A series of field trials was carried out in 1975 to investigate the amount of droplet drift that occurs when 2,4-D amine herbicide is applied by ground-rig, Spracoupe and aircraft. The program was an extension of the previous year's research and in particular was carried out to test and compare the effectiveness of several sprayer and solution modifications in reducing droplet drift hazard. The results show that the so-called standard system, viz. the Teejet 8002 nozzle operated at 210 kPa (30 psi) with 0. 5% 2,4-D amine is superior in reducing droplet drift to the various combinations of 65 degree nozzles and pressures tested in 1974. Even at winds of around 6 m/s ( approximately equals 14 mph) only 1% or so of the spray drifts beyond the swath. Use of the raindrop nozzle, a thickener in the solution, low pressure Teejet nozzles, or a shroud over the spray boom results in further reduction of droplet drift given in order of decreasing effectiveness. The Spracoupe pattern is reasonably good, over level terrain at least, with a droplet drift fraction around 5%. Aircraft spraying results in a much higher initial drift but the resultant droplet cloud is coarser and tends to fall out more readily as it moves off downwind.
