Elucidation of the mechanism of action of essential oils to control postharvest diseases of apples and peaches
Davide Spadaro: DISAFA and AGROINNOVA, University of Torino
<div>Essential oils are considered a powerful and natural resource to control postharvest pathogens of pome and stone fruit. The efficacy of these natural products has been deeply investigated <em>in vitro </em>but only few of them are applied <em>in vivo</em>. Essential oils can be applied by dipping, spraying, or fumigation the fruit surface. Thyme and savory essential oils were successfully applied through biofumigation at 0.5% and 0.1% against brown rots on nectarines and peaches. The application of thyme or savory essential oils favored a reduction of brown rot incidence, caused by <em>Monilinia fructicola</em>, but an increase of gray mold, caused by <em>Botrytis cinerea</em>. Tests <em>in vitro </em>confirmed that<em> M. fructicola</em> was more sensitive to essential oil vapors than <em>B. cinerea.</em> Essential oil volatile components were characterized in storage cabinets during postharvest. The antifungal components of the essential oils increased during storage, but they were a low fraction of the volatile organic compounds in storage chambers. In addition to direct inhibition of pathogen growth, essential oils can induce resistance in the fruit host. Thyme essential oil can promote the expression of the pathogenesis related gene PR-8 in apple, which is involved in host defense response. Moreover, essential oils showed a positive role in slowing down senescence processes reducing weight loss and preserving vitamin C and carotenoid content during storage.</div>
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