more information on scouting for clubroot infection.
For more on identification, prevention and management of clubroot, visit the websitehttp://www.industrymailout.com/Industry/Redirect.aspx?u=115755&q=226634596&lm=19904645&r=218307&qz=87675475902e28bafb783d2180076da2.