Comparison of spray dose measured on leaf surfaces with spray coverage estimated from Kromekote® paper

Abstract

The control of tomato potato psyllid largely depends on effective application of pesticides. This paper presents an experiment to measure deposition using leaf washing of spray containing water and rhodamine dye on a potato canopy. The treatments included conventional boom, canopy submerged DropSpray® combination, electrostatic spraying system (both engaged and disengaged) and air-assisted rotary atomizer. During the same experiment the quality of coverage was measured using Kromekote® paper. Comparison of both sampling methods illustrated a rapid decrease of deposited material as it descended through the canopy. The leaf washing indicated more deposition within the canopy with the DropSpray® unit and a sampler difference when the electrostatics either were engaged or disengaged. It was concluded that Kromekote® paper cannot provide direct comparative analysis of spray dose on real leaves and its position affected the results. Finally, novel spray technologies gave better deposition to the undersides of leaves.