Crop Production News - 2018
By Ministry of Agriculture
Proactive management strategies such as extended crop rotations, selection of clubroot-resistant varieties and preventing the movement of potentially infected soil can be used to prevent the introduction of the pathogen and keep spore levels low. The key to clubroot management is keeping the pathogen levels low to allow canola production in a clubroot-infested field with minimum impact on yield. The earlier that clubroot is detected, the easier it will be to manage. As a result, clubroot management can begin before symptoms are seen in a field and can even occur before the pathogen is present in a field by focusing efforts on preventing the introduction of clubroot-infested soil.
Clubroot best management practices include:
- Grow clubroot-resistant canola varieties in regions where clubroot has been identified. It is recommended that all producers in northern Saskatchewan, particularly in crop districts 9A and 9B, grow clubroot-resistant canola varieties.
- Extend your crop rotation. Aim for a three-year break between susceptible crops, even when clubroot-resistant varieties are used. A minimum of a three-year rotation (two-year break between susceptible crops including clubroot-resistant varieties) should be followed. Longer crop rotations are encouraged for fields with high disease severity and high pathogen levels (resting spore concentrations).
- Carefully scout canola crops, including both susceptible and resistant varieties. When scouting, pull up or carefully dig up plants and examine roots for the presence of swollen root tissue (galls). Near the end of the season, the galls will start to decompose and the infected roots may appear rotten. Focus your scouting efforts on field entrances and low areas or patches in the fields that are demonstrating above-ground symptoms of wilting, yellowing, stunting and premature ripening.
- In addition to scouting for visible symptoms, the presence of the clubroot pathogen in the field can be confirmed through a DNA-based test on soil collected from the field. This method of testing for the clubroot pathogen is advantageous, as it allows for the detection of the pathogen at levels lower than those required to cause disease symptoms in the field.
- Restrict the movement of potentially contaminated soil to non-contaminated areas. This can include:
- Practicing zero-till to reduce soil erosion. This will help prevent movement of contaminated soil via wind and soil erosion, but will also help to reduce the movement of the pathogen to new areas in a field if it is already present at low levels in an isolated patch within the field.
- Creating a separate exit as far as possible from the entrance to reduce the movement of the pathogen inoculum out of an infected field.
- Reduce the risk of spread of clubroot. The level of sanitation used should match the level of risk associated with field management. Sanitizing should include the removal of crop and soil debris when moving from field to field. The more soil that is moved with equipment, the higher the risk of introducing clubroot to a field. Washing with a pressure washer, using hot water or steam, and misting with a disinfectant such as two per cent sodium hypochlorite solution is also a good measure to take. Sodium hypochlorite is the active ingredient in bleach and is the most effective disinfectant. Virkon® has been found to be only moderately effective in reducing the viability of the clubroot pathogen.
- Restrict the entry of vehicles unless they have been properly sanitized.
- Restrict unwanted vehicles from entering your field by posting “no trespassing” and “no hunting” signs.
For more information, contact the Agriculture Knowledge Centre at 1-866-457-2377 or firstname.lastname@example.org.