Clubroot is a disease that affects crucifers worldwide. In the United States, there have been a number of reports of clubroot on Brassica crops from several states, varying in degree of severity and incidence.
In Canada, clubroot is primarily established in the vegetable growing regions of British Columbia, Quebec, Ontario, and the Atlantic provinces. It has also been detected in vegetable crops in both Alberta and Manitoba. Identification of clubroot in commercial canola fields in western Canada is a relatively recent occurrence.
Alberta
In 2003, clubroot was identified in commercial canola near Edmonton, AB. This was the first report of clubroot in a commercial canola field in Canada. Since 2003, clubroot has been found in an increasing number of canola crops in this region. According to information provided by the Alberta Clubroot Management Committee, clubroot has been detected in over 450 fields, with incidence levels ranging from below 30% (low) to above 70% (high).[s1] The disease distribution in infested fields has generally been patchy but in the 10 to 15% of canola crops with high levels of clubroot infestation, the disease has occurred fairly evenly throughout the field. Nineteen counties and the City of Edmonton have been affected in Alberta (see Figure 1). These counties include Sturgeon, Leduc, Parkland, Wetaskiwin, Strathcona, Westlock, Barrhead, Ponoka, Thorhild, Lac Ste. Anne, Yellowhead, Lamont, Vermilion River, Camrose, Flagstaff, Lacombe, Kneehill, Newell, and Cypress. The number of fields with positive detections in these counties is extremely variable. Sturgeon, Parkland, and Leduc each have over 45 fields, while Westlock, Barrhead, Strathcona, Wetaskiwin, and Ponoka have between 10 and 45 fields. Thorhild, Lac Ste. Anne, Yellowhead, Camrose, Flagstaff, Lacombe, Kneehill, Newell, and Cypress all have between 1 and 9 fields. Seven counties have suspected cases of clubroot currently; these include Grande Prairie, Minburn, Red Deer, Wheatland, Lethbridge, Cardston, and Warner. For information about specifics, please contact local county offices.
According to information provided by Manitoba Agriculture, Food and Rural Initiatives, the presence of the pathogen (Plasmodiophora brassicae) responsible for clubroot has been reported in Manitoba on symptomatic cruciferous vegetables. Reports have been very sparse, with the first note dating back to an unconfirmed report on rutabaga in 1925. In the 1980’s, clubroot was found on market garden cruciferous vegetables. The most recently known detection of clubroot in Manitoba occurred in 2005, on canola. This occurrence was of very low incidence, and the symptoms were of very low severity. Reports from disease surveys of canola in Manitoba, which were not targeted at clubroot, have detected no plants with symptoms of clubroot in canola production areas.
According the Saskatchewan Ministry of Agriculture, clubroot symptoms have not been observed on any of the canola crops surveyed in Saskatchewan disease surveys. However, in 2008, the clubroot pathogen's DNA was detected in a soil sample collected from one of 30 randomly-selected fields in the survey. While the pathogen appeared to be present, the clubroot disease itself was absent, since no infected canola plants were identified. In subsequent clubroot surveys in 2009 and 2010, no further evidence of this disease was found.
This case emphasizes the importance of equipment cleaning, especially when moving from affected or suspected areas to clubroot-free areas. Farmers and agronomists must be aware of this disease and be proactive in helping prevent its wide-spread establishment and spread. The finding is also a reminder that the clubroot pathogen may be present in the soil, even in the absence of disease symptoms. Proper crop rotation is another important management strategy that will prevent trace levels of the pathogen from increasing to a disease issue.
Clubroot was declared a pest under The Pest Control Act in Saskatchewan in June 2009. Under The Pest Control Act, people who own, occupy or control land are required to take measures to destroy, control and prevent the spread of pests. The Saskatchewan Ministry of Agriculture and the Saskatchewan Clubroot Initiative continue to provide information for public awareness and contribute to disease surveillance in Saskatchewan.