Identification and biological characteristics of Corynespora cassiicola causing leaf spot on Sanchezia nobilis

Appropriate spacing present experiment was conducted to clarify species and biological characteristics of Corynespora leaf spot pathogen isolated from Sanchezia nobilis. Based on pathogen isolation, morphological characteristics observation, pathogenicity test, analysis of rDNA-ITS sequence, biological characteristic test, and host range examination, the Senchezia nobilis Corynespora leaf spot pathogen was identified as Corynespora cassiicola. The suitable temperature for mycelial growth and sporulation of C. cassiicola ranged from 20°C to 28°C. The suitable temperature for spore germination of C. cassiicola ranged from 24°C to 32°C. The lethal temperature for mycelial growth was 50°C for 10 min. The suitable pHs for mycelial growth and sporulation ranged from 6 to 10 and from 4 to 8, respectively. The optimum pH for spore germination was 8. Alternation of light and darkness was beneficial for mycelial growth and sporulation. Continuous illumination inhibited the mycelial growth. The order of media suitable for mycelial growth were CA, PCA, PDA, CMA and OA in sequence. PDA was the most suitable medium for sporulation. The pathogen could infect multiple plant species such as Camptotheca acuminate and Hibiscus rosa-sinensis under wound inoculation conditions. The pathogen could easily produce conidia on common media without specific environmental requirements, and showed a wide host range and a short latent period of infection. This is the first report of Corynespora cassiicola causing leaf spot on Sanchezia nobilis.