Integrated disease management components for Fusarium wilt of banana in India: Effects of organic amendments, flooding, and paddy rotation on disease severity

The banana Fusarium wilt pathogen, Fusarium oxysporum f. sp. cubense (Foc), is a major threat to banana production globally. In India, Foc race 1 and tropical race 4 (TR4) are reported from multiple banana-growing states where it causes severe yield losses. To develop integrated approaches, in the present study the effect of organic amendments, water logging and paddy rice cultivation on Fusarium wilt development was assessed. Cavendish cv. Grand Nain (AAA) bananas were grown in small plots and pots in soils with organic amendments. Of the organic amendments, groundnut and gingelly cakes applied at 300 g per plant fully suppressed Fusarium wilt caused by Foc TR4, with an internal wilt disease score of 0 on a 0–5 scale, while groundnut and neem cake strongly suppressed the disease, with disease scores of 0.3-0.33 at the same concentration in plants infected with Foc race 1. Plant growth parameters (height, girth, number of leaves, and leaf area) were also significantly increased for plants treated with groundnut cake (Foc TR4-inoculated plants) and neem cake (Foc race 1-inoculated plants). The neem cake application significantly increased the fungal (up to 7x1010 cfu/g), bacterial (up to 33x1010 cfu/g of soil) and actinomycetes (up to 4x106 cfu/g) numbers in soil compared to soil without the organic amendment. In vitro evaluation of 49 bacterial and 14 fungal isolates identified six Bacillus and five Trichoderma spp. as highly suppressive to Foc TR4, with enhanced protease and cellulase activities and IAA production, indicating both pathogen suppression and plant growth–promoting mechanisms. Waterlogging and paddy rice cultivation under micro-plot conditions for 4 months reduced Fusarium wilt (TR4) severity to score of 2.2 and 1.13, respectively, on a 0–5 rating scale, compared with the control treatment, which recorded severity scores of 3.4 and 3.5, respectively. qPCR analysis revealed that pot soils amended with groundnut cake reduced Foc TR4 and race 1 DNA by 90.6% and 81.2%, respectively, while mustard and gingelly cakes reduced Foc TR4 by 86.9% and 84.5%, respectively, and neem cake reduced Foc race 1 by 85.1%. The waterlogging for 4 months and paddy rice cultivation in micro plots resulted in even greater reductions of Foc TR4 DNA by 98.1% and 97.8%, respectively. These results suggest that organic amendments, flooding, and paddy rice cultivation could be effective strategies for managing Fusarium wilt of banana in the field.