Efficacy of KIH-485 on Texas panicum (Panicum texanum) and selected broadleaf weeds in corn

KIH-485 is an experimental herbicide being evaluated for preemergence weed control in corn. Field experiments were conducted in Burleson County, Texas, in 2003 and 2004 to compare weed control, corn tolerance, and corn yield with various rates of KIH-485 or S-metolachlor. Each herbicide was applied in single preemergence applications at four rates, or in combination with atrazine. KIH-485 at 500 g ai/ha provided better Texas panicum control than S-metolachlor by 9 WAT. KIH-485 or S-metolachlor treatments controlled Palmer amaranth at least 91% at all evaluation dates. In 2003, no other treatment controlled velvetleaf better than 500 g/ha KIH-485. The following year, all KIH-485 rates above 125 g/ha controlled velvetleaf better than any rate of S-metolachlor alone. Moreover, KIH-485 controlled all weed species as good as or better than S-metolachlor plus atrazine, regardless of KIH-485 rate. There was no significant corn injury observed, and grain yield reflected the effects of weed control. Nomenclature: Atrazine; KIH-485, 3-[(5-difluoromethoxy-l-methyl-3-trifluoromethylpyrazol-4-yl)methylsulfonyl]-4,5-dihydro-5,5-dimethylisoxazole; metolachlor; S-metolachlor; Palmer amaranth, Amaranthus palmeri S. Wats.; #(3) AMAPA; Texas panicum, Panicum texanum Buckl., # PANTE; velvetleaf, Abutilon theophrasti Medicus, # ABUTH; corn, Zea mays L. #3 ZEAMA. Additional Index Words: Corn weed control, experimental herbicide, preemergence. Abbreviations: WAT, weeks after treatment.