Contribution of individual tree row sprayings to airborne spray drift spraying an apple orchard

For measuring absolute values of spray drift from orchard spraying it is discussed what the minimal width of the treated area should be to collect the downwind airborne drift. In field measurements it is quantified what the contribution of individual path sprayings is to the airborne drift in both a dormant as a full leaf situation of an apple orchard. Second path spraying contributed most to outside field airborne drift. This could be reduced by 22-26% by single-sided spraying of the second path. With increasing distance from the field edge airborne drift was found at greater heights. In the dormant situation airborne drift was two times higher as in the full leaf stage. Number of paths needed to recover more than 95% of collected airborne drift was 10. This relates to a width of the treated area of 30m, which is wider than the suggested width of 20m in some drift measurement protocols.