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小麦白秆病是在青藏高原上为害小麦的一种新病害,在受害的叶、叶鞘及茎秆上产生草黄色条斑和椭圆形至长方形斑点两种症状。经鉴定病害由壳月孢属(Selenophoma)真菌引起。病菌在15℃黑暗条件下的马铃薯葡萄糖琼脂上培养,形成粘质状菌落,生长缓慢,不形成分生孢子器,而在菌丝上芽殖分生孢子;在15℃黑光灯照射下的燕麦琼脂等培养基上培养,形成分生孢子器。分生孢子器分生孢子新月形,无色,单胞,大小为17.9-26×2.6-3.6μ;而芽殖分生孢子的大小及形态变异较大。病菌的生长温度范围为0—20℃,以15℃为最适宜。其寄主有小麦、黑麦及冰草等。种子和幼苗经接种后,均产生系统性条斑症状。根据病菌的形态和寄主范围,小麦白秆病菌即Selenophoma donacis(pass)sprague efA.G.Johnson,由于S.donacis 只产生斑点症状,而小麦白秆病菌产生特有的系统性条斑症状,且发生温度偏低,所以认为小麦白秆病菌是在青藏高原特殊的生境条件下,形成的一个Selenophoma donacis(pass)sprague et A.G.Johnson的“白秆(albo-culmo)生态型。
Wheat white stalk disease is a new disease on wheat in the Qinghai-Tibet Plateau, producing two kinds of symptoms, grass yellow streaks and oval to rectangular spots on the affected leaves, leaf sheaths and stems. The identified disease is caused by the fungus Selenophoma. The germs were cultured on potato dextrose agar under dark conditions at 15 ° C to form mucilaginous colonies that grew slowly and did not form a conidiophore but germinated conidia on the mycelium; Agar and other medium culture to form conidia. Conidia conidia crescent, colorless, single cells, the size of 17.9-26 × 2.6-3.6μ; budding conidia size and shape variation. Pathogen growth temperature range 0-20 ℃, 15 ℃ for the most appropriate. The host of wheat, rye and ice grass and so on. After inoculation, seeds and seedlings all produce systemic streaking symptoms. According to the morphology and host range of the bacteria, S. cerealis, ie, Selenophoma donacis (pass) sprague efA.G. Johnson, produces only speckled symptoms of S.donacis, whereas S. cerealis produces characteristic systemic streak-like symptoms that occur Therefore, it is considered that the white stalk bacterium is a “albo-culmo ecotype” of Selenophora donacis (pass) sprague et AG Johnson under the special habitat conditions of the Qinghai-Tibet Plateau.