Spray drift review: The extent to which a formulation can contribute to spray drift reduction

Mitigation of risk arising from spray drift in Europe is achieved mostly by implementation of no-spray buffer zones and the use of approved drift-reducing techniques. Although physicochemical properties of spray solutions are known to influence spray drift, they are not yet incorporated into regulatory risk assessments at the European level. In this review we give a systematic report on the relevant physical properties of agricultural spray liquids and how these influence spray characteristics. According to the data reported in literature, it can be concluded that not only spray-mix additives but also certain formulation types can be used to reduce spray drift. To complete the picture, existing drift mitigation techniques and conditions have been reviewed along with measuring equipment which is commonly used to characterize agricultural sprays and the droplet size-related biological aspects of the application process. In a final step, we discuss the possibility of estimating drift risk based on the physicochemical properties of spray liquids induced by different formulation types.