Myco-synthesized copper oxide nanoparticles as a sustainable bionanofungicide for managing Fusarium falciforme and enhancing potato productivity

Abstract Developing sustainable alternatives to chemical fungicides is imperative for sustainable agriculture. This study establishes a green nanotechnology approach by harnessing the biocatalytic potential of indigenous rhizosphere fungi to synthesize copper oxide nanoparticles (CuONPs). A consortium of soil-borne fungi, including Mucor circinelloides , was isolated from agricultural soils in Tanta, Egypt, and employed in the myco-synthesis of CuONPs. Comprehensive characterization confirmed the formation of crystalline, spherical nanoparticles (average size: 10.7 nm). The nanoparticles exhibited notable, dose-dependent antifungal activity in vitro, suppressing mycelial growth of the potato pathogen Fusarium falciforme by 33.95%, significantly outperforming bulk copper sulfate. Based on preliminary dose–response trials, 200 mg L − 1 was selected as the optimal concentration balancing antifungal efficacy and absence of phytotoxicity. In a greenhouse trial, foliar application of myco-synthesized CuONPs (200 mg L − 1 ) to F. falciforme -infected potato plants mitigated disease-induced growth inhibition, restored photosynthetic pigment levels, and rebalanced antioxidant enzyme systems, primarily enhancing catalase activity. Significantly, CuONPs supported protein homeostasis under stress and, most importantly, boosted tuber yield by up to 40% in healthy plants and appeared to restore productivity in infected ones. In contrast, the commercial fungicide showed phytotoxic effects on tuber initiation. This work establishes myco-synthesized CuONPs as a novel, dual-action agent for plant protection and growth promotion, offering a sustainable and effective strategy for integrated disease management.