Pathogenicity of Ceratocystis fujiensis Strains Associated with Ips subelongatus

This research investigated the pathogenicity of 3 associated fungal strains of Ceratocystis fujiensis which were isolated from Ips subelongatus on Larix olgensis.The results showed that CF3 strain had the strongest virulence,and CF1 and CF2 had moderate.The phloem necrotic reaction zone by solid inoculums was larger than that by liquid inoculums,which showed that the mycelium of C.fujiensis could colonize easily between the xylem and phloem.The nutrition condition in the wood fitted the growth need of associated fungi.The three strains did more damage to logs than to living sample trees.The invasion of associated fungus could induce positive defense response of living sample trees.The associated fungi could be isolated from the phloem necrotic reaction zones and the blue stain sections.