Dual Antifungal and Insecticidal Field Performance of Paulownia tomentosa –Derived Silver Nanoparticles Against Fusarium Basal Rot and Thrips in Onion

ABSTRACT

Plant‐derived nanomaterials have traditionally been recognised as green alternatives for the management of plant diseases and insect pests. The present study has been designed to evaluate the bio‐efficacy of the Paulownia plant extract as a reducing agent for silver nanoparticle (AgNP) synthesis in addition to its bioactivity against Fusarium basal rot (FBR) and onion thrips. Biosynthesised AgNPs were well‐characterised by UV–Vis spectroscopy, X‐ray diffraction, Fourier transform infrared, energy‐dispersive X‐ray spectroscopy, and scanning electron microscopy. Although there was very little efficacy from the use of Paulownia extracts alone, which resulted in inhibition levels of 12.8% against Fusarium oxysporum and 12.22% against thrips at 50 µg/mL, the biosynthesised AgNPs were highly active against F. oxysporum , exhibiting a 32.8%–100% inhibition of growth, and had an insecticidal effect that ranged up to 98%. Further, AgNPs suppressed FBR by 86.67%–88.42%, improved onion bulb quality, and significantly enhanced both bulb number and weight, 191.53 kg total, compared with untreated infected plants showing the lowest yield (76.4 kg). Thus, the present outcomes have emphasised that Paulownia ‐based AgNPs are an efficient and eco‐friendly nanobiotechnological approach towards improving plant health and crop yields.