Spring- and Fall-Tillage System Effects on Hessian Fly (Diptera: Cecidomyiidae) Emergence from a Coastal Plain Soil2

Abstract

Fall emergence of Hessian fly, (HF) Mayetiola destructor (Say), was measured from wheat stubble subjected to combinations of spring burning and tillage, and fall tillage in the South Carolina Coastal Plain. In a split-plot experiment, the main-plot effect was a spring treatment, consisting of either: no-tillage, burning, disking, burning and disking or bottom-plowing. The subplot effect was fall tillage (either disking or no-tillage). Among the spring treatments, burning alone gave no reduction in HF emergence. Spring disking reduced HF emergence 54%. Spring burning plus disking reduced emergence 70–96%. No emergence was detected from the bottom-plowed treatments. Fall disking reduced emergence 48–50% in plots that had no spring tillage. Plots disked in both the fall and spring had the same level of HF emergence as plots disked only in the spring or only in the fall. Fall disking greatly increased emergence (up to 23×) from plots where HF had been effectively buried in the spring (previously burned and disked). The disk harrow is the primary tillage implement in the southeastern Coastal Plain, and disking wheat stubble substantially reduced HF emergence. However, repetitive disking can be of limited value or detrimental, in reducing HF emergence from some Coastal Plain soils, in that previously buried puparia might be returned to the soil surface. There was no apparent effect of tillage on emergence timing.