Surfactant Effects on Environmental Behavior of Pesticides

Pesticides having a wide variety of structures have been and are being developed to exhibit an intended efficacy to pests, fungal diseases, and weeds, and are usually applied as formulations to these targets in the field. Many types of formulations have been developed by considering the physicochemical properties of the pesticide, not only to maximize their efficacy but also to prevent unfavorable environmental contamination from pesticide and its degradation products. A lower water solubility of the pesticide usually leads to utilization of a water-miscible organic solvent and formulation additives (adjuvants) including surface-active agents (surfactants) to solubilize, suspend, or disperse the active ingredient (a.i.) of pesticide in its aqueous solution being applied in agricultural practices. Among adjuvants, surfactants are some of the most important components and can improve the biological activity by modifying spray droplet size, retention, and spreading on leaf surfaces or by enhancing uptake and translocation of the a.i. to crop (Knowles 2001). The various kinds of surfactants with a wide variety of molecular weight and ionic character as well as natural and petroleum oils are used as wetting, spreading, sticking, and penetration agents and humectants (Hazen 2000; Krogh et al. 2003).