| In recent years, a kind of serious plant disease arised on the Chinese pear cultivar'Dangshansuli','Huangguan'and'Matihuang'in area of the Ancient Yellow River Valley, Anhui Province, China. At primary stage one or several minimum black spots appeared on the leaves and pear fruit skin, then that shaped as circular or anomalous whorled spot or depressed sickness spot before fruit maturation. this kind of disease, called'Black spots', spread quickly and was difficult to be controlled, not only lead the fruit rot before harvest, but also caused leaves fall out of season. Especially in 2008, the rate of sick fruit was 100% and decayed fruit rate reached to 70% in some orchard, which caused the severe economic loss to local growers.To identify the pathogenic fungus of a serious disease, which had caused a severe damage to pear in Dangshan County, Anhui Province in recent years and screen out effective chemical for inhibition of its mycelium growth and conidiophores germination, we took a field survey to the occurrence of disease in different pear orchards in Dangshan, made a statistics to the rate of diseased fruits in pear orchards which had different age and different planting density, and collected 6 samples. Isolates from diseased fruit and leaf with different type of symptom in the field were cultured on PDA medium and purified by single spore culture respectively, and initial identification was made by using of traditional methods of morphology and pathogenicity of fungal. Extracted genomic DNA of pathogen from mycelium by method of CTAB, using rDNA-ITS clone universal primers of fungal ITS1 and ITS4, then,amplified by PCR. The amplified products were recovered by Gel Extraction Kit and sequenced. Using Blast tool of NCBI on line for rDNA-ITS homology comparison of pathogens, applying procedure of BioEdit for sequence analysis, built phylogenetic trees according to neighbor joining method by using the software of MEGA 3.1. The pathogen mycelia and conidia were dealt with 24 kinds of commonly used fungicides, and their chemical inhibitory effects were observed.The main results obtained in this experiment were as follows:1. The results showed that the occurrence status in the pear orchard with different planting density were different. The most serious damage occurred on 2 m×4 m pear trees with 40.42% dieased fruit rate, and the damage on 5 m×6 m pear trees took second place with 31.24% dieased fruit rate, and the damage on 8 m×8 m pear trees was milder with 11.07% dieased fruit rate.2. Pathogen morpha and studies on pathogenicity: Fungal morphologic characteristics of six purified pathogenic strains from different samples were all the same, which were similar with the reported anthracnose pathogen Colletotrichum spp. The symptoms induced by artificial inoculation of the fungal isolates were the same as that investigated in the field, too.3. Molecular identification of the pathogen: It was determined that the six strains belonged to the same pathogen by rDNA-ITS sequence analysis, the rDNA-ITS sequences were the same as that of anthracnose pathogens, Colletotrichum sp., Glomerella cingulata and C. gloeosporioides, isolated from Taiwan jujube, Japanese supermarket fruit and Fragaria ananassa, and accessed in NCBI network by ID FJ233185, AB219012 and EU200455 respectively.4. Antibacterial test results showed that Mycelium growth could be controlled entirely by treatment solution of 43% Tebuconazole SC 4000 times and other seven chemicals, and conidiophores germination could be inhibited entirely by treatment solution of 70% Thiophanate-Methyl WP 900 times and other seven chemicals.It was demonstrated that the disease on Chinese pear'Dangshansuli','Huangguan'and'Matihuang'was caused by the pathogen Colletotrichum gloeosporioides Penz., and its teleomorph was Glomerella cingulata. There were positive differences between treatments of different chemicals to inhibite mycelium growth and conidiophores germination.
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