Droplet size spectra classification categories in aerial application scenarios

A classification of sprays based on droplet size facilitates the description of droplet size requirements on pesticide labels and in regulatory decision-making. The American Society for Agricultural and Biological Engineers (ASABE) standard S-572 has become a widely used classification system for sprays. Some pesticide labels in Australia already require certain droplet size spectra to be specified using this standard. The reference categories from very fine to extremely coarse are based on measurements of sprays under ground application conditions. There is a need for equivalent classification categories for aerial application conditions. The present paper describes a wind tunnel atomization study to determine possible candidate sprays which would produce the same droplet size categories as the ASABE S-572 reference categories under aerial application conditions.