Residue mornitoring and crop safety in soil of 5-dialkylamino sulfonylurea compounds

Chlorsulfuron, a representative sulfonylurea herbicide once was widely used for wheat, was banned for its long persistence in soil. Various alternatives have been proposed for chlorsulfuron replacement. Our previous study found that dimethylamino and diethylamino substitutions on the 5th position of sulfonylurea (Compounds Ia and Ib , respectively) could keep high herbicidal activities with accelerating degradation kinetics of sulfonylurea in acidic and alkaline soils. In order to evaluate the field soil degradation, its degradation dynamic was determined in a greenhouse (Cangzhou city, Hebei Province, China, pH 8.46) by Brassica campestris via pot-trials. The growth of B. campestris recovered gradually after Ia and Ib treatments, however, chlorsulfuron showed severe phytotoxicity with 70% of inhibition after 70 days of application (60 g a.i/hm²). As for the application of chlorsulfuron in wheat field and sulfonylureas in cereal field, the wheat and corn safety were tested further. The foliage treatment(15-60 g a.i/hm²) in wheat displayed insignificant inhibition. Meanwhile, the corn safety exhibited beneficial influence that Ia prompted the growth of corn at the concentration of 30-120 g a.i/hm² under post-emergence. Consequently, the soil degradation dynamic in pot-trials, as well as crop safety, proved the promising application value of Ia and Ib in production.