Screening and Identification of Pathogen Causing Banana Fusarium Wilt and the Relationship Between Spore Suspension Concentration and the Incidence Rate

Objective In order to provide a scientific basis for the field diagnoses of Fusarium wilt of banana,it is very important to screen and identify the pathogen which causes banana Fusarium wilt and to investigate the relationship between the spore suspension concentration and the disease incidence rate.Method A lab-screening and pot experiment was used to identify the pathogen.Result The pathogen isolated from the pseudo-crown of diseased banana showed a high pathogenicity in a pot experiment in which the disease incidence was 90% and mortality rate was as high as 70% 35 days after inoculation.A close relationship between the amount of inocula in soil and the disease incidence rate of banana wilt was found and the minimal concentration that induced the banana Fusarium wilt was 103 CFU /g soil.Disease incidence increased with the increase of inocula density in soil.Until the inocula density attained a certain degree(105 CFU/g),the disease incidence would no longer increase.The numbers of pathogen in rhizosphere soil were 1.15 to 2.06 times higher than those in bulk soil in different treatments.A pot experiment was carried out to investigate the effects of a new bioorganic fertilizer(BIO) on banana plant growth and the suppression on the disease.It was found that the BIO bio-organic fertilizer contributed to the growth-promoting of banana plants and to the low occurences of fusarium-wilt disease.Conclusion It was related to background number of the pathogen in diseased soil that the banana Fusarium wilt occurred or not,while the disease incidence was mainly determined by the number of the pathogen in plant rhizosphere soil.These results would be served for the diagnosis of banana wilt.