Field assessment of a newly-designed pneumatic spout to contain spray drift in vineyards: evaluation of canopy distribution and off-target losses

BACKGROUND: The efficacy and environmental sustainability of pesticide application largely depend on maximizing target coverage, while minimizing off-target losses. Recently, laboratory-based measurements were used to develop new cannon type spout to increase the droplet size spectra produced by a pneumatic vineyard sprayer. The study described below evaluated the effectiveness of the new device to reduce off-target losses (both in-field and off-field ground losses), and to distribute an adequate canopy spray. Field trials were conducted to measure canopy spray deposition, canopy coverage, and off-target losses from a multiple-row pneumatic sprayer equipped with newly-designed spout under three different positional configurations. The configurations were defined by the variation of liquid release positions from the inner to the outer part of the cannon- type spout: conventional, alternative, and extreme. Each configuration was tested in a vineyard by applying a solution of water and yellow-dye tracer. RESULTS: It was confirmed that the increased droplet size corresponding to the alternative and extreme liquid release positions has no effect on total canopy deposition or coverage. The alternative and extreme configurations produced reduced off-field losses, up to 75% and 83%, respectively, by increasing the droplet size spectra. These reduced off-field losses imply increased in-field losses of 13% and 16%, respectively. CONCLUSIONS: The newly-designed pneumatic spout offers the first effective option for environmentally-friendly pneumatic spray pesticide application with the guarantee of canopy spray deposition and coverage levels similar to those obtained with conventional pneumatic application.