By Barb Ziesman, AAg Provincial Specialist, Plant Disease
The key to clubroot management is to keep pathogen levels low to minimize yield loss. When clubroot is identified early, proactive management strategies including extended crop rotations (minimum of a three-year rotation) and the use of clubroot-resistant varieties can be used to keep pathogen levels low. If these tools are not used proactively and clubroot is not detected until pathogen levels and disease severity are high, management of the disease can be more challenging.
Scouting fields for clubroot symptoms is one important way to monitor fields for clubroot. With routine monitoring, clubroot symptoms can be identified when pathogen levels are still low. Another tool available to farmers is DNA-based soil testing to detect the clubroot pathogen levels at low levels (lower than those required to cause visible symptoms under field conditions).
As part of the clubroot monitoring program, the Ministry of Agriculture and SaskCanola will be running a voluntary soil testing program. Through this program, producers can pick up a soil testing kit (maximum of one per farm) from a Ministry of Agriculture Regional Office. The soil sample should then be dropped back off at the regional office, where it will be submitted to the lab for clubroot testing at no cost to the farmer.
- Where to get a soil testing kit: Soil testing kits can be picked up from a regional office from July to September. If you would like to sign up sooner, contact your regional Crop Extension Specialist or visit the Ministry’s Farm Progress Show or Ag in Motion booths. We will take your contact information and send you a clubroot testing kit.
- Timing for soil sampling: Soil samples for clubroot testing should be collected in late summer close to or after swathing time. If clubroot galls are present, they will be starting to decompose and will be released back into the soil, which improves the ability to detect the pathogen using DNA-based testing methods.
- Confidentiality of testing results: In order for the lab to process the samples, producers will be asked to provide their name, contact information and field location.
- The specific land location will only be shared with the rural municipality (RM) if they have enacted a clubroot bylaw.
- If the RM does not have a clubroot-specific bylaw enacted, the specific location of the field will be kept confidential.
- The general location of the field (to an RM level only) will be used to update the Saskatchewan Clubroot Distribution map to ensure that it is as accurate and robust as possible.
- Interpreting the results of a clubroot soil test: A positive clubroot soil test means that the clubroot pathogen is present in the field and clubroot infection is possible. If pathogen levels are low, visible symptoms may not yet be present in the field. When the clubroot pathogen is detected at low levels, the producer can effectively keep pathogen levels low and minimize potential losses due to clubroot through the use of extended crop rotations and the use of clubroot-resistant varieties. However, since the clubroot pathogen often has variable occurrence in the field there is a chance of a false negative, which will occur when the test fails to detect the pathogen when it is present in the field. To avoid the risk of false negatives, it is important to ensure that soil samples are collected in are areas of the field that have the highest clubroot risk. For more information see Clubroot Soil Sampling on the Prairies and How to Interpret a Clubroot Soil Test Result.
- For more information, contact your Regional Crop Extension specialist or the Agriculture Knowledge Centre’s general inquiries line at 1-866-457-2377.