Effect of Herbicide Combinations on Weeds and Soybeans

Abstract

Herbicide treatments of 3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea (linuron), 2,4-bis(isopropylamino)-6-(methylthio-s-triazine (prometryne), or methyl ester of 3-amino-2,5-dichlorobenzoate (chloramben ester) were applied preemergence to soybean (Glycine max (L.) Merr. ‘Dare’ or ‘Bragg’) plots previously treated with S-propyl dipropylthiocarbamate (vernolate), α,α.α,-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin), or 4-(methylsulfonyl)-2,6-dinitro-N,N-dipropylaniline (nitralin). Sequential treatments of vernolate with linuron, prometryne, or chloramben ester controlled weeds more effectively in soybeans than did trifluralin or nitralin applied with the same preemergence treatments. Soybean injury was not severe enough to reduce seed yields in any year. Yields were greater in 1970 when soybeans were treated with vernolate than when treated with either trifluralin or nitralin. Soybean yields also were greater in 1970 when treated with chloramben ester than when treated with linuron or prometryne. In 1969 when soybeans were planted in a sandy loam, prometryne reduced stands more than did linuron or chloramben ester.