Comparison of spray retention on synthetic superhydrophobic surface with retention on outdoor grown wheat leaves.

A method has been designed to test the retention of drops generated by a moving agricultural nozzle using high speed imaging both o n synthetic and leaf surfaces. The method allows a precise investigation of spray retention by a characterisation of impact speed, drop diameter and impact behaviour . The paper presents a comparison of the spray behaviour on the synthetic surface with the behaviour on outdoor grown wheat leaves fixed on a microscope sl ide. Target surfaces were horizontal. A range of surface tension was tested u sing the tank-mix adjuvant Break-Thru S240 at different concentrations in dist illed water. Results show the relevance of a synthetic surface for use as referen c for the assessment of spray application efficiency. The drop behaviour on the s uperhydrophobic slide was representative of difficult-to-wet leaves surfaces. The reference surface avoids the natural variability of leaves and is therefore more suited to conduct comparative assessment of formulation retention performance.