The aim of this study is to investigate the technology of applying liquid preparations to crops using an unmanned aerial vehicle (UAV). Spring wheat was treated using an XAG P100 quadcopter. The following factors were evaluated: flight height, flight speed, droplet size, application rate, and operating width. Spraying effectiveness was assessed using the area of wheat leaf surface covered with the solution, measured with DropSight® technology. A coloring agent that fluoresces under ultraviolet light was added to the water solution. The leaves of the plants, after the flight of the quadcopter, were covered in a solution. They were collected and placed in a special chamber with an ultraviolet lamp. Using special software, the area covered by the solution was measured as a percentage of the total leaf area. Based on the results of the experiment, a regression equation was created to assess the significance of different factors. The two most significant factors were the dose of the drug and the distance from the flight path axis to the sampling point. These factors had the greatest impact on the uniformity of solution distribution over the leaf.