Objective  The pathogen and its biological characteristics of camellia petal blight disease were investigated for improving the quality and protecting the ornamental value of the floral plant.

  Method   A pathogen was isolated from of diseased Camellia japonica at the Botanical Garden in Kunming City by tissue separation method and confirmed by pathogenicity assay as well as morphological and molecular biological identifications. Biological characteristics of the isolate were studied.

  Result  A suspected microbe was isolated from the diseased tissue and inoculated onto healthy camellia flower petals. With the appearance of yellowing and browning petals with dry or wet rots and fungal mycelial growth, the similar symptoms shown on the infected plants in the field, the isolate was studied further for a confirmed identification. On a PDA medium, the fungal colonies displayed yellow mycelia and produced black spores and lemon-like ascospores at late stage. The phylogenetic analysis of multiple genes of ITS, LSU, and EF1 clustered the isolate with Chaetomium pseudocochliodes clade. Subsequently, the optimal conditions for the growth of the isolated fungus were found to be at 25 ℃ on LB and OMA culture medium,without special requirement of light,beef paste as a nitrogen source and fructose as a carbon source have the highest utilization rates, and the lethality at 55 ℃ in 10 min.

  Conclusion  C. pseudocochliodes was identified as the pathogen that caused floral petal blight disease on C. japonica. The pathogen grew optimally at 25 ℃ on LB and OMA culture medium ,without a specific light requirement, beef paste as a nitrogen source and fructose as a carbon source have the highest utilization rates, and it was killed by exposure to 55 ℃ for 10 min.