Characterization of Disease Symptoms and Morphological Identification of Associated Fungal Isolates in Selected Vegetable Crops

Abstract

Fungal diseases significantly reduce the yield and quality of vegetable crops, necessitating integrated assessment of symptom prevalence and associated pathogens. This study evaluated disease symptoms and morphologically identified fungal isolates from four vegetables: Brassica oleracea, Telfairia occidentalis, Cucumis sativus, and Solanum lycopersicum. A total of 12 distinct symptoms were recorded, with frequencies ranging from 25.0% to 100.0%. The most prevalent symptom was pale yellow angular spots (100.0%) in B. oleracea, followed by transparent brown patches (91.7%) in T. occidentalis. Several symptoms exhibited high prevalence (83.3%), including circular spots (B. oleracea), circular and sunken cankers and yellowish irregular spots (C. sativus), and brownish-black colouration (S. lycopersicum), while white leaf spot lesions (25.0%) were least frequent. Crossvegetable analysis revealed dominance of high-frequency symptoms (≥83.3%), indicating consistent disease expression. Morphological characterization yielded 17 fungal isolates belonging to diverse taxa, including Fusarium spp. (4 isolates), Trametes spp. (4 isolates, including T. versicolor and T. duplexa), Meyerozyma spp. (2 isolates), Penicillium sp., Aspergillus flavus, and Pithomyces chartarum, alongside mixed cultures (n = 4). Microscopic features such as septate hyphae, conidiophores, macro- and microconidia, and yeast budding structures supported identification. Multivariate analysis (clustering, PCA, and heatmap) revealed distinct host-specific symptom patterns and clear separation among vegetables. These findings demonstrate high fungal diversity and symptom variability, providing a robust baseline for fungal disease diagnosis and management in vegetable production systems.