Worldwide banana production has become increasingly vulnerable to infections from Fusarium oxysporum f. sp. cubense race 4 (Foc TR4), given the dominance of the Cavendish banana (90%) which is highly vulnerable to the infection. To improve current Foc TR4 disease management used, this study considers alternatives control, like the use of soils that resist the disease along with their beneficial microbiota and ability to limit fungal development. The research involved analysis of soils from plantations in Tulunan, Cotabato, Philippines, where crops remained healthy despite outbreaks nearby and considered it as suppressive while the opposite was conducive. In particular, suppressive soils differed from conducive soils by being characterized as neutral pH, sandy clay loam, higher organic and phosphorous availability while conducive were sandy loam, acidic, and low organic content. A total of 26 microorganisms were extracted from suppressive soils, among which five species showed strong antagonistic activity against Foc TR4: Phlebiopsis gigantea, Paecilomyces fulvus, Aspergillus niger, Trichoderma harzianum, and Talaromyces viridulus. The results from three assays (dual culture assay, test for volatile organic compounds, and culture filtrate assay) performed showed that, A. niger and T. harzianum significantly reduced the rate of the pathogen growth by nearly 80% through resource competition; P. gigantea inhibited 54% by producing volatiles, and T. viridulus by 27% via metabolite production. All these experiments prove suppressiveness is not random but dependent on unique physical, chemical, and biological conditions.
