Prevent Clubroot
Information adapted from Agri-Facts, Clubroot Disease of Canola and Mustard, Alberta Agriculture and Rural Development, May 2007 Revision.
Prevention of clubroot requires all participants in the canola industry to be vigilant. Stopping the introduction of clubroot to clean fields is the only way to prevent clubroot because there are currently no economically viable options for controlling clubroot in canola once it is established in a field. Since wide-spread clubroot infestations are still relatively localized in the Edmonton area of Alberta, take precautionary measures to curb the spread of this disease outside known infested areas.
Clubroot is spread mainly by the movement of soil containing soil-borne resting spores. Soil transport can occur by wind and water erosion, on field machinery (see Figure 12), in manure from animals fed contaminated feed, and in soil attached to seeds (earth tag). The amount of soil required to initiate infection in a new field is unknown. So any soil transfer from an infected field should be viewed as a risk. Clubroot surveys in Alberta have found that almost all new infestations begin near the field access, which indicates that contaminated equipment is the predominant spread mechanism.
Growers, custom operators and all land users (including oil and gas industry, recreationalists) must be diligent in removing potentially contaminated soil from equipment prior to leaving fields.
The best approach to managing clubroot is to be proactive. If you are a grower or landowner, ask agronomists, custom operators, researchers, and anyone else coming onto your land (oil and gas crews) about the sanitation measures they use to prevent the spread of clubroot.
Recommended Best Management Practices
The following have been adapted from the Alberta Clubroot Management Plan, February 2008 Revision:
- Use appropriate canola rotations. Although this practice will not prevent the introduction of clubroot to clean fields, it will restrict this and other disease development within the field and probably avert a severe infestation. Canola growers in high risk situations (confirmed clubroot in the area) should follow traditional canola rotation recommendations (one canola crop every four years). Under very light infestations, a three-year rotation break from canola will keep the clubroot level very low. Under moderate to high infestations, the rotation break must be five years or more to reduce clubroot to low levels.
- Control volunteer canola and cruciferous weeds to prevent three weeks of growth to avoid the production of new resting spores.
- Practice good sanitation to restrict the movement of potentially contaminated soil (this approach will also help reduce the spread of other diseases, insects and weed seeds). The resting spores are most likely to spread via contaminated soil. Moderate to high infestations will leave high spore concentrations in soil on field machinery. Sanitation is very important in these situations. All farmers should follow the practice of cleaning soil and crop debris from field equipment before transport from all fields. Cleaning equipment involves knocking or scraping off soil lumps and sweeping off loose soil.
- For risk averse farmers or for fields with heavy infestations, additional cleaning steps will slightly decrease the risk of spread, but these steps involve considerably more work and expense:
i. After removal of soil lumps, wash equipment with a power washer, preferably with hot water or steam.
ii. Finish by misting equipment with weak disinfectant (1-2% active ingredient bleach solution). The use of Virkon as a disinfectant is being explored, but currently there is no data supporting its effectiveness specifically for clubroot resting spores.
iii. The use of a disinfectant without first removing soil is not recommended as soil inactivates most disinfectants.
iv. Seed an area to grass near the field exit to clean off equipment more effectively.
- Use direct seeding and other soil conservation practices to reduce erosion. Resting spores move readily in soil transported by wind or water erosion and by overland flow. Reducing the amount of tillage on any given field will reduce the spread of the organism within the field and to other fields.
- Minimize traffic to and from fields.
- Scout canola fields regularly and carefully. Identify causes of wilting, stunting, yellowing and premature ripening. Do not assume anything.
- Avoid the use of straw, hay, greenfeed, and manure from infested or suspicious areas. Clubroot spores are reported to survive through the digestive tracts of livestock.
- Avoid common untreated seed (including canola, cereals and pulses). Earth tag on seed from infested fields could introduce resting spores into clean fields. The effect of current seed treatment fungicides on resting spore viability on seed requires research. Certain seed treatment fungicides may control spores on contaminated seed but further research is required to confirm.
- The risk of spreading clubroot by contaminated seed or plant material is much less than by transporting contaminated soil on field equipment.
Recommended Guidelines for Field Entry Activities
This document was developed to provide guidance on field entry procedures in both clubroot and clubroot suspect areas.
Recommended Guidelines for Field Entry Activities
Recommended Guidelines for Field Entry Activities
Clubroot Field Entry Checklist
This checklist can be used as a simple way to document that appropriate steps were taken during a field visit in both clubroot and clubroot suspect areas.
Clubroot Field Entry Checklist
Recommended Guidelines for Disinfesting Farm Machinery and Equipment
This document outlines detailed steps that can be utilized to minimize the risk of clubroot spread via contaminated soil on field equipment. Any inquiries regarding this document should be directed to duke@gov.ab.ca.
Recommended Guidelines for Disinfesting Farm Machinery and Equipment
Recommended Guidelines for Canola Field Research Activities
This document was developed by members of the canola research community in Canada to provide coordinated guidance that will help ensure that research activities are executed in a manner which will help prevent the spread of clubroot.
Recommended Guidelines for Canola Field Research Activities
Recommended Guidelines for the Oil and Gas Industry
Currently in Development – Coming Soon!