Special Issue: Management of clubroot (Plasmodiophora brassicae) on canola (Brassica napus) in western Canada

Clubroot, caused by Plasmodiophora brassicae, has emerged as a serious disease threatening the canola production industry in western Canada. This review summarizes results from studies, conducted since 2007, on the development of effective strategies for the management of clubroot in canola. Several options have been proposed for the control of this disease in infested fields, including liming the soil to increase soil pH, crop rotation with non-hosts and bait crops, manipulating the sowing date, sanitization of farm equipment, and the deployment of resistant cultivars, all aimed at reducing the severity of infection. Research began by assessing existing clubroot treatments, originally developed for the cole crop vegetable industry, for their applicability to canola production systems. Although these treatments provide good levels of clubroot reduction for the intensive production of short-season brassica vegetables, most are not economically feasible for the large-scale production of canola, which requires protection over a greater field acreage. Genetic resistance to P. brassicae has been shown to be a practical option for the management of clubroot on canola, but resistance stewardship, coupled with crop rotation and appropriate cultural practices, will be required to maintain the performance and durability of genetic resistance. Pathogen resting spores can be disseminated on infested soil carried on both machinery and seed. Efforts to minimize spread of the pathogen between canola fields have focused largely on the sanitization of field equipment and seed.