Glyphosate-Resistant Common Ragweed Control in Corn with Postemergence Herbicides
Four field trials were conducted on a farm infested with glyphosate-resistant (GR) common ragweed during 2016 and 2017 to evaluate various postemergence (POST) herbicides for the control of GR common ragweed in GR corn. Dicamba at 600 g∙a.i.∙ha−1 , dicamba/diflufenzopyr at 200 g∙a.i.∙ha−1 , dicamba/atrazine at 1500 g∙a.i.∙ha−1 , topramezone + atrazine at 12.5 + 500 g∙a.i.∙ha−1 , bromoxynil + atrazine at 280 + 1500 g∙a.i.∙ha−1 , glufosinate at 500 g∙a.i.∙ha−1 and 2,4-D ester at 560 g∙a.i.∙ha−1 provided 58% to 85% control at 4 WAA and 49% to 88% control at 8 WAA. Other herbicides evaluated controlled GR common ragweed 9% to 41%. Common ragweed density was reduced 97%, 95%, 95% and 87% and shoot dry weight was reduced 93%, 95%, 94% and 90% with bromoxynil + atrazine, dicamba, glufosinate and topramezone + atrazine applied POST in GR corn, respectively. Results show that dicamba, bromoxynil + atrazine, topramezone + atrazine and glufosinate applied POST are the most efficacious herbicides among the herbicides evaluated for the control of GR common ragweed in GR corn.