Blackleg presence is higher than usual on canola in Manitoba and southeastern Saskatchewan. If you see grey lesions with black picnidia (peppery spots) on leaves, monitor the field. The variety may have adult resistance, so early infection on the leaves may not result in severe stem damage.
Spraying is not likely economical. Blackleg can infect canola all season long, so fungicide application timing can be challenging and expensive as applications may need to be repeated to control this disease
If blackleg is serious at harvest and yield loss is likely, avoid planting canola on that field for a few years and next time consider a different variety with different resistance genes.
Recovering crop needs nutrients
Canola fields are recovering with the past week of warm weather. Crops recovering well from excess rains, which leached away nitrogen and sulphur reserves, may benefit from a fertilizer topdress. Applying 20 to 30 pounds of actual N and S in the form of ammonium sulphate can help, especially where canola shows signs of nutrient deficiency.
When canola reaches complete ground cover, keep these tips in mind before fertilizing:
—Apply dry fertilizer when plants are dry so prills roll off leaves for minimum leaf burn.
—Dribble band liquid fertilizer when plants are wet so the fertilizer washes off plants and into the root zone.
Topdressing with a sprayer nozzle when canola is at complete ground cover is not recommended as leaf burn will occur, further stressing the crop.
Applying C3 as a fix for poor rooting? There is very little published research on this practice. For anyone trying a product like this, leave a check strip — and monitor the check strip through to harvest. “The crop may green up and look better right away, but that doesn’t always carry through to final yield,” says Derwyn Hammond, CCC senior agronomy specialist for Manitoba.