Pathogen Identification Of A New Disease On Nai-Plum And Control Of The Disease

In June 2013, a special disease was happened on Nai-plum which were collected from Yongzhou in Hunan province. Since the pathogen of Nai-plum disease was not clear, and the effective prevention measures were absent, a large area outbreak of the disease was happened, which have caused a great economic loss of agricultural production. To provide theoretical basis for recognizing and controlling the new disease, related researches were conducted.Based on single spore separation, we have obtained the purified pathogens of Nai-plum disease, the cultural characteristics and the biological characteristics of pathogens were studied too. The results showed that white aerial hyphae with dense growth are observed on PDA medium at 28? with black stromata on 16d post-incubation, conidia with the shape from ovoid to spindle, hyaline, unicellular,5.41-7.51 um×2.33-3.22 um, oil globule with round ends. Compared the symptoms expressed on fruits of Nai-plum fruits by mycelium group, conidia group, mycelium and conidia mixtures group, we found mycelium and conidia mixtures group worked best, artificial inoculation with mixtures group showed that symptoms are developed on inoculated fruits of Nai-plum about 2 to 4 days with elliptic or irregular lesion then brown necrosis to rotten, in accordance with disease symptoms in the field. ITS (internal transcribed spacer, ITS)?TUB (beta-tubulin, TUB)?CAL (Calmodulin, CAL) and ACT (actin, ACT) genes of pathogens were amplified and sequenced. To combine biological characterization with ITS, BUT, CAL and ACT sequences analysis, we were confirmed that the pathogen should be Phomopsis longicolla, named Phomopsis longicolla YZ. It was the first report on the disease of Nai-plum caused by Phomopsis longicolla YZ in Hunan Province.By using the method of plate colony inhibition, the toxicological test of carbendazim, tebuconazole, triclopyricarb, prothioconazole, validamycin were finished. The results of toxicological test showed that the EC50 value of Carbendazim was 0.0819 ug/mL, had the highest sensitivity among the five kinds of tested bactericides.Trichoderma viride and Photosynthetic bacteria also showed the excellent prevent effect by using the method of plate colony inhibition. Biological control this disease with Trichoderma viride, the average inhibition rate of pathogenic bacteria was 83.39% 3d later. The photosynthetic bacteria fermentation liquid had obvious antagonistic effect on pathogenic bacteria, and the inhibitory rate of the pathogen was 66.7%, which was 36h on the plate which was made by the volume of PDA culture medium and the fermentation liquid of photosynthetic bacteria.