Total coverage of potato plants with fungicide usually provides the best protection from disease. A technique has been developed to measure the spray coverage on plant leaves with the use of fluorescent dye, a CCD camera, and a computer with the appropriate software to determine area of coverage. This method is used to compare the coverage efficiency of various types of spray equipment. Several applicators have been studied, including conventional sprayers, air assist sprayers and spray planes. Air-assist sprayers have shown slightly improved application efficiency as compared to conventional sprayers at equal application rates. Most ground sprayers show improved coverage over aircraft, but the application rate for ground sprayers is usually much higher than for aircraft.