兰州市草坪禾草根腐病的发生及病原菌鉴定

Occurrence of Pythium root rot in turf grass and identification of the pathogen

2007—2008年对兰州市13个小区混播草坪禾草根腐病症状表现和发病情况进行了调查。结果表明，发病严重的草坪禾草根腐病发病率为83．33％，病情指数为36．67。该病在草坪禾草不同部位上引起的症状不同，将其归纳为3种症状类型：叶尖黄化型、叶片中部缢缩型和根茎部褐变腐烂型。经对草坪禾草根腐不同发病部位进行分离培养，致病性测定等确定了引起草坪禾草根腐病的主要致病菌为腐霉属（Pythium spp．）的瓜果腐霉（P．aphanidermatum），根茎部病原菌分离频率达100％。潜育期测定结果表明在温度35℃，湿度90％的条件下该病原菌的潜育期最短为14～15h。

In 2007 and 2008, Pythium root rot of turf grass was surveyed in 13 district of Lanzhou City. The incidence in the most seriously affected fields was 83.33% with a disease index of 36. 67. The disease caused three types of symptoms on the turf grasses depending on. Leaf tip blight, leaf middle shrink and rhizomebrown rot. The chief pathogen, based on morphology, cultural characteristics, and pathogenicity, was identified as P. aphanidermatum with an isolation frequency of 100% from rhizomes. The incubation period for P. aphanidermatum is 14-15 h at 35℃ with a relative humidity of 90%.