Influence of Planting Date, Preplanting Weed Control, Irrigation, and Conservation Tillage Practices on Efficacy of Planting Time Insecticide Applications for Control of Lesser Cornstalk Borer in Field Corn12

Abstract

Experiments during 1974–78 demonstrated that banded applications of chlorpyrifos and fonofos at a rate of 0.22 kg AI/1000 m row had most consistent control of lesser cornstalk borer (LCB), Elasmopalpus lignoselius (Zeller), infestations in corn, Zea mays L., at various planting dates, in different soil types, in fields of conservation tillage and conventional tillage, under conditions of preplanting weed control, and in irrigated fields. Carbofuran, Isazofas®, (chemical definition unavailable) and terbufos also controlled infestations but consistency of control was low. At 0.11 kg AI/1000 m row, only seed furrow applications of carbofuran were effective. Efficacy of banded applications of carbofuran, diazinon, and fensulfothion was not greatly increased at rates up to 0.7 kg AI/1000 m row, whereas higher rates of chlorpyrifos, terbufos, and parathion were more effective. Infestations were substantially lower in early season plantings and in fields of conservation tillage and preplanting weed control. Interaction of insecticide treatment and of these cropping practices provided an effective integrated control system for LCB. Normal irrigation practices had little effect on LCB infestations. Regression models of LCB damage and yield indicated a 2.824 and 2.472% increase in yield for grain and silage, respectively, for each 1% control of LCB infestations.