Antifungal activity of some essential oils against the post-harvest fungal pathogens of guava (Psidium guajava L.)

Guava (Psidium guajava L.) is a nutritionally and medicinally valuable fruit, but postharvest losses are primarily caused by fungal pathogens at various stages of harvesting. Chemical fungicides, while effective, pose risks to human health and the environment, prompting the search for natural alternatives. Essential oils from aromatic plants have demonstrated significant antifungal properties, making them potential substitutes for synthetic fungicides. This study evaluated the antifungal efficacy of essential oils against postharvest fungal pathogens isolated from guava fruit. A total of eight fungal species were identified: Alternaria alternata, Aspergillus flavus, Aspergillus niger, Aspergillus versicolor, Colletotrichum gloeosporioides, Monilia fruticola, Penicillium sp, and Pestalotia psidii. Essential oils from Acorus calamus, Callistemon citrinus, and Juniperus indica were tested against A. alternata, C. gloeosporioides, and P. psidii. Essential oils were extracted through hydrodistillation using Cleavinger’s apparatus, followed by GC-MS analysis to characterize their physicochemical properties relevant to antifungal activity. All tested oils significantly inhibited mycelial growth, with A. calamus exhibiting complete inhibition at 20 μl/ml and 40 μl/ml concentrations. These findings highlight the potential of A. calamus essential oil as a natural fungicide to control postharvest fungal pathogens. However, further in vivo research is necessary to assess its efficacy under storage conditions, along with evaluations of toxicity, sensory impact, and economic feasibility for commercial application.