Effects of canopy density on spray deposition in kiwifruit

Abstract

A study was undertaken to evaluate the effects of canopy density on eficiency of spray deposition on kiwifruit pergola canopies. A dense canopy was pruned to also provide medium and lighter density canopies. Airblast sprays (water + luorescent dye) were applied in typical dilute application volumes to the three canopies. Deposits were measured at four height positions through the canopy in both the centre-of-row and leader zones. Mean deposits on the dense canopy (at 2000 litres/ha) were inadequate and lowest in all zones; approximately 40% less than the medium (1500 litres/ha) and light (1000 litres/ha) canopies. This suggests dense pergola canopies cannot be adequately covered by protectant sprays applied in the typical dilute volumes used by the kiwifruit industry, even with good sprayer setup. Spray deposits on all foliage zones in the medium and light canopies were generally acceptable conirming that pergola canopies can be fully protected with groundapplied sprays if they are managed to reduce their density. © 2013 New Zealand Plant Protection Society.