Effect of nonylphenol ethoxylation on the biological activity of three herbicides with different water solubilities

Changing the number of ethylene oxide (EO) units on a nonylphenol surfactan t changes its physicochemical and biological properties. Increasing the num ber of EO units makes the surfactant more hydrophilic and increases its hyd ropbilic-lipophilic balance (HLB). Surfactants with high HLB values, more t han 16, were the most active with the hydrophilic herbicide glyphosate. Mor e lipophilic surfactants with HLB values from II to 13 were more active wit h the lipophilic herbicide, the ethyl ester of quizalofop-P, Surfactants wi th intermediate HLB values were the most active with the herbicide that had intermediate water solubility, nicosulfuron, Matching the physicochemical properties of the herbicide and surfactant improved biological efficacy on giant foxtail.