Soil Placement of Insecticide Granules for the Control of Cabbage Root Fly on Transplanted Canliflowers

SUMMARY Seven organophosphorus insecticides were evaluated as granular formulations for the control of cabbage root fly, Erioischia brassicae (Bouche), in west Yorkshire, on transplanted cauliflowers from 1966 to 1970 inclusive. The insecticides were chlorfenvinphos, diazinon, dimethoate, fonofos, mecarbam, pirimiphos‐ethyl and thionazin. Various methods of application were compared and the work evolved into a comparison of the effectiveness of continuous bands of granules applied below the surface immediately before plant insertion with that of surface bands applied immediately after plant insertion. The methods employed and the equipment involved are described. Chlorfenvinphos was the most effective chemical for protecting the roots from cabbage root fly attack. Diazinon, dimethoate, fonofos, mecarbam and thionazin all reduced damage in the early part of the season (except when applied by the bow‐wave method). The subsurface method of placement of all these chemicals except dimethoate was consistently more effective in reducing root damage and promoting higher yields than surface placement. Pirimiphos‐ethyl was not effective in protecting the roots by either method.