Environment and Chlorsulfuron Phytotoxicity

Abstract

Glasshouse and growth chamber experiments were conducted to determine chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino] carbonyl] benzenesulfonamide} phytotoxicity to kochia [Kochia scoparia(L.) Schrad. ♯ KCHSC] and green foxtail [Setaria viridis(L.) Beauv. ♯ SETVI] as influenced by temperature and humidity for 1 week after treatment, and by soil moisture and nitrogen. Chlorsulfuron was more phytotoxic to both kochia and green foxtail at 95 to 100% than at 45 to 50% relative humidity for 1 week after treatment whether at 10, 20, or 30 C. Chlorsulfuron phytotoxicity was similar with all posttreatment temperatures at each humidity, except that phytotoxicity was lower at 30 C than at 10 or 20 C at 90 to 100% humidity. Surfactant added to chlorsulfuron exhanced control of kochia more than that of green foxtail and overcame temperature and humidity effects on chlorsulfuron phytotoxicity. A simulated rainfall of 2 mm after chlorsulfuron application reduced toxicity of chlorsulfuron to green foxtail more than to kochia. Chlorsulfuron was more phytotoxic to green foxtail growing with a high than a low soil nitrogen level. High soil moisture following chlorsulfuron application enhanced phytotoxicity to kochia and green foxtail compared to high soil moisture before treatment.