Effects of spray height and spray angle on spray deposition in tobacco plants

Due to the decreasing availability of authorized plant protection products, adequate pest control becomes more difficult in tobacco. 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 tobacco plants. Yet, spray height and spray angle might improve crop protection management considerably. Spray application technique will influence the spray deposition and as such its efficiency. In this study, the effects of spray height (0.2 m, 0.3 m, 0.4 m) and spray angle (90°, 45°, 0°) on spray deposition in tobacco plants were tested by a electrostatic sprayer with hollow-cone nozzle. Spray deposition was measured by a quantitative method (Allura-Red). The deposition value of the upper layer increases as the height increasingly, while the maximum value located at 0.4m. Spray coverage was evaluated by water sensitive paper (WSP). And the coverage of liquid was 52.9-86.0%, 29.5-52.7% and 18.7-39.6% for upper layer, middle layer and lower layer, respectively. Utilization rate of liquid on the plants could be improved 1.7-fold using the appropriate application technique.