Cabbage Maggot Control in Root and Stem Crucifers with New Insecticides1

Abstract

Fensulfothion ( O,O -diethyl O-[p -(methylsulfinyl) phenyl] phosphorothioate), chlorfenvinphos, and carbofuran were the most effective of several insecticides tested for control of Hylemya brassicae (Bouche) on rutabagas, Brassicae rapa L. Although a single-furrow treatment at planting time was inadequate, the addition of 1 or 2 supplementary drench applications gave good control. A pre- or post emergence drench treatment plus another in late August, also gave adequate control. The drench application near the time of plant emergence was equally effective, whether applied just prior to or just after emergence. Phytotoxicity of this treatment was reduced with the precmergence time for application. Phorate as a preseeding furrow treatment, followed by thionazin ( O,O -diethvl O -pyrazinyl phosphorothioate), in drench applications, provided satisfactory control. Diazinon, fonofos ( O -ethyl S-phenyl ethylphosphonodithioate), N-2596 ( S-(p chlorophenyl) O -ethyl ethylphosphonodithioate) and trichloronat ( O -ethyl O -(2,4,5-trichlorophenyl) ethyl phosphonothioate) were not consistently effective. None of the chemicals provided satisfactory control of the cabbage maggot on radish when applied as preplant broadcast treatments at 4 lb AI/acre. Pesticide residues in rutabagas treated with fensulfothion, chlorfenvinphos, N-2596, and trichloronat were 0.1 ppm or less at harvest. No detectable residues were found from the other 3 insecticides. With the long-term crops cabbage, Brassicae oleracea , or cauliflower, Brassicae oleraceae var. bolrytis no residues of any of the 6 pesticides were detected, but with the radish, Raphanus sativus L., residues of 5 insecticides were measurable and two exceeded 0.1 ppm.