The Silsoe Spray Drift Model: A model of spray drift for the assessment of non-target exposures to pesticides

A computer model of spray drift was developed, from an earlier particle-tracking model (Miller and Hadfield, 1989), which can be used to predict non-target exposures to pesticides. The extended model includes the effects of multiple nozzles on a boom and a forward speed so that it is better able to simulate application conditions appropriate to current field practice, particularly in the UK. The model was specifically developed for improving estimates of bystander dermal and inhaled spray drift exposure. It was validated against three experimental datasets of downwind airborne spray and ground deposit for FF110/1.2/3.0 conventional flat-fan nozzles spraying over either short grass or 0.65 m tall wheat crop. The model showed good agreement with measurements, but future work is required to validate the model against other nozzle designs.