白绢病又称白丝病、菌核病或霉菌病。发病始自兰株近地茎颈部,初呈黄色至淡褐色的流水病斑,后变褐至黑褐色腐烂,并在根际土壤表面及茎基部蔓延,破坏茎部并感染幼叶和根部,叶鞘、根部产生白色菌丝;被害部位呈水渍状,腐烂变软发黑,直至叶片枯萎,易折断,扩染假鳞茎,菌核由白色变为赤褐色至茶褐色坏死,严重时整株叶丛枯死。病原为半知菌亚门的小菌核属白绢病菌。病菌以菌核在土中或堆肥中及未腐烂的残体上越冬。菌核翌年萌发菌丝在土中蔓延,从兰叶基部侵入为害。菌核对不良环境抵抗力强,在土中可存活数年,借流水、灌溉水、雨水溅射和施肥传播。土壤偏 Sclerotium also known as white silk disease, sclerotisis or mycosis. The onset begins with the near-surface stems and neck of the blue plant, beginning with a yellow to light brown watery lesion that turns brown to dark brown and decay and spreads on the rhizosphere soil and stem base, destroying the stem and infecting young leaves and roots , Leaf sheath, the root of white mycelium; damaged parts were water-like, decay softened black, until the leaves withered, easy to break, expand pseudobulb, sclerotia from white to brown to brown necrosis, severe whole plant leaves Bushes dead. The pathogen is known to be half of the fungus subfamily of Sclerotinia. Germs in the soil or in the composting and non-decaying bacteria overwintering. The next year mycelium germination hyphae spread in the soil, invasion from the base of blue leaves damage. Bacteria nuclear adverse environmental resistance, in the soil can survive for several years, by water, irrigation water, rain and fertilization spraying. Soil partial