Professor Emeritus, Michigan State University, East Lansing, MI
Research Associate, Ohio State University, OARDC, Wooster, OH
Director Emeritus, Molecular and Cellular Imaging Center, OARDC, Wooster, OH
Senior Research Scientist, USDA/Agricultural Research Service, Application Technology Research Unit, OARDC, Wooster, OH
Pages: 17 Published: Jan 2003
The multiple role of adjuvants in spray application of systemic agrochemicals is reviewed with special reference to tree fruits. The spray application process can be viewed as a series of interdependent events, namely formulation, atomization, spray transfer and interaction with the plant surface leading to retention and penetration. Adjuvants play a role in each event for they are used extensively in formulation and as a tank mix during application. They facilitate solubilzation of the active ingredient and modify the physico-chemical properties of the spray solution. The size distribution of the spray may be shifted to a lower or higher VMD by surfactants and drift retardants, respectively. Spray retention and spreading are increased on difficult to wet plant surfaces. Foliar penetration can be increased by stomatal pore infiltration by surfactants that lower surface tension to < 30 mN m-1. Transcuticular penetration may be depressed by adjuvants that do not penetrate, but reside on the surface, in the spray droplet residue and solubilize/complex the agrochemical in micelles (or other momomer agregrates) and effectively reducing the driving force. Other surfactants penetrate into the cuticle and plasticize the waxes, leading to increased transcuticular diffusion of the active ingredient. Implications for the presence of multiple spray additives in the spray solution and droplet residue on performance of the active ingredient are stressed.
pesticide, surface tension, surfactants, cuticle, spray retention, penetration
Paper ID: STP11116S