Spray drift: impact of requirements to protect the environment

Abstract

Spray drift studies in the US have evaluated the effects of application, meteorological and tank mix variables on spray drift. The data have been incorporated into models to predict drift from aerial applications, and to evaluate worst-case drift from ground rig (boom) and orchard airblast applications. An atomisation model has also been developed to predict droplet size for applications of tank mixes with user-defined or reasonable worst-case physical properties through a wide range of hydraulic nozzles applicable to aerial applications. The database and models help provide the exposure risk input to risk assessments for developing appropriate labelling based on exposure and toxicity risk to non-target sensitive areas. This needs to be balanced with allowing crop protection using careful risk/benefit assessments. Buffers or no spray zones may be based on spray quality, release height and other variables such as wind speed where necessary for protecting specific sensitive areas. The impact of protection measures aimed at minimising the incidence and impact of spray drift is discussed in the present paper.