Exploring the Antifungal Potential of Plant Extracts against Pathogenic Fungi

The present study was undertaken to evaluate the in vitro potential of aqueous extracts of plant leaves to inhibit pathogenic fungi. The activities of plant extracts have been shown to be environmentally friendly and effective against plant pathogens. The effect of leaf extract and concentration on growth inhibition of organism I (Aspergillus flavus) in vitro revealed that a concentration of 100g/mL, Moringa oleifera leaf extract (MLE) gave the highest growth inhibition (59.14) followed by Neem (Azadirachta indica) leaf extract (NLE) (49.70) and Bitter leaf (Vernonia amygdalina) extract (BLE) (45.84) respectively while the least growth inhibition on organism 1 (Aspergillus flavus) was by MLE at concentration of 40 g/mL (30.11) followed by NLE at 60 g/mL (32.11) and BLE at 40 g/mL (40.13). On organism 2 (Penicillium waksmanii), MLE at a concentration of 100 g/mL gave the highest growth inhibition of (50.49) followed by NLE (49.01) and BLE (36.72) respectively while the least inhibition on growth of organism 2 in vitro was by BLE at concentration of 60 g/mL (16.05) followed by MLE (40.70) and NLE (40.70) at concentration of 80 g/mL respectively. On organism 3 (Botryodiplodia theobromae), MLE at concentration of 100 g/mL gave the highest inhibition of growth (57.00) followed by NLE (52.71) and BLE (50.15) respectively while the least inhibition on growth of organism 3 in vitro was by BLE at 40 g/mL (21.50) followed by MLE at 60 g/mL (31.06) and NLE at 40 g/mL (41.89). On organism 4 (Fusarium oxysporum), the BLE at 100 g/mL (44.41) while MLE showed the least growth inhibition at 60 g/mL (24.04) followed by BLE at 40 g/mL (26.60) and NLE at 40 g/mL (30.12). The aqueous extracts of leaves of Moringa oleifera, Azadirachta indica and Vernonia amygdalina were found to be effective in inhibiting the radial growth of the fungal organisms in vitro, with inhibition varying from one extract to another. NLE showed the highest grand inhibitory effect of extract concentration on growth inhibition of organism 5 (Colletotrichum asianum) in vitro at 100 g/mL (53.68) followed by MLE at 100 g/mL (51.51) and BLE at 100 g/mL (40.94). The least inhibitory effect on the growth of organism 5 in vitro was by BLE at 80 g/mL (21.26) followed by NLE at 40 g/mL (22.25) and MLE at 40 g/mL (32.69). The controls ranged from 2.23 to 4.31 across all extract concentrations and fungal isolates. There were significant differences in growth inhibition between extract concentrations and their controls on all fungal isolates. The use of plant extracts provides an alternative means for controlling plant pathogenic fungi. This is an important step in developing plant-based biopesticides as ideal treatments for future plant disease management programmes. These botanicals are not only environmentally friendly, cost-effective, easy to produce and easy to apply formulations, but they are also safe for consumers and provide alternative means for controlling plant pathogenic fungi.