Toward a new method to classify the airblast sprayers according to their potential drift reduction: comparison of direct and new indirect measurement methods

BACKGROUND: Drift is one of the most important issues to consider for realising sustainable pesticide sprays. This study proposes an alternative indirect methodology for comparative measurements of drift reduction potential (DRP) generated by airblast sprayers, aimed at overcoming the practical inconveniences and drawbacks of standardized ISO 22866:2005. A test bench in the absence of target crop and wind was employed to measure drift potential values (DPVs). A variation to the proposed method that introduced a crop between sprayer and test bench device was considered to study the canopy effect (absence/presence) and to validate the method. In parallel, direct spray drift measurements (ISO 22866) were performed to obtain thedrift value (DV).Arepresentative vineyardairblast sprayerwas evaluated in four configurations (a combination of two fan airflowrates and two nozzle types). The configurations tested under the threemethods (direct and indirects)were classified according to achieved drift reduction percentages (ISO 22369-1:2013) and compared. RESULTS: Indirect methods discriminated DPVs from different nozzles (conventional, air induction) and fan airflow rate (high, low) combinations. Indirect methods also showed that despite crop influence on drift amount, target absence has a negligible effect when used specifically forDRPdetermination/classification. In fact, identicalDRPfinal classificationswere achieved for the two methodologies tested. Alternatively, all tested configurations resulted in lower DR values following the ISO 22866 field method, which caused different final classifications due to the high dependence of results on external factors. CONCLUSIONS: The alternative test bench methodology, characterized by the absence of target crop and calm of wind, was considered feasible for comparative measurements of airblast sprayer DRP.