Preliminary Study On Pathogens Of Three Grape Rot Diseases In Jiangxi Province

Grape is one of the fastly developing fruit trees in Jiangxi province in recent years. However, with the expansion of grape cultivation areas, fruit rot diseases occur more and more seriously in the late fruiting phase, and they severely affect the local grape industry. At present, the research on grape rot diseases is quite few in China and abroad. Based on the results of our previous studies, pathogens causing three main grape rot diseases (bitter rot of grape, white rot and grape canker)in Jiangxi province were identified, and the basic biological characteristics of the pathogens were studied. Meanwhile, the molecule detection techniques of Greeneria uvicola and indoor toxictiy of seven fungicides on Coniella castaneicola were also studied. The main findings are as follows.(1) On the basis of its morphological characteristics, pathogenicity, rDNA-ITS and TEF-1α sequence analysis, the casual agent of bitter rot of grape was identified as G. uvicola, and the casual agent of grape white rot was identified as C. diplodiella and C. castaneicola with C. diplodiella as the dominant pathogen (the isolation rate of C. diplodiella was 87.1%). Three kinds of fungi were responsible for grape canker in Jiangxi province. They are Botryosphaeria dothidea, Lasiodiplodia theobromae and Neofusicoccum parvum. The isolation rate of each of these three fungi were 8.38%, 2.7% and 13.5% respectively.(2) The results of the biological characteristics of G. uvicola showed that PSA (Potato sucrose Agar) was the optimal medium for mycelial growth. G. uvicola could grow between the temperature 5 to 32℃, and the optimal temperature was 28℃. The optimum pH for the fungus growing was 5. Light period had no significant influence on mycelial growth. The mycelium lethal temperature was 53℃,10 min. For mycelial growth of the pathogens, the optimum carbon source was sucrose and the optimum nitrogen source was beef extract.The optimal medium for C. castaneicola growing was AEA (Alfalfa extract Agar). The pathogen of grape white rot could grow between the temperature 5 to 32℃, and the most optimum temperature was 25～28℃. The optimum pH was 4～6, and the mycelium lethal temperature was 58℃,10 min. For mycelial growth of the pathogen, the optimum carbon source was mannitol and the optimum nitrogen source was ammonium nitrate.The pathogens of grape canker could grow between 10℃ and 32℃, and the most optimum temperature was 30℃. The best medium for their growth was PSA, pH 8. For mycelial growth of the pathogens, the optimum carbon source was mannitol, and the optimum nitrogen source was beef extract.(3) Reaction systems of nest PCR and qPCR for detecting G. uvicola were established by using our self-designing specific primer pair GF3(5’-GGTGGC CCTGTAAACTCTTGT-3’) and GR3(5’-TGATCCGAGGTCAACTTTCAG-3’). Indoor toxicity test of seven fungicides against C. castaneicola by using mycelial growth rate method was carried out. The results showed that two fungicides of epoxiconazole SC and flusilazole EC were strongly toxicant to C. castaneicola. The EC50 values of two fungicides to C. castaneicola. were 0.0719 μg/mL and 0.0876 μg/mL respectively.