Eco-friendly nanoparticle-based strategy for controlling Fusarium wilt in tomato using biosynthesized copper oxide nanoparticles

Fusarium wilt, caused by <i>Fusarium oxysporum</i> f. sp. <i>lycopersici</i> (Fol), severely limits tomato productivity, while excessive use of chemical fungicides raises environmental and resistance concerns. This study reports the green synthesis of copper oxide nanoparticles (CuO NPs) using neem (<i>Azadirachta indica</i> L.) leaf extract and evaluates their antifungal and growth-promoting effects. UV-vis, FTIR, and SEM analyses confirmed successful nanoparticle formation; the slightly blue-shifted UV-vis absorption band (250-320 nm), frequently observed in plant-mediated CuO NP synthesis, is attributed to phytochemical capping effects. The absence of XRD, TEM, and Zeta potential analyses due to laboratory limitations is acknowledged and discussed. <i>In vitro</i> assays showed enhanced germination and seedling vigor at 25 ppm, while antifungal activity increased in a dose-dependent manner, reaching 97.6% disease suppression at 100 ppm. Comparative controls-including neem extract alone and CuSO₄ solution-were included to distinguish nanoparticle-specific effects. Greenhouse trials demonstrated reduced wilt incidence, improved plant growth, and increased phenolic and proline accumulation, indicating activation of host defense pathways. Overall, neem-mediated CuO NPs functioned as dual-action agents-potent antifungals and growth stimulants-highlighting their novelty and potential as an eco-friendly, sustainable alternative to chemical fungicides for tomato wilt management.