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Clubroot is a soil-borne disease that affects canola and vegetable crops in the Brassica family, including cauliflower, broccoli, and cruciferous weeds. Once established, it is tough to eradicate since the resting spores can persist in the soil for up to 20 years. Serious yield loss can occur as well as detrimental effects on oil quality.
Clubroot is caused by Plasmodiophora brassicae, an unusual organism that doesn’t easily fit into the standard classification of life, which makes clubroot difficult to control. Plasmodiophora brassicae starts its life cycle as a resting spore. It infects the roots of host plants and produces club-shaped galls that restrict water and nutrients uptake. This results in reduced seed production, stunting and premature death of the plant.
Symptoms in the field will vary depending on the growth stage of the crop when infection occurs. These include yellowing, premature ripening, and seed shriveling. However, such symptoms may be wrongly attributed to drought during periods with high temperatures or to other diseases such as Sclerotinia or Fusarium wilt.
Clubroot favors soils that are warm (20°C to 24°C) and acidic (pH less than 6.5). However, moist areas, such as depressions and spots with higher clay content, also see the most severe infestations. In fact, more mud means more chances to spread the disease through the movement of soil contaminated with resting spores. Clubroot spores can ride along on tires and equipment frames, can be moved by wind and water erosion or by people walking through. This makes it a concern not only in the affected areas but also where it does not occur yet.
The best approach to managing clubroot is to be proactive. Swathing or digging up plants to check for gall formation on roots are undoubtedly an excellent opportunity to spot clubroot infestations. However, clubroot galls can be mistaken for hybridization nodules or swellings caused by exposure to phenoxy herbicides.
Testing soil for the presence of clubroot is the most effective diagnostic method to determine whether a field is healthy. Exova’s accredited laboratory in Edmonton tests for the presence of clubroot spores through the PCR method (Polymerase Chain Reaction). Specifically, we quantify Plasmodiophora brassicae DNA by Real-Time PCR (or qPCR), which has been proven reliable for identifying very low levels of clubroot infection.
Our developed methodology has added advantages over other methods. It allows:
- accurate DNA quantification
- a high degree of specificity
- faster results than traditional methods of DNA analysis.
Whether assessing land for agricultural purposes, for transportation or oil and gas production, tracking the spread of clubroot is important. Testing soil, in combination with proper sampling techniques, will help determine whether a field is infected and how far the disease has spread.
Identifying contaminated sites can help prevent spreading the disease by equipment movement and traffic, in an effort to mitigate the risk of clubroot manifestation and ensure environmental integrity.
Learn more about our Real-Time PCR testing methodology, its advantages and how to accurately sample soil for clubroot testing:
About Exova
Exova is an international provider of testing, advisory and certification services. We are trusted by many of the world’s best organizations to test and advise on the safety, quality, and performance of their products and operations. All our methods undergo strict and rigorous quality control validation procedures as per ISO/IEC 17025. Additionally, we are now an accepted test facility for the Canola Council of Canada: http://www.canolacouncil.org/canola-encyclopedia/diseases/clubroot/identify-clubroot/
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