Pyrazosulfuron-ethyl, a new sulfonylurea herbicide for paddy rice.
In greenhouse studies, NC-311 (pyrazosulfuron-ethyl) demonstrated excellent herbicidal activity pre- and post-em. I75 values for pre-em. NC-311 were below 10 g/ha for 12 major weeds of rice, but not for Echinochloa crus-galli. Broadleaved weeds and sedges were especially sensitive to the herbicide. The selectivity of NC-311 between rice cv. Nihonbare seedlings and Cyperus serotinus was adequate, while that between rice and E. crus-galli was marginal in water culture studies. However, NC-311 demonstrated good control of E. crus-galli in field trials in China (in Guangdong in 1988) and in other countries. It was necessary for NC-311 to be combined with grass herbicides in dry-sown rice or in countries where high performance and a wide application window are required. NC-311 application to clay loam soil in pot trials and in field trials in Japan in 1989 did not result in carry-over problems, and no influence was observed on neighbouring crops (cucumbers, tomatoes, soyabeans and okra).