AIRBORNE OFF-TARGET LOSSES AND DEPOSITION CHARACTERISTICS FROM A SELF-PROPELLED, HIGH-SPEED AND HIGH CLEARANCE GROUND SPRAYER

In order to quantify the drift and deposition characteristics of a sel f-propelled, high-speed, and high-clearance sprayer, a series of 15 fi eld trials was carried out applying a herbicide:dye mix along a test s wath. Three different types of nozzle tips were used, an XR11002 (Exte nded Range XR Teejet((R))), and two ''low-drift'' tips, a DG11002 (Dri ft Guard Teejet((R))) and a TT11002 (Turbo Teejet((R))). 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((R )) samplers. In wind speeds of 10 to 31 km h(-1), airborne droplet dri ft 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 stand ard lips were attributed to reductions in the total volume emitted as drift-prone droplets by the low-drift tips, resulting from their inher ent design characteristics. On-swath deposit uniformity was best with the DG11002 tips and worst with the TT11002 tips, with the XR11002 tip s being intermediate. Off-swath-deposits increased with wind speed. Of f-swath deposits between 5 and 10 m were proportional to the total air borne mass at 5 m.