Evaluation of potential spray drift generated by different types of airblast sprayers using an “ad hoc” test bench device

Drift is one of the most important issues to be consider for realise a sustainable pesticide application. This study proposes an alternative methodology for quantify the Drift Potential (DP) for vineyard crop sprayers, trying to avoid the difficulties faced in conducting field trials according to the reference standard protocol (ISO 22866:2005(E): Equipment for Crop Protection—Methods for Field Measurements of Spray Drift, International Organization for Standardization, Geneva, Switzerland, 2005). Thanks to a specific test bench device, it is possible to collect and quantify the spray fraction that remains suspended over the test bench immediately after passage of the sprayer and that can potentially be carried out of the target zone by environmental air currents, defined as “potential drift fraction”. The proposed methodology requires to made the test in absence of target and in calm of wind. Contextually, a variation of original test method (absent a target) was used to investigate both the possible effect of the target on the final results and the suitability of the test bench device to measure potential spray drift generated by multiple-row sprayers. The methodologies have been tested using two types of vineyards sprayers, namely conventional axial fan tower shaped and pneumatic single or multiple rows, in different configurations. By the comparison with the results obtained from a reference sprayer the resulting drift reduction potential (DRP), obtained from the two indirect methodologies investigated (presence or not of the target), were compared. The test bench trials confirmed the ability of the proposed methodology to discriminate the DP generated by different vineyard sprayers and their configurations tested. Furthermore, the results obtained from the two methodologies, indicate that, although the vineyard target influence the total amount of liquid collected by test bench, the absence of target is negligible and irrelevant in terms of final drift reduction sprayers classification.