The best time to survey canola fields for disease incidence and severity is just before swath timing – which is 50-60% seed colour change on the main stem. If not swathing, you can still use this crop-stage timing to check for disease. Some fields across the Prairies are at this stage. The rest will follow over the coming weeks.
At the swath-timing stage, any diseases present will be near peak intensity and fairly easy to identify. This will provide an accurate assessment of disease, which can be used to enhance long-term management decisions (such as disease-resistant seed choices, crop rotations and fungicide use). It could also be used to make harvest timing decisions for this year.
The following quiz questions (and detailed answers) will help you identify the disease symptoms you’re seeing.