杨树烂皮病Valsa sordida Nit又名杨柳腐烂病。是杨、柳树的重要枝干病害。这种病害是一种常见病和多发病,能引起杨树大片死亡,一般发生在主干和枝条上,表现出于腐和枯梢两种类型。初期出现暗褐色水肿状病斑,皮层腐烂,后失水下陷,有时龟裂,病斑有明显褐色边缘。当病部包围树干一周时,其以上部分即行枯死。皮层腐烂,纤维分离如麻状,易自木质部剥离。有时木质部边材也变色,病害发生在小枝上时,初 Poplar rot disease Valsa sordida Nit, also known as willow rot. It is an important branch disease of poplar and willow. This disease is a common disease and frequently-occurring disease, can cause large-scale poplar death, usually occurs in the trunk and branches, showing rot and the shoots of two types. Early dark brown edema-like spots, cortical decay, water loss after subsidence, and sometimes cracking, lesions have significant brown edges. When the diseased part of the trunk surrounded by a week, the above part of the line to die. Cortical decay, fibrous separation, such as hemp, easy stripping from the xylem. Woody sapwood sometimes discoloration, disease occurs on the twigs, early