FUNGITOXIC EFFECT OF AZADIRACHTA INDICA AND VERNONIA AMYGDALINA EXTRACTS ON ASPERGILLUS NIGER AND FUSARIUM OXYSPORIUM THE CAUSAL ORGANISMS OF YAM (DIOSCOREA ROTUNDATA) ROT

Abstract

This study investigated the antifungal effects of Azadiratcha indica and Vernonia amygdalina (leaf extract) on rot causing organisms of yam: Aspergillus niger and Fusarium oxysporium. Pathogenicity test showed that all the four tested organisms induced rot in healthy yam tubers, with Aspergillus niger (74%) being the most virulent while Rhizopus stolonifer (10%) was the least virulent. Although, all the extracts showed varying degrees of antimycotic efficacy, there was no significant difference across the organisms tested .The potency of the extracts varied with plant material, extraction medium and concentration of the extract. Inhibition of fungal growth increased with a corresponding increase in the concentration of extract. Azadiratcha indica roved to be more effective than Vernonia amygdalina. Methanolic extract of Azadiratcha indica (80.88  2.84) was the most fungitoxic and significantly better than other interactions. The significance of these findings was discussed in relation to biological control method of yam rot using leaf extracts (Azadiratcha indica and Vernonia amygdalina).

Keywords

• Antifungal effect,
• yam
• rot
• plant extract