Preliminary Results on the Correlation Between Drop Size, Foliar Deposition and Surface Coverage to Reduce Plant Protection Product Use

Drop size spectrum, percentage of covered surface of the target and foliar deposition are the most important factors affecting the results of a plant protection treatment, as well as the environment and operator safety. The main objective of this research was to study the correlation between drop diameters, foliar deposition on orange leaves and surface coverage on Water Sensitive Papers (WSP) under laboratory conditions. The first results showed that the foliar deposition per unit surface (µL/cm2) was positively and significantly correlated with the percentage of covered surface and all main characteristic diameters of the spray (volumetric diameters, Sauter mean diameter, and numeric median diameter). It may be estimated from percentage of covered surface on WSP and spray drop diameters by means of a multiple linear regression (determination coefficient between observed and predicted deposits equal to 0.96), but further experiments are necessary to validate the model in field and to cope with different practical situations in terms of spray quality and covered surface.