Abstract:

In order to identify the pathogen and provide effective disease control, a series of fungal isolation, purification, plant reinoculation were conducted, and six indoor fungicides toxicity was determined. The experimental results showed one fungal pathogen was isolated from the infected leaves. Pathogenicity tests were conducted by inoculated the isolates by wound inoculation with a sterile needle into tender leaves of young dendrobium plants. After 20 days at 25°C, all inoculated leaves showed black spots, just similar to that observed in the field. A fragment of approximately 600bp of the rDNA-ITS gene was amplified via PCR with the universal primer and sequenced. Subsequent database searches in the NCBI indicated that the resulting sequences had 100% identity with the corresponding gene of Phyllosticta sp. Six fungicides toxicity on mycelial growth of Phyllosticta sp was tested in laboratory. The results showed that Cabria and Sportak could inhibit the Phyllosticta sp mycelial growth effectively. This study provided a scientific basis for dendrobium leaf black spot disease control.