A model canopy for spray drift measurements in orchards.

A model canopy offers the advantage of being able to compare drift characteristics of sprayers under standardized conditions and independently from the season. A steel structure covered with a net similar to the EvaSpray- Viti viticulture test stand was developed to mimic a common orchard. The selection of the net was made on the basis of preliminary tests on droplet and wind permeability. A net with mesh size of 1.38 mm by 1.38 mm was found best suited to reproduce the characteristics of a natural foliage and was used to cover the six-row model layout. Drift measurements were carried out with different types of sprayer design in the model system and in orchards. The drift reduction values showed a good congruence. The drift behaviour of the sprayers could be realistically reproduced in the model system. The effect of different nozzles and reduced working pressure could also be shown in the model canopy. Further measurements at other locations are required to demonstrate reproducibility. [ABSTRACT FROM AUTHOR]