Root Maggot Control Trial Rutabga (2009) - 3 pages
Root maggots (Delia radicum) represent a major problem for growers of cole crops in
Saskatchewan. Maggots damage to the roots renders them less capable of delivering the water
and nutrients required for optimal growth. In vegetable crops grown for their roots (rutabaga and radish), the scars left by the feeding maggots make the roots unmarketable. Biological and cultural control practices may reduce problems with maggots but some form of chemical control is usually required. In Canada, the standard approach to controlling maggots is to apply the insecticide chlorpyrifos (Lorsban) as a root drench on several occasions through the growing season. The chlorpyrifos must be applied in enough water to carry the chemical deep into the soil profile to where the maggots are feeding. The timing of application is targeted to correspond to the development of the maggot population. Applications of chlorpyrifos must cease 30 days prior to harvest for rutabaga. As organophosphates like chlorpyrifos are relatively toxic to both the applicator and the environment this type of pesticide has been targeted for phase-out as soon as effective reduced risk alternatives have been identified. The objective of this project was to test new reduced-risk products for potential use as a tool for root maggot management in vegetables.
The project was conducted in 2009 using a standard protocol at four sites across Canada (BC, SK, ON and QC). The Saskatchewan site was managed by the U of S in Saskatoon. Repeated
cropping of this site to crucifer vegetables, coupled with the presence of commercial canola fields nearby has resulted in a large population of root maggots at this site.