Antifungal Activities and Mode of Action of Cymbopogon citratus, Thymus vulgraris, and Origanum heracleoticum Essential Oil Vapors against Botrytis cinerea and Their Potential Application to Control Postharvest Strawberry Gray Mold

Gray mold caused by Botrytis cinerea is one of the most destructive postharvest decay of strawberry fruit. The present study aims to identify essential oils with antifungal activity against B. cinerea and the underlying mechanisms and their potential application in controlling postharvest decay. In the screening test, essential oils from Cymbopogon citratus (Cc), Thymus vulgraris (Tv), and Origanum heracleoticum (Oh) exhibited maximum inhibition of B. cinerea mycelial growth. The three essential oils altered the hyphal morphology and ultrastructure and resulted in many blebs around the hyphae. The essential oils damaged the plasma membrane of B. cinerea cells and resulted in the leakage of intercellular nucleic acids, proteins and soluble sugars. The exposure of strawberries to the vapors of these three essential oils in commercial package reduced gray mold, with Tv and Oh exhibiting strong efficiency and disease index reduction by 53.85% and 57.69%, respectively. Oh also inhibited postharvest decay and maintained fruit quality, preventing weight loss and soluble solid degradation. The study proposes using plant essential oils as an alternative to chemical fungicides in controlling the gray mold of strawberries.