Sulfonylurea herbicide; blocks branched-chain amino acid synthesis by inhibiting the plant enzyme, acetolactate synthase. Prepd (not claimed): P. H. Liang, US 4774337 (1988 to DuPont); and use in herbicidal mixtures: idem, EP 341011 (1989 to DuPont), C.A. 113, 6360 (1990). Comprehensive description: H. L. Palm et al., Brighton Crop Prot. Conf. - Weeds 1989, 23-28. HPLC, TLC determn and environmental fate: G. E. Schneiders et al., J. Agric. Food Chem. 41, 2402 (1993). Field trials in potatoes: C. V. Eberlein et al., Weed Technol. 8, 428 (1994).