By: Alireza Akhavan, PhD, AAg, Provincial Specialist-Plant Disease;
Raul Avila, MSc, PAg, Provincial Specialist-Pest; Regulatory, Crops and Irrigation Branch, Regina; and
Homa Askarian, PhD, AAg, Research Specialist-Crops, Agriculture
Research Branch, Regina
July 2022
Clubroot is a soil-borne disease of cruciferous crops, including canola, that causes deformed, swollen roots (galls) which restrict the plant’s ability to obtain water and nutrients from the soil. If not properly managed, clubroot can cause significant yield loss, as high as 30 to 100 per cent in fields with severe infestations. This suggests that clubroot poses a significant threat to the Saskatchewan canola industry.
Resting spores are the main survival structures of the clubroot pathogen. They are extremely resilient to harsh environmental conditions and can survive in the soil for years. Clubroot was first identified on canola in Alberta, in 12 fields in Sturgeon County in 2003. By 2020, more than 3,000 fields in Alberta with confirmed clubroot infestations had been reported, meaning the pathogen can spread rapidly. Managing the disease is challenging and most cultural or chemical control methods are either not practical or too expensive to implement. The deployment of clubroot-resistant canola cultivars has been the most convenient and cost-effective way to manage the disease, but the recent identification of novel pathotypes capable of overcoming this resistance represents an additional challenge to clubroot management.
Clubroot was declared a pest under The Pest Control Act in 2009 in Saskatchewan to strengthen clubroot surveillance, prevention, and control in the province. To date, clubroot visible symptoms have only been officially confirmed in 80 commercial canola fields in 29 Rural Municipalities (RMs) in Saskatchewan. This still suggests a relatively limited spread of the disease in the province and underlines the need to continue monitoring and managing clubroot effectively. Rural Municipalities have authority under The Pest Control Act to undertake prevention and enforcement measures related to the spread and control of the disease. The Saskatchewan Ministry of Agriculture is committed to a science-based and farmer-driven approach to clubroot regulation and to working with RMs to develop effective and consistent management plans. The key to clubroot management is to keep pathogen levels low to minimize yield loss. This can be accomplished through an integrated approach that includes extended crop rotations (a minimum of a three-year rotation which is a two-year break from canola and other cruciferous crops) and the use of clubroot-resistant varieties, regardless of whether clubroot is confirmed in the area. In areas and fields where clubroot and/or the clubroot pathogen are not known to be present, the spread or introduction of clubroot can be minimized by limiting soil movement.
Producers and agrologists wish to test for clubroot can sign up for a free soil test. The testing kit comes with a brochure on how to collect a sample and where to mail it. The 2021 Clubroot Distribution in Saskatchewan Map is also available for anyone who wants to know where cases have been confirmed.