Assessment of Spray Drift with Various Adjuvants in a Wind Tunnel

Abstract

When pesticides are sprayed, a significant portion of the droplets drifts away from the target. Using an adjuvant in spray liquid is an easy option for reducing droplet drift because there is no need to make any changes to the sprayer. The objective of the study was to determine the effects of seven commercially available adjuvants (Surfeco plus, Starguar, Kantor, Sterling, Control, Control WM, and Control DUO) with varying active ingredients on droplet size, surface tension, and viscosity. Since these properties affect droplet formation, these adjuvants were evaluated in terms of their drift-reducing performance in a wind tunnel at various wind speeds (2.0, 3.5, and 5.0 m/s) and spray pressures (3, 4, and 5 bars). The ground and airborne components of drift were evaluated. With the use of a patternator, the potential for the ground drift of adjuvants was measured; for airborne drift, polyethylene lines that were stretched along the cross-section area of the wind tunnel at various heights were employed. The number of deposits of a tracer dye–adjuvant mixture that was sprayed on the polyethylene lines was measured via fluorometric methods for determining the airborne drift potential. The test results showed that the adjuvant Control Duo containing a polymer blend, which had the highest dynamic viscosity (4.27 mPa.s), increased the Dv0.5 droplet diameter up to 192 μm at 3 bar with nozzle XR11002. This adjuvant reduced the ground drift potential (Dc) by 60.53% compared to tap water. The maximum airborne drift potential reduction percentage (DPRP) was obtained as 85.76% with Surfeco plus containing organic silicone at a pressure of 3 bar and a wind velocity of 5 m/s. When considering the airborne drift-reduction potential of the adjuvants used, it was found that the adjuvants Control WM, Control, Starguar, and Surfeco plus significantly reduced the airborne droplet drift compared to spraying tap water.