苹果银叶病目前已呈上升趋势，果树一旦染上此病，则很难治愈，轻者2～4年，重者1～2年，则全株死亡。果树发病时树叶变小，表面呈银灰色，故称银叶病。15年以上大树发病较多。在春秋两季，雨水出现较多，是病菌侵染的有利时期。发病初期，先出现在部分枝条上，然后逐渐扩展到? Apple silver leaf disease has been on the rise, if the disease once infected with fruit trees, it is difficult to cure, light 2 to 4 years, severe 1 to 2 years, the whole plant died. When the incidence of fruit trees smaller leaves, silver gray surface, so called silver leaf disease. More than 15 years old tree disease. In spring and autumn, there is more rain, is a favorable period of germ infection. Early onset, first appeared in some branches, and then gradually extended to?