Clubroot disease - photo credit to Canola Council of Canada

By Autumn Barnes

Help keep canola clubroot “low and local”

Oct 13, 2021 | 1:45 PM

LETHBRIDGE, AB. — With canola crops now in the bin, the Canola Council of Canada is taking the opportunity to remind producers about growing clubroot-resistant canola and the steps needed to keep disease spores from spreading.

Autumn Barnes, an agronomy specialist and clubroot lead with the Canola Council of Canada, has penned an article on how to tackle clubroot and steps producers need to keep in mind when planning next spring’s planting, as clubroot pathogens are able to over-winter.

Tips to curtail clubroot –

A new factsheet available at clubroot.ca distills the key practices to mitigate clubroot and maintain profitability.

Practices include growing clubroot-resistant (CR) cultivars responsibly on all canola acres. In 2020, only 39 per cent of the canola cultivars grown in the Canadian Prairies were CR, according to Canadian Grain Commission data. While CR will be a standard feature on most canola hybrids by 2025, canola growers should start to use CR and other integrated management strategies immediately.

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Clubroot is the disease caused by soil-borne spores of the protist and obligate parasite, Plasmodiophora brassicae. Spores spread easily and early infections can be missed for years while clubroot-susceptible canola multiplies spores to catastrophic levels. Planting CR cultivars before the disease gets established will help slow spore reproduction.

Keeping spore concentration low helps maintain yield and protect CR traits. Growers who wait until the disease has taken hold in a field before choosing CR could be stuck with challenging levels of clubroot for a long time.

Clubroot cycle – Canola Council of Canada

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. (The goal is to keep spore concentrations “low”).

Clubroot – credit Canola Council of Canada

Preventing the introduction and spread of P. brassicae spores will prevent the clubroot disease from establishing and spreading. (The goal is to keep spores “local”).

Responsible use of CR cultivars includes an integrated approach to clubroot management, which will help to protect the CR trait. Integrate the following practices to keep spores low and local.

Clubroot — Canola Council of Canada

Keep spores low –

• Rotate crops. Maintain a minimum 2-year break between canola (1-in-3 rotation).

• Scout. Examine roots in every canola field during late summer/fall. Pay special attention to high-traffic and high-moisture areas. Soil testing may help identify spores before physical symptoms appear.

• Grow clubroot resistance (CR) on all canola acres. Early infestations can be missed for years while susceptible hosts multiply spores to catastrophic levels. Clubroot resistance (CR) should be grown on all canola acres as part of an integrated management strategy.

• Control brassica weeds in all crops. Host weeds (like volunteer canola, stinkweed, flixweed, shepherd’s purse and mustards) should be controlled early to minimize gall formation and resting spore release.

• Manage clubroot patches. Identify clubroot areas and manage those patches separately from the rest of the field to reduce spore concentration and prevent spores from spreading. The new “Manage Clubroot, Minimize Risk” factsheet at clubroot.ca has specific tips for patch management.

Clubroot – credit the Canola Council of Canada

Keep spores local –

• Take biosecurity measures. Commit to a biosecurity plan to prevent the introduction and spread of spores on contaminated inputs and equipment. Communicate sanitation expectations with all relevant parties before field entry.

• Reduce tillage. Minimize soil (and spore) movement within and between fields.

Visit clubroot.ca to learn more about the clubroot disease cycle and management, and to see the full factsheet.

The “Manage Clubroot, Minimize Risk” factsheet, can be found on the Canola Council website:

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