Control of glufosinate/glyphosate-resistant corn volunteers in imazamox- and quizalofop-resistant sorghum

Abstract Volunteer corn is a problem weed in sorghum fields rotated with corn. The commercial availability of imazamox-resistant (igrowth®) and quizalofop-resistant (Double Team™) sorghum allows the use of imazamox and quizalofop, respectively, for controlling grass weeds; however, information is not available regarding their efficacy for control of volunteer corn. The objective of this study was to evaluate the efficacy of imazamox and quizalofop for control, density and biomass reduction of glufosinate/glyphosate-resistant corn volunteers in imazamox- and quizalofop-resistant sorghum. Two separate field experiments were conducted near Clay Center, NE, in 2023 and 2024. Imazamox applied early postemergence (E-POST) and late postemergence (L-POST) (53 and 79 g ai ha –1 ) controlled up to 98% and 89% of corn volunteers 28 d after application (DAA) in 2023 and 2024, respectively, in igrowth® sorghum. Similarly, quizalofop applied E-POST and L-POST (58 and 73 g ai ha –1 ) provided 98% and 99% control of volunteer corn in 2023 and 2024, respectively, in Double Team™ sorghum. Quizalofop reduced volunteer corn density (0 to 0.2 plants m –1 ) and biomass (0 to 13 g m –2 ) compared to nontreated control in both years. The results suggest that imazamox and quizalofop could be used as POST herbicides for control of glufosinate/glyphosate-resistant corn volunteers in imazamox- and quizalofop-resistant sorghum, respectively.