An appraisal of nozzles and sprayers abilities to meet regulatory demands for reduced airborne drift and downwind fallout from arable crop spraying

Until recently, the emphasis in agrochemical spray drift studies was on the airborne component, but legislation now concentrates on downwind fallout. This paper describes measurements of both components in a wind-tunnel and i n the field. The effect of spray quality dominated that of operating pressu re and wind speed for conventional nozzles, while drift-reducing pre-orific e and air-inducing nozzles reduced drift losses by more than 75 % at equiva lent outputs. Drift reduction via nozzle design alone may be associated wit h coarser sprays than BCPC Coarse, raising deposition and efficacy question s. In contrast, air assistance allows the use of the spray quality given on the agrochemical label while still reducing drift. Air assistance improved all nozzles' performance further, for example, with drift-reducing nozzles fallout was up to 95 % reduced compared to a conventional F110/1.6/3.0 noz zle without air assistance.