Identification Pathogen Causing Black Spot Disease on Wax Apple(Syzygium samarangense Merr.et Perry)and its Biological Characteristics

In order to identify the causal agent of black spot disease on wax apple (Syzygium samarangense Merr.et Perry) in its taxonomic status, the causal fungi FJAT-9860 was isolated and characterized with pathogenicity test, morphology and culture feature observation, rDNA-ITS sequences assay and biological characteristics test.The results indicated that the causal agent belong to Lasiodiplodia theobromae.The colony of strain FJAT-9860 on PDA was white at first, then gradually became as grey to black.The monadic conidia were elliptic to round, and colourless.The rDNA-ITS sequence of the strain shared 99%identity with that of Lasiodiplodia theobromae strain.The results showed that the optimum temperature for mycelium growth of this pathogen was 25℃and the optimum pH was 8.0.The mycelial growth was affected by different carbon sources and the best one was mannitol.