INTEGRATED PEST-MANAGEMENT OF THE CABBAGE ROOT FLY AND THE CARROT FLY

Improved insecticide application and pest forecasting have reduced drastically the amounts of insecticides applied to vegetable crops to control the cabbage root fly (Delia radicum) and the carrot fly (Psila rosae). By growing plants that are partially resistant to the carrot fly, it is possible to apply less insecticide than the dose recommended for the crop. The application of smaller amounts of even the more selective chemicals is now being demanded on crops grown for certain supermarket chains. Analysts from the UK Ministry of Agriculture, Fisheries and Food and the supermarkets ensure that pesticide residues do not exceed the levels permitted. In crops where only small amounts of insecticides are now applied, natural predators should prevent large increases in pest insect populations and natural parasitoids should reduce the numbers of pest insects entering subsequent generations. The use of physical (crop covers), cultural and microbial (e.g. fungi, bacteria and nematodes) types of control is also discussed. Undersowing brassica crops with clover appears to have potential for producing commercially acceptable vegetable crops without the use of synthetic insecticides.