Nanoemulsions of Selected Plant Oils for Controlling Root-Knot Nematode and Fusarium in Tomato

Tomato (Solanum lycopersicum L.) productivity is severely affected by soil-borne pathogens, particularly the root-knot nematode Meloidogyne incognita and the fungus Fusarium foetens. This study developed and evaluated nanoemulsion formulations of selected plant oils as eco-friendly biocontrol agents. Nanoemulsions of neem (Azadirachta indica), camphor (Cinnamomum camphora), castor (Ricinus communis), and fenugreek (Trigonella foenum-graecum) oils were prepared in three systems: oil in water nanoemulsion (NE), chitosan coated nanoemulsion (CS-NE), and chitosan silver nanoparticle-loaded nanoemulsion (CS-AgNP-NE). Characterization confirmed the formation of stable, spherical nano droplets (<30 nm) with high positive zeta potential values (> +27 mV). GC–MS analysis identified key bioactive compounds associated with nematicidal and antifungal activities. Pathogenicity screening of 58 fungal isolates revealed F. foetens as the most virulent species. In bioassays, the neem oil loaded chitosan silver formulation (Neem-CS-AgNP-NE) exhibited the highest efficacy, achieving 91.4% mortality of M. incognita juveniles at 400 ppm with an EC₅₀ of 46.13 ppm, and inhibiting F. foetens mycelial growth by 89.7%. Camphor formulations also showed strong activity, while castor and fenugreek nanoemulsions produced moderate inhibition. These findings demonstrate that CS-AgNP nanoemulsions are a promising, eco-friendly platform for delivering plant derived bioactives to manage key soil borne diseases.