New approach for pesticides doses adjustment with regards to vegetation structure and sprayers based on predictive modeling

Abstract

Society expects that using of pesticides is reduced. One mean recognized as possible would be to reconsider the expression of dose rate on target vegetation. In France, the approved dose is expressed with regards to ground surface area and does not take into account the evolution of vegetation and vineyard structure. The amount of product that is actually deposited on vegetation also depends on the sprayers’ performances. IRSTEA Montpellier and IFV have developed an artificial vine bench Evaspray-Viti to study performance of sprayers in realistic conditions by measuring amount of product deposited per unit area on vegetation. The deposit is quantified by measuring the amount of tracer (Tartrazine) on artificial leaves with spectrophotometry. The data obtained allow building models that link spraying technologies, vegetation structure and amount of deposited product. However, due to the many technologies for spray emission and transport and the many possible arrangement for geometry and number of emission sources, sprayers and configurations of sprayers that are commercially available are very numerous. Extensive studies of all these configurations would not be cost effective.

The decomposition method has been developed for building predictive models that require fewer measures. The deposition profile according to vegetation depth and height is estimated thanks to unit models of spraying organs (u.m, e.g of a nozzle) that are obtained from measurements on Evaspray-Viti sprayer bench. The first results show the validity of this method for two different types of sprayers: a pneumatic sprayer “4 hands – 4 spouts” and a multi-row air-assisted sprayer. The method allows characterizing technologies and ranking their efficiencies according to uses. The quality of prediction of models will be evaluated by experiments in real vineyards. One output of this research may be to propose a new expression for approval doses on vineyards that would take vegetation structure into account.