Chlorsulfuron
Chlorsulfuron is an ALS (acetolactate synthase) inhibitor herbicide, and is a sulfonylurea compound. It was discovered by George Levitt in February 1976 while working at DuPont, which was the patent assignee. Brand names Originally introduced in 1982 under the brand name Glean by DuPont, later also as Telar, in North America. Chemistry The first synthesis of chlorsulfuron was disclosed in a patent filed by DuPont in 1977. 2-Chlorobenzenesulfonyl isocyanate was condensed with 2-amino-4-methoxy-6-methyl-1,3,5-triazine to form the sulfonylurea product. Mode of action Chlorsulfuron is an herbicide of the acetolactate synthase inhibitor (ALS inhibitor) class, HRAC (Herbicide Resistance Action Committee) group 2 (legacy HRAC Group B). Efficacy Triticum aestivum is naturally resistant via aryl hydroxylation then conjugation with glucose compounds into non-herbicidal conjugates. Widespread weed resistance to chlorsulfuron has been found across North America and around the world. T. aestivums close relative Lolium rigidum was found to be using the same mechanism by Christopher et al 1991 and Cotterman & Saari 1992. A North American population of Stellaria media was found by Hall and Devine 1990 to be resistant by way of an ALS target mutation rather than by improved disposal. Increased P450 activity can also be effective, such as in Alopecurus