THE RE-TREATMENT OF SOILS WITH DIELDRIN FOR THE CONTROL OF CARROT FLY.

This article focuses on the re-treatment of soils with dieldrin for the control of carrot fly in Great Britain. Experiments in progress for the past five years have shown that an excellent control of carrot fly Psila rosae can be obtained by mixing aldrin, dieldrin or heptachlor into the top 4 inches of soil before sowing carrots. In general, dieldrin is the most satisfactory of these insecticides and it is now being widely used at doses of 0.75 and 1.5 pound per acre in mineral and highly organic fen soils respectively. In some areas, carrots are grown in very short rotations and re-treatment of the soil may occur within 2 or 3 years of a previous application.