小麦链格孢叶枯病的病原学研究

ETIOLOGICAL STUDY ON Alternaria LEAF BLIGHT OF WHEAT

自 70年代以来 ,在黄河中游麦区发生了一种病原菌未知的小麦叶枯病 ,1993年至 1996年依据柯赫氏证病律进行了病原学研究。结果由陕西、甘肃和河南等省采集的田间病叶标样 ,发现了 11个小麦链格孢 ( Alternaria triticina Prasada and Prabhu)分离菌株。在 PCA平板上培养 ,该菌的初生分生孢子梗着生由 ( 1～ ) 2～ 5个孢子构成的短链 ,分生孢子褐黄色 ,宽卵球形、椭圆形 ,具 3～ 8个横隔 ,0～ 5个纵隔或斜隔 ,分隔处缢缩 ,孢子体 2 0～ 50μm× 10～ 15μm,假喙柱形或膝状 ,5～ 4 7.5μm×4～ 5μm。接种小麦叶片上出现长卵形、椭圆形褐色斑点 ,进而扩展成长条形和不规则形病斑 ,周边有亮黄色晕圈。严重发病常导致叶枯 ,叶片大部死亡。

The wheat leaf blight caused by an unknowing pathogen occurred in the middle reaches of Yellow River from the 1970s. The etiological study following Koch’s postulates,was conducted in 1993-1996. Eleven isolates were identified as Alternaria triticina Prasada and Prabhu,which isolated from field specimen collected in Shaanxi,Gansu and Henan. When cultured on PCA plate,the fungus sporulated as distinct clumps with(1-)2-5 conidia on primary conidiophores. The conidia were tawny brown,broadly ovoid or ellipsoid,restricted,with 3-8 transverse and 0-5 longitudinal or oblique septa. The conidium body measured 20-50 μm× 10- 15 μm. Pseudorostrum was geniculate or cylindrical,5-47.5 μm×4-5 μm . Brown,oval to elliptical spots,on inoculated leaves,became irregular and usually surrounded with bright yellow marginal zone. Severe infections often caused leaf blight and killed a large majority of the leaves.