Sustainable use of nanotechnology in crop protection requires an understanding of the plant’s life cycle, potential toxicological impacts of nanomaterials and their mechanism of action against the target pathogens. Herein, we show some properties of a candidate antifungal nanocomposite made from copper oxide (CuO; otherwise an essential soil nutrient) nanoparticles (NPs), with definite size and shape, decorating the surface of reduced graphene oxide (rGO) nanosheets. The successful preparation of the rGO-CuO NPs was confirmed by spectroscopic and microscopic analyses, and its antifungal activity against wild strains of Fusarium oxysporum affecting tomato and pepper plants was successfully confirmed. A comparative analysis in vitro indicated that this nanocomposite had higher antifungal activity at only 1 mg/L than the conventional fungicide Kocide 2000 at 2.5 g/L. Further investigation suggested that rGO-CuO NPs creates pits and pores on the fungal cell membranes inducing cell death. In planta results indicated that only 1 mg/L from the nanocomposite is required to reduce Fusarium wilt and root rot diseases severity below 5% for tomato and pepper plants without any phytotoxicity for about 70 days. Comparatively, 2.5 g/L of Kocide 2000 are required to achieve about 30% disease reduction in both plants. The present study contributes to the concept of agro-nanotechnology, showing the properties of a novel ecofriendly and economic nanopesticide for sustainable plant protection.

The extensive use of agrochemicals for crop protection is increasing their environmental risks. Due to the incredible antimicrobial potential of nanomaterials, research into their potential use in sustainable agriculture as alternatives to chemical fungicides is advancing rapidly. In this study, we evaluated the possible antifungal properties of copper oxide nanocomposite (CH@CuO NPs) coated with chitosan in order to fend off Fusarium wilt diseases in tomato plants caused by F. oxysporum f. sp. lycopersici (FOL) throughout in vitro and in vivo experiments. Here, we demonstrate some of the characteristics of a potential antifungal nanocomposite composed of copper oxide nanoparticles (CuO NPs), firmly immobilized on chitosan nanoparticle (CH) surfaces as dark spots, with an irregular shape and 54.22 nm in size, as indicated by Transmission electron microscope (TEM) analysis. Spectroscopic and microscopic investigations, as well as its antifungal efficacy, verified that the successful synthesis of the CH@CuO NPs at three different concentrations (1, 25, and 50) mg/L against three different wild isolates of the pathogenic Fusarium oxysporum that infect tomatoes was successfully proven to be effective. In vitro comparisons revealed that CH@CuO NPs showed stronger antifungal activity at only 1 mg/L (96.22 ± 1.35) than the classical chemical fungicide “Kocide 2000” at conc. 2.5 g/L (77.34 ± 0.33), for example, in the case of FOL1 isolate. In accordance with the in vivo data, tomato plants can be treated with only 1 mg/L of CH@CuO NPs for up to 75 days, by which time Fusarium wilt disease severity is reduced by 91.5% In contrast, 2.5 g/L of Kocide 2000 is required to reduce disease in tomato plants by about 90%. This research expands our understanding of agro-nanotechnology by outlining the characteristics of a unique, environmentally friendly, and economically viable nanopesticide for long-term plant protection.

Fusarium oxysporum f.sp. lycopersici (FOL) wilt endangers Egyptian tomato productivity. Nanotechnology has emerged as an efficient tool for managing plant diseases. This study evaluated salicylic acid nanoparticles (SA-NPs) and glycyrrhizic acid ammonium salt nanoparticles (GAS-NPs) against F. oxysporum in vitro. SA-NPs reduced F. oxysporum growth by 37.8%, and GAS-NPs by 18.9% at 3 ml/L, while SA-NPs at high doses significantly reduced the bacterial count in the tomato rhizosphere. Under greenhouse conditions, high doses of SA-NPs suppressed disease by 73%, compared to 87-93% for other treatments, coinciding with a significant decrease in the overall bacterial count in the tomato rhizosphere. A high dose of SA-NPs reduced heterotrophic, copiotrophic, and fluorescent pseudomonads in the tomato rhizosphere but did not affect the total number of fungi. In vitro, a high dose of both nanoparticles did not significantly reduce bacterial growth in four tested strains: Leclercia adecarboxylata, Pseudomonas putida, Enterobacter ludwigii, and Bacillus marcorestinctum. This suggests that while SA-NP doesn’t directly affect bacterial growth, it may interact with tomato roots, indirectly affecting the rhizosphere bacterial population. All treatments increased the expression of ethylene-responsive transcription factor 3 (RAP), xyloglucan endotransglucosylase 2 (XET-2), catalytic hydrolase-2 (ACS-2), phenylalanine ammonia-lyase 5 (PAL5), lipoxygenase D (LOXD), proteinase inhibitor II (PINII), and pathogenesis-related protein 1 (PR1). The highest gene expression levels were obtained from 1 ml/L GAS-NPs and SA-NPs field applications. Furthermore, SA-NPs at 1 ml/L were the most efficient in controlling tomato Fusarium wilt, followed by GAS-NPs. This study investigates the possibility of nanotechnology-based techniques for decreasing Fusarium wilt in tomatoes. However, because of the deleterious impact on the soil bacterial community, high dosages of NPs, particularly SA-NPs, should be applied with caution. Future research should focus on optimizing NPs doses to maintain a balance between efficient disease control and the maintenance of the beneficial complexity of soil microbial biodiversity.