榉树枯萎病的发生为害调查及病原鉴定

Investigations on blight disease of Zelkova schneideriana and pathogen identification

榉树枯萎病(blight disease ofZelkova schneideriana)是在榉树上发现的一种新的病害,为了解该病害的发生发展,确定该病害的病原,笔者对病害的发生和为害情况进行了实地调查,用柯赫氏法则确定了病原,并对病原进行了形态与分子鉴定。研究结果表明,病害在林地和苗圃均有分布,导致榉树大树和幼苗死亡,榉树地上部分逐渐失绿枯萎,根部变色腐烂。对枯萎病病原进行了分离、接种和再分离,确定该病病原,并通过形态学特性和rDNA-ITS序列分析,鉴定该病害病原为尖孢镰刀菌(Fusarium oxysporum)。对该病的传染性进行分析确定了该病害为土传病害,病害的发生与地形地势有关,低洼地段病害往往发生较重,有随地表水流到处传播特点。病原物尖孢镰刀菌产生大量厚垣孢子,孢子从植物根部入侵,造成根部皮层腐烂,地上部分枯萎。

Blight disease ofZelkova schneiderianais a disease found firstly in theZ. schneideriana. In order to investigethe blight disease ofZ.schneiderianaand pathogen identification. The occurrence of the blight disease in Zhenjiang areawas investigated. The pathogen was determined by Koch？？s postulates. The species of the pathogen were identified basedon morphological and molecular characteristics. The detailed results are listed as follows ： The disease occurs in forestand nursery, and leads to the death of trees and saplings. The symptoms include slow chlorosis of leaves and rot of itsroots. The pathogen was identified through isolation,inoculation and re-isolation. After further research on morphologicproperties and rDNA-ITS sequences, the pathogen was identified asFusarium oxysporum.This study also indicates thatthe disease is a soil-borne diseases, and the occurrence of disease is concerned with topography, and severe diseaseoften occurs in low-lying wet areas in the field. The disease is transmitted through surface water. Large quantities of chla-mydospores are produced byF. oxysporum. These spores invade the roots. Then root cortex begins to rot, tree begins towither.