Effect of air support and spray angle on coarse droplet spray in Ivy pot plants

Due to the decreasing availability of authorized plant protection products, adequate pest control has become more difficult in many ornamentals. Although much attention is given to predator-pest interactions in integrated control, almost no research is available about the optimization of spray application techniques in ornamentals. Yet, spray boom systems, instead of the still predominantly used spray guns, might improve crop protection management in greenhouses considerably. Spray application technique will influence the spray deposition and as such its efficiency. In this study, the effect of air support and spray angle (-30°, 0°, 30°) on spray deposition in ivy pot plants was tested using a coarse droplet spray nozzle (Lechler ID 90 02 at 6.0 bar). Spray deposition was measured using a quantitative method (mineral chelates). Spray coverage was assessed by a visual method using water-sensitive paper. All applications were performed in the laboratory with a fully automated spray system. Spray deposits were measured at three plant levels on the top and on bottom sides of leaves, together with off-target depositions. The use of air support improved crop penetration and deposition on the bottom sides of the leaves and reduced spray deposition in the top layer on the top sides of the leaves, resulting in a more uniform spray distribution aver the crop canopy. The effect of air support on crop penetration was most pronounced with the standard 0° spray angle. Without air support, spray angling improved crop penetration but not the deposition on the bottom sides of the leaves.