Assessment of the Incidence and Severity of Common Fungal Diseases of Cowpea in Benue State

Cowpea is a vital protein source and cash crop in Nigeria's Middle Belt, and fungal diseases represent a major constraint to its productivity in the humid agroecological conditions of Benue State. This study assessed the incidence and severity of common fungal diseases of cowpea (Vigna unguiculata L. Walp.) in Gboko and Makurdi Local Government Areas, Benue State, North Central Nigeria. A field survey was conducted during the 2023 growing season, with 30 farmer fields visited at 2-week intervals across three growth stages (vegetative, flowering, and podding). Diseases assessed included Cercospora leaf spot, brown blotch, septoria leaf spot, and Colletotrichum seed rot. Disease incidence and severity were rated using standardised scoring scales. Pathogen identification was confirmed through laboratory cultural and morphological characterisation. Results showed that Cercospora leaf spot was the most prevalent disease, with a mean incidence of 72.3 percent and a mean severity score of 3.2 on a 1-to-5 scale. Brown blotch showed the highest severity in the podding stage (mean score 3.8). Disease incidence was significantly higher in fields without crop rotation (p < 0.05) compared with rotated fields. Late-planted fields showed higher fungal disease pressure than early-planted ones. The study concludes that fungal diseases pose a significant production challenge in Benue cowpea systems and recommends disease-resistant variety adoption, crop rotation, and appropriate fungicide application timing as integrated management strategies. Keywords: cowpea, fungal diseases, Cercospora leaf spot, disease incidence, Benue State