Clove Essential Oil and Eugenol as Natural Antifungal Agents to Reduce Postharvest Losses in Melon (Cucumis melo)

Melon is a global crop with a value of USD 31 billion. However, up to 30% of yield is lost due to phytopathogens. Essential oils are a sustainable approach to crop protection and storage, enhancing food security and reducing agricultural losses. We evaluated the antifungal potential of clove essential oil and pure eugenol against Alternaria alternata, Curvularia hawaiiensis, Fusarium oxysporum f. sp. lycopersici (FOL), Fusarium solani f. sp. cucurbitae (FSC), Rhizoctonia solani, and Verticillium dahliae in vitro. We also evaluated the resistance of melons, including eugenol-poor Cucumis melo cv. vedrantais (CMV) and eugenol-rich C. melo cv. makuwa (CMM), to infection caused by FOL and FSC. Chemical analysis of clove oil reveals that eugenol was the main compound, at 89.28%. Clove oil and eugenol at 300 μg/mL reduced the growth of all fungal species. Pure eugenol exhibited the strongest antifungal activity, with 95–100% growth inhibition. Eugenol-rich melons did not show necrosis or internal rot when inoculated with FSC, and had minimal lesions, while eugenol-poor melons revealed more advanced rot symptoms. Clove oil and eugenol are antifungal alternatives that may improve food safety. These findings demonstrate the high potential of eugenol to reduce postharvest losses in melon and contribute to future breeding programmes aimed at developing contamination-resistant cultivars.