Nanoformulations containing rosemary oil for gray mold control in strawberries

Abstract

Gray mold, caused by Botrytis cinerea, affects strawberry crops (Fragaria x ananassa) and can cause major losses. Managing the disease with fungicides can harm health and the environment and can lead to the selection of pathogens resistant to their active ingredients. The use of essential oils (EOs) represents an alternative control method due to their richness in antimicrobial compounds, such as rosemary EO (Rosmarinus officinalis). However, the high volatility of several components of these oils makes commercial use difficult, and nanoencapsulation presents a technology to increase stability. In the present study, three formulations containing rosemary EO—nanoemulsion (NE), nanostructured lipid carrier (NLC), and nanocapsules with chitosan (NC)—were evaluated on strawberry fruits and against the fungus. The nanoformulations retained their characteristics (mean values: size 142 nm; polydispersity index 0.131; pH 4.99; zeta potential -20.2 mV for NE and NLC, and 19.1 mV for NC) when stored at 40 °C for 60 days. All nanoformulations had a direct effect on spore germination and mycelial growth of B. cinerea, possibly due to damage caused to the cell wall and plasma membrane, and changes in the pathogen's oxidative balance. NE containing 2 % EO, when applied by immersion, reduced the incidence and severity of the disease by around 40 % and 70 %, respectively, 6 days after treatment. The fruits treated with this formulation maintained their physicochemical characteristics for longer. Thus, the use of rosemary oil from NE can be an option for managing gray mold and increasing the shelf life of the fruits.