Effects of Different Auxiliaries on Spray Performance of Plant Protection Unmanned Aerial Vehicles and Control EfficacyAgainst Empoasca pirisuga Matumura in Tea Plantations

Purpose To reduce insecticide drift during the control of Empoasca pirisuga Matumura by plant protection unmanned aerial vehicles (UAVs), improving control efficiency by increasing deposition amount.

Methods Using allure red as a tracer and 2.5% beta-cyfluthrin emulsion as a control agent, in the initial stage of E. pirisuga, the DJI MG-1P plant protection UAV was used to evaluate the effects of different auxiliaries (Red Sun, neem oil, and plant oil) on the atomization performance, deposition amount, and control effect of 0.3% azadirachtin emulsion. The residue amount after 10 and 20 days of azadirachtin application was determined.

Results The deposition distribution of droplets on different parts of tea tree was as follows: canopy>middle layer>bottom layer. The addition of plant oil and neem oil increased the coverage rate and deposition amount of droplets. Specifically, the plant oil produced droplets with a D₅₀ of 349.60 μm and a D₉₀ of 709.80 μm, while neem oil significantly increased droplet density to 120.58 cm⁻². After 10 days of spraying, the control efficacy of 0.3% azadirachtin emulsion combined with plant oil and Red Sun against E. pirisuga was 62.97% and 60.38%, respectively; after 20 days of spraying, they still maintained the highest control efficacy, which were 57.74% and 59.95%, respectively. The azadirachtin residue amount in tea was 0.0014 mg/kg and 0.0009 mg/kg respectively after 10 and 20 days of spraying.

Conclusion Plant oil and Red Sun can improve the spray performance of plant protection UAVs, increase droplet deposition amount and promote control effect against E. pirisuga.