Essential Oil-Based Nanoemulsions as Sustainable Control Method Against Colletotrichum gloeosporioides and Neofusicoccum parvum on Citrus

Fungal diseases represent one of the major threats to citrus production, such as anthracnose caused by Colletotrichum gloeosporioides and Fungal Trunk Diseases (FTDs) associated with Botryosphaeriaceae, with Neofusicoccum parvum being the most prevalent species. In response to the need to reduce chemical fungicide use, this study evaluated the antifungal activity of essential oil-based nanoemulsions (N-EOs) as alternative management methods. Seven N-EOs (citronella, clove, fennel, garlic, laurel, lavender and peppermint) were first screened in vitro against multiple isolates of both pathogens through mycelial growth and conidial germination assays. Based on estimated EC50 and EC90 values, clove and garlic N-EOs exhibited the highest inhibitory activity, while lavender displayed intermediate but promising efficacy, particularly against N. parvum. These N-EOs were subsequently evaluated in vivo on lemon fruits inoculated with C. gloeosporioides and on detached lemon twigs inoculated with N. parvum. In vivo assays largely confirmed the in vitro trends, with clove and garlic significantly reducing lesion development. In contrast, lavender displayed limited efficacy under in vivo conditions. The phytotoxic effects at higher concentrations limited the range of applicable doses. Overall, the results suggest that N-EOs, particularly those based on clove and garlic, may offer potential as alternative tools for citrus disease management. However, host tissue interactions, formulation stability, volatility, and validation under field conditions remain critical aspects requiring further investigation.