What is clubroot?
Clubroot is a soil-borne disease caused by the pathogen Plasmodiophora brassicae. Clubroot affects the roots of cruciferous field crops such as canola, mustard, camelina, oilseed radish and taramira, and cruciferous vegetables such as arugula, broccoli, Brussels sprouts, cabbage, cauliflower, Chinese cabbage, kale, kohlrabi, radish, rutabaga and turnip. Cruciferous weeds (such as stinkweed, shepherd's purse and wild mustard) can also serve as hosts.
Root infection of host plants by the clubroot pathogen results in swelling of the root tissue (galls), which reduces the plant’s ability to obtain water and nutrients from the soil, resulting in yield loss. The level of yield loss will be related to the amount of pathogen in the soil, the susceptibility of the host crop and environmental conditions.
Clubroot-infected roots will have swollen root tissues (galls).
Clubroot galls will initially appear white and fleshy. Later in the season they will start to decompose and appear rotten.
Above-ground symptoms of stunting, yellowing and premature ripening may occur. These symptoms may indicate the presence of a clubroot patch, but could also be associated with other diseases or adverse environmental conditions. As a result, it is important to examine plant roots for the presence of clubroot galls.
Clubroot resting spores survive in the soil and can be moved any way that soil can be moved. This includes soil movement on agriculture or industrial equipment, vehicles, tires, shoes, animals, wind or water erosion, or contaminated inputs such as manures. Activities that move large volumes of soil are considered to have a higher risk, as do activities that move soil over large geographic regions and from regions where clubroot is known to be present.
The focus of clubroot prevention is preventing the introduction of clubroot-infected soil. The following practices can be used to prevent clubroot introduction and minimize the spread of clubroot once it has been confirmed in a field and/or region:
The key to clubroot management is to keep pathogen levels low to allow continued canola production in the infested fields with minimum impact on yield.