Sicklepod (Cassia obtusifolia) Management in Soybeans (Glycine max)

Abstract

Greenhouse and on-farm tests were conducted in North Carolina in 1979 and 1980 to evaluate sicklepod (Cassia obtusifoliaL. # CASOB) management in soybeans [Glycine max(L.) Merr.]. All postemergence herbicide applications gave better sicklepod control when applied following vernolate [S-dipropylthiocarbamate) preplant incorporated than when applied following alachlor [2-chloro-2,6-diethyl-N-(methoxymethyl)acetanilide] preemergence. This resulted from decreased fatty alcohols and hydrocarbons in the epicuticle of vernolate-treated sicklepod. When applied sequentially to vernolate, toxaphene (chlorinated camphene, 67 to 69% chlorine) plus an oil concentrate and acifluorfen {5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid} applied postemergence to the first true-leaf stage of sicklepod resulted in 95 and 90% control, respectively. Linuron [3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea] and metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one] applied alone or as tank mixes with 2,4-DB [4-(2,4-dichlorophenoxy)butyric acid] provided greater than 90% sicklepod control when applied postemergence-directed to soybeans. Metribuzin was more injurious to soybeans than linuron.