Occurrence of foliar fungal diseases of cowpea and their management with garlic (Allium sativum L.) extracts in Abuja Nigeria

Abstract

This study assessed the incidence and severity of foliar fungal diseases in selected cowpea varieties and the efficacy of garlic (Allium sativum L) extract in the management of the major disease in Abuja, Nigeria. Four cowpea varieties namely, Sampea 20T, Sampea 14, Abuja local white, and Abuja local Brown obtained from the National Biotechnology Development Agency (NABDA), Abuja were used. A Randomized Complete Block Design was adopted in the study. The experiment covered two growing seasons -2021 and 2022. Three levels of garlic extract treatment, one level of mancozeb (synthetic fungicide) as the positive control, and de-chlorinated water application as the control. Each treatment was replicated thrice. Garlic extract at (100%, 50%, and 25%) and synthetic fungicide (mancozeb 3.33g/L) were used for field application. Cercospora leaf spot (CLS) and brown blotch cowpea diseases were obviously identified. The results indicated a significantly higher incidence (p≤0.05) of Cercospora leaf spot diseases on Sampea 20T at 8 and 10 WAS, with 52.47% and 55.20%, respectively. The incidence of BB disease at 8 and 10 WAS was also significantly higher (p≤0.05) in Sampea 20T at 50.80% and 63.90%, respectively, compared to other varieties. Abuja local (white) had significantly higher (p≤0.05) days to 50% flowering in the two seasons. The 100% garlic extract and mancozeb treatments significantly lowered (p≤0.05) CLS disease incidence and severity at 10 WAS on the field compared to other treatments and the control. This study highlights the effectiveness of environmentfriendly garlic extract for managing leaf spot and brown blotch diseases in cowpeas, the possibility in including it in an integrated approach to cowpea disease management.