ABSTRACT
The addition of different concentrations (0.005 to 5.0%) of three cationic polyoxyethylene fatty amine surfactants and a nonionic polyoxyethylene nonylphenol surfactant markedly influenced the foliar uptake of glyphosate [N-(phosphonomethyl) glycine], applied to winter wheat (Triticum aestivum L.) seedlings. At a concentration of 0.5% (w/v), the surfactant Ethomeen® * T/25 (polyoxyethylene [15] tallow amine) gave the highest absorption rate compared with the other surfactants at 0.5%.
High absorption rates of glyphosate were observed at a concentration of 5.0%. Alone, Ethomeen HT/60 (polyoxyethylene [50] hydrogenated tallow amine) reduced the absorption by a factor of five at high concentrations (2.5 and 5.0%).
The spreading of the drops and their drying time were influenced by surfactant type and concentration. The results indicated that increased drop spreading and a shorter drying time may reduce the absorption of glyphosate. This reduction was observed with Renex® ** 688 (polyoxyethylene [8] nolyphenol) and Ethomeen C/12 (polyoxyethylene [2] coco amine) at a concentration of 0.05%, but was not observed at the other concentrations.
