Spray mass balance in pesticide application: A review

• Following pesticide application a part of the applied dose was not accounted for calculating a spray mass balance.
• The missing fraction was larger following application with orchard sprayers than with boom sprayers.
• Using tunnel sprayers only a small fraction of the applied spray was not accounted for.
• The spray mass balance was strongly influenced by weather conditions during application.

When pesticides are applied to arable and orchard crops, the pesticide will be deposited in the field on either the crop or the ground, or the pesticide can be transported outside the treated area as spray drift. Spray drift is divided into two fractions, sedimenting spray drift and airborne spray drift. Deposits on the crop and the ground as well as sedimenting spray drift are measured using documented and validated methods. Airborne drift is more difficult to quantify, and the methods need to be improved. A review of studies reporting crop and soil deposits in the treated area was used to calculate spray mass balances. Taking into account standard values of sedimenting spray drift for the application method applied, the airborne spray drift fraction was calculated as the difference between the applied dose and the sum of the recovered doses on crop and soil and sedimenting spray drift. This resulted in high values for airborne spray drift with the lowest values recorded in studies on application in field crops using boom sprayers and in vineyards using tunnel sprayers. In studies using traditional orchard sprayers in vineyards and tree fruit, large fractions of the spray were not found in the recovery analysis.