Effect of imidacloprid droplet deposition characteristics on Myzus persicae control

To investigate the effect of imidacloprid droplet deposition characteristics on Myzus persicae control efficacy, the effects of 70% imidacloprid concentration (WP), droplet density, and droplet volume median diameter on Myzus persicae control were studied using laboratory bioassay and field experiment methods. The 3WP-2000 walking spray tower was used to simulate spraying indoor. The results showed that when the imidacloprid concentration was 0.05-1.00 g/L, and the deposition density was 23-248 droplets/cm², there was a positive correlation between the concentration and droplet density, and in turn the control efficiency. The diameter of the imidacloprid droplet volume was negatively correlated with control efficiency. The control efficiency was better when the concentration was higher than 1 420 mg/L and the droplet diameter was less than 154 μm. The field trial results showed that the control efficacy of imidacloprid at 0.20 g/L, 18 L/667 m²(droplet density 151/cm²)and 36 L/667 m²(droplet density 264/cm²)on Myzus persicae reached 97.13% and 98.86%, respectively, which was significantly higher than that of conventional application of 50 L/667 m²(control efficacy 94.30%, P < 0.05), indicating that the optimum droplet density could reduce the amount of imidacloprid used and promote the control efficacy. Therefore, the best parameters for field application of imidacloprid should be 0.20 g/L, 18 L/667 m², 151 droplets/cm², and nozzle type TR80-02.