Integration of Plant Resistance, Insecticides, and Planting Date for Management of the Hessian Fly (Diptera: Cecidomyiidae) in Winter Wheat

Abstract

The Hessian fly, Mayetiola destructor (Say), can cause severe damage to soft red winter wheat, Triticum aestivum L. em Theil, in the southeastern United States. The efficacy and cost effectiveness of in-furrow applications of disulfoton and phorate as alternatives to planting date modification and plant resistance for controlling Hessian fly damage in winter wheat was studied during the 1987-1988 and 1988-1989 seasons near Midville and Plains, Ga. The study consisted of a split-split plot design of two planting dates, three insecticide treatments, and four or six cultivars of soft red winter wheat. Populations were small and damage was minimal during the first season, but populations were large and damage was severe during the second season. Planting before the recommended planting date increased the severity of Hessian fly injury, but planting at the recommended date did not necessarily avoid Hessian fly damage during the fall. Applications of phorate and disulfoton were equally effective in controlling infestations in the fall and winter. Spring infestations also tended to be lower in treated than untreated plots. Plant resistance controlled Hessian fly damage throughout the season. Phorate reduced wheat seedling establishment in some trials, but this reduction did not adversely affect wheat productivity and economic returns. Low populations had little effect on wheat yield, test weight, and economic returns in 1987-1988. Hessian fly damage in 1988-1989 reduced grain yield, test weight, and straw weight in untreated susceptible cultivars. Use of a systemic insecticide at planting on Hessian fly susceptible cultivars provided a positive economic return regardless of planting date, and disulfoton and phorate provided similar economic benefits. When infestations were large, resistant cultivars provided a large economic benefit compared with an untreated susceptible cultivar. Insecticide use on a resistant cultivar was not economically justified. Planting a high-yielding, resistant cultivar without an insecticide provided similar or better economic returns than other management options. However, if high-yielding resistant cultivars are not available, use of a systemic insecticide at planting on susceptible cultivars in conjunction with proper cultural practices is a cost-effective alternative approach to managing the Hessian fly in wheat.