Diversity and Pathogenic Potential of Field-Isolated Foliar Fungi Infecting Maize (Zea mays L.) in Bayelsa State, Nigeria

Maize (Zea mays L.) is one of the most important cereal crops in sub-Saharan Africa, yet its productivity is frequently constrained by foliar fungal diseases. This study investigated the diversity and pathogenic potential of field-isolated foliar fungi infecting maize in Bayelsa State, Nigeria. Symptomatic leaves were collected from the Agricultural Field of the Federal University Otuoke, the surface-sterilized, and cultured on Potato Dextrose Agar (PDA). Fungal isolates were purified and identified based on macroscopic and microscopic features. Pathogenicity was confirmed on healthy maize seedlings using Koch’s postulates. Six fungal species were identified: Bipolaris maydis (48 %), Exserohilum turcicum (34 %), Curvularia lunata (28 %), Phyllosticta maydis/Phoma spp. (18 %), Phaeosphaeria maydis (12 %), and Cercospora zeae-maydis (8 %). B. maydis and E. turcicum were the most frequent and virulent isolates, producing characteristic necrotic lesions on inoculated leaves within seven days. The results highlight the dominance of Bipolaris and Exserohilum species as major foliar pathogens of maize in the humid tropics. Understanding their prevalence and virulence will aid in targeted breeding and integrated disease management strategies for sustainable maize production in southern Nigeria.