Screening Of Actinomycetes Resistant To Fusarium Oxysporum(Specialized Type In Cuba) And Biological Control

The Fusarium oxysporum f.sp.Cubense(FOC)No.4 physiological race(FOC4)can cause a large area of banana deaths worldwide each year,seriously affecting the development of the banana industry.In this study,soil was collected from around three national nature reserves in Guangxi and the antagonistic antibacterial agents that had a controlling effect on banana wilt were isolated.The result are as follows:1.The microorganisms were separated and purified in the soil,a total of 121 strains were isolated.Among them,23 strains were isolated from Guangxi Shiwandashan National Nature Reserve,38 strains were isolated from Guangxi Jinhuacha National Nature Reserve,and 60 strains were isolated from Guangxi Nonggang National Nature Reserve.In this study,a total of 53 strains of actinomycetes were obtained from the periphery of the three nature reserves,accounting for 43.80% of the total number of strains,and 68 strains of bacteria,accounting for 56.20% of the total number of strains.2.The anti-bacterial preliminary screening was carried out by the flat-panel confrontation method,and 22 strains with anti-FOC4 activity were obtained,including 10 strains with significant anti-FOC4 activity,and the bacteriostatic rates were 69%,73%,69%,67%,72%,72%,63%,57%,72% and 71%,respectively.We conducted the follow-up experiments with the four antagonistic actinomycetes No.2,No.22,No.4 and No.1 with the best antagonistic effect.3.In the course of the research,we explored a new method for improving the germination of banana wilt disease spores.A new spore germination method was used to determine the spore germination inhibition rate of 4 antagonistic actinomycetes against FOC4 pathogens.The results showed that in the fermentation broth when diluted 5-folds,the inhibition rates of the antibacterial fermentation broths No.1,No.2,No.4 and No.22 on the spore germination of FOC4 pathogens were 95%,94%,93% and 79%,respectively,indicating that these antagonistic antibacterial fermentations can effectively inhibit spore germination of Fusarium oxysporum f.Sp.Cubense.The 16 S DNA sequencing method was used to identify these four antagonistic bacteria.The results showed that the 1st,2nd,4th and 22 th antagonistic bacteria were Stretpomyces ahygroscopicus,Streptomyces mycarofaciens,Stretpomyces ahygroscopicus and Streptomyces albulus?4.In order to obtain antagonistic bacteria that can be used in the field,pot experiment was conducted on these 4 strains of antagonistic bacteria.The results showed that these four strains of antibacterial bacteria had better effects of preventing and treating banana wilt in different treatments,but their preventive effects were better than the therapeutic effects.Therefore,control of banana fusarium wilt should be a combination of prevention and treatment.