In vitro Evaluation of Fungicides against Seed-borne Mycoflora Associated with Groundnut (Arachis hypogaea L.)

Abstract

Seed-borne fungi are important constraints on groundnut production because they adversely affect seed quality, germination and seedling establishment. The present investigation was undertaken to isolate and identify seed-borne mycoflora associated with groundnut seeds and to evaluate the in vitro efficacy of selected fungicides against the predominant fungi. Groundnut seed samples were examined using the standard blotter and agar plate methods. Based on morphological and microscopic characteristics, the predominant fungi were identified as Rhizopus stolonifer, Aspergillus niger, A. flavus and Penicillium notatum. The efficacy of seven fungicidal treatments was evaluated against these fungi using the poisoned food technique in a completely randomised design with three replications. All tested fungicides exhibited considerable variation in their inhibitory effects, indicating differential responses among the fungal species. Metalaxyl 4% + Mancozeb 64% @ 0.2% was the most effective and consistent treatment, completely inhibiting the mycelial growth of all four test fungi and resulting in 100.00 per cent inhibition. Carbendazim 12% + Mancozeb 64% @ 0.2% also showed excellent efficacy by completely inhibiting A. niger, A. flavus and P. notatum, but it was ineffective against R. stolonifer. Carboxin 37.5% + Thiram 37.5% @ 0.05% completely inhibited R. stolonifer and A. niger and produced 70.00 and 85.18 per cent inhibition against A. flavus and P. notatum, respectively. The findings demonstrated that fungicide efficacy was fungus-dependent and that Metalaxyl 4% + Mancozeb 64% @ 0.2% showed the broadest spectrum of activity against the seed-borne fungi associated with groundnut.