苹果白粉病(Podosphaera leucotr-icha(E11.etEv.)Salm.)是一种发生普遍、分布很广的苹果树主要病害。在秦安县苹果园和苗圃幼苗中危害严重。一般10年以上的成龄大树发病株率平均在20%以上,最高为52%;平均单株发病枝梢为25.4%,最高为75%;苗圃地幼苗发病株率平均为22.14%,最高为41.7%。幼苗感病后,全株布满白粉,叶片皱缩卷曲,生长缓慢,轻者 Podosphaera leucotr-icha (E11.etEv.) Salm.) Is a common and widely distributed apple tree major disease. In Qin’an County apple orchard and nursery seedlings in serious harm. Generally, the incidence rate of mature trees with the age of more than 10 years averaged above 20% and the highest was 52%. The average shoot incidence was 25.4% and the highest was 75%. The average incidence rate of seedlings in nursery was 22.14% 41.7%. After the seedlings are infected, the whole plant is covered with white flour, the leaves are crimped and curled, the growth is slow and light