151 canola fields were inspected for the presence of clubroot in 2020. Of those, 18 fields were confirmed positive for the disease. All of the fields were previously unknown locations to Red Deer County, bringing our known total of clubroot field in the County to 61. This result was consistent with last year’s findings that about 10% of the field we survey in we find clubroot. However, we do suspect that clubroot is more common than this number reflects.
The good news; the majority of the time where we do find clubroot, it is being well managed and having a minimal impact on the crop yield. The bad news; it is usually the result of a pathotype shift that leads to wide spread disease and yield losses and this pathotype shift can be difficult to notice before it creates a larger problem in a field.
A pathotype shift happens because there are multiple pathotypes of clubroot present in a field at the same time. The first generation of clubroot resistance genetics were effective against the predominant pathotypes that were originally common in Alberta. Overtime, the pathotypes that were not being controlled by this first generation of resistance were able to complete their life cycles, depositing more spores into the soil, ultimately shifting the predominant pathotype in the field to that of one that can overcome the first generation genetics, resulting in wide spread crop loss in a field with a CR variety.
This is why aggressive scouting and a minimum of a two year break between canola crops is so important.
If a patch of clubroot is found in a field with a CR variety this gives evidence to a pathotype shift and a producer can begin to implement strategies to minimize the effect this will have on their operation. The earlier this patch is identified the more effective management strategies become. Some of the strategies include lengthening crop rotations, rotating available genetics, patch management through seeding to grass or liming, adopting a separate entrance and exit to the field and increasing sanitation between fields. This is not an extensive list and more information on managing clubroot can be found at clubroot.ca or canolacouncil.org.
The more often canola is grown the higher the selection pressure becomes and the greater chance of causing a pathotype shift in a field to a virulent strand that can overcome clubroot resistance. Scientist and researchers are working hard to find new genetics that are resistant to these virulent pathotypes and the longer current genetics remain effective the more time they have to develop new ones. Longer rotations between canola crops is one of the only ways to keep spore levels low, reducing disease pressures, and keeping current genetics effective for as long as possible.
This information is important for any producer who grows canola, but it is also important for anyone who lives in our rural community. When accessing agricultural land for recreational purposes, such as hunting, fishing, horseback riding, ATVing, hiking, etc., we can accidently and unknowingly be spreading clubroot or a virulent pathotype from one field to the next. An individual should always ask the landowner for permission on an annual bases before accessing agricultural land to mitigate this risk.
And it’s not just clubroot that could be a concern to the producer. Weed seeds and other diseases can be spread by these activities. Unharvested grain or swathes could be covered by the snow and traveling across these by truck, ATV or snowmobile could cause a high amount of damage and crop loss. Cattle may be grazing in the crop stubble and gates left open could cause them to escape. For these reasons and more, permission should always be obtained before accessing.
For more information please call or email Agriculture Services at 403-342-8654 or email@example.com.