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(28-02) Off-crop pesticide drift sediments on plant surfaces - exposure of non-target habitats. Koch, Heribert*,1, Weisser, Peter1, Landfried, Mark1, Strub, Oliver1, 1 State Agency for Agronomy and Plant Protection, Essenheimerstr. 144, Mainz, Germany ABSTRACT- Spray drift deposits on off-crop plant surfaces were investigated in grassland and hedgerows. The drift potential of conventional nozzles (XR 110 03, 2 bar) was compared to air induction nozzles (AI 120 025, 3 bar) at a water volume of 200 litres ha-1. The AI-nozzle is registered in Germany as 50% drift reducing spraying equipment. Measurements were done with a tracer (sodium fluorescein) using a meadow as a standard scenario. This allowed the driving direction to be almost perpendicular to the prevailing wind direction. Sampling was done in 4 replicates at 1, 3, 5 and 10 m distance from the treated area. After 10m none of the 26 investigated samples of the drift-reducing nozzle showed a deposit above the limit of detection. The drift deposits showed the expected gradient and a huge variability at a small scale. The retention of drifting particles was different from the retention of a spray, which is characterised by bouncing and reflecting of the largest droplets. Drift-reducing nozzles reduced the deposits by a factor of 10 in the meadow. Measurements in hedges required a specific sampling technique in the 3-dimensional canopy. Sampling was done in cubic sectors 50cm in height and width in order to describe the spatial distribution in the canopy. Deposits achieved by the drift reducing nozzle in the hedgerow were reduced by a factor of 5 with deposits on a much lower level. Key words: non-target organisms, pesticide exposure, exposure measurement, risk assessment |
