Natural solutions against <i>Botrytis cinerea</i> : Use of plant extracts and essential oils for postharvest apples preservation

Abstract Botrytis cinerea ( B . cinerea ) is a phytopathogenic fungus causing gray mold on postharvest apples. Fungicide application remains a conventional strategy against this pathogen. However, due to the impact of these chemical agents on human health and environment, new alternatives and safe management strategies are currently more preferred by farmers. Thanks to their potential antifungal effect against B . cinerea , plant extracts and essential oils (EOs) constitute promising natural solutions. This review aims to compile and analyze, for the first time, several studies testing the antifungal activity of plant extracts and EOs against B . cinerea both in vitro and in vivo on apples, with the goal of highlighting their importance and encouraging their use by farmers. Furthermore, the mechanisms of action are discussed. Additionally, the challenges related to practical applications and formulation stability are addressed. Overall, our review underscores the antifungal potential of different extracts and EOs against B . cinerea . Indeed, in vitro experiments showed that Cinnamomum zeylanicum and Satureja hortensis extracts induced 100% inhibition of mycelial growth, at the concentrations of 0.08 and 10%, respectively. Moreover, EO of Pelargonium graveolens (0.0003%) induced a total inhibition of B . cinerea mycelial growth using volatile activity assay. Additionally, in vivo assays revealed that Azadirachta indica extract resulted in up to 90% decrease in disease severity at the concentration of 25%. Besides, Eugenia caryophylata EO was also efficient in the in vivo test, showing 95% reduction in disease incidence at the concentration of 0.2%. Further studies are needed to prove the in vivo efficiency of all tested plant extracts and EOs. Furthermore, multi-target antifungal strategies, such as the combination of plant extracts and EOs with other biocontrol agents should also be developed in order to overcome the problem of fungal resistance to these natural compounds.