Equimolar concentrations of 4-phenylsulfonyltrifluoromethanesulfono-o-toluidide (hereafter referred to as MBR-8251), S-ethyl dipropylthiocarbamate (EPTC), and 2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide (alachlor) were compared using a quartz gravel nutrient culture method for detecting toxicity to yellow nutsedge (Cyperus esculentus L.), okra (Hibiscus esculentus L.), cabbage (Brassica oleracia var. captata L.), cucumber (Cucumis sativus L.), and flax (Linum ustitatissimum L.). MBR-8251 was more active on yellow nutsedge than EPTC or alachlor, and MBR-8251 treated nutlets were controlled for a longer period. In general, crops were more tolerant of MBR-8251. Field studies comparing the effectiveness of MBR-8251 to EPTC, S-propyl dipropylthiocarbamate (vernolate), 2-chloro-4-(ethylamino)-6-isopropylamino-s-triazine (atrazine), 3-isopropyl-2,1,3-benzothiazinone-(4)-2,2-dioxide-6,7,8 (BAS-3510), alachlor, and 2-chloro-N-(ethoxymethyl)-6′-ethyl-o-acetotoluidide (MON-097) indicated that after 10 weeks yellow nutsedge control was excellent with MBR-8251, MON-097, and alachlor.