Integrated disease management (IDM) for Fusarium wilt of banana in India: The effect of organic amendments, waterlogging and cultivation with paddy rice on disease severity

Thangavelu Raman^1*Murugan Loganathan²Perumal Ganga Devi²Boopathy Nithya²Altus Viljoen³Guy Blomme⁴Thangaraj Sekar²RAMASAMY SELVARAJAN²

• ¹National Research Institute for Integrated Pest Management, Indian Council of Agricultural Research (ICAR), New Delhi, India
• ²National Research centre for Banana, Indian Council of Agricultural Research (ICAR), New Delhi, India
• ³Stellenbosch University, Stellenbosch, South Africa
• ⁴Alliance of Bioversity International and International Center for Tropical Agriculture, Rome, Italy

The banana Fusarium wilt pathogen, Fusarium oxysporum f. sp. cubense (Foc), is a major threat to banana production globally, affecting the livelihoods of millions of the people. In India, Focraces 1 and tropical race 4 (TR4) are widespread in most banana-growing states where it causes severe yield losses and a drastic reduction in cultivation area. In recent years, integrated approaches to manage banana Fusarium wilt have been proposed. 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 (height, girth, number of leaves, and leaf area) also significantly increased for plants treated with groundnut cake (FocTR4-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 found six Bacillus and five Trichoderma spp. to be highly suppressive to FocTR4. Waterlogging and paddy rice cultivation reduced Fusarium wilt (TR4) to a disease severity score of 2.2 and 1.13, respectively, on a 0-5 rating scale, compared to the control treatment with scores of 3.4 and 3.5, respectively. qRT-PCR analysis revealed a FocDNA reduction in soils treated with groundnut and neem cake of 90.6% for Foc TR4 and 85.1% for Foc race 1, respectively, while waterlogging and paddy rice cultivation reduced FocTR4 by 98.1% and 97.8%, respectively. These findings highlight the potential use of organic amendments, flooding and paddy rice cultivation for the management of Fusarium wilt of banana.