Published online by Cambridge University Press: 20 January 2017
Rapid adoption of glyphosate-resistant (GR) corn hybrids has led to thereemergence of volunteer corn as a problematic weed in soybean and has madecontrolling the initial stand of corn in a replant situation more difficult.If volunteer corn in soybean or the initial corn stand in a replantsituation is not controlled, yield loss can occur. Clethodim and glufosinateare often used to control GR corn in corn replant situations and in soybean.The objectives of this research were to evaluate the response of two hybridcorn varieties and their F2 progeny to clethodim and glufosinateand to evaluate the effect of plant nitrogen (N) concentration on clethodimand glufosinate efficacy. First, a dose-response study was conducted withclethodim and glufosinate on DeKalb 60-18 and 60-18F2, and DeKalb63-42 and 63-42F2 to compare the response of the hybrids andtheir F2 progeny to the herbicides. DeKalb 63-42 was moretolerant to clethodim than 60-18 and 60-18F2. No differences werefound between the hybrids and their respective F2 progeny in theresponse to clethodim or glufosinate. In a second dose-response studyassessing the effect of N conditions on herbicide efficacy, both clethodimand glufosinate were less injurious to plants growing in low N than in highN availability.