Glyphosate spray drift management with drift-reducing nozzles and adjuvants

Field experiments were conducted to evaluate the effect of five spray-nozzle types and three drift-control adjuvants (DCA) on glyphosate spray drift. The extended-range (XR) flat-fan nozzle at 280 kPa was used as the standard comparison. DCAs were evaluated for drift reduction with the use of the XR and air-induction (AI) nozzles. Wind speed ranged from 1.3 to 9.4 m/s (3 to 21 mph). Lethal drift (D-L) and injury drift (D-I) were determined by downwind visual observation of grain sorghum response. Drift distances were measured from the spray swath edge. The Turbo FloodJet and Al nozzles reduced D-L distance by 34%. All four drift-reducing (D-R) nozzles reduced D-1 distance by 22 to 32%. Reducing the pressure of the XR flat-tan nozzle from 280 to 140 kPa did not reduce D-L or D-I distance. When applied through AI nozzles, each DCA increased droplet Volume diameter, one DCA reduced D-I distance and none reduced D-L distance when applied through XR tips. The DCAs did not affect D-L or D-I distance.