Abstract / Summary
Abstract Fusarium wilt caused by Fusarium oxysporum is an important constraint to the production of Corchorus olitorius L. in tropical production systems. Information on the efficacy of indigenous fungal antagonists against this pathogen in West African production systems remains limited. This study evaluated the antagonistic activity of indigenous Trichoderma harzianum , Aspergillus niger and Aspergillus flavus against F. oxysporum using complementary in vitro and screenhouse assays. Antagonistic activity was evaluated using a dual-culture assay, while a completely randomised screenhouse experiment comprising nine predefined treatment combinations was used to assess disease incidence, disease severity and plant growth at two pathogen inoculum concentrations (1 × 10 8 and 1 × 10 10 conidia mL -1 ). The fungal antagonists differed in their ability to inhibit pathogen growth. T. harzianum produced the highest inhibition of F. oxysporum radial growth (68%), followed by A. niger (55%) and A. flavus (48%). At 5 weeks after planting, the F. oxysporum + T. harzianum treatment at 1 × 10 10 conidia mL -1 recorded disease incidence and disease severity index values of 24.2 and 19.6%, respectively. This treatment was also associated with greater plant height, stem girth, leaf length, leaf width, and leaf number than the pathogen-only treatments. Disease severity and plant height were strongly negatively correlated (r = −0.957, P < 0.001), with the fitted regression model explaining 91.6% of the observed variation in plant height. Under the controlled conditions of this study, the indigenous T. harzianum isolate showed promising antagonistic activity against F. oxysporum and was associated with improved growth of C. olitorius . Molecular identification, biosafety assessment, and field validation are required before practical application.