Abstract

The antifungal effects of ethanolic and aqueous extracts of Vernonia amygdalina, Gongronema latifolium and Ocimum gratissimum were investigated against fungi associated with the spoilage of cocoyam. Standard mycological and agar-well diffusion methods were used to isolate the fungi associated with the spoilage of cocoyam and to determine the antimicrobial effect of the plant species. Five fungi species were isolated from spoiled cocoyam which included Aspergillus flavus, Aspergillus fumigatus, Mucor hiemalis, Aspergillus versicolor and Rhizopus stolonifer. The fungitoxic effect of the plant extracts was determined by zone of inhibition (mm) at three concentrations of 100mg/ml, 75mg/ml and 50mg/ml. The diameter zones of inhibition for Ocimum gratissimum extract ranged from 6mm – 24mm, Vernonia amygdalina 6mm – 22mm, while that of Gongronema latifolium ranged from 6mm – 22 mm. The diameter of growth inhibition zone was different at varying concentrations for the plant extracts used. However, extract of O. gratissimum showed higher diameter growth inhibition zones than extract of G. latifolium and V. amygdalina at all concentrations used. It was observed that the inhibitory activity of the plant extract increased with increase in the concentration of the extracts. The fungicidal attribute evidenced in this study can be useful to identify the plant extracts that would act as fungicides in the control of fungal spoilage of cocoyam.