Emerging nanotechnological approaches for plant disease diagnosis and sustainable crop management

Introduction

Agriculture, which encompasses the diverse methods by which cultivated plants and domesticated animals support the global population through the provision of food and other essential goods, has served as a fundamental pillar of human civilization, delivering nourishment, economic value, and critical resources throughout history. (Kalu et al., 2026; Nandini et al., 2023) [11,2] The need for sustainable agricultural methods that guarantee food security while reducing disease incidence in plant production has increased with the world's population growth. (Kalu et al., 2026; Nandini et al., 2023) [11,2] Globally, plant diseases caused by various phytopathogens, including nematodes, bacteria, viruses, and fungi, drastically reduce crop yield and quality. (Worrall et al., 2018; Ameen et al., 2021) [12,3] Despite their effectiveness, traditional disease control techniques such as chemical pesticides and synthetic fertilisers often pollute the environment, promote the emergence of resistant pathogens, and negatively affect beneficial microorganisms that are not their intended targets. (Worrall et al., 2018; Ameen et al., 2021) [12,3] These limitations highlight the pressing need for innovative, environmentally sustainable, and practical strategies in plant disease management. (Avila-Quezada et al., 2022) [4] Nanotechnology has emerged as a promising tool to address these challenges by providing innovative solutions, such as NPs with unique physicochemical properties, including a high surface area to volume ratio, increased reactivity, and adjustable release profiles. (Avila-Quezada et al., 2022) [4] Nanotechnology is a scientific subject focused on the design, production and use of structures, devices and systems by manipulating atoms and molecules at a scale of less than 100 nanometres The word "nano" means one billionth of a meter. This alteration resulted in unique features and behaviours; its high reactivity is attributed to the greater surface area relative to volume that nanoparticles possess compared to macroscopic particles. These nanoparticles have remarkable physicochemical features, including altered thermal conductivity, chemical stability, catalytic reactivity and biological activity, which are absent in the identical materials at the macroscopic scale. This review provides a comprehensive overview of various methods of nanoparticle synthesis, the different types of NPs, and their characterization techniques. It further highlights the pivotal role of NPs in plant pathology, with a particular focus on their applications in disease detection and management. In addition, the review explores how NPs influence phytohormone signalling pathways, contributing to the mitigation of abiotic and biotic stress in plants. Nanotechnology is increasingly recognized as a critical tool in addressing challenges related to global food production and food security. NPs interact with plants through various mechanisms, including nutrient uptake enhancement, modulation of the antioxidant system, and regulation of hormonal pathways. These interactions enhance the use of NPs in plant disease identification and treatment. NPs' application in plant disease management improved plant defence mechanisms, reduced the need for hazardous chemicals, and increased overall crop productivity. Silver (Ag-NPs), zinc oxide (ZnO NPs), copper oxide (CuO-NPs), and titanium dioxide (TiO 2 -NPs) are examples of metal and metal oxide NPs that exhibit antimicrobial activity against a range of phytopathogens. Metal NPs, such as ZnO and FeO 4 , enhance plant growth and productivity. Plant immune responses can be stimulated by NPs, increasing resistance to diseases. Some NPs, such as copper and silver, show antimicrobial properties, preventing pathogenic microorganisms while supporting beneficial microbes. (Kalu et al., 2026; Jabran et al., 2024) [11,13]

Nanotechnology in agriculture

Nanoparticles (NPs), generally 1-100 nm in size, possess unique properties such as a high surface area to volume ratio and strong adsorption capacity, making them useful in modern agriculture. (Kalu et al., 2026; Nandini et al., 2023) [11,2] They are used as nanopesticides, nanofungicides, nanobactericides, nanoherbicides, nanofertilizers, nanosensors, and nanoremediators. (Kalu et al., 2026; Nandini et al., 2023) [11,2] NPs can improve plant resistance to both biotic and abiotic stresses by influencing stress related signaling pathways and phytohormones such as auxin, ethylene, and abscisic acid (ABA). (Worrall et al., 2018; Khan et al., 2022) [12,14] They can also alter the expression of stress responsive genes and enhance plant defense mechanisms. (Worrall et al., 2018; Khan et al., 2022) [12,14] Therefore, NPs have considerable potential for developing climate resilient and sustainable agriculture. (Chandrashekar et al., 2023; Mgadi et al., 2024) [9,10] However, their exact mechanisms of interaction with plants, particularly their effects on phytohormone biosynthesis and signaling, are still not fully understood and require further research. (Kalu et al., 2026; Jabran et al., 2024; Ali et al., 2020) [11,13,1] Among the various applications of nanotechnology in agriculture, nanoparticles (NPs) are particularly important because of their unique physicochemical properties, including high surface area, enhanced reactivity, and the ability to interact with biological systems at the molecular level. (Worrall et al., 2018; Nandini et al., 2023) [12,2] NPs have diverse applications in sustainable agriculture. (Worrall et al., 2018; Nandini et al., 2023) [12,2] Nanoformulated herbicides, such as atrazine loaded PCL nanoparticles, can improve weed control while reducing their impact on crops. (Chauhan et al., 2023; Bora et al., 2022) [15,6] Similarly, fungicide loaded nanoparticles, including chitosan based formulations, can enhance antifungal activity and minimize phytotoxic effects. (Chauhan et al., 2023; Bora et al., 2022) [15,6] Insecticide nanoparticles can improve pest control efficiency while reducing toxicity to non target organisms. (Qiao et al., 2024; Zhang et al., 2024) [16,17] In addition, nanoparticles can be used for the controlled delivery of plant growth regulators, promoting plant growth and enhancing tolerance to environmental stresses. (Qiao et al., 2024; Zhang et al., 2024) [16,17] Overall, major applications of nanoparticles in sustainable agriculture include nanofertilizers, nanopesticides, nanosensors, and improved soil and water management, which contribute to efficient resource utilization and environmentally sustainable crop production. (Kalu et al., 2026; Dutta et al., 2023; Worrall et al., 2018) [11,18,12]

Basics of nanotechnology

Nanoparticles and their properties

Nanoparticles can be classified according to different criteria, including composition, size, shape, surface characteristics, and intended application. (Nandini et al., 2023; Wadhwa et al., 2022) [2,19] Based on their composition, common categories include metal nanoparticles, metal oxide nanoparticles, carbon based nanoparticles, polymeric nanoparticles, and biological or organic nanoparticles. (Nandini et al., 2023; Wadhwa et al., 2022) [2,19] Characterization of these nanoparticles generally involves evaluating their size, morphology, surface properties, chemical composition, stability, and other physicochemical characteristics to determine their suitability for specific applications. (Kalu et al., 2026; Jabran et al., 2024; Ali et al., 2020) [11,13,1] Nanoparticles and their formation Nanoparticles (NPs) can occur in different shapes and structural forms, depending on the material used and the method of synthesis. (Nandini et al., 2023; Wadhwa et al., 2022) [2,19] Common morphologies include spherical, tubular, rod shaped, triangular, cubic, and irregular forms. (Nandini et al., 2023; Wadhwa et al., 2022) [2,19] Their shape and size strongly influence properties such as surface area, reactivity, stability, mobility, and interaction with plant tissues. (Daniel et al., 2023; Ameen et al., 2021) [22,3] NPs may also occur as dispersed particles, aggregates, or agglomerates. (Daniel et al., 2023; Ameen et al., 2021) [22,3] Well-dispersed nanoparticles remain separated in a medium, whereas aggregation or agglomeration occurs when particles come together because of weak attractive forces or inadequate stabilization. Therefore, synthesis and stabilization conditions are important for maintaining the desired particle size and morphology. (Ali et al., 2020; Yadav et al., 2018) [1,20] [20] and Kalu et al. (2026) [20,11] .

1. Top-down approach [13] and Kalu et al. (2026) [13,11] .

The top-down approach involves converting a bulk material into nanosized particles by progressively reducing its size. (Tanwar et al., 2024; Wadhwa et al., 2022) [21,19] In this method, larger materials are broken down using physical or chemical techniques. (Tanwar et al., 2024; Wadhwa et al., 2022) [21,19] Common techniques include milling, grinding, lithography, laser ablation, etching, and mechanical attrition. (Ali et al., 2020; Bora et al., 2022) [1,6] The major advantage of the top-down method is that it can produce nanoparticles di-rectly from bulk materials. (Ali et al., 2020; Bora et al., 2022) [1,6] However, it has several limitations. The process can require high energy consumption, specialized equipment, and longer processing times. It may also produce particles with a broad size distribution and irregular shapes. Furthermore, mechanical processes can introduce impurities or structural defects into the nanoparticles. Thus, achieving highly uniform nanoparticles can be challenging using this approach. (Ali et al., 2020; Yadav et al., 2018) [1,20] [21] and Ali et al. (2020) [21,1] .

Bottom-up approach

The bottom-up approach is based on the construction of nanoparticles from smaller building blocks such as atoms, ions, molecules, or molecular clusters. (Ali et al., 2020; Bora et al., 2022) [1,6] These components gradually assemble through processes such as nucleation, growth, precipitation, reduction, condensation, and self assembly to form nanoparticles. (Ali et al., 2020; Bora et al., 2022) [1,6] Examples of bottom-up techniques include chemical reduction, sol gel synthesis, precipitation, hydrothermal synthesis, biological synthesis, and microbial or plant-mediated synthesis. (Nandini et al., 2023; Wadhwa et al., 2022) [2,19] Compared with top-down methods, bottom-up techniques generally provide better control over particle size, morphology, composition, and size distribution. (Nandini et al., 2023; Wadhwa et al., 2022) [2,19] They can also require less energy and may be more economical and suitable for large scale production. (Ali et al., 2020; Yadav et al., 2018) [1,20]

Characterization of nanoparticles

Comprehensive characterization of nanoparticles (NPs) is essential for determining their size, shape, structure, composition, surface properties, stability, and functional characteristics. (Wadhwa et al., 2022; Zhang et al., 2024) [19,17] After synthesis, nanoparticles must be carefully analyzed to confirm that they possess the desired properties and are suitable for their intended applications. (Wadhwa et al., 2022; Zhang et al., 2024) [19,17] Important parameters include particle size and size distribution, morphology, crystallinity, chemical composition, surface area, optical properties, dispersibility, and thermal stability. ( [11,13,23] Several analytical techniques are commonly used for nanoparticle characterization. (Wadhwa et al., 2022; Zhang et al., 2024) [19,17] 1.

(Wadhwa et al., 2022; Zhang et al., 2024) [19,17] UV-Visible (UV-Vis) spectroscopy is mainly used to confirm nanoparticle formation and evaluate their optical properties and stability by detecting characteristic absorption peaks. (Tanwar et al., 2024; Wadhwa et al., 2022) [21,19] X-ray diffraction (XRD) provides information about the crystalline structure, crystal size, and phase composition of nanoparticles. (Tanwar et al., 2024; Wadhwa et al., 2022) [ 21, 19] Dynamic light scattering (DLS) and particle size analysis (PSA) are used to determine particle size distribution and assess the stability of nanoparticle suspensions. ( [13,23,24] 2.

(Wadhwa et al., 2022; Zhang et al., 2024) [19,17] Fourier transform infrared spectroscopy (FTIR) is used to identify functional groups present on the nanoparticle surface and to determine their possible involvement in nanoparticle synthesis and surface modification. ( [19,17] Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) provide detailed information about nanoparticle morphology, size, shape, surface structure, and aggregation. (Tanwar et al., 2024; Nandini et al., 2023) [21,2] TEM generally provides higher resolution visualization of individual nanoparticles. (Jabran et al., 2024; Zhang et al., 2024) [13,23] 3.

(Ali et al., 2020; Wasule et al., 2024) [1,5] Energy dispersive X-ray spectroscopy (EDS) is often coupled with SEM or TEM to determine the elemental composition of nanoparticles and confirm the presence of desired elements and their purity. (Ali et al., 2020; Wasule et al., 2024) [1,5] Thermogravimetric analysis (TGA) evaluates thermal stability by measuring changes in nanoparticle weight during controlled heating. (Nandini et al., 2023; Bora et al., 2022) [2, 6] It can also help determine moisture content, organic coatings, and decomposition temperatures. (Nandini et al., 2023; Bora et al., 2022) [2,6] 4.

Advanced techniques provide additional information about nanoparticle surfaces and structures. Atomic force microscopy (AFM) provides nanoscale surface topography, while Raman spectroscopy helps investigate molecular structure and chemical interactions. X-ray photoelectron spectroscopy (XPS) provides detailed information about surface elemental composition and chemical states.

Thus, no single technique can provide complete information about nanoparticles. (Wadhwa et al., 2022; Zhang et al., 2024) [19,17] The combined use of UV-Vis, XRD, DLS/PSA, FTIR, SEM, TEM, EDS, TGA, AFM, Raman spectroscopy, and XPS provides a comprehensive understanding of their physicochemical characteristics. (Wadhwa et al., 2022; Zhang et al., 2024) [19,17] Such characterization is particularly important for agricultural nanoparticles because their size, morphology, surface chemistry, stability, and composition directly influence their interaction with plants, pathogens, soil, and agrochemicals. (Jabran et al., 2024; Zhang et al., 2024) [13,23]

Biosynthesis of nanoparticles using biological agents

Nanoparticles (NPs) can be synthesized through physical, chemical, and biological methods. (Ali et al., 2020; Wasule et al., 2024) [1,5] Physical methods are often energy intensive and may require specialized equipment, whereas chemical methods can involve toxic reducing and stabilizing agents that may pose environmental and health risks. (Ali et al., 2020; Wasule et al., 2024) [1,5] Therefore, biological or green synthesis has gained considerable attention as a safer, cost effective, and environmentally sustainable alternative. (Nandini et al., 2023; Bora et al., 2022) [2,6] In biological synthesis, plants, bacteria, fungi, algae, and plant viruses use their natural biomolecules, enzymes, and metabolites to reduce metal ions and stabilize the resulting nanoparticles. (Nandini et al., 2023; Bora et al., 2022) [2,6] This approach can produce a wide range of nanoparticles, including silver (Ag), gold (Au), selenium (Se), platinum (Pt), iron oxide, copper oxide, and zinc oxide nanoparticles, with potential applications in agriculture and plant disease management. ( [1,5,15] 1. Plant mediated nanoparticle synthesis Plant mediated synthesis is one of the simplest and most widely studied green approaches. (Chauhan et al., 2023; Tanwar et al., 2024) [15,21] Leaves, fruits, roots, stems, flowers, seeds, peels, and other plant materials can be used to prepare extracts containing phytochemicals such as phenolics, flavonoids, proteins, carbohydrates, alkaloids, and terpenoids. (Chauhan et al., 2023; Tanwar et al., 2024) [15,21] These compounds act as natural reducing and capping/stabilizing agents, converting metal ions into stable nanoparticles while limiting the need for hazardous chemicals. (Ali et al., 2020; Nandini et al., 2023) [1,2] Generally, plant material is washed, dried, ground, and extracted in water. (Ali et al., 2020; Nandini et al., 2023) [1,2] The extract is filtered and mixed with an appropriate metal salt solution. 2023) [1,5,15] 2. Bacteria mediated synthesis Bacteria can synthesize nanoparticles through intracellular or extracellular mechanisms. (Ali et al., 2020; Bora et al., 2022) [1,6] Their enzymes, proteins, and other cellular metabolites facilitate the reduction of metal ions and stabilization of the nanoparticles. (Ali et al., 2020; Bora et al., 2022) [1,6] Factors such as pH, temperature, incubation conditions, and bacterial cell-wall functional groups influence nanoparticle formation, size, and morphology. (Tanwar et al., 2024; Nandini et al., 2023) [21,2] Bacterial species such as Pseudomonas, Bacillus, Escherichia, Clostridium, and Rhodococcus have been reported for the synthesis of silver, gold, iron sulfide, and magnetite nanoparticles. (Tanwar et al., 2024; Nandini et al., 2023) [21,2] Although bacterial synthesis is environmentally friendly and can produce biocompatible nanoparticles, limitations include labour intensive processing, downstream purification requirements, and difficulties in precisely controlling particle size and shape. (Ali et al., 2020; Wasule et al., 2024) [1,5] 3. Fungal assisted synthesis Fungi are considered effective biological nanofactories because they produce large amounts of extracellular enzymes and metabolites capable of reducing and stabilizing metal ions. [1,15] Nanoparticle synthesis can occur either inside fungal cells or extracellularly, with extracellular synthesis being more advantageous because it simplifies nanoparticle recovery and purification. (Ali et al., 2020; Chauhan et al., 2023) [1,15] Fungi such as Fusarium oxysporum, Aspergillus fumigatus, Penicillium spp., and Verticillium spp. have demonstrated the ability to synthesize metallic and metal sulfide nanoparticles. (Bora et al., 2022; Nandini et al., 2023) [6,2] Compared with bacteria, fungi generally offer higher biomass production, efficient secretion of biomolecules, easier cultivation, and better suitability for large-scale production. (Bora et al., 2022; Nandini et al., 2023) [6,2] These characteristics make fungal mediated synthesis a promising route for sustainable nanoparticle production. ( [1,5,15] 4. Algae mediated synthesis Algae, including microalgae, macroalgae (seaweeds), and cyanobacteria, are another important source for green nanoparticle synthesis. (Ali et al., 2020; Chauhan et al., 2023) [1,15] Algal cells contain proteins, polysaccharides, pigments, lipids, antioxidants, and other bioactive compounds that can function as natural reducing and stabilizing agents. (Ali et al., 2020; Chauhan et al., 2023) [1,15] Species belonging to Cyanophyceae, Chlorophyceae, Phaeophyceae, and Rhodophyceae have been used to synthesize metallic and metal oxide nanoparticles, particularly silver and gold NPs. (Nandini et al., 2023; Bora et al., 2022) [2,6] Algae offer advantages such as rapid growth, easy harvesting, metal accumulation ability, scalability, and low environmental impact. (Nandini et al., 2023; Bora et al., 2022) [2,6] Nanoparticles synthesized using Chlorella and Sargassum species have also shown promising antimicrobial activity. ( [25,26] Plant viruses and virus-like particles possess highly organized and uniform structures that can serve as natural nanoscale scaffolds. (Young et al., 2008; Xue et al., 2023) [25,26] Their biocompatibility, biodegradability, structural uniformity, and ability to encapsulate or deliver biological molecules make them useful for advanced applications in agriculture and biotechnology. (Avila-Quezada et al., 2022; Zhang et al., 2024) [4,17] Viral particles can also be genetically modified or produced through plant based molecular farming and other scalable systems. (Avila-Quezada et al., 2022; Zhang et al., 2024) [4,17] Although this technology is still developing, PVNPs have considerable potential as precision delivery and nanobiotechnology platforms. (Ali et al., 2020; Wasule et al., 2024) [1,5]

Nanoparticles synthesized from chitosan and other biopolymers and metallic nanoparticles

Chitosan nanoparticles

Chitosan nanoparticles (CNPs) are biodegradable and biocompatible nanomaterials derived from chitosan, a natural polysaccharide obtained by deacetylation of chitin, which is abundantly present in crustacean exoskeletons. (Chouhan et al., 2021; Moussa et al., 2013) [27,28] Chitosan is considered an environmentally friendly material because of its low toxicity, biodegradability, antimicrobial properties, and biocompatibility. (Chouhan et al., 2021; Moussa et al., 2013) [27,28] When converted into nanoparticles, its surface area and biological activity increase, resulting in enhanced antifungal and antimicrobial effects. (Wasule et al., 2024; Chouhan et al., 2021) [5,27] CNPs have therefore attracted considerable attention as sustainable alternatives to conventional chemical fungicides. (Wasule et al., 2024; Chouhan et al., 2021) [5,27] For example, CNP application has been shown to substantially reduce gray mold severity in strawberry, while chitosan based nanoparticles have also been reported to enhance plant growth, secondary metabolite accumulation, and disease resistance in Capsicum species. Furthermore, combining CNPs with beneficial microorganisms such as Trichoderma longibrachiatum and Penicillium polonicum has demonstrated strong inhibitory activity against Fusarium equiseti. Thus, CNPs have considerable potential as eco friendly antifungal agents and plant defense enhancers, although their precise molecular mechanisms and optimal field application conditions require further investigation. (Worrall et al., 2018; Wasule et al., 2024) [12,5]

Metallic nanoparticles

Metallic nanoparticles (MNPs), including silver, zinc oxide, silica, copper, iron oxide, titanium dioxide, and selenium nanoparticles, are increasingly being explored for plant disease management. (Worrall et al., 2018; Khan et al., 2022) [12,14] Their effectiveness is associated with their high surface area to volume ratio, strong redox activity, and ability to interact with microbial cells. (Worrall et al., 2018; Khan et al., 2022) [12,14] Depending on their composition, MNPs can damage pathogen cell membranes, generate reactive oxygen species (ROS), interfere with enzymes and DNA, and inhibit spore germination and mycelial growth. (Avila-Quezada et al., 2022; Tariq et al., 2022) [4,29] Consequently, they can act against a broad range of fungal, bacterial, and viral phytopathogens and may provide an alternative or complementary strategy to conventional pesticides. ( [11,13,12,5]

Silver nanoparticles

Silver nanoparticles (Ag NPs ) are among the most extensively studied nanomaterials for plant disease management because of their broadspectrum antibacterial and antifungal activity. (Tariq et al., 2022; Avila-Quezada et al., 2022) [29,4] Their antimicrobial action is largely associated with the release of Ag + ions, which interact with microbial cell membranes and proteins, increase membrane permeability, disturb enzymatic functions, and cause cellular and DNA damage. (Tariq et al., 2022; Avila-Quezada et al., 2022) [29,4] Ag NPs have demonstrated activity against important pathogens such as Fusarium, Colletotrichum, Sclerotinia, Rhizoctonia, Bipolaris, and Ralstonia. (Ameen et al., 2021; El-Shetehy et al., 2021) [3,30] They have also shown potential against plant viruses, with studies reporting reduced viral concentration and disease severity following AgNP application. (Ameen et al., 2021; El-Shetehy et al., 2021) [3,30] Green-synthesized Ag NPs , particularly those produced using plant extracts, are gaining attention because they may reduce dependence on hazardous chemical synthesis. (Tariq et al., 2022; El-Shetehy et al., 2021) [29,30] However, concerns regarding silver toxicity, environmental persistence, and accumulation highlight the need for careful dose optimization and assessment of their environmental safety. ( [11,12,5]

Zinc oxide nanoparticles

Zinc oxide nanoparticles (ZnO-NPs) are promising alternatives for disease management because they combine antimicrobial activity with the nutritional importance of zinc. (Daniel et al., 2023; Avila-Quezada et al., 2022) [22,4] Their antifungal effects are associated with disruption of fungal hyphae, inhibition of spore and conidia formation, ROS generation, DNA damage, and disturbance of cellular redox balance. (Daniel et al., 2023; Avila-Quezada et al., 2022) [22,4] ZnO-NPs have demonstrated activity against pathogens including Fusarium oxysporum, Penicillium expansum, Botrytis cinerea, and Xanthomonas oryzae. (Daniel et al., 2023; Nandini et al., 2023) [22,2] They have also shown potential in controlling diseases such as rice blast and bacterial leaf blight. (Daniel et al., 2023; Nandini et al., 2023) [22,2] Green synthesized ZnO-NPs prepared using plant extracts provide an additional sustainable approach. (Ameen et al., 2021) [3] Because ZnO-NP toxicity depends on particle properties, concentration, exposure conditions, soil chemistry, and plant species, their use requires dose optimization and environmental assessment. Their antimicrobial activity and role as a zinc source nevertheless make them promising candidates for integrated crop protection. ( [11,13,12,22,3,31]

Silica nanoparticles

Silica nanoparticles (SiO 2 -NPs) can enhance plant resistance against both biotic and abiotic stresses. (El-Shetehy et al., 2021; Khan et al., 2022) [30,14] Their protective effects involve strengthening plant cell walls and cuticles, creating physical barriers against pathogens, stimulating defense-related enzymes and activating defense signalling, including salicylic acid associated responses. (El-Shetehy et al., 2021; Khan et al., 2022) [30,14] SiO 2 -NPs can also promote the production of defensive compounds such as phenolics and flavonoids. (El-Shetehy et al., 2021; Nandini et al., 2023) [30,2] Recent research indicates that low concentrations of SiO 2 -NPs can activate SA-dependent immune responses and improve resistance against bacterial pathogens. (El-Shetehy et al., 2021; Nandini et al., 2023) [30,2] In addition to disease protection, mesoporous silica nanoparticles can function as nanocarriers for the controlled delivery of DNA and other bioactive molecules, making them valuable tools for plant biotechnology and precision agriculture. ( [11,13,23,30] Copper nanoparticles

Copper nanoparticles (Cu NPs ) possess strong antibacterial and antifungal properties and have considerable potential in agricultural disease management. (Worrall et al., 2018; Avila-Quezada et al., 2022) [12, 4] Their antimicrobial activity is associated with the generation of reactive species, particularly hydroxyl radicals, which can damage essential cellular components such as proteins, membranes, and DNA. (Worrall et al., 2018; Avila-Quezada et al., 2022) [12,4] Cu NPs have demonstrated broad spectrum activity against pathogens including Alternaria alternata, Curvularia lunata, Fusarium oxysporum, Phoma destructiva, Xanthomonas campestris, Botrytis cinerea, and Fusarium kuroshium. (Khan et al., 2022; Tariq et al., 2022) [14,29] In some studies, Cu NPs have shown greater pathogen inhibition than conventional copper formulations. (Khan et al., 2022; Tariq et al., 2022) [14,29] Moreover, incorporating Cu-based compounds into nanohydrogels can enable controlled and targeted delivery, potentially improving fungicide efficiency while reducing unnecessary chemical application. ( [11,12,5] [12] , Agronomy 8:285 [12] .

Detection of plant pathogens

Early detection of plant diseases is essential for reducing crop losses and enabling timely disease management. (Cardoso et al., 2022; Shivashakarappa et al., 2022) [7,8] Nanotechnology based tools such as nanosensors, nanochips, quantum dots, and nanobiosensors provide rapid, sensitive, and accurate detection of plant pathogens. (Cardoso et al., 2022; Shivashakarappa et al., 2022) [7,8] Nanosensors can identify viruses and other pathogens at early infection stages using specific biological recognition molecules. (Khan et al., 2022; Zhang et al., 2024) [14,17] Nanochips detect pathogen-specific genetic sequences with high sensitivity and specificity, while quantum dots and gold nanoparticles provide strong optical signals for pathogen identification. (Khan et al., 2022; Zhang et al., 2024) [14,17] These technologies have been applied to detect important pathogens such as Phytophthora infestans and Xanthomonas campestris. (Cardoso et al., 2022) [7] When combined with molecular diagnostics and smartphone based systems, nano based detection offers a portable, rapid, and reli-able approach for field level disease monitoring and precision crop protection. ( [11,13,23,24] Plant disease management using nanoparticles Effective management of plant diseases is essential for protecting crops and agricultural products both before and after harvest. (Worrall et al., 2018; Nandini et al., 2023) [12,2] Fungal, bacterial, and viral pathogens are major causes of crop losses, and conventional disease control methods often face limitations. (Worrall et al., 2018; Nandini et al., 2023) [12,2] Host plant resistance through conventional breeding is an important strategy, but it is time consuming because resistant genes must be identified and selected over several generations. (Avila-Quezada et al., 2022; Khan et al., 2022) [4,14] Transgenic approaches can provide broader and longer lasting resistance by introducing useful resistance genes into crops. (Avila-Quezada et al., 2022; Khan et al., 2022) [4,14] However, the development and adoption of such approaches can also involve technical, regulatory, and public-acceptance challenges. (Kalu et al., 2026) [11] Nanotechnology offers a promising complementary approach to conventional disease management. (Kalu et al., 2026) [11] Traditional pesticide application can result in spray drift, runoff, photodegradation, off target deposition, and environmental contamination. [11,18,12] Figure 5. Nanotechnology-based strategies for sustainable management of bacterial plant diseases. Malook et al. (2026) [32] , Environmental Science: Nano (Malook et al., 2026) [32] .

Nanoparticles (NPs) can overcome some of these limitations because their small size and modifiable surface properties allow controlled, targeted, and efficient delivery of active compounds. (Worrall et al., 2018; Qiao et al., 2024) [12,16] NPs can be used directly as antimicrobial agents or as nanocarriers for pesticides, fungicides, insecticides, and RNA-interference (RNAi) molecules. (Worrall et al., 2018; Qiao et al., 2024) [12,16] Nanoparticles can act through different mechanisms, including disruption of pathogen cell membranes, generation of reactive oxygen species (ROS), inhibition of enzymes, damage to nucleic acids, and interference with pathogen growth and reproduction. (Qiao et al., 2024; Avila-Quezada et al., 2022) [16,4] Their nanoscale size may also facilitate better interaction with plant surfaces and, for suitable formulations, movement within plant tissues. (Qiao et al., 2024; Avila-Quezada et al., 2022) [16,4] In particular, NPs have shown potential for targeting plant viruses and reducing pathogen multiplication, making them an emerging tool for viral disease management. (Zhang et al., 2024) [17] An important advantage of nanotechnology is its potential for precision crop protection. (Zhang et al., 2024) [17] Nanocarriers can protect active ingredients from premature degradation and release them gradually or at specific sites, potentially reducing the quantity of pesticide required and minimizing environmental losses. NPs can also be combined with RNA-based technologies, enabling targeted delivery of molecules that suppress pathogen genes or interfere with infection processes. In addition to disease control, nanoparticles can improve plant tolerance to abiotic stresses such as drought, salinity, heat, cold, and heavy metal stress. For example, Fe, ZnO, Se, TiO₂, Si, Ag, and Fe₃O₄ nanoparticles have been reported to improve plant growth, photosynthetic activity, antioxidant defense, nutrient uptake, and stress related biochemical responses. These effects may involve increased antioxidant enzyme activity, reduced oxidative damage, improved water and nutrient balance, and modulation of stress responsive genes. ( [11,18,12,5]

Concluding remarks and future perspectives

Agricultural nanotechnology offers promising opportunities for sustainable and efficient crop production through applications such as nanofertilizers, nanopesticides, targeted delivery systems, nanosensors, and stress management technologies. (Worrall et al., 2018; Nandini et al., 2023) [12,2] Nanoparticles can improve nutrient use efficiency, enhance plant resilience, reduce agrochemical losses, and support effective control of pests and plant diseases. (Worrall et al., 2018; Nandini et al., 2023) [12,2] However, their widespread adoption is still limited by concerns regarding environmental persistence, bioaccumulation, toxicity, effects on beneficial soil microorganisms, production costs, and large scale consistency. ( [11,13,5,23,3,31] Future research should focus on developing biodegradable and eco friendly nanoparticles, improving targeted delivery systems, and conducting long term laboratory and field studies to evaluate their effectiveness and safety. (Wasule et al., 2024; Ameen et al., 2021; Cox et al., 2016) [5,3,31] Clear regulatory frameworks, standardized risk assessments, cost effective production, and evaluation of socioeconomic factors are also essential for successful commercialization. (Wasule et al., 2024; Ameen et al., 2021; Cox et al., 2016) [5,3,31] Greater collaboration among researchers, farmers, industries, and policymakers will be necessary to build confidence and facilitate responsible adoption. (Qiao et al., 2024; Mgadi et al., 2024) [16,10] Overall, with appropriate safety assessment and sustainable development, nanotechnology has significant potential to contribute to precision agriculture, food security, environmental sustainability, and climate resilient farm [11,13,5,32,33] [33] .

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35. How to cite this article: Dhakad A. Emerging nanotechnological approaches for plant disease diagnosis and sustainable crop management. International Journal of Advanced Biochemistry Research. 2026;SP-10(9):2345-2354. doi: https://www.doi.org/1