Abstract
Field studies conducted in 1990 and 1991 at five locations in Georgia and one location in Virginia in 1991 evaluated imazethapyr [2-[4,5-dihydro-4-methyl-4-(l-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-ethyl-3-pyridinecarboxylic acid] and AC 263,222 [(±)-2[4,5-dihydro-4-methyl-4-(l-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-methyl-3-pyridinecarboxylic acid] for weed control, peanut tolerance, and yield. Imazethapyr and AC 263,222 applied early postemergence (EPOST) controlled smallflower morningglory [Jacquemontia tamnifolia (L.) Griseb], Ipomoea morningglory species, prickly sida (Sida spinosa L.), and coffee senna (Cassia occidentalis L.) greater than 90%. Imazethapyr did not control Florida beggarweed [Desmodium tortuosum (SW.) DC.] or sicklepod (Cassia obtusifolia L.) adequately, with control generally less than 40%. AC 263,222 controlled Florida beggarweed greater than 92% when applied EPOST and from 54 to 100% when applied postemergence (POST). Imazethapyr applied preplant incorporated (PPI) controlled bristly starbur (Acanthospermum hispidium DC.) 89% and imazethapyr and AC 263,222 applied EPOST controlled at least 96%. Imazethapyr controlled yellow nutsedge (Cyperus esculentus L.) 83% when applied PPI and 93% as an EPOST application. AC 263,222 controlled yellow nutsedge at least 90%. Peanut yields were higher with AC 263,222 than with imazethapyr. Imazethapyr systems that included alachlor (2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide), lactofen ([(±)2-ethoxy-l-methyl-2-oxoethyl 5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoate] + 2,4-DB [4-(2,4-dichlorophenoxy)butanoic acid], paraquat [1,1′-dimethyl-4,4′-bipyridinium ion] + 2,4-DB, pyridate [O-(6-chloro-3-phenyl-4-pyridazinyl)-S-octyl carbonothioate] + 2,4-DB, metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-l-methylethyl)acetamide], or 2,4-DB provided yields equivalent to AC 263,222.