Incidence and severity of Fusarium wilt on Bambara nut (Vigna subterranea L.) landraces in Western Kenya

Abstract

Bambara nut, Vigna subterranea (L.) Verdc. is one of the indigenous legume crops grown in Kenya. The crop is highly nutritious and drought tolerant with the ability to produce higher yields than other legumes such as common groundnuts and beans produced under the same conditions. Bambara nut demand is on the increase due to the current focus on neglected underutilized crop species. The crop yield is however low because of biotic stresses among others. Fusarium oxysporum Schlechtend f.sp. voandzeia is one of the most destructive fungal pathogens affecting Bambara nut in Kenya. A greenhouse experiment was therefore carried out to determine the incidence and severity of the disease on local landraces of Bambara nut. The experiment was laid out in a completely randomized design replicated three times. Disease incidence and severity varied significantly with landrace. The maroon speckled and brown dark eyed landraces had the highest disease incidences (80.5% and 80.0%). Followed by brown light eyed, maroon and black landraces with diseases incidences of 79.5%, 78.9% and 78.6% respectively and lastly the red landrace with least disease incidence of 76.2%. Disease severity also varied with landrace. The maroon followed by the brown dark eyed landraces had the highest disease severities of 45.5% and 44.3% then the red, maroon speckled and black landraces with severities of 43.5%, 43.1% and 42.8% respectively. The Brown light eyed landrace had the least disease severity of 42.6%. There was a significant interaction between landrace and days after inoculation with respect to disease severity. At 75 days after inoculation disease severity was similar for all the landraces with approximately 40% severity. The area under disease progress curves (AUDPC) varied with landrace. The Maroon landrace had the highest AUDPC while the Brown landrace had the least area. The study confirmed the virulence of the pathogen on the crop and the need to manage the disease for improved yield performances.