## 5 Conclusions  
The research results in this study show that the ESW, DDU, DPR, and even the spraying efficiency are closely related to the operation parameters. The above results reflected that with the aerial spraying parameters optimized, the obtained control effects of aphids, powdery mildew, and head blight could meet the actual requirements in general. Therefore, it is considered that the combined operation parameters used in actual application is inappropriate. It should be combined with the agronomic requirements to select the appropriate parameters based on the crop types, the growth period, the pests and diseases characteristics, and even the environmental conditions to achieve good prevention and control effects.  
For wheat, stripe rust, powdery mildew, and head blight are the major diseases that are harmful to the wheat yield [3; 40; 5; 39; 40], and different requirements are required in chemical crop protection applications, respectively. The stripe rust would occur from the wheat Tillering stage to the Filling stage [40], the powdery mildew mainly occurs between the Heading stage and the Milky stage of wheat [40], and the head blight mainly occurs from the Heading stage to the Filling stage [41]. For the disease occurrence parts, the stripe rust occurs in the middle and lower parts of the wheat, the powdery mildew occurs and develops from the bottom to the top layer, and the head blight is concentrated on the upper layer (ears) of wheat. According to the results of this study, when controlling the head blight, priority should be given to increase the ESW, and the FS is appropriately reduced, taking into account the aerial spraying efficiency. When controlling the powdery mildew, the penetration of droplets is an effective consideration, and the FH should be reduced possibly. When controlling the stripe rust, the ESW and the penetration should be both considered for the parameter optimization combined with the growth period of wheat.  
In this study, the CPUAS of CE20 was tested, and the conclusions above were only applicable to it. Different type CPUASs may have different spraying and droplet deposition characteristics, such as single-rotor and multi-rotor CPUAS; thus, systematic experiments should be carried out to determine the optimal parameter combinations before application. Future research should be focused on the relationship among the parameters [8; 16; 17], the canopy structure [42], and the wind field [43; 44] on the droplet deposition effect, and establish the correlation of them to achieve the best management practice and control effect.  
[PERSON], [PERSON], and [PERSON] conceived the idea of the experiments. [PERSON], [PERSON], [PERSON], [PERSON], and [PERSON] performed the experiments and analyzed the data. [PERSON], [PERSON], and [PERSON] wrote and revised the paper. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Key Research and Development Program of China (Grant No. 2017 YFD0701000), the National Natural Science Foundation of China (Grant No. 31701327), the earmarked fund for China Agriculture Research System (CARS-12), the Agricultural Science and Technology Innovation Project of the Chinese Academy of Agricultural Sciences, Crop Protection Machinery Team (Grant No. CAAS-ASTIP-CPMT), the Science and Technology Development Plan of Suzhou, Jiangsu Province (Grant No. SNG2020042), the Jiangsu Science and Technology Development Plan (BE2019305).