Response of glufosinate-resistant Bt sweet corn (Zea mays) cultivars to glufosinate and residual herbicides

Abstract

Field studies were conducted in 1999 and 2000 at Simcoe and Exeter, Ontario to determine the effect of glufosinate, applied alone or in combination with s-metolachlor/atrazine, on weed control and crop safety on six glufosinate-resistant Bt sweet corn cultivars. A single application of glufosinate at 0.5 or 1.0 kg ha-1 gave 89% or better control of redroot pigweed, common ragweed, wild buckwheat and lady’s-thumb in 1999 and pale smartweed and redroot pigweed in 2000. Glufosinate applied alone gave reduced control of wild buckwheat and barnyard grass in 2000 and reduced control of crab grass in 1999 and 2000 at Simcoe. S-metolachlor/atrazine applied preemergence, followed by glufosinate postemergence, improved control of these species. In the untreated control, yield of all cultivars, except Bonus Bt at Exeter, was reduced at all locations. Yield of Cupola Bt and SS Jubilee Bt was reduced when glufosinate was applied alone at 0.5 kg ha-1. Yield of Cupola Bt, Empire Bt and SS Jubilee Bt was reduced with s-metolachlor/atrazine used alone. Maximum yields were obtained with a sequential treatment of s-metolachlor/atrazine followed by glufosinate. Glufosinate did not cause any injury, plant height reduction or delayed maturity of any glufosinate-resistant Bt sweet corn cultivars. Key words: Cultivar, sensitivity, herbicide injury, glufosinate, Zea mays