Pathiraja, P. M. N. M.Damunupola, J. W.Athukorala, A. D. S. N. P.2026-01-082026-01-082024-08-29Proceedings of the Peradeniya University International Research Sessions (iPURSE) – 2024, University of Peradeniya, P 1761391-4111https://ir.lib.pdn.ac.lk/handle/20.500.14444/7416Postharvest diseases play a major role in food losses worldwide. Therefore, strategies for postharvest disease management are essential for sustainable food production. The use of biocontrol agents is one of the strategies presently used. This study focused on the isolation and characterization of (tomato) Solanum lycopersicum indigenous microflora from tomato fruit exocarp and screening their biocontrol ability against common postharvest pathogens isolated from tomatoes. Tomatoes were obtained from the Kandy market and the preferred variety was Roma variety. Potential biocontrol agents were isolated from healthy tomatoes using standard microbiological procedures. Pathogens were isolated using standard triple sterilization procedure and their pathogenicity on tomato epidermis was confirmed through Koch’s postulate. Dual culture assay, and in vitro assay (spore germination assay) were performed to screen the degree of pathogenicity and biocontrol ability. Equal volumes of spores of each biocontrol agent and pathogen spore suspension (equivalent to 1x10⁵) were inoculated onto the middle side of the tomato exocarp with each pathogen and biocontrol agent spore suspension individually inoculated as control. Healthy tomatoes yielded four fungal species, Yeast sp., Trichoderma spp., and two unidentified isolates as indigenous microflora, while Rhizopus sp., Botrytis sp., and Geotrichum sp. (Rhizopus rot, Gray mold disease, and sour rot disease respectively) were isolated as pathogens. Inhibition percentages by Trichoderma spp. against pathogens in vitro study were 39.06%, 27.84%, and 74.97% against Rhizopus sp., Botrytis sp., and Geotrichum sp. respectively. Trichoderma spp. and pathogen interaction revealed coil formation by Trichoderma spp. suggesting mycoparasitism as its mechanism of action. Trichoderma sp. caused a 90%, 100%, and 100% reduction in disease incidence compared to the control for each of the three pathogens tested in the tomato epidermis. This study revealed the potential of using indigenous microflora of tomato epidermis to control postharvest diseases.en-USAntagonisticIndigenous MicrofloraPostharvestTomatoTrichoderma sp.Article