Giant foxtail (Setaria faberi) control in sethoxydim-resistant corn (Zea mays)

Field studies were conducted at Dekalb and Urbana, IL, in 1995 and 1996 to evaluate the effectiveness of sethoxydim for giant foxtail control in sethoxydim-resistant (SR) corn. Experiments studied sequential and total postemergence applicat ions of grass herbicide standards compared to sethoxydim. Additional studies evaluated the compatibility of sethoxydim with postemergence broadleaf herbicides. Metolachlor plus atrazine and metolachlor followed by dicamba plus atrazine gave at least 88% control of giant foxtail at both locations in both years. Metolachlor plus flumetsulam plus clopyralid provided 90% or greater grass control over all experiments, with the exception of only 75% control at Dekalb in 1995 due to a heavy giant foxtail infestation. In comparison, flumetsulam plus clopyralid followed by postemergence applications of sethoxydim or nicosulfuron provided the same level of grass control as preemergence metolachlor, except at Dekalb in 1995 where control was 72% for both sethoxydim and nicosulfuron. Sequential applications of sethoxydim increased control of giant foxtail compared to a single sethoxydim application in 1995. Sethoxydim applied alone controlled giant foxtail 8% better than nicosulfuron at Urbana in 1996. Postemergence sethoxydim applied alone provided 87% or better control of giant foxtail. Sethoxydim performance was consistent when applied with flumetsulam plus clopyralid plus 2,4-D (NAF-73), halosulfuron plus dicamba, and bromoxynil. The efficacy of sethoxydim was reduced in combination with dicamba plus atrazine in three of the four trials, and bentazon plus atrazine as well as primisulfuron plus prosulfuron in all trials. Sethoxydim outperformed nicosulfuron in combinations with bromoxynil at Urbana. These studies indicate sethoxydim has excellent potential to be used in corn for postemergence control of giant foxtail.