TOTAL POSTEMERGENCE WEED-CONTROL IN IMIDAZOLINONE-RESISTANT CORN (ZEA-MAYS)

Field experiments were conducted in 1994 and 1995 to evaluate weed con trol in imidazolinone-resistant corn with postemergence applications o f imidazolinone and sulfonylurea herbicides. Imazethapyr controlled 10 0% of redroot pigweed, jimsonweed, and eastern black nightshade. Contr ol of fall panicum with imazethapyr was inconsistent, with control ran ging from 42 to 85%. Imazethapyr provided less than 55% control of com mon lambsquarters and 43% of large crabgrass. Imazethapyr plus either atrazine, 2,4-D, or dicamba increased control of common lambsquarters compared to imazethapyr alone. Fall panicum control was > 95% with nic osufluron. CGA-152005 and MON 12000 did not control eastern black nigh tshade. In 1995, corn yield was greater with the hand-weeded check com pared to all herbicide treatments. The greatest return over herbicide cost with imazethapyr was obtained with imazethapyr plus atrazine. Nic osulfuron plus CGA-152005 provided the greatest return over herbicide cost when averaged across years.