由白粉病菌[Podsphaera leucotriha(Ell.et Ev)salm]引起的苹果白粉病,在西藏分布很广,危害十分严重。几乎所有的苹果园都有不同程度的危害,尤以林芝、米林、朗县、加查等地危害最为严重。如玛果园的祝光苹果树,枝条发病率高达95％以上,病情严重度为65％左右,4级病枝率在85％以上。因白粉病危害,致使新梢生长极短,有的新梢被害致死,基本丧失了结果能力。据估计,目前全区苹果树因苹果白粉病危害,每年减产达100—150万斤。 Powdery mildew caused by powdery mildew [Podsphaera leucotriha (Ell.et Ev) salm] is widely distributed in Tibet, and the damage is very serious. Almost all apple orchards have different degrees of harm, especially in Nyingchi, Milin, Langxian, Gacha and other places most seriously. Such as apple orchard apple tree, the incidence of branches up to 95% or more, the severity of the disease is about 65%, grade 4 branches rate above 85%. Due to powdery mildew hazards, resulting in a very short shoot growth, and some shoot death killed, the basic loss of ability to result. It is estimated that due to the current apple powdery mildew hazard in the region, the annual output of 100-150 million kg.