中华常春藤黑腐病及其病原菌鉴定

中华常春藤是一种在我国南方广泛栽培的园艺植物。2009年秋,在杭州西湖风景区发现该植物发生黑腐病。该病害主要发生在9月至11月,植物感病后,首先在叶片边缘、叶柄基部和匍匐幼茎处发病,发病初期形成水渍状黑色病斑,叶柄感病后缢缩黑色坏死,在受侵害的叶片上出现较大的不规则形状的病斑,湿度大时,产生白色絮状菌丝,最后整根藤蔓枯死。田间发病中心明显,蔓延迅速,连片发病严重。采用组织分离法从病健交界处分离病原菌株,病原菌的形态学观察结果表明:分生孢子壁薄、无隔、纺锤形到窄椭圆形,大小为(18～25)μm×(4～5)μm,平均为19.3μm×4.7μm;子囊双层壁,每个子囊内含8个子囊孢子,子囊孢子单孢、无色透明、壁光滑,大小为(19～28)μm×(7～9)μm,平均为22.3μm×7.5μm。病原菌株的rDNA ITS序列长度为557 bp。通过对病原菌形态学观察与核糖体DNA ITS序列分析,侵染中华常春藤的菌株被鉴定为葡萄座腔菌Botryosphaeria dothidea de Not,无性型为七叶树壳梭孢Fusicoccum aesculi Corda。致病性试验表明,中华常春藤是葡萄座腔菌的寄主。

The black rot disease of Hedera nepalensis and its pathogen identification

Hedera nepalensis var.sinensis(Araliaceae) is an ornamental plant that is widely planted in gardens in southern China.Black rot were observed on H.nepalensis in autumn of 2009 in Hangzhou,Zhejiang Province.The disease was usually found to be common from September to November.Black water-soaked spots initially appeared in the edge of the leaves,on the base of leaf petioles and creeping young stems,followed by irregular large lesions in the infected leaves and black constriction in the infected petiole.During long wet periods,the surface of the infected plants showed white mycelium while the inside become soft and watery.At last the disease resulted in the whole vines death.The occurence of disease in fields had obvious center and spread rapidly,and showed contiguous serious disease.The strain was isolated from the boundary between the diseased and healthy part by using tissue isolation technique.The morphological observations showed that the conidia wall was thin,non-septate,spindle-shaped to narrow oval,and the size was(18-25) μm×(4-5) μm,average of 19.3 μm× 4.7 μm.The ascus had double wall,eight ascospores in each ascus,ascospores monospores,colorless,transparent,smooth-walled,and the size was(19-28) μm×(7-9) μm,average of 22.3 μm× 7.5 μm.The strain rDNA ITS sequence is 557 bp.The isolated strain was identified as Botryosphaeria dothidea de Not(anamorph is Fusicoccum aesculi Corda) based on its morphological characteristics,pathogenicity tests and rDNA ITS sequence analyses.