Biocontrol Potentials and Pathogenicity of Fungi Associated with Leaf Spots of Groundnuts

Abstract

Groundnut (Arachis hypogaea L.) is an important legume, valued globally for its high protein and edible oil content. However, foliar fungal diseases continue to severely limit productivity, causing significant annual yield losses. This study evaluated the pathogenicity and biocontrol potential of fungi associated with groundnut leaf spots in Lafia, Nasarawa State, Nigeria. Fungi isolated from diseased groundnut leaf tissues were artificially inoculated on healthy groundnut leaves to evaluate pathogenicity for a period of 7 days. The biocontrol potential of the non-pathogens was assessed through dual culture tests. Pathogenicity tests revealed significant differences in the virulence of fungal isolates (P < 0.05). The highest leaf spots (45.80%) were produced by Aureobasidium pullulans, followed by Lecanicillium lecanii (38.30%), Curvularia lunata WF2F (30.83%), C. lunata NF2H (30.00%), and Fusarium sp. (28.30%). Dual culture assays demonstrated significant variations in antagonistic activity among the tested antagonistic fungi (P < 0.05). Non-pathogenic A. pullulans exhibited the highest inhibition of L. lecanii (42.33%) and C. lunata (26.58%), while Trichoderma sp. was most inhibited by A. pullulans (35.06%). Whereas Mucor sp. produced the highest inhibition of Fusarium sp. (38.8%). The study identified A. pullulans, L. lecanii, and C. lunata as highly virulent foliar pathogens of groundnut, requiring targeted management to minimize yield losses. Furthermore, non-pathogenic strains of A. pullulans, Trichoderma sp., A. niger, Mucor sp., and C. rosea showed promising antagonistic activity against leaf spot pathogens, highlighting their potential as effective biocontrol agents of pathogens causing fungal leaf spots of groundnuts.