Evaluation of the Impact of Hessian fly (Mayetiola destructor) on Oklahoma Winter Wheat Systems

Over 6 million acres of winter wheat are planted annually in Oklahoma. With an increasingly unstable economy and increasing of fuel prices, a small percentage of Oklahoma farmers have switched to no-till farming systems. This increase in no-till acreage corresponds with the recent increase in virulent Hessian fly populations in the Southern Plains. The Hessian fly, Mayetiola destuctor (Say), is one of the most economically threatening pests to crop production in all major wheat-growing areas of the United States. The studies in this thesis were designed to determine the biotype composition of Oklahoma, to evaluate what impact of Hessian fly infestation on wheat yield, as well as if no-till can be an effective method of infestation control. The results of the distribution survey demonstrated that Hessian fly populations are established throughout most of the major wheat growing counties in Oklahoma. On average, populations are low, but in a few fields in central and northern Oklahoma, populations are high enough to cause economic losses. It was possible to establish a negative relationship between Hessian fly infestation and wheat yield. As Hessian fly infestation increased, wheat yield decreased linearly. Based on the comparison of cumulative fly infestation levels between tillage treatments, our data indicate that tillage appears to reduce infestations of Hessian flies. This finding was most easily observed when fly populations were high, but difficult to detect with low populations.Department of Entomology and Plant Patholog