(181d) Use of Cinnamon Essential Oil Nanoemulsions to Manage Gray Mold in Tomato

Gray mold, caused by the necrotrophic fungal pathogen Botrytis cinerea, considerably reduces tomato yield and quality. Essential oils (EOs), when formulated as nanoscale emulsion droplets or nanoemulsions, present a sustainable and environmentally friendly alternative to conventional chemical fungicides. This study investigated the antifungal properties of a cinnamon essential oil nanoemulsion (EONE) against B. cinerea under both in vitro and in planta conditions. In vitro experiments demonstrated that EONE-treated media significantly limited fungal growth relative to untreated controls, with the most pronounced inhibition occurring three days after inoculation (88.67% reduction on PDA; 54.57% on V8 agar). For in planta trials, tomato roots were treated with EONE before leaflet inoculation with B. cinerea. EONE application did not negatively impact the physiological health of non-inoculated plants. In infected plants, typical declines in Fv/Fm, chlorophyll levels, and NDVI were observed, yet these physiological effects were notably alleviated by EONE treatment. Cinnamon EONE applied in volumes between 200 and 2000 µL—corresponding to 5.98 to 59.38 mg/L EO—was able to reduce lesion area caused by gray mold by up to 44.50% compared to infected controls. The individual ingredients of the nanoemulsion were also assessed, with inert components showing no significant protective or antifungal activity. While unformulated EO provided greater immediate suppression of lesion formation when inoculation occurred 24 hours post-treatment, the EONE formulation exhibited superior sustained protection, especially evident when inoculation took place five days after treatment. These results highlight the cinnamon EONE as a promising candidate for managing B. cinerea infections, offering a potentially durable solution for disease suppression in tomatoes