The Dynamics Of Fusarium Oxysporium F.Sp.Cubense4in Different Conditions

Banana wilt disease is a devastating soil-borne vascular disease, it is caused by Fusarium oxysporium f. sp. cubense (FOC), and its pathogenic bacteria have many races, race4almost harm all banana varieties, and FOC4is the biggest threat to banana industry in our country. In order to understand the dynamics of FOC4in the soil, grasp the occurrence regularity of banana wilt disease, and provide scientific theoretical basis for controlling the occurrence and spread of banana wilt disease. In this paper, we study the dynamics of FOC4in the soil under different conditions. The main results are shown as follows:(1)Without any treatment measures, the quantity of FOC4in the soil is increased at first, then decreased, and stable at last. Once the soil is infected by FOC4, its quantity increased rapidly, reach the top at28days, then decreased a little, keep stable after42days. And find out the best selective medium for screening fusarium oxysporium, it is the improved PEA medium.(2) After7days, the quantity of FOC4in the soil is zero when treatment with dazomet and calcium. Its quantity decreased rapidly when treatment with chlorine dioxide and brmo chloro hydantoin, but the quantity keep stable after7days. The toxicity of four varieties of soil disinfection disinfectants was determined by the method of mycelium growth and spores germination of FOC4, and the control effects by pot experiment. The results show that dazomet is the best soil disinfection disinfectant.(3) When banana seedlings are planted in the soil, the quantity of FOC4in the soil is increased at first, then decreased, and stable at last. Once the soil is infected by FOC4, its quantity increased rapidly, reach the top, then decreased a little, keep stable at last. And the minimal concentration that induced the banana wilt disease is103cfu/g soil, disease incidence show serious when the concentration is more than103cfu/g soil; but banana is healthy when the concentration is less than103cfu/g soil.(4) Five antagonistic strains against FOC4are isolated and screened from the rhizosphere soil of the banana, Strain1-g-59possess the most prominent bioactivity; When treatment with the fermentation filtrate of strain1-g-59, the quantity of FOC4in the soil is decreased at first, then stable at last. The quantity reduce the most in1-3days, and keep stable after21day; By studying the morphology, cultural, physiological and biochemical properties,16S rDNA and phylogenetic tree, the results show that strain1-g-59is identified as Streptomyces lunalinharesii; Pot experiment showed that control effects of the fermentation filtrate of strain1-g-59on banana fusarium wilt disease was64.9%.