Insecticidal control of greenbugs in grain sorghum.

Abstract

Irrigated grain sorghum yields were significantly increased by controlling Schizaphis graminum (Rondani) with disulfoton granules applied as a furrow treatment at planting time and as a later sidedress. Dosages of 1 and 2 lb active ingredient per acre were effective as furrow treatments at planting, and 0.85 lb/acre was effective as a sidedress. Disulfoton-impregnated fertilizer soil treatments did not control greenbugs or increase irrigated grain sorghum yields. Greenbugs were satisfactorily controlled in irrigated grain sorghum with foliar applications of carbaryl and parathion sprays. Excellent control was also obtained with a foliar application of disulfoton granules. Grain yields were increased with these insecticides. Carbaryl and disulfoton also satisfactorily controlled the corn leaf aphid, Rhopalosiphum maidis (Fitch) Plant stands of dryland grain sorghum were lowered by disulfoton-granule treatments applied in the furrow along with the seed at planting. Greenbug reduction was generally unsatisfactory. Foliar spray applications of disulfoton, parathion, and dimethoate gave satisfactory greenbug control in dryland grain sorghum. Dimethoate at 1/2 lb/acre was little or no more effective than 0.15 lb/acre for the 3-week period. Disulfoton was as effective at 0.25 lb/acre as at 0.50 lb. Use of these insecticides did not increase dryland grain yields. Foliar applications of disulfoton-impregnated fertilizer gave unsatisfactory green bug control when applied to dryland grain sorghum at the rate of 1.0 lb of disulfoton/acre, but satisfactory results were obtained at the rate of 1.5 lb/acre. Disulfoton granules gave satisfactory greenbug reduction at 1.0 lb AI/acre.