By Barbara Ziesman Provincial Specialist, Plant Disease A.Ag, PhD
Clubroot is an important soil-borne disease of canola and other brassicas that can cause yield losses of 50 per cent or greater under extreme conditions. Yield loss will be highest when pathogen levels are high, a susceptible crop is grown and when environmental conditions are favourable for disease development. Low pathogen levels will result in smaller galls, or swollen root tissue, which will have a reduced impact on yield compared to large galls which will occur when pathogen levels are high.
In 2017, clubroot was confirmed in a limited number of canola fields in Saskatchewan crops districts 9A and 9B. Currently the distribution of clubroot in Saskatchewan is limited, putting the province in a good position to get ahead of the disease and take precautions to minimize the spread and severity of clubroot. The first step towards this goal is to increase our understanding of the distribution of clubroot in Saskatchewan. To address this gap in knowledge, the Ministry will conduct an extensive clubroot survey in the highest risk regions of Saskatchewan (blue area in the image below).
The survey area covers:
- Regions where clubroot has been confirmed;
- Areas in close proximity to clubroot infested areas along the Alberta-Saskatchewan and Saskatchewan-Manitoba borders;
- High canola production areas; and
- Regions with favourable environmental conditions.
This survey will start in mid-August. One field will be randomly surveyed in each township throughout the survey area. In each field, plants will be uprooted to examine for clubroot galls on the roots. Soil samples will also be collected at the field entrance for DNA testing to detect if the clubroot pathogen is present in the soil.
When positive fields are found, the landowner and/or producer will be contacted and informed of the positive clubroot finding. Since clubroot is a regulated pest in Saskatchewan, the legal land location of all positive fields will be reported to the appropriate rural municipality (RM). Under The Pest Control Act, RMs have the authority to undertake prevention and enforcement measures related to the spread and control of clubroot.
The Ministry is encouraging that RMs regulate clubroot in a fair and consistent manner that follows a farmer-driven approach. This approach enables landowners and producers to have a say in how clubroot will be managed on their farms. They will have the opportunity to work with a Professional Agrologist to develop a clubroot management plan for the clubroot infested fields. If the clubroot management plan meets a minimum set of science-based standards related to canola variety selection, crop rotation and sanitation practices, it will become the formal agreement between the landowner and/or producer and the Pest Control Officer.
The general location of all clubroot infested fields will be shared publicly through a clubroot distribution map. This map will indicate the distribution and severity of clubroot within the surveyed area and will be used to raise awareness and encourage informed and proactive clubroot management.