Exploring the Modern Fungicides for the In vitro Management of Pokkah Boeng Disease of Maize Caused by Fusarium verticillioides (SACC.) Nirenberg

Abstract

Pokkah boeng disease caused by Fusarium verticillioides is an emerging fungal disease affecting maize recently leading to substantial yield losses. The increasing resistance of pathogens to older fungicides, along with environmental concerns, underscores the need for new management strategies that incorporates next-generation fungicides. In response to this challenge, a comprehensive and systematic survey was conducted in 2022-23 across the Dharwad district of Karnataka. The survey documented disease symptoms such as chlorosis at the base of leaves, malformation and twisting of the foliage. The pathogen was isolated and confirmed as F. verticillioides through molecular diagnosis. In the present study, the pathogen was tested for in vitro efficacy of modern fungicides at three different concentrations viz., 0.1, 0.15 and 0.2 per cent using poisoned food technique. In vitro testing of new generation fungicides revealed that, Tebuconazole 25.9%EC and combinations fungicides viz., Carbendazim 12%+Mancozeb 63%WP and Trifloxystrobin 25% + Tebuconazole 50%WG resulted in 100 per cent inhibition of the mycelial growth of the pathogen. Hexaconazole 5%SC, Azoxystrobin 23%SC, Trifloxystrobin 25%SC, Tricyclazole 18%+Mancozeb 62% WP and Azoxystrobin 18.2%+Difenoconazole 11.4%SC inhibited mycelial growth by 99.15, 85.49, 85.57 93.08 and 86.87 per cent, respectively. The mycelial growth in fungicide-treated media appeared either fluffy or cottony. Among the fungicides tested, Carbendazim 12% + Mancozeb 63% WP, Trifloxystrobin 25% + Tebuconazole 50% WG, and Tebuconazole 25.9%EC demonstrated 100 per cent efficacy in inhibiting pathogen mycelial growth, even at a low concentration of 0.1%. These results suggest a promising direction for disease management, while the other fungicides tested were found to be less effective.