A Potential Isolate of Trichoderma viride NRCB1 and its Mass Production for the Effective Management of Fusarium Wilt Disease in Banana

Thirty-one isolates of Trichoderma viride, out of 110 isolates of Trichoderma spp. isolated from the rhizosphere of banana were effective in the initial screening tests conducted in vitro against banana wilt pathogen Fusarium oxysporum f.sp. cubense (Foc). These 31 isolates of Trichoderma viride and 6 isolates of other species of Trichoderma viz., T. viride-6, T. harzianum, T. koningii, T. pseudokoningii and T. hamatum, were subjected to intensive in vitro screening by dual culture and spore germination assay. Among these, T. viride isolate NRCB1 resulted in the maximum reduction in mycelial growth and spore germination. Different organic substrates were tested with two jaggery concentrations (1 and 5%) to mass-produce this isolate. The results showed that the fastest coverage of the entire substrate (5 days) as well as high population density (6 × 10 31 CFU/g of material) occurred in rice chaffy grains added with 5% jaggery solution, compared to other substrates. Studies on shelf life indicated that population density of T. viride NRCB1 was significantly higher in rice chaffy grains formulation at both storage temperature (37 and 25°C), even after 5 months compared to other substrates and talc powder formulation. The pot culture and field studies indicated that the soil application of T. viride NRCB1 as chaffy grain formulation significantly reduced the Fusarium wilt disease of banana (up to 80%) and increased the plant growth parameters as compared to the talc powder formulation. The analyses of induction of PO and PAL and total phenolic content both in T. viride applied and Foc challenge inoculated plants revealed that these were significantly higher compared to control plants and plants inoculated with the pathogen (Foc) plants alone.