All the pictures of apple leaf diseases were collected from four different apple experimental demonstration stations of Northwest University of agriculture and forestry science and technology in Northwest China. These images were taken using glory V10 mobile phone. Apple leaf images with different degrees of disease were taken in the laboratory (about 51.9%) and the real cultivation field (about 48.1%), under different weather conditions and at different times of the day. These diseases include alternating leaf spot, gray spot, brown spot and rust.