Antifungal metal structures, using silver at nanoscale, were synthesized using leaves extract of two indigenous trees i.e., Morus alba (white mulberry) and Aegle marmelos (bael fruit). The antifungal characteristics of synthesized silver nanoparticles (AgNPs) was verified against Fusarium oxysporum, the causal agent of Fusarium wilt and Macrophomina phaseolina, the pathogen of charcoal rot, taking tomato as a model plant. Synthesized nanoparticles were checked against selected fungi in concentrations of 25, 50, 75 and 100 μg/mL. Negative control received no nanoparticles but sterilized water, whereas positive control plants were treated with chemical fungicide (Nativo). Result of in vitro and greenhouse experiments confirmed the potential of synthesized nanoparticles to reduce fungal growth and disease incidence. However, the NPs synthesized using leaves extract of white mulberry were more effective. In green house trials, the plants treated with NPs in a concentration of 100 μg/mL showed parallel results as were recorded in plants receiving fungicide. Similarly, both selected fungi also depicted slight variation in their responses towards various treatments as percentage of growth inhibition as well as disease incidence was more in F. oxysporum than in M. phaseolina. UV-spectrophotometer ascertained the optimization conditions by adjusting concentrations of silver nitrate between 1, 1.5, 2, 2.5 and 3 mM, incubation period of 24, 48, 72 and 96 h and pH of biosynthesis system adjusted at 4, 6, 8, 10 and 12. FTIR confirmed the presence of different functional groups available both in plant extracts and nanoparticles while, SEM indicated spherical, polydisperse morphology of AgNPs with size ranges from 20–48 nm respectively. In pot experiment nanoparticles synthesized using white mulberry leaves reduced fusarium infection up to 97% and macrophomina rot up to 92%. Nanoparticles synthesized using bael leaves extract were comparatively less effective against selected fungi than those synthesized using white mulberry leaves extract. Hence these results provided basis for the use of green synthesized NPs using white mulberry leaves extract as an alternative to conventional fungicides to help reduce environmental pollution. © 2021 Friends Science Publishers