Long-Term Control of Perennial Broadleaf Weeds and Triazine-Resistant Common Lambsquarters (Chenopodium album) in No-Till Corn (Zea mays)

Control and regrowth of hemp dogbane, wild blackberry, and triazine-resistant common lambsquarters (TR-CHEAL) were studied in no-till corn from 1992 to 1994. Hemp dogbane, wild blackberry, and TR-CHEAL population increased 10, 123, and 177%, respectively, between 1992 and 1994 in plots treated with PRE applications of paraquat, atrazine, and metolachlor (weedy checks). POST applications of tank mixtures of 35 g ai/ha nicosulfuron or 20 g/ha primisulfuron with 280 g/ha 2,4-D or 140 g/ha dicamba, and 560 g/ha dicamba applied alone controlled hemp dogbane, wild blackberry, and TR-CHEAL 67 to 98%. These treatments reduced the population or prevented expansion of these weeds the year following treatment. In 1992, corn yield response to weed control was inconsistent. In 1993 and 1994, all plots treated with POST herbicides yielded higher than the weedy check. Corn yield of plots treated with combinations of nicosulfuron or primisulfuron with 2,4-D or dicamba and 560 g/ha dicamba applied alone were 102 to 149% and 124 to 153% higher than the weedy check in 1993 and 1994, respectively. Nomenclature: Atrazine, 6-chloro-N-ethyl-N'-(1-methylethyl) -1,3,5-triazine-2, 4-diamine; dicamba, 3,6-dichloro-2-methoxybenzoic acid; metolachlor, (2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-meth- oxy- 1-methylethyl) acetamide); nicosulfuron, 2-(((((4,6-dimethoxy-2-pyrimidinyl)amino)- carbonyl) amino)sulfo nyl)-N,N-dimethyl-3-pyridinecarboxamide; paraquat, 1,1 '-dimethyl-4,4'-bipyr- idiniumion; primisulfuron, methyl 2-(((((4,6-bis (difluoromethoxy)-2-pyrimidinyl) ami