Abstract: Leaf spot was one of the important diseases,which seriously affected the quality and yield of oat. Tianzhu Tibetan Autonomous County was the main planting area of oat in Gansu Province. In order to clarify the occurrence and pathogenic species of leaf spot in this area,the occurrence of leaf spot was investigated and diseased samples were collected from 5 villages and towns in Tianzhu County. The pathogenic fungi were identified by pathogenicity test,morphological characteristics and rDNA-ITS sequence analysis. The results showed that Heimaquanhe Village in Songshan Town and Shangquan Village in Dongdatan Town had the most serious disease among the 5 surveyed areas,among which the leaf incidence was more than 92% and the disease index was more than 60. Liushu Village in Anyuan Town,Nannigou Village in Zhuaxixiulong Town and Suancigou Village in Dongdatan Town were also serious,which the leaf incidence was about 64% and the disease index was about 23. After isolation and identification,there were 4 genera and 5 species of pathogens were found causing oat leaf spot in Tianzhu County,among which 2 species of Drechslera,others were Alternaria,Epicoccum and Cladosporium. The occurrence of leaf spot in Tianzhu County was serious. There were 5 species of pathogens were isolated and identified,except for Drechslera avenae,other pathogenic fungi had not been reported in domestic oat.

Key words: Tianzhu county, Leaf spot disease, Pathogenic identification, rDNA-ITS

摘要： 叶斑病（Drechslera avenacea）是燕麦（Avena sativa）的重要病害之一，严重影响燕麦的品质和产量。天祝藏族自治县是甘肃省燕麦的主要种植区，为明确这一地区叶斑病的发生情况及其病原菌种类，本研究对天祝县5个村镇的燕麦田进行了叶斑病发生情况调查和病样采集，对病原菌进行了致病性测定、形态特征观察和rDNA-ITS序列分析。结果表明，5个调查区域中松山镇黑马圈河村和东大滩乡上泉村发病最严重，病叶率高达92%以上，病情指数60以上；安远镇柳树村、抓喜秀龙乡南泥沟村和东大滩乡酸茨沟村发病也较重，发病率在64%左右，病情指数23左右。经分离鉴定，发现引起天祝县燕麦叶斑病的病原菌共有4属5种，其中德氏霉属（Drechslera）2种，链格孢属（Alternaria）、附球菌属（Epicoccum）和枝孢菌属（Cladosporium）各1种。天祝县燕麦叶斑病发病较严重，共分离筛选出的5种病原菌，除德氏霉属的燕麦内脐蠕孢（Drechslera avenae）外，其它病原菌在国内燕麦上未见报道。

关键词: 天祝县, 叶斑病, 病原菌鉴定, rDNA-ITS