COMBINED EFFECTS OF SOIL-INCORPORATED AND FOLIAR-APPLIED INSECTICIDES IN BED-SYSTEM PRODUCTION OF BRASSICA CROPS

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Abstract
In a 4-yr study (1974–1977), combinations of selected soil-incorporated insecticides (carbofuran, chlorfenvinphos, disulfoton, fensulfothion, terbufos and isofenphos) and foliar-applied insecticides (Dipel®, methomyl, ethiofencarb/Thuricide®, methamidophos and permethrin) were studied to determine their effects on occurrence of cabbage maggot (Hylemya brassicae [Bouché]) and its parasites, and of various leaf-feeding lepidopterous larvae and aphids during bed-system production of broccoli (Brassica oleracea var. italica Plenck), Brussels sprouts (Brassica oleracea var. gemmifera Zenker), cabbage (Brassica oleracea var. capitata L.) and cauliflower (Brassica oleracea var. botrytis L.). Several soil-incorporated insecticides reduced the numbers of emergent seedlings. Plants treated with carbofuran and chlorfenvinphos had least maggot damage in their roots. Disulfoton was ineffective. The best aphicide was ethiofencarb closely followed by methamidophos. Permethrin was ineffective as an aphicide but very effective against lepidopterous larvae. Numbers of overwintering puparia of H. brassicae were greatest from untreated plants and least from plants treated with chlorfenvinphos. Percentage parasitism by the staphylinid beetle Aleochara bilineata Gyll. averaged 32% in puparia from untreated plots, but only 5.5% in those from treated plots.