Crop related aspects of crop canopy spray interception and spray drift from downward directed spray applications in field crops

Abstract

When spraying Plant Protection Products (PPPs), spray drift and crop interception are two important factors which influence the exposure of aquatic organisms in surface water to PPP. This exposure occurs either in a direct way via deposition of spray droplets on the surface water through spray drift or in an indirect way via the exposure of the soil underneath plants followed by transport of PPP to the surface water by drainage and/or runoff. Edge of field scenarios for the exposure of aquatic organisms in surface water were developed for downward directed spray applications in field crops. A software tool, DRAINBOW, is being developed to facilitate the calculations needed to assess the exposure of aquatic organisms in surface water. Authorisation is given based on the PPP label, which specifies among others the dose, the application technique (e.g. spraying, seed treatment), timing and frequency of the application and possible mitigation measures (e.g. spray drift reducing technologies, width of a crop-free buffer zone). Because spray drift and crop interception depend on the information specified on the label it is necessary to link all these parameters carefully. This report describes the data and the methods used in the DRAINBOW tool to link spray drift and crop interception to the information on the PPP label for downward directed spray applications. Spray drift deposition on surface water is shown to be different depending on spray drift reducing technology class (DRT), crop dependent last nozzle position, width of the crop-free buffer zone, crop growth stage and position and width of the surface water.