Silver nanoparticles were biosynthesized using three plant extracts i.e., Neem, garlic, and
lemongrass. Silver nanoparticles were formed by treating aqueous solution of AgNO3 with plant
leaf extracts as reducing agent of Ag+
to AgO. The synthesized silver nanoparticles were
characterized with transmission electron microscopy (TEM), Dynamic Light Scattering- nano
sizer (DLS) and Zeta potential. In vitro, Neem AgNPs at concentration 800 µL/L inhibited
completely the mycelium growth and sporulation of Fusarium oxysporum f.sp. lycopersici
(FOL). Silver Nanoparticle synthesized by neem extract was the most effective treatments in
decreasing disease incidence and severity. Moreover, increased the fresh and dry weight of shoot
and root of treated plants. Results revealed that plants treated with silver nanoparticles exhibited
an increase in activities of defense enzymes such as peroxidase, polyphenol-oxidase, chitinase,
phenylalanine ammonia and phenol contents over the control plants. In this respect, silver
nanoparticles synthesized by neem extract also were the best treatment. The present results
suggest that silver nanoparticles synthesized by plant extracts had fungicidal activity, and it
could be an efficient, safe and affordable alternative to chemical fungicides.