###### Abstract
However, adjuvant types that generate oil-enhanced droplets within the spray solution (crop oils, petroleum oils, some water-insoluble emulsifiers, and surfactants) can unpredictably produce an increase in the droplets size [14]. In turn, the researchers of [15] show that using adjuvants of the oil-containing type results in the largest droplet size, while silicone surfactants and polymer-based adjuvants produce the smallest. Finally [16] indicate that adding adjuvants to the spray solution results in an increase in the volume median diameter of the droplets, and better homogeneity (relative span) of the droplet size. The study of [17] saw an increase in the pinning probability and the pinned volume of the droplets after shattering on surfaces (on fat-hen or Teflon) due to the addition of surfactant. Accordingly, the effect of using adjuvants combined with using a low application rate and twin flat fan nozzles results in droplets with bigger diameter, while spraying insecticide via hollow cone nozzles without adjuvants results in a higher percentage of droplet drift [4]. Indeed, ref. [18] report a 63% decrease in drift when using adjuvants, depending on the combination of formulation/adjuvant, while the study results of [19] demonstrate a 39% reduction in the drift percentage. In turn, refs. [4; 20] report similar results wherein the addition of adjuvant reduced the drift percentage, while [11] hold that the large values of surface tension for large droplets can be attributed to the cohesive forces within the solution molecules. Moreover, they see a difference in the surface tension of the water used in their study than that of normal water, and attribute this difference to the molecular size, entrained charge, and conductivity interactions of monosize droplets. Due to the fact that adding adjuvant increases the wetted area of spray [3; 11; 12], spray coverage can also be increased (depending on the surface of the target) when applying the spray with adjuvant. Agricultural nozzles produce a wide spectrum of droplet sizes within their plumes [21]. The percentage of spray droplets having a diameter less than 100 \(\upmu\)m is expected to increase when the spray droplet size is classified as fine spray. However, in some cases when using certain adjuvants types, a reduction in this percentage was noticed [10]. For example, ref. [22] report that using different types of adjuvants (high surfactant oil concentrate, nonionic surfactant, and acidifier and microemulsion drift-reduction agent) with glyphosate alone results in a decrease in the percentage of droplets <100 \(\upmu\)m, compared with using the glyphosate solution. They also indicate that glyphosate with polymer solution results in the highest percentage of droplets <100 \(\upmu\)m, compared with other solutions. The study of [23] indicates that the droplet size spectrum is influenced by the nozzle type. Pesticide drift is the main problem accompanying the pesticide application process, and fine droplet size is the main cause. Reducing the number of droplets of fine droplet size within the nozzle spray plume can reduce the possibility of spray drift. Adding adjuvants to the spray is one solution to this problem. However, their effect is unknown when they are mixed at lesser concentrations than that recommended by the manufacturer. In addition, the effect of adjuvant addition can be influenced by the type of water used to mix the adjuvant with the sprayed material. The objective of this study was to investigate the changes in the droplet size spectra due to the effect of adding two types of adjuvants with different concentrations to a spray solution consisting of water from two different sources.