Abstract: Synergistic herbicidal activity is displayed by a composition comprising the following two components:(a) a pyrrolidone of the formula ##STR1## in which X is selected from the group consisting of hydrogen, chlorine and methyl; Y is selected from the group consisting of hydrogen, chlorine and bromine; Z is selected from the group consisting of chlorine and bromine; R.sup.1 is selected from the group consisting of hydrogen and C.sub.1 -C.sub.4 alkyl; R.sup.2 is selected from the group consisting of hydrogen, C.sub.1 -C.sub.4 alkyl, acetyl, trifluoromethyl, nitro, cyano, C.sub.1 -C.sub.4 alkoxy, C.sub.1 -C.sub.4 alkylthio, C.sub.1 -C.sub.4 alkylsulfonyl, C.sub.1 -C.sub.4 alkylsulfinyl, trifluoromethylthio, trifluoromethylsulfinyl, trifluoromethylsulfonyl, pentafluoropropionamido, and 3-methylureido; and R.sup.3 is selected from the group consisting of hydrogen, C.sub.1 -C.sub.4 alkyl, chlorine and trifluoromethyl; and(b) a urea of the formula ##STR2## in which R.sup.