GIANT FOXTAIL (SETARIA-FABERI) CONTROL IN SETHOXYDIM-RESISTANT CORN (ZEA-MAYS)

Field studies were conducted at Dekalb and Urbana, IL, in 1995 and 199 6 to evaluate the effectiveness of sethoxydim for giant foxtail contro l in sethoxydim-resistant (SR) corn. Experiments studied sequential an d total postemergence applicat ions of grass herbicide standards compa red to sethoxydim. Additional studies evaluated the compatibility of s ethoxydim with postemergence broadleaf herbicides. Metolachlor plus at razine and metolachlor followed by dicamba plus atrazine gave at least 88% control of giant foxtail at both locations in both years. Metolac hlor plus flumetsulam plus clopyralid provided 90% or greater grass co ntrol 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 o f sethoxydim or nicosulfuron provided the same level of grass control as preemergence metolachlor, except at Dekalb in 1995 where control wa s 72% for both sethoxydim and nicosulfuron. Sequential applications of sethoxydim increased control of giant foxtail compared to a single se thoxydim application in 1995. Sethoxydim applied alone controlled gian t foxtail 8% better than nicosulfuron at Urbana in 1996. Postemergence sethoxydim applied alone provided 87% or better control of giant foxt ail. Sethoxydim performance was consistent when applied with flumetsul am plus clopyralid plus 2,4-D (NAF-73), halosulfuron plus dicamba, and bromoxynil. The efficacy of sethoxydim was reduced in combination wit h dicamba plus atrazine in three of the four trials, and bentazon plus atrazine as well as primisulfuron plus prosulfuron in all trials. Set hoxydim outperformed nicosulfuron in combinations with bromoxynil at U rbana. These studies indicate sethoxydim has excellent potential to be used in corn for postemergence control of giant foxtail.