The effect of cationic and nonionic surfactants on the efficacy of ALS-inhibitor herbicides against Avena sterilis

A major challenge is selection of a suitable surfactant for a given herbicide. A series of dose-response experiments were conducted during 2013 at Ferdowsi University of Mashhad, Iran under greenhouse and outdoor conditions to determine whether the efficacy of four acetolactate synthase (ALS)-inhibitor herbicides on Avena sterilis could be improved by adding two surfactants at two concentrations. Both surfactants were effective at lowering the surface tension of all herbicide solutions with the nonionic surfactant being more effective than the cationic one. According to effective dose (ED)-values, the ranking of the ALS-inhibitor herbicides to control A. sterilis was: sulfosulfuron > mesosulfuron-methyl + iodosulfuron-methyl-sodium with safener mefenpyr > mesosulfuronmethyl + iodosulfuron-methyl-sodium with safener mefenpyr-diethyl > metsulfuron-methyl + sulfosulfuron. The EDs of all herbicides decreased when applied with surfactants. Cationic surfactant had a greater ability to enhance the efficacy of the tested herbicides than nonionic surfactant.