Control of Volunteer Corn with the AAD-1 (aryloxyalkanoate dioxygenase-1) Transgene in Soybean

Volunteer Enlist corn with the AAD-1 (aryloxyalkanoate dioxygenase-1) transgene can become a problem when glyphosate-resistant (GR) soybean follows Enlist corn in the rotation. Field trials were conducted at Ridgetown, Ontario in 2013 and 2014 to evaluate the control of volunteer Enlist corn in GR soybean. Glyphosate plus clethodim at 30 g ai ha⁻¹ provided 75 to 92% control of volunteer Enlist corn at 1, 2, 4, and 8 weeks after treatment application (WAT) and reduced volunteer Enlist corn density and dry weight 95 to 97%. Glyphosate plus clethodim at 60 g ai ha⁻¹ provided 84 to 98% control of volunteer Enlist corn at 1, 2, 4, and 8 WAT and reduced volunteer Enlist corn density and dry weight 97 to 99%. Glyphosate plus sethoxydim at 150 g ai ha⁻¹ provided 66 to 86% control of volunteer Enlist corn at 1, 2, 4, and 8 WAT and reduced volunteer Enlist corn density and dry weight 91 to 97%. Glyphosate plus sethoxydim at 300 g ha⁻¹ provided 84 to 96% control of volunteer Enlist corn at 1, 2, 4, and 8 WAT and reduced volunteer Enlist corn density and dry weight 96 to 98%. Glyphosate plus fenoxaprop-p-ethyl, fluazifop-p-butyl, and quizalofop-p-ethyl applied POST provided 0 to 9% control of volunteer Enlist corn at 1, 2, 4, and 8 WAT and reduced volunteer Enlist corn density and dry weight 18 to 44%. Soybean yields closely reflected the level of volunteer Enlist corn control. Based on these results, the cyclohexanedione herbicides, clethodim and sethoxydim, provide adequate control of volunteer Enlist corn in GR soybean. In contrast, the aryloxyphenoxypropionate herbicides, fenoxaprop-p-ethyl, fluazifop-p-butyl and quizalofop-p-ethyl do not provide control of volunteer Enlist corn in GR soybean.Nomenclature: ACCase, acetyl-CoA carboxylase; AAD-1, aryloxyalkanoate dioxygenase-1 transgene; aryloxyphenoxypropionate; clethodim; cyclohexanedione; fenoxaprop-p-ethyl; fluazifop-p-butyl; quizalofop-p-ethyl; sethoxydim; corn, Zea mays L.; soybean, Glycine max (L.) Merr.