Synthesis and Characterization of CuO Nanoparticles with Differential Antifungal Activity Against Fusarium graminearum and Trichoderma harzianum

Copper oxide nanoparticles (CuO NPs) have attracted increasing interest in agriculture due to their antimicrobial properties and potential for sustainable plant disease management. In this study, CuO NPs were synthesized via chemical precipitation, and their antifungal activity and morphological impacts were evaluated against the phytopathogen Fusarium graminearum and the biocontrol agent Trichoderma harzianum. Comprehensive physicochemical characterization confirmed the formation of highly pure, quasi-spherical CuO NPs with an average size of 10.9 ± 0.7 nm as determined by TEM. Furthermore, Raman spectroscopy and X-ray diffraction (XRD) revealed a highly crystalline monoclinic tenorite phase (space group C2/c) with an average crystallite size of 9.6 ± 0.7 nm, confirming the single-crystal nature of the nanomaterial. The CuO NPs exhibited marked antifungal activity against F. graminearum, achieving 100% growth inhibition at 500 ppm, accompanied by severe hyphal deformation and cell wall collapse. In contrast, T. harzianum showed tolerance, maintaining growth up to 800 ppm. SEM analysis revealed that under sublethal stress, both fungi differentiated vegetative mycelium into chlamydospores as a survival strategy. Furthermore, a low concentration (50 ppm) of CuO NPs stimulated T. harzianum sporulation by 30.4% relative to the control, consistent with a hormetic-type response. These findings highlight a differential sensitivity of the two fungi to CuO NPs in vitro. While the nanoparticles effectively inhibit the phytopathogen, the beneficial biocontrol fungus exhibits remarkable tolerance. Although these results provide a promising basis for exploring the combined use of CuO NPs and T. harzianum-based biofungicides, further in vivo studies evaluating this interaction with the plant are necessary to confirm their compatibility and efficacy in sustainable integrated disease management.