Isolation And Identification Of The Pathogens Causing Garlic Dry Rot Disease And Fungicides Screening

Dry rot disease is one of the important diseases in garlic growing and storage period, the occurrence of the disease causes the yield and quality of garlic to decline, especially in the area of Heilongjiang, the incidence of garlic dry rot seriously affects the production of garlic during the winter storge. In this study, the garlic bulbs of susceptible line Z-1001were used as test materials, the garlic dry rot pathogens were isolated and identified, and its biological characteristics were studied, at the same time had the indoor screening of fungicides. The main findings are as follows:Isolation and identification of pathogens:The garlic line Z-1001which showed symptoms of dry rot was used.After the isolation and single spore purification of pathogen, we got F, J, H, G these4purified strains. According to the pathogenicity determination of pathogen, we confirmed that the F and J strains were the main pathogenic strains of garlic dry rot. The application of combinating pathogens morphological observation with the rDNA ITS sequence analysis identified that F strain was Fusarium oxysporum Schlecht and J strains was Fusarium proliferatum (Matsush.) Nirenberg indicating that Fusarium oxysporum Schlecht and Fusarium prolieratum (Matsush.) Nirenberg are the main pathogens of garlic dry rot.Biological characteristics of the pathogen:The biological characteristics of pathogen was studied preliminarily under laboratory conditions. The results showed that:the optimum growth temperature range of Fusarium oxysporum and Fusarium proliferatum was25-30℃, light conditions had little effect on mycelial growth of Fusarium oxysporum and Fusarium proliferatum. Fusarium oxysporum and Fusarium proliferatum grew well in alkaline environment, the mycelium optimum pH was about8. Fusarium oxysporum made use of sucrose best and the worst effect was fructose during the tested carbon sources; Fusarium proliferatum made use of glucose, sucrose best and the worst effect was maltose, during the tested nitrogen sources, most nitrogen sources were conducive to the growth of the two pathogens, Fusarium oxysporum grew well in NH4C1, phenylalanine.significant difference compared with other nitrogen sources.but Fusarium oxysporum growed worst under the conditions of NaNO2and NH4H2PO4as a nitrogen source, Fusarium proliferatum grew well in NH4NO3and L-group phenylalanine.significant difference compared with other nitrogen sources. Fusarium proliferatum growed worst under the conditions of NH4CI NH4H2PO4and L-arginine as a nitrogen sourceThe indoor screening of fungicides:The application of six kinds of tested pesticides to screen indoor Fungicide. The results showed that:the antibacterial effect of60%white carbendazim (Carbendazim) best and root wilt stop on garlic dry rot was best. Selecting the two pharmaceutical to prepare drug-containing medium of different concentrations, to do the antibacterial experiments and make the virulence regression equation.According to the virulence regression equation, EC50value of60%white carbendazim was51.76mg/L and the EC5o value of root wilt stop was29.65mg/L to prevent Fusarium oxysporum. And the EC50value of60%white carbendazim was16.25mg/L and the EC50value of root wilt stop was69.82mg/L to prevent layer Fusarium proliferatum. On the basis of60%white carbendazim and the EC5o value of root wilt stop, the mixed efficiency Experimental results showed that the volume ratio of60%of carbendazim and root wilt stop for7:3,6:4,2:8and1:9, the mixed volume ratio was the efficiency ratio, having the synergistic effect on the suppression of Fusarium oxysporum. When the proportion of the two tested pesticides pharmaceutical60%carbendazim and root wilt stop for9:1,8:2,3:7and2:8, the mixed volume ratio was the efficiency ratio, having the synergistic effect on the suppression of Fusarium proliferatum.