汉源县位于川西南山区,果树资源丰富,有多种温带和亚热带水果。梨树栽培历史尤为悠久,种植面积和产量居全省首位。但目前梨树的黄叶病已成为果品生产中的一大问题。据调查,全县患有黄叶病的梨树计一万余株。此外,苹果、柑桔、李等果树也普遍发生黄叶现象。 Hanyuan County is located in the mountainous area of ​​southwestern Sichuan. The fruit trees are rich in resources and have a variety of temperate and subtropical fruits. Pear cultivation history is particularly long, planting area and output ranks first in the province. However, the yellow leaf disease of pear tree has become a major problem in fruit production. According to the survey, the county suffering from yellow leaf disease pear count more than 10,000 strains. In addition, apple, citrus, plum and other fruit trees are also commonly occurring yellow leaf phenomenon.