杜鹃茎基腐病病原菌的鉴定

IDENTIFICATION OF THE PATHOGEN OF RHODODENDRON FOOT ROT

1992～1993年江苏省宜兴市的比利时杜鹃上发生了严重的茎基腐病,大量植株枯死。从植株和基质中获得的38个分离物中,14个为腐霉Pythium spp.,13个疫霉Phytophthoraspp.,7个拟盘多毛孢Pestalotiopsis spp.,3个青霉Penicillium spp.和1个刺盘孢Collectotrichum sp.。其中,只有腐霉和疫霉具有较强的致病力。作者对代表菌株RH-1和RH-3进行了种的鉴定。结果表明,昆明腐霉Py.kunmingense和柑橘褐腐疫霉Ph?citrophthora为杜鹃茎基腐病的致病菌。

Rhododendron foot rot was a severe disease in Yixing, Jiangsu Province, in 1992-1993. This disease occurred at both seedling and adult stages. The basic part of the diseased plants showed in cortices the brown lesions that could spread upward to the twigs and inward to the xylem. Then the parts rotted and the plants wilted or died with all leaves shed. In this experiment, among the 38 isolates obtained from the substrata and different parts of diseased plants, 14 were identified as Pythium spp. , 13 as Phy-tophthora spp. , 7 as Pestalotiopsis spp. , 3 as Penicillium spp. and 1 as Collectotrichum sp.. The results of pathogenicity tests suggested that only RH-1 and RH-3, two representative isolates which were identified as Py. kunmingense and Ph. citrophthora, respectively, were pathogenic to rhododendron. Thus it was concluded that these two species of fungi be the pathogens of the disease.