Comparison of Thyme Oil Vapor and Thyme Guard Immersion on Peach Postharvest Brown Rot Control

Essential oils (EOs) offer a promising natural alternative to conventional postharvest fungicides, providing enhanced food safety and reduced environmental impact while minimizing the risk of pathogen resistance. In this study, we evaluated the efficacy of thyme oil (TO) fumigation and Thyme Guard (TG) immersion for controlling brown rot in peaches. Peaches were subjected to TO fumigation or TG immersion at varying concentrations and durations, and their antifungal activity, phytotoxic effects, and cultivar-specific sensitivities were assessed. Both treatments effectively reduced postharvest lesion development, but excessive concentrations and prolonged exposure led to phytotoxicity, with distinctly different symptoms observed for fumigation and immersion. Notably, TO fumigation at 250 ppm for 24 hours and TG immersion at 0.5% for 30 s followed by 2-hour air drying at 24 °C provided optimal disease management while minimizing phytotoxicity. This study highlights the importance of pretesting EO concentrations for different cultivars to ensure safe and effective postharvest applications. Given its lower cost and superior industrial feasibility, immersion was identified as a more practical approach than fumigation. Future research should focus on integrating EO treatments with other postharvest technologies to enhance the consistency and efficacy of disease management strategies.