石韦叶斑病病原鉴定

Identification of the Pathogen of Pyrrosia lingua Leaf Spot

对采自广西大化县的石韦叶斑病病原进行分离鉴定和生物学测定。结果表明,引起该病的病原为胶孢炭疽菌[Colletotrichum gloeosporioides （Penz.） Sacc.]。病害叶部症状初为凹陷的小斑点,后扩展成近圆形、椭圆形或不规则形;病斑中部褐色,病斑外缘可见黄色晕圈。该菌菌丝生长、分生孢子产生和分生孢子萌发的温度范围均为15~35℃,最适温度为30℃,在pH 3~10的范围内该菌均能生长,最适pH 6,分生孢子致死温度为50℃10 min。光照处理对该菌生长发育无显著影响。分生孢子在饱和湿度或水滴中萌发率最高,在相对湿度低于90%时不能萌发。菌丝生长的最适碳、氮源分别为D-果糖、葡萄糖、甘露醇和硝酸钾,分生孢子形成最适碳、氮源分别是甘露醇、可溶性淀粉和大豆粉。

The identification and biological character of the pathogen, caused Pyrrosia lingua leafe spot from Dahua county, Guangxi Province, were studied. The result showed that Pyrrosia lingua leafe spot was caused by Colletotrichum gloeosporifes （Penz.） Sacc. The symptom of the disease on leaves first appeared the spot as sunken circular and later spreaded to elliptic, oblong or irregular shapes. The lesions enlarged and became reddish brown in the center and circular spots surrounded by chlorotic haloes. For the mycelial growth, sporulation and conidial germination of Colletotrichum gloeosporifes, the range of temperature was 15℃-35℃, the optimum being 30℃. The range of pH for the mycelial growth was 3-10 , the optimum being 6. The lethal temperature for the conidia was 50℃ remaining 10 minutes. The treatment of darkness with fluorescent light or with alternative fluorescent did not have significant effect on the mycelial growth , sporulation ang conidial germination. When relative humidity reached 100% or in water , the percentage of conidial germination was highest. , for the mycelial growth, the best carbon and nitrogen were D-fructose, glucose, mannitol and potassium nitrate, respectively. The suitable carbon and nitrogen for the sporulation of the pathogen were soluble starch and soybean , respectively.