Random soil tests can pick up clubroot DNA before you see visual symptoms. Labs that test soil for clubroot DNA are listed here. These labs can detect spores at levels of 1,000 per gram, which is considered fairly low risk for the development of galls. These early-stage results give farmers a chance to introduce apply the clubroot risk management recipe. Note that clubroot is a patchy disease: A negative soil test result means no clubroot spores were found in the submitted sample, but the sample might not represent the whole field.
How to take a proper soil test for clubroot analysis. Obtain approximately two to three cups of soil for this test. This should be a composite sample taken in a “W” pattern near the major approach or entrance to the field, or other high clubroot risk areas in the field. Sample soil from the top 5 to 10 cm (A horizon), excluding as much surface organic matter as possible. The provincial agriculture departments for Alberta, Manitoba and Saskatchewan produced two helpful factsheets: Clubroot soil sampling on the Prairies. Interpreting a clubroot soil test result.
Participate in the Saskatchewan Clubroot Survey. Farmers who invest in SaskCanola can submit a voluntary sample from their field for complimentary testing. For a sampling kit, please contact SaskCanola at 306-975-0262 or firstname.lastname@example.org to get one mailed or stop by any Ministry of Agriculture Regional Office. If you are hosting an upcoming field day in Saskatchewan and would like a SaskCanola representative to attend to talk about clubroot and the provincial survey, please contact SaskCanola using the contacts above.
Manitoba Canola Growers can get a free clubroot soil test from PSI Lab. (Members can also get free blackleg and herbicide-resistant kochia tests.) Details here.
Sanitation when scouting. When scouting for clubroot, make sure to clean boots and tools before moving to the next field. Bleach is the best product for boot baths, hand tool cleaning and washing quad wheels, but it’s not the only product that works. Read more.