Abstract

Cowpea (Vigna unguiculata [L.] Walp) is an important food legume in tropical and sub-tropical Africa. It is grown for food, fodder, a cover crop and consumed as dried seeds rich in carbohydrates, proteins and vitamins. Production of cowpea has not been practiced on a large scale in the forest/savanna transition agro ecology of Nigeria due to high relative humidity, diseases and insect damage. In 2012 and 2013 cropping seasons, twelve cowpea varieties were assessed on the field for their adaptation to the forest/savanna transition agroecology of Osun State Nigeria. Three foliar diseases (cowpea bacterial blight disease, cowpea mosaic diseaseand cowpea leaf spot disease) and level of insect damage on leaves were observed under natural infections. At sixty days after sowing (60DAS), all cowpea varieties tested showed varying degrees of infections by cowpea bacterial blight disease, cowpea mosaic disease, cowpea leaf spot disease and insect damage. Number of flowers produced per plant per week was not significantly different (P≤0.01) among the varieties. Variety sample 5 showed the least level of infection by the three foliar diseases while the number of pods produced per plant per week was highest in TVX 3236 and least in Dan Borno (88 DAS). Insect damage was least in sample 6 and TVX 3236 but highest in sample 7. Proper management of these three important foliar diseases will enhance the production of some of the promising varieties in the forest/savanna transition agroecology of Osun State.

Key words: Cowpea, adaptation, foliar diseases, forest/savanna transition agroecology.