Abstract:
Tomato (Solanum lycopersicum) is among the world’s eight most valuable agricultural
commodities, according to the Food and Agriculture Organization of the United Nations
(FAO). However, postharvest losses of tomatoes caused by fungi are a major problem.
Chemical fungicides have been widely used to control phytopathogenic fungi in tomatoes,
despite their potential risks to human health and the environment. This issue can be addressed
sustainably through the development of safer, eco-friendly alternatives such as plant-based
biocontrol agents. This study aimed to investigate the antifungal activity of the ethanolic leaf
extract of Moringa oleifera against three fungal species, Aspergillus flavus, A. niger and A.
fumigatus isolated from contaminated tomatoes. The fungal isolates were cultured on potato
dextrose agar (PDA) and identified through the microscope at the Biology Laboratory, South
Eastern University of Sri Lanka. M. oleifera extracts were prepared using the maceration
method. The antifungal activity was evaluated in vitro using the disk diffusion method to
determine the minimum inhibitory concentration (MIC) antimicrobial susceptibility. Results
revealed that ethanolic leaf extract of Moringa oleifera exhibited the maximum zone of
inhibition, measuring 9.73±0.08mm against A. niger and the second-highest inhibition zone
value against A. flavus which is 8.44±0.01mm and lowest inhibition zone against A.
fumigatus is 6.87±0.05 mm. The minimum inhibitory concentrations of the extract were
determined as 8.09 mg/ml for Aspergillus niger and Aspergillus flavus, and 16.18 mg/ml for
Aspergillus fumigatus. Treated and untreated (control) tomatoes were observed in vivo over
seven days to determine the disease severity on the fruit surface. Untreated tomatoes were
severely damaged by A. niger, showing deep fissures likely resulting from rapid enzymatic
degradation and tissue acidification. A. flavus induced localized epidermal breakdown,
whereas A. fumigatus displayed lower natural virulence in healthy fruit tissues. M. oleifera
extract was more effective against A. flavus and A. niger compared to A. fumigatus indicating
difference in fungal virulence and infection behaviour.
