Evaluation of antagonistic effects of ethanol leaf extract of Azadirachta indica on tuber rot pathogens of yam tuber

Abstract

One of the main constraints to yam availability in Nigeria is losses in storage due to fungal rot. The use of plant extracts for controlling yam rots had rather proved effective. Therefore, this study was conducted to investigate the effects of ethanol extracts of Azadirachta indica (A. Juss), on four isolated rot fungi: Aspergillus flavus, Aspergillus glaucus, Aspergillus niger and Botryodiplodia theobromae. Rot fungi were isolated from infected yam tubers and cultured on potato dextrose agar (PDA). Pathogenicity test was carried out by inoculating the fungal isolates into healthy yam tubers and these were observed for rot symptom while ethanol at varied concentrations were used as extractants on dried and pulverised leaves of the test plant. The effects of the extracts on the fungi were determined using poisoned food method. All the extracts were inhibitive at varied degrees as they significantly inhibited the mycelia growths of the pathogens both in vivo and in vitro with varied percentage inhibition, Both 10% and 50% ethanol extract of A. indica at 50g/100ml inhibited A. niger to 97.67% and 99.17% respectively. All the effects of the extracts on the rot pathogens were significantly different from the effects of the standard and control.