Measuring Pesticide Drift at Distances to Four Miles

Drift resulting from pesticide spray operations is an environmental contaminant and potential hazard. In order to quantitatively evaluate the relationship between a source and the extent of its contamination, it is necessary to measure the downwind amounts of pesticide that are still airborne as well as the deposition on the ground and foliage. Furthermore, it is also necessary to quantitatively characterize the droplet size parameters of these airborne and deposited amounts in order that the results of any given field test be extended for use in a general evaluation of the drift problem. A simple tracer technique to measure the required characteristics of the spray drift is described. The fluorescent particle (FP) spray tracing technique essentially consists of adding a known number of insoluble, micron-sized FP to the pesticide liquid prior to the spray operation. After spraying, the samples of artificial or natural surfaces are assessed. The number of FP grouped within an individual droplet pa...