Morphological Identification of Fungi Associated with the Incidence of Groundnut Leaf Spots in Lafia

Abstract

Fungal leaf spots pose a serious threat to groundnut (Arachis hypogaea L.) production, resulting in significant yield losses annually. This study was carried out to evaluate the incidence and identify the fungi associated with leaf spots of groundnuts in Lafia, Nasarawa State, Nigeria. Incidence of groundnut leaf spots was evaluated in four randomly selected farms in four cardinal locations in Lafia, using a 4 m × 4 m quadrat, and the data were analysed using ANOVA at the 5% level of significance. Fungi from infected groundnut leaves were isolated on PDA and morphologically identified. The highest incidence of leaf spots was recorded in Lafia East (54.47%), followed by Lafia North (49.72%), Lafia South (26.32%), and Lafia West (22.86%) (P<0.05). A total of 17 species were identified, comprising Trichoderma sp. 1 (n=23), Trichoderma harzianum (n=9), Trichoderma sp. 2 (n=3), Trichoderma sp. 3 (n=1), Fusarium incarnatum (n=5), Fusarium sp. 1 (n=1), Fusarium chlamydosporum (n=1), Fusarium sp. 2 (n=1), Aspergillus terreus (n=7), Aspergillus niger (n=3), Curvularia lunata (n=10), Colletotrichum sp. (n=2), Mucor sp. (n=4), Clonostachys rosea (n=3), Aureobasidium pullulans (n=7), Penicillium oxalicum (n=3), and Lecanicillium lecanii (n=4). These findings imply that leaf spots of groundnuts may be the product of a pathogen complex rather than a single entity; however, pathogenicity tests are required to establish the etiology of the disease, as the next critical step towards selecting appropriate disease management approaches to improve crop health and enhance groundnut yield of groundnuts in the study area.