Characterization and efficacy of green-synthesized silver nanoparticles against Puccinia species - in vitro

Puccinia species cause substantial losses in wheat production and productivity across the globe, creating a serious challenge to food security. The environmental and health risks associated with conventional fungicides necessitate sustainable alternatives. The present study examines the eco-friendly synthesis of silver nanoparticles (AgNPs) employing Eucalyptus globulus leaf extract through a biological reduction approach and evaluates antifungal efficacy against wheat rust pathogens. GC-MS identified bioactive compounds in the phytoextract, primarily alkaloids and flavonoids. UV-visible spectroscopy confirmed AgNPs formation. Fourier transform infrared spectroscopy, Scanning electron microscopy, X-ray diffraction, dynamic light scattering, and zeta potential analysis established their functional groups, surface morphology and size (22–50 nm), crystalline nature, and colloidal stability. In vitro antifungal activity against P. graminis , P. triticina , and P. striiformis was evaluated by cavity slide method. AgNPs exhibited dose-dependent inhibition of uredospore germination, achieving 98.49 ± 0.3% suppression of P. graminis , 98.38 ± 0.3% of P. striiformis , and 99.71 ± 0.2% of P. triticina at 40 ppm. The use of a single green-synthesized AgNP system against all three major wheat rust pathogens highlights its potential as a broad-spectrum approach for wheat rust management. These findings highlight the potential of Eucalyptus -derived AgNPs as an eco-friendly alternative for the management of wheat rust pathogens under in vitro conditions. However, further greenhouse and field studies are required to validate their efficacy, phytotoxicity, and environmental safety before agricultural application.