Objective This study aims to evaluate the control efficacy of biocontrol agents combined with hymexazol against banana Fusarium wilt in substrate cultivation, in order to provide a theoretical basis for preventing pathogen infection and transmission during the cultivation of banana secondary seedlings.

Method Molecular identification of strains LMSY3Y-8 and XSZSY2Y-7-1 was performed based on 16S rRNA sequences. The inhibitory activity of the strains was determined using the plate confrontation method, and their functions in amylase production, phosphorus solubilization, and potassium release were assessed using functional media. In coconut husk substrate, the inhibitory activity of individual bacterial agents and their combination with hymexazol against the Fusarium wilt pathogen was tested under different container types (sealed bags, nutrient cups, tissue culture bottles). The control efficacy of the biocontrol agents and hymexazol against banana Fusarium wilt was evaluated in banana substrate cultivation.

Result The strains LMSY3Y-8 and XSZSY2Y-7-1 were identified as Bacillus velezensis and Pseudomonas sp., respectively. Although the antimicrobial and growth-promoting functions of strain LMSY3Y-8 were weaker than those of strain XSZSY2Y-7-1, the pathogen inhibition rate of strain LMSY3Y-8 treatment in coconut husk substrate was higher than that of XSZSY2Y-7-1, reaching 87.4%. Furthermore, the combination of the high-activity strain LMSY3Y-8 with hymexazol achieved a 100% inhibition rate against the pathogen after 18 days. Pot experiment results showed that both the strain LMSY3Y-8 treatment and its combination with hymexazol achieved a control efficacy of over 60% against banana Fusarium wilt and significantly increased the plant height and root weight of banana seedlings.

Conclusion The combination of B. velezensis LMSY3Y-8 and hymexazol can serve as an effective measure for controlling banana Fusarium wilt in substrate cultivation. However, further exploration is needed regarding their interaction mechanisms, optimal concentration ratio, and stable, efficient formulation forms.