THE INFLUENCE OF FOXTAIL ON THE POPULATION DYNAMICS AND ECONOMIC IMPACT OF CORN ROOTWORMS (INTEGRATED PEST MANAGEMENT, AGRICULTURE)
Abstract
Field studies were conducted during 1981-1983 to determine the influence of foxtail infestations in survival of corn rootworm (CRW) larvae under early May and early June corn planting dates. Delaying corn planting significantly (P = 0.05) reduced CRW larval and adult populations in both foxtail-infested and weed-free corn plots. Compared to weed-free corn plots, weedy plots had significantly (P = 0.05) fewer larvae and adults in one of three years and numerically fewer in three years. Delaying corn planting significantly (P = 0.05) delayed 50% occurrence of CRW adults. Foxtail infestation also delayed CRW emergence, but differences were non-significant. The influence of foxtail populations on oviposition by CRW adults was studied from 1980-1983. Four foxtail populations (400, 40, 4, and 9 seedlings/m-row) were established in conventional tillage to determine their influence on egg density and horizontal distribution in the soil. In another study, the influence of foxtail density on egg numbers was investigated under moldboard plow, chisel plow, and zero tillage systems. Foxtail populations did not exert a conclusive influence on oviposition in either experiment. Oviposition did not differ significantly among tillage systems but root damage from CRW the following year did. The influence of simultaneous infestations of foxtail and CRW larvae on corn plant growth and grain yield was studied in field experiments during 1981-1983. Percentage grain yield losses from CRW larvae increased under heavy foxtail infestations, particularly during 1983. The influence of foxtail populations on root damage ratings was also investigated and economic thresholds for CRW larvae under different foxtail populations were calculated.
Degree
Ph.D.
Subject Area
Entomology
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