大花蕙兰根腐病病原菌的分离与鉴定

从唐山地区采集大花蕙兰根腐病病株样品50份,按照柯赫氏法则对其进行了病原物的分离、纯化、致病性测定及菌株鉴定.结果表明,发病部位分离物中有2类病原菌,为镰孢属(Fusariumspp.)和枝顶孢属(Acremoni-um link=Cephalosporiumcorda).但主要优势菌群为镰孢属.分离物经致病性测定和复合接种试验发现,茄病镰刀菌(F.solani)及尖孢镰刀菌(F.oxysporum)致病性最强,接种后发病株率达85%以上,木贼镰刀菌(Fusariumequiseti)、串珠镰孢中间变种(F.moniliformevar.intermediumNeish et Leggetl)和占枝顶孢霉(A.strictum Gams.)致病性弱,潜伏期长,接种发病率为5%~18%.占枝顶孢霉与茄病镰刀菌和尖孢镰刀菌混合接种后的发病率均高于单独接种的发病率.证实大花蕙兰根腐病是以茄病镰刀菌及尖孢镰刀菌为主要病原菌,并由木贼镰刀菌、串珠镰孢中间变种和占枝顶孢霉复合侵染导致的一种病害.

Isolation and Identification of the Pathogens Causing Root Rot Disease of Cymbidium hybrida

Fifty samples of root rot diseased Cymbidium hybrida were collected from house of Tangshan during 2004.Pathogenicity of fungal isolates obtained from these samples were tested by verifial standard means of the Koch's Postulation.Two kinds of pathogens isolated at the same time were Fusarium spp.and Cephalosporium corda.The results showed that the isolates mainly belonged to Fusarium spp.Infection analysis indicated that F.solani and F.oxysporum had the strongest virulence with a diseased seedlings rate of more than 85%,whereas pathogenicity rate of F.equiseti,F.moniliforme var.intermedium Neish et Leggetl and A.strictum Gams.ranged from 5% to 18%.When A.strictum Gams.was coinoculated with F.solani and F.oxysporum,the diseased induces of mixed inoculations were all higher than those of their individual infection.Our results revealed that F.solani and F.oxysporum were the major pathogens of root rot disease of Cymbidium hybrida,whereas F.equiseti,F.moniliforme var.intermedium Neish et Leggetl and A.strictum Gams.only played an accessory roles in the complex infection.