Droplet deposition characteristics and weed control effects of spraying herbicide Bentazone on oat fields by plant protection drones

<bold>Objective</bold> This study aims to investigate the distribution characteristics of droplet deposition and weed control effect of plant protection UAV in weeding operation of oat field by changing flight height，flight speed and spray width. <bold>Method</bold> DJI T30 plant protection drone was selected as a test instrument to determine the droplet deposition rule of oat leaves by three factors and three levels orthogonal test of working height，speed and spray width design.In addition，field experiments were conducted to determine the control effect of herbicide spraying on target weeds in oat mixed sowing field. <bold>Result</bold> The test results showed that when the spraying parameters were 4 m/mL，the working height was 1.5 m，and the working speed was 5 m/s（i.e.，treatment 7），the fog droplet coverage rate on oat leaves was 6.98%，and the droplet deposition density was 107.80 cm².With an average droplet diameter of 1 447 μm，it was the highest of all the treatments set.The analysis showed that the main factors affecting the fog coverage and deposition density of oat leaves were working height，working speed and spraying amplitude，while the factors affecting the fog drop diameter were working speed，spraying amplitude and working height.The optimal flight parameters were 4 m spray width，1.5 m flight height and 5 m/s flight speed for T30 plant protection UAV.The plant control efficiency was 87.07% and fresh weight control efficiency was 91.45% at 40 d after application.Compared with the control，the yield increase was 437.47 kg/hm²，with an increase of 10.09%. <bold>Conclusion</bold> The study reveals the distribution of droplet deposition and its effect on weeding in oat field when the plant protection UAV T30 was sprayed with 480 g/L Bentazone AS，which provides data support and technical support for the extensive application of the plant protection UAV in the agricultural field.