## 1 Introduction  
The use of chemical pesticides is currently one of the main methods in plant protection operations to control crop diseases and insect pests. Surfactants have been utilized in order to achieve the reduction of pesticides and to increase efficiency, improve pesticide application equipment and minimize pesticide drift [1, 2], as well as to optimize atomization effects [3]. Surfactant is a substance added in the pesticide spraying process, which can improve the physical properties and atomization performance of the pesticide liquid, thereby increasing the deposition of droplets on the target and the utilization rate of the pesticide. The degree of pesticide atomization directly affects the deposition effect of the chemical solution on the target and the drift of the non-target area [4, 5, 6, 7], which in turn affects the control effect of pesticides on pests and diseases [8, 9, 10]. Larger droplets can reach the target faster and are not easy to drift, however, too large droplets can easily cause uneven coverage and liquid loss [11]. Smaller droplets are more likely to evaporate and drift due to their low mass and large air resistance [12, 13], but small droplets help to improve the coverage and uniformity of the pesticide solution on the target. Because of the existence of the above phenomenon, it is of great significance to study the influence of the addition of surfactants on the atomization effect and deposition characteristics of the pesticide liquid and to discern the most appropriate amount. [PERSON] et al., [PERSON] et al. [14, 15] believed that adding surfactants of different components to the spray solution could improve the droplet size distribution and have a significant effect on reducing droplet drift. [PERSON] et al. [16] added surfactants to the spray mixture containingwater and pesticides and found that 343 \(\upmu\)m droplets were formed on the leaves of Begonia at 60% RH, the evaporation time was greatly reduced, and the maximum coverage area was increased. [PERSON] et al. (2017) studied the dispersion and evaporation of a single droplet with a diameter of 300 \(\upmu\)m on the surface of four soybean plants (front and back leaf surface, petiole, basal stem) and found that the adjuvants can improve the homogeneity of spraying pesticides, increase coverage and effectively slow down the evaporation of droplets. [PERSON] et al. (2018) used a rotating disc atomizer to study the effects of two surfactants on the droplet size and deposition characteristics of nine sprays in the laboratory and found that the low deposition of small droplets on the sampling device was recovered, but the droplet size of formulations containing non-ionic surfactants increased; thereby very high spray deposits were recovered on the sampling device. [PERSON] (2019) studied the spray with drift control adjuvants, collected the deposition and downwind drift of vineyard canopy on filter paper, and concluded that the deposition was highly correlated with drift distance and concentration of adjuvants. Additionally, in the treatment with adjuvants, almost no deposition was found on the filter paper within the range of 2-4 m. It can be seen that extensive studies have shown that different types of surfactants have significant effects on the atomization and deposition characteristics of spray droplets. As a surfactant commonly used in pesticide sprays, polyethylene glycol (PEG) should be taken seriously for its effect on the atomization effect of pesticide liquids and the deposition characteristics on the target, because this determines whether the pesticide liquids can be effectively atomized and get good coverage on the target. However, the research on the surfactant polyethylene glycol is so far poorly investigated and related studies need to be expanded. The particle size distribution of the droplets is the main detection index for the degree of pesticide atomization ([PERSON] and [PERSON], 2019; [PERSON], 2019; [PERSON], 2019).