Use of Cinnamon Essential Oil Nanoemulsions to Manage Gray Mold in Tomato

Gray mold, caused by the fungus Botrytis cinerea, significantly reduces tomato yield and quality. The use of essential oils (EOs), here formulated as nanoemulsions, offers a safe and eco-friendly strategy to manage gray mold without conventional pesticide application. This study evaluated the antifungal effect of cinnamon essential oil nanoemulsion (EONE) against B. cinerea in vitro and its impact on plant physiological health and gray mold suppression in planta. EONE-treated media significantly reduced B. cinerea mycelial growth area compared with nontreated controls, with greatest inhibition observed at 3 days postinoculation (potato dextrose agar: 88.67%, P < 0.01; V8 agar: 54.57%, P < 0.01). In tomato plants, roots were treated with EONE prior to foliar inoculation with B. cinerea. EONE showed no adverse effects on physiological parameters of noninoculated plants. Inoculated plants exhibited reduced Fv/Fm, chlorophyll content, and normalized difference vegetation index compared with noninoculated plants, but these effects were mitigated in EONE-treated plants, particularly at 200-μl application volume. Cinnamon EONE, applied at volumes ranging from 200 to 2,000 μl (5.98 to 59.38 mg/liter cinnamon EO), suppressed gray mold lesion area by up to 44.50% compared with the B. cinerea-inoculated control. Evaluation of individual EONE components showed that inert ingredients had no significant plant-protective or disease-suppressive effects. Although unformulated EO was more effective in suppressing disease lesion area in the short term (plants inoculated 24 h posttreatment), EONE provided longer-lasting protection when inoculated 5 days posttreatment. These findings suggest that cinnamon EONE is a promising tool for managing B. cinerea, with potential for a long-term protective effect in disease management.