白粉病是香椿的主要病害,南方地区发生较普遍,一般病株率３０%～５０%,严重时病叶达５０%以上,显著影响树冠发育和树势,降低椿芽的产量和品质。症状识别白粉病主要为害叶片,有时也侵染枝条。在叶面、叶背及嫩枝表面形成白色粉状物,后期于白粉层上产生初为黄色,逐渐转为黄褐色至 Powdery mildew is the main disease of Toona sinensis. It occurs more commonly in southern area, with the rate of diseased plants generally ranging from 30% to 50%. In severe cases, the diseased leaves up to over 50% significantly affect crown development and tree vigor and reduce the yield and quality of toona sinensis. Symptoms identification Powdery mildew is the main damage leaves, and sometimes infected branches. In the foliage, leaves and shoots formed on the surface of the white powder, later in the white layer on the beginning of the yellow, gradually turned to brown to