Clubroot is a soil-borne disease that infects Brassica species including crops such as canola, broccoli and cauliflower, and weeds such as wild mustard, shepherd's purse, and stinkweed. The roots of clubroot-infected plants become swollen or galled, causing premature death of the plant.
Clubroot is caused by the pathogen Plasmodiophora brassica, and belongs to a group of protists. It is not a fungus or bacteria, and therefore cannot be controlled through the use of pesticides. Clubroot resting spores can survive 20 years or more in soils, and cannot be eradicated from a field. There are multiple pathotypes (strains) of clubroot, which can exist together in field populations.
The pathogen moves from one field to another through the movement of soil in erosion causes by wind and water or through soil movement on equipment. Producers should take care to reduce the spread of clubroot infected soils. Producers with clubroot-positive fields should maintain crop rotations with a 2 to 4 year break from canola, and control volunteer canola seedlings to keep clubroot spore counts low. Early detection of clubroot infestation and early deployment of clubroot resistant canola varieties are important in clubroot management.
Clubroot is not a regulated pest in Ontario. Clubroot has been present in Ontario vegetable crops for many decades, but was first detected in spring canola in 2016. Clubroot is present in many canola growing regions of the province. Read more about the disease and its distribution in the province in the attached documents, and at www.clubroot.ca.