Biological Control of Wilt Disease Caused by F. oxysporum Schlecht. in Bok Choy(Brassica campestris var. chinensis L.) using a Combination of Antagonistic Agents

HistoryFusarium wilt is a significant disease caused by Fusarium oxysporum Schlecht, leading to severe crop damage in bok choy (Brassica campestris var.chinensis L.).Biological control, which uses biotic entities to reduce pathogen inoculum density, has emerged as a potentially effective method for managing plant diseases.This study aims to evaluate the effectiveness of combinations of antagonistic agents in controlling Fusarium wilt in bok choy.The fungal inoculum of F. oxysporum was sourced from bok choy, which showed typical symptoms of Fusarium wilt.The isolated pathogen was characterized based on its morphological and physiological properties, purified, and stored on PDA media for further testing.The antagonistic isolates were preserved on PDA slants for Trichoderma harzianum TR-01 and Gliocladium virens GR-01 and King's B medium for Pseudomonas fluorescence PR-01.The in vitro antagonistic assay was conducted using the dual culture method, while the antagonistic agent's field tests were applied one week before planting, alongside the manure application.The combination of antagonistic agents in the H treatment significantly reduced the incidence of damping-off both before (7.00%) and after appearing at the ground level (7.16%) compared to the control treatment (A) (P<0.01).This treatment also extended the disease incubation period to 5 days, showing an increase of 32.86% compared to controls, who showed only 3 days of incubation (P<0.01).The pathogen population in treatment H was recorded to be 39.25% lower than in treatment A. In addition, there was an increase in the number of healthy plants by 14%, from 80 plants (A) to 94 plants (H) (P<0.01).In vitro dual culture assays revealed inhibition rates of 45.56% for T. harzianum, 41.11% for G. virens, and 32.22% for P. fluorescens (P<0.05).Field trials showed that the combined application of these agents significantly reduced disease incidence and improved plant health and yield.The antagonist potential assay of three antagonistic isolates against Fusarium oxysporum demonstrated that the combined application of Gliocladium virens GR-01, Trichoderma harzianum TR-01, and Pseudomonas fluorescens PR-01 was most effective in suppressing the pathogen.This integrated biocontrol treatment significantly reduced pre-and post-emergence damping-off, lowered pathogen populations, increased the number of healthy plants, and enhanced plant growth and yield.Overall, this approach offers a sustainable and effective alternative to conventional synthetic fungicides for managing F. oxysporum-induced diseases.