Response of spray drift from aerial applications at a forest edge to atmospheric stability

Abstract

A biological pesticide was aerially applied to a hardwood forest – corn field edge in a replicated series of single spray swaths. The drift of small droplets, which remained suspended in the air after each spray swath, was monitored remotely and mapped with the University of Connecticut portable, elastic-backscatter lidar. Plumes of small droplets were tracked which drifted off after every spray swath and dispersed into the atmospheric boundary layer. Plume movement and the rate of near field plume dilution was primarily dependent on the stability of the atmosphere, which implies that concentrations in the air in adjacent areas can be partially controlled by correct timing of the spray operations. The study results support the hypothesis that widespread dispersal of a small amount of pesticide is inevitable, even in well-conducted spraying operations.