Airborne off-target losses and deposition characteristics from a self-propelled, high speed and high clearance ground sprayer

Abstract

In order to quantify the drift and deposition characteristics of a self-propelled, high-speed, and high-clearance sprayer, a series of 15 field trials was carried out applying a herbicide:dye mix along a test swath. Three different types of nozzle tips were used, an XR11002 (Extended Range XR Teejet®), and two "low-drift" tips, a DG11002 (Drift Guard Teejet®) and a TT11002 (Turbo Teejet®). On-swath and off-swath deposits were sampled using petri-dish collectors, while the airborne cloud was sampled 5 m downwind of the swath using Rotorod® samplers. In wind speeds of 10 to 31 km h−1, airborne droplet drift was reduced by a factor of two with both "low drift" designs. The differences in the behaviour of the two low-drift tips from the standard tips were attributed to reductions in the total volume emitted as drift-prone droplets by the low-drift tips, resulting from their inherent design characteristics. On-swath deposit uniformity was best with the DG11002 tips and worst with the TT11002 tips, with the XR11002 tips being intermediate. Off-swath-deposits increased with wind speed. Off-swath deposits between 5 and 10 m were proportional to the total airborne mass at 5 m. Key words: Pesticide, Spra-Coupe, droplet drift, flat-fan tips, deposition variability, droplet size, droplet volume