Vol. 9, Special Issue 10, Part T (2025)

Potato (Solanum tuberosum L.) is a key vegetable crop worldwide. Late blight, caused by Phytophthora infestans, remains the most devastating disease of potato, famously causing the Irish Famine of 1845. The present study, conducted at the Department of Plant Pathology, Chandra Shekhar Azad University of Agriculture and Technology, Kanpur (2023-24 to 2024-25), investigated the efficacy of biologically synthesized silver and copper nanoparticles from Trichoderma harzianum at concentrations of 50, 75, 100, and 125 ppm for inhibiting P. infestans radial mycelial growth under in vitro conditions. Nanoparticles were synthesized by mixing cell-free T. harzianum culture filtrate with either aqueous silver nitrate or copper sulphate solution, followed by incubation and recovery of nanoparticles through centrifugation and drying. At 7 days after inoculation (DAI), silver nanoparticles at 125 ppm exhibited the highest inhibition of radial growth, with up to 87.8% reduction compared to control, while copper nanoparticles at the same concentration achieved 77.2% inhibition. Lower concentrations also showed moderate effectiveness (AgNPs at 100 ppm: 73.6% inhibition; CuNPs at 100 ppm: 65.4% inhibition). These findings demonstrate that T. harzianum-derived silver and copper nanoparticles, especially at higher concentrations, have strong antifungal activity against P. infestans, highlighting their potential as eco-friendly alternatives to chemical fungicides for late blight management.