Spray techniques: how to optimise spray deposition and minimise spray drift

A summary is given of research within the field of application technology for crop protection products for the past 10 years in The Netherlands. Results are presented for greenhouse, orchard, nursery tree and arable field spraying for the typical Dutch situation. Research predominantly focussed on the quantification of spray deposition in crop canopy and the emissions into the environment, especially spray drift. The risk of spray drift is related to defined distances and dimensions of the surface water adjacent to a sprayed field. Spray deposition and spray drift research was setup in order to identify and quantify drift-reducing technologies. Results are presented for cross-flow sprayers, tunnel sprayers and air-assisted field sprayers. For field crop spraying with a boom sprayer the effect of nozzle type on spray deposition in crop canopy and spray drift is highlighted both with a modelling approach as based on field experiments. The use of spray drift data in regulation is discussed. A relation between spray deposition and biological efficacy is outlined for drift-reducing spray techniques. The effect of spray drift-reducing technologies in combination with crop- and spray-free buffer zones is outlined. It is concluded that spray technology plays an important role to minimise spray- and crop-free buffer zones, and to maintain biological efficacy and acceptable levels of ecotoxicological risk in the surface water.