For farmers faced with damaged canola seedlings this spring, the crucial step in deciding whether to reseed is to accurately assess the crop injury and estimate the yield potential of the surviving stand.
Growers often overrate the injury and thus underestimate the potential of canola seedlings to recover.
Canola seedlings injured by insects, wind or frost need several days of recovery before an accurate survival assessment can be made.
There is no “minimum number of plants” because growing conditions can have a significant impact on plants’ ability to compensate.
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A reasonable threshold for conventional varieties is 32-43 plants per sq. metre early in the seeding season.
However, 11-22 plants per sq. m can be adequate with herbicide-tolerant systems, dry seedbed conditions or late in the seeding season.
Thin stands such as these probably will yield 90 percent of the normal stand, but will mature later.
Crops replanted late in the season typically yield less than earlier plantings that had poor stands.
Therefore, the decision to reseed is often difficult and must be based on thorough agronomic and economic assessments, including an accurate evaluation of seedling mortality, surviving stand density and yield potential of the existing stand versus reseeding.
Weed growth has been heavy for this time of year due to favourable moisture conditions.
Split applications of herbicides on emerged crops are being performed or contemplated in many areas because of the high levels of grassy weeds.
Growers are encouraged to control weed flushes early to maintain crop yield potential.
