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Chestnut blight is a worldwide forest disease caused chunks of canker lesions, often chestnut twigs seriously affect the quality of chestnut trees and fruit yield. Earlier research on the disease, but there are no effective prevention and control research reported. The purpose of this study is to determine the cause the chestnut ulcers blotch pathogen to understand the biological characteristics of the bacteria, fungicide efficacy trials and disease-resistant varieties of chestnut initial screening. The results are as follows:. Collected from Hubei Jingshan, Tongcheng Luotian typical incidence branches, isolated four strains JS-4, JS-6, TC-4, LT-1. Inoculated with mycelium block vitro chestnut branches, confirmed the disease pathogen Cryphonectria parasitica. Pathogens cultured for 2 d on PDA medium, the delicate mycelium colorless, 6 d after mycelium yellowish, orange or colorless, denser, less aerial hyphae, hyphae diameter of 1.1-4.5μm, branches conidia were the transparent round or oval, with the main branch Duocheng right angle branching, mycelium in the substrate or petri dish cover first assembled into a yellow, orange or white colonies 7 d after the colored colony color deepened. rDNA-ITS sequencing results the GeneBank sequence homology comparison showed that the strains with the highest homology Cryphonectriaparasitica, up to 99%. Based on morphological characteristics and molecular identification results further determine the pathogen C.parasitica. The measurement results show that the virulence of different strains, different the endanger size of the different strains of the same species, chestnut, virulence strength difference. Biological characteristics research results show that the strain could grow in the range of 10-30 ℃ between 25 ° C to -30 ° C, the optimum temperature for mycelial growth, colony diameter of 7.45 cm after 5 d. Bacteria capable of effective use of a variety of carbon and nitrogen, but different carbon and nitrogen sources have a significant impact on mycelial growth. Glucose as the carbon source and calcium nitrate as nitrogen source, the fastest mycelial growth mycelium dry weight of 0.3955 g and 0.4982 g after 5 d. The strain mycelium lethal temperature to 50 ℃, 10 min. Results show that the impact study on mycelial growth by adding nutritional elements, Mn, B, Ca in the concentration of the test have a certain influence on the mycelial growth, while Zn had no significant effect on mycelial growth; different strains of nutrients There are differences. Affinity determination of colonies showed that there is a difference in the affinity of the different colonies. 3.PDA tablet antibacterial Experimental results show that the five kinds of agents in the test set different concentration on the growth of pathogenic bacteria have certain inhibition, 50% carbendazim WP inhibitory effect best, followed by 5% the soluble powder Jinggangmycin, 10% of the world highly dispersible granules and 65% of the generation Sen zinc ultrafine WP 20.67% Wanxing EC worst effect. 4. Mycelium block the inoculated fresh chestnut branches vitro determination of the incidence of chestnut branches in different periods under natural conditions. The results show that, Nanking consistently demonstrated the resistance of three strains, which is consistent with the reported. In late Li also show some resistance. Other varieties of chestnut resistance in flowering and fruiting period is better than the poor, the resistance to a period of dormancy. 5 branches vitro inoculation, initial screening of nine kinds of varieties planted in the investigation varieties JK4 in TK6, LK3 and Park, as early as Toho, Guangde Dahongpao Chongyang Li Song, Big Bird shells as early as July several varieties, Yichang deep puncture virulent strains JS-6 show some resistance; Chongyang Li, Song early Big Bird shells, as early as July, August Red, Yichang deep puncture caused disease stronger strain TC-4 showed some resistance; addition to the garden planting varieties LG2, LG4, LG5, LG6 LK2 are LK4 and Dawu local plant several varieties virulence than other varieties weak strain LT-1 exhibits a certain resistance. In the investigated varieties JK4 and in TK6 LK3 showed resistance with laboratory inoculated consistent.
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