Canola diseases a 'significant yield risk' for future crops

Date:07-07-2011


Weather conditions, strong commodity prices and tighter canola rotations are creating serious concerns about disease risks for canola growers. According to a recent report from Statistics Canada, canola acres are anticipated to reach nearly 20 million this year, an increase of more than two million acres from 2010. With reports pointing to the potential breakdown of canola variety resistance to blackleg, disease pressure is even a higher concern for this season and into next year's crop.

"Tight rotations can allow blackleg inoculums to build up and increase resistance risk," says Glen Forster, Technical Specialist with BASF Canada. "If blackleg resistance breaks down, it can lead to a significant yield risk with more disease pressure. What's more, tight rotations can create a situation of repeated incidence of blackleg on future canola crops."

An infestation of blackleg and other canola diseases increases the risk for repeated infestations on future crops. Canola growers can benefit from regular scouting of fields several times per week early in the season to identify potential blackleg infections as a disease management strategy. This is especially important for any field that has had an outbreak of blackleg previously. Early blackleg signs include grayish lesions with small black spots on leaves, and long lesions on stems, eventually forming blackened basal cankers that appear at the base of the stem. Scouting fields during swathing is one of the best times to understand potential disease risk for future growing seasons.

Weather is another key factor in disease management for canola crops. Blackleg spores carried by wind and rain droplets can quickly cause infection and spread to neighbouring plants. Sclerotinia, another serious canola disease, is incredibly mobile, spreading by wind across great distances to infect nearby canola crops.

Forster recommends field scouting combined with wider crop rotations and fungicide application to manage disease risks for current and future crops. To protect against early season blackleg infestations, an application of Headline fungicide should be used preventively to maximize yield. "An early application of Headline to control blackleg, followed by an application of Lance at the 20 to 50 per cent bloom stage to control sclerotinia, will provide the best possible protection against two key diseases in canola," he says. "A healthier canola crop results in maximum yield and quality for growers."