Efficacy of Fungicides against Alternaria sesami Causing Leaf Blight of Sesame and Aspergillus niger Causing Collar Rot of Groundnut

Abstract

Fungal diseases such as Alternaria leaf blight of sesame and collar rot of groundnut significantly limit the productivity of these important oilseed crops. The present study was undertaken to evaluate the in vitro efficacy of six commonly used seed treatment fungicides against Alternaria sesami and Aspergillus niger using the poisoned food technique. The fungicides were tested at six concentrations ranging from 100 to 2000 µg/mL under a completely randomised design with three replications. The results revealed significant variation among fungicides, concentrations, and their interactions in inhibiting the mycelial growth of both pathogens. Among the treatments, Carboxin 37.5% + Thiram 37.5% DS and Prochloraz 24.4% + Tebuconazole 12.1% EW exhibited superior efficacy. Both completely inhibited A. niger at concentrations of 250–2000 µg/mL; for A. sesami, complete inhibition was achieved at 1000–2000 µg/mL with Carboxin 37.5% + Thiram 37.5% DS and at 500–2000 µg/mL with Prochloraz 24.4% + Tebuconazole 12.1% EW. In contrast, Thiram 75% DS was the least effective fungicide overall, showing comparatively lower inhibition across the concentration range. A consistent dose-dependent response was observed, with increased inhibition at higher concentrations. The enhanced performance of combination fungicides may be attributed to their multiple modes of action. The findings of this study provide a basis for selecting effective fungicides for further field evaluation and integration into disease management strategies for sesame and groundnut.