CHEMICAL CONTROL OF THE ONION FLY /DELIA ANTIQUA MEIG./ IN POLAND

In 1986–1987 field experiments on chemical control of the onion fly /Delia antiqua Meig./ were carried out at the Research Institute of Vegetable Crops in Skierniewice. The experiments, each consisting of four replicates, were conducted at two sites in Poland. The area of each plot was 16 m² in a randomized block design. In order to determine the effect of insecticides on the control of onion fly, the number of infested onion plants on each plot was recorded every 10 days after emergence. Yield was assessed by weight of onion at harvest from each plot. The experiments showed that the best results were obtained with a seed dressing of Oftanol T /Izofenphos + Thiuram/, applied at the rate of 50 g/kg of onion seed. Oftanol T, at the rate of 40 g/kg, and Marshal 25 STW /Carbosulfan/ 70 g/kg of seed, also gave effective control. Furadan 35 ST /Carbofuran/ and Furadan 300 Combi /Carbofuran + Captan/, each at the rate of 40 g/kg of onion seed, were effective but showed some phytotoxicity. The above experiments showed seed dressing to be the most economical form of applying insecticides for control of onion fly, and the one which is least harmful to the environment.

On the average, seed dressings require 6 times less active ingredients than granules and about 20 times less than drenching.