Ultrasound-Assisted Hydrodistillation of Essential Oils for Eco-Friendly Biocontrol of Botrytis cinerea in Grapevines

Botrytis cinerea is a major fungal pathogen of grapevine responsible for gray mold, causing significant economic losses worldwide. Under specific environmental conditions, controlled development of Botrytis cinerea may lead to “noble rot,” a quality-enhancing attribute of premium wines; however, the same fungus can rapidly develop into destructive gray mold, causing significant grape losses. Consequently, the challenge is not necessarily the complete eradication of the pathogen, but the regulation of its development to prevent uncontrolled disease progression while preserving grape quality. The present study investigated the potential of using essential oils extracted from selected aromatic plants using ultrasound-assisted hydrodistillation (UAHD) as eco-friendly biocontrol agents against Botrytis cinerea. The extraction process was optimized by evaluating the effects of biomass particle size, ultrasonic power, and distillation time on essential oil yield. Antifungal activity was assessed through in vitro poisoned food and disk diffusion assays and validated in vivo on artificially inoculated grape berries by evaluating disease incidence, disease severity, treatment efficacy, and weight loss. Ultrasound pretreatment increased essential oil yield by up to 29.58% compared with conventional hydrodistillation, with optimal conditions achieved using 1 cm biomass, 150 W ultrasonic power, and 85 min distillation. Oregano, thyme, sage, and lemon balm essential oils achieved 100% inhibition of Botrytis cinerea mycelial growth at the tested concentrations, whereas lavender essential oil showed 95.03% inhibition at 0.125% and complete inhibition at 0.25%. In vivo, essential oil formulations markedly reduced gray mold development, with the 2.0% formulation providing the highest treatment efficacy and the lowest disease severity. These findings show that UAHD-derived essential oils represent promising sustainable alternatives for the management of Botrytis cinerea in viticulture. However, these findings represent preliminary evidence obtained under controlled in vitro conditions, necessitating further validation in real-world applications.