Abstract
Uniform application of agri-chemicals will improve orchard pest management. An air-blast(orchard) sprayer designed for vineyards has been used: however, few research on the uniformity and coverage of the sprays has been reported. Distributions of spray coverage were measured with artificial targets and analyzed to enhance the efficiency of spray application. A structure was built to place water sensitive papers, sampling spray droplets blasted from the orchard sprayer. The sampling cards were collected from five directions at three distances (2.5, 3.0 and 3.5m) for two fan speeds (2,075 and 3,031 rpm), and analyzed using an image analysis system. The distribution of the coverage percent area did not follow the wind velocity pattern. The coverage by the low fan speed was more uniform and higher than that by the higher fan speed. The coverage percent area decreased with an increase of distance. The distribution of droplet density was similar to that of coverage. However, the coverage contribution by smaller droplets became more significant as the distance increased. The upward blasting distance was limited within 3m, but the limit to the ground level was expanded the distance more than 3.5m because of the concentrated droplets.
