海南石斛兰叶片黑点病的病原鉴定及室内药剂毒力测定

为明确石斛兰黑点病的病原物种类，对其病原菌进行了分离、纯化和致病性测定，以及室内6种杀菌剂的毒力测定。结果发现，从患黑点病的兰花叶片上分离到一个真菌分离物，该分离物接种石斛兰嫩叶20天后，发现能引致与田间自然发病相似的症状。rDNA-ITS序列分析发现该菌株与Phyllosticta sp.的同源性为100%。6种杀菌剂室内平板抑菌实验结果表明：凯润、施保克都有较好的防治效果。本研究为石斛兰黑点病的防治提供了理论依据。

Identification on Causal Agent of Dendrobium Black Spot and Indoor Determination of Fungicide Toxicity

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 Pbyllosticta sp mycelial growth effectively. This study provided a scientific basis for dendrobium leaf black spot disease control.