Contribution of individual tree row sprayings to total spray drift deposition next to an apple orchard

Drift experiments in the Netherlands are carried out according to an ISO standard (ISO/CID 22866; 2004) adapted for the situation in the Netherlands following a Dutch protocol (CIW, 2003). A swath-width of at least 20 metres is obligatory, assuming that 95% of the spray drift on a measuring point will be collected. In orchards spray drift (soil deposition) is expressed as percentage of the application rate of the sprayer (spray dose). The total spray drift (as soil deposition and airborne droplets) outside the orchard is the sum of the spray drift caused by individual tree row sprayings. In a series of experiments the contribution of individual tree row spraying to the total spray drift deposition was measured. Sprayings were carried out with a (reference) Munckhof cross-flow sprayer and standard settings for Dutch fruit growing (i.e. Albuz lilac hollow cone nozzles and a spraying volume of appr. 175 - 200 litres per ha). The experiments were carried out in early (dormant) and late growth stage (full canopy) of the trees. The contribution of individual row spraying to the total soil deposition was calculated. Soil deposition decreased with increasing distance of the spray path. Spraying in the second path caused most drift deposition. The relative contribution of the different driving (=spraying) paths to the total drift deposition was dependent on the growth stage of the trees. Dormant trees had no effect on spray drift.