Blackleg is one of the key diseases faced by Prairie canola producers and has largely been kept in check with the use of resistant varieties and crop rotation. However, over the past 10-20 years there have been concerns regarding observed shifts in blackleg pathogen virulence in response to the major gene resistance used in a number of varieties.
Changes in virulence patterns emphasize the critical need to stay on top of this disease. Producers and crop scouts can play a critical role by scouting fields to monitor blackleg and detect any unexpected increases in disease levels on resistant varieties. For blackleg of canola a critical time for scouting is later in the season to assess the prevalence, severity and impact of this disease issue.
When assessing blackleg incidence and severity, it is critical to correctly identify symptoms of blackleg and differentiate these from normal or premature canola crop ripening due to a range of abiotic and biotic factors. Recent Prairie research has shown limited responses to in-crop fungicide when resistant varieties are grown, and especially where this resistance is still highly effective.
The Canola Council has a blackleg yield loss calculator that can be used to estimate yield losses based on crop characteristics and observed blackleg levels.
Verticillium stripe is a relatively new canola disease and there may be concerns regarding differentiating it from blackleg. Fortunately, the Canola Council of Canada along with colleagues from research and extension have developed background information on this disease and tips related to differentiating it from other canola diseases including blackleg.
Here is the latest survey protocols and scouting information for blackleg of canola.
Blackleg scouting information: