Essential Oils in the Alternative Control of Postharvest Diseases in Strawberries: Anthracnose and Gray Mold

Strawberry (<i>Fragaria</i> × <i>ananassa</i>) is one of the most perishable fruits, requiring care from harvest to consumer arrival. Gray mold and anthracnose are the diseases that most affect this crop in the postharvest period. Essential oils have bioactive compounds that may help maintain fruit quality and retard fruit decay. This study aimed to evaluate the essential oils of <i>Cymbopogon citratus</i> (DC.) Stapf, <i>Rosmarinus officinalis</i> L., <i>Cymbopogon winterianus</i> Jowitt., <i>Melaleuca alternifolia</i> (Maiden & Betche) Cheel, and <i>Cinnamonum camphora</i> var. <i>linaloolifera</i> in the control of postharvest phytopathogens <i>Botrytis cinerea</i> and <i>Colletotrichum acutatum</i> in <i>in vitro</i> and <i>in vivo</i> assays. The essential oils were extracted by steam distillation and chemically analyzed (GC-MS). The antioxidant activity of the oils was evaluated by inhibiting DPPH^• and ABTS^•+ radicals. The <i>in vitro</i> treatments were zero and polysorbate 0.20% v/v, 0.01%, 0.05%, 0.10%, 0.15, and 0.20% v/v of each essential oil, diluted in polysorbate 20 (1:1), using the PDA culture medium. The evaluations were performed by measuring the average diameter of the colonies at 3, 5, 7, 10, and 14 days. For the <i>in vivo</i> test, the treatments were sprayed on the fruits; the two best concentrations of the <i>in vitro</i> test were mixed with water and the surfactant polysorbate 20 (1:1). After incubation, disease severity was assessed visually using a diagrammatic scale. Firmness, pulp pH, soluble solid content, and titratable acidity were also assessed. The essential oils tested in this study demonstrated fungicidal effects on both phytopathogens, whose concentrations varied between 0.05% and 0.20% v/v. Regarding the antioxidant and antifungal effects, the essential oils of <i>C. citratus</i> and <i>C. winterianus</i> had the highest antioxidant capacity and the strongest antifungal effect, suggesting a potential link between these biological effects. The essential oil of <i>C. citratus</i> showed, at a concentration of 0.05% v/v, total control of the development of <i>B. cinerea</i> and <i>C. acutatum</i>. It also demonstrated better soluble solid content and titratable acidity, resulting in better fruit flavor, thus providing better productivity and quality of strawberry fruits.