Effect of Manure on Maize Tolerance to Western Corn Rootworm (Coleoptera: Chrysomelidae)

Abstract

This study evaluated the potential of manure and maize tolerance to serve as alternative management strategies for reducing yield losses in maize, Zea mays (L.), by the western com rootworm, Diabrotica virgifera virgifera (LeConte). The interactions between manure and 2 maize hybrids and their subsequent effects on the growth and development of maize infested with western com rootworm were investigated in 1992 and 1993. Treatment combinations included 2 maize hybrids (Pioneer hybrid 3733 and Cornell 281), 4 manure rates (0, 45, 90, and 135 MT/ha), and 3 western com rootworm egg densities (1992: 0, 500, 700 eggs per 30.5-cm row; 1993: 0, 400, 800 eggs per 30.5-cm row). All plots received adequate nutrients (supplied by manure, inorganic fertilizer, or both) to satisfy or exceed soil test recommendations. Manure increased plant height, root recovery, and overall silage and grain yields, and decreased early feeding injury and lodging in 1 or both years of the study. However, manure had no effect on final root injury or on silage quality. Effects of manure were seemingly more pronounced in a wetter than average year. Pioneer 3733 had lower root injury ratings at the low western com rootworm density in 1993, equal root recovery, less lodging, and higher silage and grain yields with less loss to western com rootworm than Cornell 281. In both hybrids, manure produced an environmentally induced tolerance by increasing root recovery and in some cases reducing yield losses.