Effect of width of spray-free buffer zones, nozzle type and air assistance on spray drift

In a series of field experiments (2004–2006) the effect of four unsprayed buffer zone widths (0 m, 3 m, 14 m and 24 m) on spray drift was assessed when spraying a potato
crop. The effect of the spray-free (unsprayed) buffer zones was evaluated for two different nozzle types: a standard flat fan (XR 11004) and a low drift nozzle (pre-orifice flat fan DG 11004). For the standard situation (0 m buffer zone) the pre-orifice flat fan was combined with a low drift IS 8004 end nozzle to prevent overspray on the edge of the field. Both nozzle types were used conventionally and in combination with air assistance on a 24 m boom sprayer. Spray drift measurements were carried out adding the fluorescent dye Brilliant Sulpho Flavine to the spray agent. Spray drift deposition was measured by placing collectors up to 25 m downwind of a sprayed swath (24 m width) of potatoes
(standard situation = 0 m spray-free). With increasing width of the spray-free zone the drift deposition downwind of the sprayed field decreases. The combination of spray
technology (nozzle type, air assistance) and the use of spray-free buffer zones makes it possible to obtain drift reductions of more than 99% compared to the reference situation
(conventional XR 11004). At 1–5 m from the last nozzle the spray-free buffer zones can be classified in three different spray drift reduction classes: 3 m zone in >75%, 14 m zone
in >90% and 24 m in >95%.