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Inclusion of any one of several ethoxylated nonionic surfactants in aqueous spray mixtures of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron) greatly increased its toxicity to crabgrass (Digitaria sanguinalis (L.) Scop.). Phytotoxicity of sprays made up from commercially formulated diuron was greater than when technical diuron was used. The toxicity of diuron was also increased by the addition of any of several low-molecular-weight alcohols to the spray mixture. The turbidity of diuron suspensions was greatly decreased by addition of any of several nonionic, anionic, or cationic surfactants which contained a fatty acid or fatty acid derivative as the hydrophobic portion of the molecule. Phytotoxicity of diuron applied with ethoxylated nonylphenol surfactants was associated with ethylene oxide (hydrophil) content. Surfactants containing nonylphenol, alkylthiol, or tridecylphenol as hydrophobes appeared essentially equal in their abilities to increase diuron toxicity, but dodecylphenol surfactants were slightly less effective.
Weeds © 1963 Weed Science Society of America