Screening of Newer Generation Fungicides against Alternaria solani Causing Early Blight in Tomato under in vitro Condition

Abstract

Tomato (Solanum lycopersicum L.) is a globally vital horticultural crop, yet its productivity is severely threatened by early blight, caused by Alternaria solani. In a 2024 field survey across districts in Tamil Nadu, disease incidence ranged from 25.4% to 53.9% Per cent disease index, with the pathogen affects 60% in tomato field. Alternaria solani isolates were characterized morphologically, confirming typical septate, branched mycelia and muriform conidia. In vitro antifungal screening of eight newer-generation fungicides revealed that achieved the highest inhibition zone (48.15%), followed by difenoconazole at 42.73%, while hexaconazole exhibited the lowest activity (21.78%). These findings align with global studies demonstrating strobilurins’ superior efficacy in managing A. solani. The results suggest that azoxystrobin, either alone or in combination with triazoles, offers a promising tool for integrated early blight control in tomato cultivation. However, field trials, optimum dosing regimens, resistance monitoring, and integration with cultural practices are recommended to develop sustainable disease management strategies in tropical and subtropical regions.