Nicosulfuron is used with surfactant or oil adjuvant to enhance postemergence efficacy. Yellow foxtail fresh weight reduction from nicosulfuron varied from 10 to 92% depending upon surfactant in greenhouse experiments. Oil adjuvants differed in enhancement of nicosulfuron phytotoxicity to yellow foxtail or large crabgrass with methylated canola oil being most effective, followed by vegetable oils, and petroleum mineral oil as least effective. Percentage and type of surfactant used as an emulsifier in an oil adjuvant was important to nicosulfuron phytotoxicity especially when applied with the less effective oils, but was of minimal importance when applied with methylated canola oil. Adjuvant effectiveness was directly related to nicosulfuron absorption. These data indicated that recommendations for adjuvants to maximize nicosulfuron phytotoxicity should be limited to specific products.
