Low and Local – Controlling Clubroot in Canola
Who should grow clubroot-resistant canola?Clubroot continues to build up across the Prairies, driven by the multiplication and spread of the soil-borne spores of the parasite Plasmodiophora brassicae. Effective, integrated clubroot management techniques focus on reducing the quantity and movement of P. brassicae spores – keeping them low and local.
Deployment of clubroot resistant (CR) cultivars is one key to maintain a low P. brassicae spore concentration and minimize clubroot risk. Regardless of the presence or absence of clubroot in a community, all canola acres should be CR.
If there are still clubroot susceptible (CS) cultivars grown in your area, agronomists and agri-retailers can use 2021 to learn about the CR options that perform best in your growing conditions, and ensure all canola seed booked for 2022 is CR.
Agronomists and agri-retailers can also help canola growers integrate the following practices to keep spores low and local:
Keep spores low
Higher concentrations of P. brassicae spores lead to larger clubroot galls, more risk to yield, more resting spores released back to the soil, and fewer management options. Integrate these practices to keep spores low.
Maintain a minimum two-year break between canola crops (one in three-year rotation). A longer rotation may be necessary to reduce spore concentrations in heavily infested patches or fields.
Look for galls on canola roots in every canola field, every year. Pay special attention to high traffic and/or high moisture areas. Soil testing may help identify P. brassicae spores in specific locations before physical symptoms appear.
Grow CR canola
Early infestations can be missed for years while clubroot-susceptible canola multiplies spores to catastrophic levels. Clubroot resistant (CR) cultivars should be deployed on all canola acres to keep spores low.
Control brassica weeds in all crops
Clubroot hosts like volunteer canola, mustards, flixweed, shepherd’s purse, stinkweed, etc. can increase soil spore levels, even in non-canola years.
Heavily infested zones may benefit from a longer rotation away from canola. Establish a non-host crop, like a perennial grass, and consider applications of lime.
Keep spores local
Preventing the introduction and spread of P. brassicae spores will prevent the clubroot disease from establishing and spreading. Integrate these practices to keep spores local.
A committed biosecurity plan can prevent P. brassicae introduction and spread by contaminated inputs and/or equipment. Communicate sanitation expectations with all relevant parties prior to field entry.
Minimize soil movement within and between fields.
Establish a non-host crop and avoid travel in the infested zone to help minimize the spread of P. brassicae spores within and between fields.
The clubroot chapter of the Canola Encyclopedia, available at clubroot.ca, has it all. Look under the “Manage Clubroot” heading for a list of clubroot-resistant varieties.
For timely field updates on clubroot and so much more, subscribe to Canola Watch.
* from the Canola Council of Canada
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