Biological Efficiency of Calotropis procera Extracts Against the Growth of Selected Fungal Plant Pathogens

Plant secondary metabolites and plant-based fungicides appear to be one of the better alternatives as they are known to have negligible environmental impact and health hazard to consumers, compared with synthetic pesticides. This study aimed at assessing the antifungal activities of crude extracts obtained from leaf, stem bark, and roots of Calotropis procera against the fungal pathogens Aspergillus niger, Fusarium oxysporum, and Fusarium solani. The stems, roots, and leaves of the selected plant species were shade-dried and ground to powder, and the bioactive components were extracted using ethanol (99.5%), hexane (99.8%), and distilled water. The antifungal activity of the extracts against the three selected pathogens were evaluated using the agar-well diffusion method and inhibitory zones were measured in millimeters at four different concentration levels (30, 40, 50, and 60 mg/ml). Carbendazim and sterile distilled water were used as positive and negative controls, respectively. Among the selected plant materials, stem bark extracts showed the highest yield (10.45%) in ethanol crude extracts, whereas, the lowest yield (1.45%) was for water crude extract from the roots. The bioassay studies revealed that the crude extracts of ethanol, hexane and water had antifungal activity on all three fungal species at all concentrations and with all solvents. Ethanol extracts had the highest growth inhibitory effects as compared to those of the hexane and water crude extracts. In this study, the selected solvent crude extracts had fewer antifungal activities than carbendazim. A. niger, F. oxysporum, and F. solani growth was highly affected by ethanol leaf extract as compared with hexane and water extracts. Conversely, stem bark hexane extract showed higher antifungal activity only against F. oxysporum. In this study, among the selected plant parts of C. procera, leaves showed the highest antifungal activity compared with stem bark and root extract. Keywords: Antifungal, Calotropis procera, organic solvents, plant pathogens.