Antifungal Effects of Crude Extracts of Moringa oleifera on Aspergillus niger V. Tieghem Associated with Post Harvest Rot of Onion Bulb

This studies was carried out to isolate, identify and establish the pathogenicity of fungi associated with post-harvest rot diseases of onion bulb, a crop which is highly perishable and seasonal in Nigeria, and to determine the effect of various concentrations of crude extracts from the stem and leaves of Moriga olifera in vitro on the causative agents . Fungi associated with onion bulb rots were isolated on Potato Dextrose Agar medium and their pathogenicity was established by testing for their ability to induce rot in healthy onion bulbs. Ethanol extracts of leaves and stems of Moriga olifera were then screened for the potential to control a strain of Aspergillus niger v. Tieghem which had the highest frequency of occurrence on onion bulbs. Plate and broth assays were used at 12.5%, 25%, 50% and 75% concentrations of extract in Potato Dextrose Agar and Potato Dextrose Broth respectively. The stem extracts inhibited the growth of the fungus at all concentrations tested. A progressive inhibition with increasing concentration of the stem extract was observed on both plates and broth cultures. On the other hand, lower concentrations (12.5%, 25%, 50%.) of leaf extract did not inhibit fungal growth on agar plates. Some level of inhibition was however observed at 75% concentration of leave extract. The reality of using antifungal plants to control most especially from moringa olifera is therefore highly recommended as bio protective agent on onion rot which serves as good option to chemical control.