The solvent-dependent efficacy of moringa leaf extract as an antifungal ingredient of organic coatings for citrus fruit
Application of chemical fungicides and waxes on fresh horticultural produce receive consistent criticism because they pose residual threats to consumer's health, are expensive, and cause environmental pollution. In this study, moringa (Moringa oliefera) leaf extract (MLE) extracted using pure water (0MLE), 50% ethanol (50MLE), 80% ethanol (80MLE) or 100% ethanol (100MLE) was assessed as organic antifungal agent for suppressing Penicillium digitatum, a nuisance fungus causing green moulds of citrus fruit in postharvest storage. The potato dextrose agar for in vitro experiment was amended with 3 mL of the extracts per 140 mL to make up the final concentration of 0.83% medium in which isolates of P. digitatum were placed. Prepared PDA plates were incubated at 25°C and radial mycelia growth was measured daily until the growth in control treatment filled the plates. The solvent concentration had a significant (p<0.01) effect on the antifungal activity of the extracts. The percentage inhibition of the pathogen mycelial spread by the extracts relative to the control was 45.68% for 0MLE, 45.57% for 100MLE, 43.07% for 50MLE, and 39.91% for 80MLE on the final day of in vitro test. Incorporation of a water based MLE in formulation of postharvest organic coatings was recommended because it had higher antifungal activity against P. digitatum and is relatively cost effective.
Ncama, K., Magwaza, L.S., Mditshwa, A., Tesfay, S.Z. and Mbili, N.C. (2021). The solvent-dependent efficacy of moringa leaf extract as an antifungal ingredient of organic coatings for citrus fruit. Acta Hortic. 1306, 317-322
Penicillium digitatum, organic fungicides, plant extracts