The effect of tillage and seeding rate on infestations of cabbage root maggots, Delia radicum (L.) (Diptera: Anthomyiidate) in canola, Brassica napus (L.), in Manitoba

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Hawkins-Bowman, Amy K.
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Delia radicum (L.) is an important pest of canola on the Canadian prairies, feeding on the roots of canola and other Brassica crops. In both vegetable and canola crops D. radicum can cause significant yield losses. Natural controls, predators and parasitoids, have not been reducing the populations sufficiently to prevent yield losses in canola. No insecticides are registered for use on D. radicum in canola. Agronomic practices may be the best method of reducing yield loss associated with this pest. Two management practices tillage treatment and seeding rate were applied to experimental fields of canola at the Carman Research Station in Manitoba. Tillage treatment was applied as zero tillage or conventional tillage. Seeding rate treatment was applied as high or low seeding rates. Results show that zero tillage systems have lower root damage ratings then conventionally tilled systems in Manitoba. Also that lower seeding rates have lower root damage ratings then higher seeding rates in Manitoba. Currently in Manitoba, D. radicum is not affecting yield. This study supported the recommendations that zero tillage or minimal tillage should be implemented when growing canola in Manitoba and canola should be seeded at higher rates to reduce damage associated with this pest.