In field and greenhouse studies, alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide] was found to antagonize buthidazole {3-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-4-hydroxy-1-methyl-2-imidazolidinone} injury to corn (Zea mays L.) when both herbicides were preplant incorporated. Similar results were found with five of seven other acetanilide herbicides tested. The antagonism between buthidazole and alachlor also occurred with common cocklebur (Xanthium pensylvanicum Wallr.) and ivyleaf morningglory [Ipomoea hederacea (L.) Jacq.] but not with five other weed species. Preplant-incorporated applications of alachlor had little to no effect on the response of corn to postemergence applications of buthidazole, but alachlor increased the susceptibility of ivyleaf morningglory to postemergence applications of buthidazole. No antagonism was observed when alachlor was included in postemergence applications of buthidazole to corn or ivyleaf morningglory.
