New clubroot pathotype in Manitoba is an important reminder to implement management plans, including fall scouting
September 10, 2019 – Manitoba Agriculture’s discovery of a clubroot pathotype in South Central Manitoba that is able to overcome the original source of clubroot resistance should encourage all canola growers to implement clubroot management strategies, including scouting fields now for symptoms of the disease. Outside of Alberta, very few fields have been found to contain novel pathotypes like this, and this is the first finding in Manitoba.
The discovery of pathotype 3A in the Rural Municipality of Pembina comes after multiple cases of clubroot DNA and plant symptoms having been found throughout the province of Manitoba since 2013.
“This is yet another cue for the industry to continue to take this disease seriously and implement clubroot management plans,” says Dan Orchard, agronomy specialist with the Canola Council of Canada. “We still have an opportunity to get ahead of this disease and limit the impact it has on canola producers and the industry.”
All canola producers are encouraged to grow clubroot resistant varieties, limit the movement of soil, extend rotations to at least a two-year break between canola crops, control canola volunteers and other brassica hosts, and diligently scout.
Symptoms of the disease are most noticeable late in the season, and can still be seen during and after harvest on plant roots. Producers are strongly encouraged to familiarize themselves with clubroot symptoms and start scouting this fall.
“The development of clubroot and discovery of a pathotype that is virulent to the original source of clubroot resistance is concerning to Manitoba canola farmers,” says Ron Krahn, Manitoba Canola Growers Association director and chair of the Research Committee. “Clubroot is one of the latest challenges in canola production. We know how important canola is for a profitable crop rotation, which is why we feel the research dollars that MCGA spends every year on current production challenges is money well spent.”
The Canola Council has a variety of resources available to put the latest research on clubroot into action on the farm including:
- New clubroot management video focusing on key management strategies
- Clubroot.ca – a comprehensive website resource for clubroot management, including a section on scouting and identification
- Understanding Clubroot Resistance brochure
Clubroot (caused by Plasmodiophora brassicae) is a soil-borne disease that causes swellings and gall formations on the roots of susceptible brassica plant hosts, restricting uptake of water and nutrients. Low resting spore concentrations will produce no or very discrete symptoms, whereas total yield loss can occur with high spore concentrations and conducive environmental conditions.
The Canola Council is working with industry and academics through the Clubroot Steering Committee to ensure that clubroot resistant varieties are used effectively in a clubroot management plan. Even when implementing resistant varieties, growers need to carefully scout to ensure the resistance deployed is effective against the pathotypes in the field and determine whether new sources of resistance are necessary. Under high resting spore loads, symptoms can occur after using the same resistance source two or three times, or even sooner.
“It is critically important to limit the pressure we put on resistance by using resistant varieties before spore concentrations are high, extending the break between canola crops and changing up resistance sources if necessary,” says Orchard.
Read Manitoba Agriculture’s notification: New pathotype of clubroot identified in Manitoba.
The Canola Council of Canada is a full value chain organization representing canola growers, processors, life science companies and exporters. Keep it Coming 2025 is the strategic plan to ensure the canola industry’s continued growth, demand, stability and success – achieving 52 bushels per acre to meet global market demand of 26 million metric tonnes by the year 2025.
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