Derivative of urea. Prepn and use as pre-emergence herbicide: N. E. Searle, US 2756135 (1956 to du Pont). Use as pre- and post-emergence herbicide in wheat and barley: H. Hack et al., GB 1085430 (1967 to Bayer). Herbicidal properties: H. Hack, Pflanzenschutz-Nachr. 22, 331 (1969). Toxicity studies: G. Kimmerle, E. Lser, ibid. 351. Use in winter cereals: D. C. Clark et al., Proc. 12th Brit. Weed Control Conf. 163 (1974). Mode of action: G. F. Collet, Weed Res. 9, 340 (1969). Long-term effect on soil: P. L. Huge, Pflanzenschutz-Nachr. 34, 97 (1981). Brief review: P. Lours, Def. Veg. 24, 91 (1970).