Nonselective pre- and post-emergence sulfonylurea herbicide for noncropland use; inhibits branched chain amino acid biosynthesis. Prepn: G. Levitt, EP 7687; idem, US 4394506 (1980, 1983 both to Du Pont); idem, Pestic. Chem.: Hum. Welfare Environ., Proc. 5th Int. Congr. Pestic. 1, 243 (1983). Herbicidal activity and toxicity: R. H. Harding et al., Proc. West. Soc. Weed Sci. 34, 120 (1981). Mechanism of action: T. B. Ray, Proc. Br. Crop Prot. Conf. - Weeds 1985, 131. HPLC determn in soil and water: E. W. Zahnow, J. Agric. Food Chem. 33, 479 (1985). Degradation and bioaccumulation studies: J. Harvey et al., ibid. 590; J. J. Anderson, J. J. Dulka, ibid. 596. Field trials: R. L. Atkins et al., Proc. South. Weed Sci. Soc. 36, 300 (1983); in afforested areas: A. Nir, Z. Arenstein, Proc. Br. Crop Prot. Conf. - Weeds 1987, 787.