May 12, 2005
Source: Canadian Phytopathological Society, Vol 27 [edited]

Identification of clubroot of crucifers on canola in Alberta
JP Tewari, SE Strelkov, Department of Agricultural, Food and Nutritional Science, 410 Agriculture /Forestry Centre, University of Alberta, Edmonton; D Orchard, Sturgeon Valley Fertilizer Ltd, PO Box 292, Station Main, St
Albert, AB; M Hartman, Alberta Agriculture, Food and Rural Development, 5030 50 Street, Lacombe, AB; RM Lange, Alberta Research Council, PO Bag 4000, Vegreville, AB; TK Turkington, Lacombe Research Centre, Agriculture and Agri-Food Canada, C & E Trail, Lacombe, AB. Accepted 16 Oct 2004.

Clubroot, caused by _ Plasmodiophora brassicae_, was detected for the 1st time on canola in Alberta. Galling, typical of the disease, was observed on roots of canola (_Brassica napus_) in a dozen fields near St Albert, AB.
Presence of resting spores of the pathogen was confirmed by light and electron microscopy. Spores of the pathogen were isolated from diseased tissue and used to inoculate roots of _B. napus_ 'Westar', on which they
produced symptoms similar to those observed in the field.

Resting spores were recovered from galls on inoculated plants. Identification of clubroot on the Alberta canola crop is a matter of concern, as the disease is associated with appreciable yield losses and can be managed only with extended intervals between host crops, because other management strategies may be too expensive to implement or are of limited effectiveness. Further studies are under way to determine the extent of the problem.

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[Clubroot, caused by _Plasmodiophora brassicae_, remains one of the important diseases affecting members of the mustard family (_Cruciferae_). It is a soilborne disease of field crops such as canola, mustard, cabbage,
broccoli, cauliflower, radish, and turnip. Clubroot is not a new disease and is common in British Columbia and eastern Canada. According to the authors, this is the 1st report in which clubroot has been found on canola in the Canadian prairies. The origin of the present outbreak is under investigation. Given the previous reports of clubroot in home and market gardens, it is possible that vegetable gardens may be acting as initial foci of infection, particularly if growers are unknowingly importing contaminated transplants.

Links:
<http://vegetablemdonline.ppath.cornell.edu/factsheets/Crucifers_Clubroot.htm>
<http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/faq7389?opendocument> 
<http://www.strathcona.ab.ca/Strathcona/Rural+Life/Country+Talk/March+2004/Clubroot+of+canola.htm>
- Mod.DH]