As clubroot disease spreads in Western Canadian soil, growers who have yet to see symptoms in their fields have a decision to make: when should they start growing varieties that are marketed as resistant to clubroot?
“From the Canola Council’s perspective, ideally, we all start growing clubroot-resistant varieties early. We take a proactive approach and grow it before we have a real problem,” explains Angela Brackenreed, agronomy specialist with the Canola Council of Canada, in this Canola School video.
In reality, there are other yield-limiting issues or variety characteristics that can take precedence over a clubroot resistance trait. Variety decisions might be based on high blackleg disease pressure, wanting a shatter reduction for straight cutting, or a specialty canola oil contract.
“We need to look at is there clubroot close by? In what concentrations? Are we scouting for the disease? And what kind of rotation are we on?,” she notes. “If we’re in a short canola rotation and know there’s clubroot in the area, it’s a pretty high-risk situation and we really should be looking at adoption of a clubroot-resistant variety.”
Submitting soil samples from field entrances to a lab that tests for clubroot levels can help a grower understand that risk. (Find a list of labs that offer clubroot testing here.)
Although different clubroot pathotypes have started overcoming the common resistance genes in commercialized varieties, breeders are working on integrating new sources of resistance.
Seed companies are also combining clubroot resistance with other desired characteristics, such as reduced pod shatter, giving growers access to varieties that address multiple priorities.