Responses of Ipomoea spp. and Cassia spp. to Preemergence Applied Herbicides

Abstract

Responses of six morningglories (Ipomoea spp.) and two Cassia spp. to 13 preemergence applied herbicides were determined at two locations in southern Alabama. Pitted (I. lacunosa L.), cypressvine (I. quamoclit L.), and willowleaf morningglories (I. wrightii Gray) were readily controlled with metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one]; entireleaf [I. hederacea (L.) Jacq. var. integriuscula Gray], tall [I. purpurea (L.) Roth.], and ivyleaf morningglories [I. hederacea (L.) Jacq.] were not controlled. Norflurazon [4-chloro-5-(methylamino)-2-(α,α,α-trifluoro-m-tolyl)-3(2H)-pyridazinone] controlled cypressvine morningglory, but did not adequately control the other morningglory species. Perfluidone {1,1,1-trifluoro-N-[2-methyl-4-(phenylsulfonyl)phenyl] methanesulfonamide} gave acceptable control of cypressvine and willowleaf morningglories, but gave poor control of other morningglory species. Sicklepod (C. obtusifolia L.) was controlled better than coffee senna (C. occidentalis L.) with 2.2 kg/ha diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] and 2.2 kg/ha cyanazine {2-[[4-chloro-6-(ethylamino)-s-triazin-2-yl]amino]-2-methylpropionitrile} controlled sicklepod better than coffee senna at one location each. Oxadiazon [2-tert-butyl-4-(2,4-dichloro-5-isopropoxyphenyl)-δ²-1,3,4-oxadiazolin-5-one] was more effective in controlling coffee senna than sicklepod. Induction of population shifts toward incidental species of these genera seems unlikely based on the herbicides included in these experiments. In most cases the incidental species were more readily controlled than the prominent weed species.