新疆玉米青枯病病原菌分离和鉴定

５年来从全疆１０个地州１８个县市对近百个玉米杂交种和自交系田的典型青枯病株分离、鉴定出腐霉（Ｐｙｔｈｉｕｍ）属３个种、镰刀菌（Ｆｕｓａｒｉｕｍ）属２个种，分别对５个种不同地区的代表菌株在北京和乌鲁木齐两地进行苗期和成株期致病测定，其中肿囊腐霉（Ｐ．ｉｎｆｌａｔｕｍ）致病性强，可重复田间的青枯症状，是引起新疆玉米青枯病的主要致病菌。Ｐ．ｇｒａｍｉｎｉｃｏｌａ致病性较弱，Ｐ．ｏｌｉｇａｎｄｒｕｍ基本不致病。镰刀菌的Ｆ．ｇｒａｍｉｎｅａｒｕｍ和Ｆ．ｍｏｎｉｌｉｆｏｒｍｅ发病率低，发病过程缓慢。研究还发现，分离方法上的差异对分离结果具一定影响，其中标样的发病程度、采集后至分离的间隔时间以及分离所用培养基的不同均可使腐霉和镰刀菌的分离频率发生变化。

Etiology of Corn Stalk Rot in Xinjiang

Two hundred thirty seven samples of stalk rot of corn were collected from 8 counties in Xinjiang Autonomous Region during 1991-1995.1205 Cultures were isloated from them and 5 species were identified and described. These are Pythium inflatum, P.graminicola,P.oligandrum.Fusarium graminearum and F. moniliforme. Isolation frequency of the species of Pythium and Fusarium was 47.63% to 34%. Pathogenicity tests in both Urumqi and Beijing showed that P. inflatum was most virulent,P.graminicloa was second to it while P.oligandrum was avirulengt in adult plants. Lower disease incidence and longer course of the disease process of Fusarium graminearum and F.moniliforme were observed. lsolation results were influenced by the methods used, the difference of disease grade,interval from samping to isolation and culture medium also had some effect on the isolation frequency of Pythium and Fusarium.