Herbicidal formulations and enhanced composite microspheres

Abstract

The present invention relates to a herbicidal formulation comprising a herbicidally active ingredient in an aqueous solution and composite microspheres that enhance the herbicidal efficacy against weeds in crops; wherein the composite microspheres in powder form are present in a concentration ranging from 2% to 100% w / w relative to the herbicide when combined with the aqueous solution, and wherein the composite microspheres comprise chitosan with an average molecular weight ranging from 190,000 to 310,000 g / mol and comprise a cross-linking agent. These composite microspheres enhance the herbicidal efficacy against weeds in crops.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 621,881, filed January 17, 2024, which is incorporated herein by reference in its entirety. Technical Field

[0003] This invention relates to the field of smart materials aimed at improving the efficiency of chemicals used in agricultural processes. Specifically, it relates to a microstructured polymer compound with customized chemical composition, charge distribution, and advantageous properties, suitable for the dosage and controlled release of agrochemicals in sustainable agricultural practices. In particular, it relates to herbicides enhanced with composite microspheres. The invention also includes scalable, high-conversion, validated, and verified methods for their preparation. Background Technology

[0004] The use of fertilizers and pesticides has always been the cornerstone of modern agricultural development, making it possible to increase crop yields to meet the world's growing food demand.

[0005] In layman's terms, agrochemicals are understood to encompass any natural or synthetic substance or mixture of substances used to prevent, eliminate, and / or control any pests, diseases, or weeds in agricultural activities. These substances are often referred to as pesticides or crop protectants—also known as phytosanitary products—and include insecticides, herbicides, fungicides, acaricides, and so on. This category of agrochemicals also includes substances designed to provide elements that promote plant growth, often referred to as fertilizers and plant growth regulators.

[0006] Fertilizers and plant growth regulators are agrochemicals used to improve crop quality and growth. Fertilizers provide plants with essential nutrients, improve root quality in the soil, and promote faster and higher-quality plant growth and development. Plant growth regulators, on the other hand, are products that regulate plant growth and are typically composed of plant hormones. Their main function is to stimulate or inhibit the growth of plant roots and above-ground parts.

[0007] Herbicides are used to eliminate major harmful plants that affect crops, commonly known as weeds. They come in various types based on their characteristics, such as the timing of application, the extent of their impact on plants, or the specific stage of application.

[0008] Crops face numerous challenges, including insects, pests, diseases, and pesticide-related toxicity. Pests cause global wheat yield losses of up to 50% and cotton yield losses of up to 80%. Other crops with significant production losses include soybeans (26-29%), maize (31%), rice (37%), and potatoes (40%) [Oerke, 2006]. Insect pests account for approximately 30% of crop losses [Vinutha, 2013], while weeds cause approximately 34%.

[0009] Besides pests, fungal diseases also impact crops globally. Fungi cause approximately 70% of diseases in major crops [Agrios, 2005], including wheat, potatoes, cotton, tomatoes, peanuts, grapes, and cotton [Dhekney, 2005]. The severity of the situation is evident considering that the agricultural industry loses over $200 billion annually to fungal diseases (in the field and post-harvest). In contrast, over $600 million is spent annually on fungicides in the United States alone [Fernandez-Perez, 2000]. Globally, approximately one-quarter of food crops are damaged by fungal toxins such as aflatoxin, ergot toxicants, fusarium toxins, patulin, and Alternaria alterniflora ketones [Razzaghi-Abyaneh, 2014].

[0010] Weeds compete with crops for light, water, nutrients, and space. This competition reduces crop growth and affects its development (Segundo Congreso Argentine de Girasol, ASAGIR Workshop on Sunflower Weeds). Depending on the type and density of weeds, yield reductions of 10% to 90% have been observed in extreme cases.

[0011] Fallowing (the practice of leaving a plot of land uncultivated for months or years before replanting) typically requires weed control between crop cycles. Improper management during fallowing can lead to the emergence of herbicide-resistant weeds, such as amaranth (…). Amaranth spp. ) and ryegrass ( Lolium spp. This poses a significant challenge in the humid Pampas region of Argentina [Bedmar, 2002].

[0012] The impact of weed competition on soybean crop yield depends on the timing of weed emergence and the duration of disturbance. The following factors have been identified in this regard: 1. Early competition (first 4-6 weeks): The most critical period is the initial growth stage (up to V4 or V5), during which soybeans establish their structure and produce leaves for photosynthesis. If not properly controlled, weed competition at this stage can reduce yield by 20-50%.

[0013] 2. Disturbance from problem weeds: such as barnyard grass (Echinochloa crus-galli). Echinochloa spp. ) and the genus *Baijiu* ( Conyza spp. These weeds are particularly competitive. If not managed properly, they can cause yield losses of up to 80% in cases of severe infestation.

[0014] 3. Control Strategies: The use of pre-emergence and post-emergence residual herbicides is key to reducing weed impact during sowing and crop growth. In areas with high pressure from resistant weeds, continuous monitoring and a combination of different herbicide modes of action are essential.

[0015] In soybean cultivation, yield losses due to weed competition during fallow periods and early growth stages range from 10% to 70%. In poorly managed fields or areas with resistant weeds, losses can exceed 90% if competition is not controlled in time. Therefore, weed control during fallow periods and early crop stages is crucial for maximizing soybean yield and preventing significant economic losses. Small improvements in weed control (from 85% to 90%) may seem like small percentages, but they have a significant impact on agricultural yields [Green-Tracewicz, 2012].

[0016] Pesticides have been widely used to combat pests; however, their widespread application has had devastating effects on humans and other organisms, with a growing incidence of human poisoning.

[0017] The negative impacts of using agricultural chemicals on human health are described below: Chronic diseases: Long-term exposure to agricultural chemicals is associated with chronic diseases.

[0018] Acute health problems: Accidental exposure to high doses can cause acute poisoning, with symptoms including dizziness, vomiting, difficulty breathing, and even death.

[0019] Risks to vulnerable populations: Pregnant women and children are particularly vulnerable to the neurotoxic and endocrine-disrupting effects of certain agrochemicals, which may affect physical and cognitive development [Islam, 2024].

[0020] Indiscriminate use of agrochemicals disrupts the natural balance and has adverse effects on various ecosystems, including: Soil pollution includes processes such as reducing natural fertility, altering microbial communities, and salinization or acidification.

[0021] Water pollution: Excessive application of agricultural chemicals can seep into rivers, lakes and groundwater, leading to water pollution and eutrophication. Excessive nutrients promote the proliferation of toxic algae, affecting water quality and aquatic life.

[0022] Biodiversity loss: Overuse of agricultural chemicals leads to resistance in pests, weeds and pathogens.

[0023] A report on the environmental and health impacts of pesticides and fertilizers, prepared in close collaboration between the Food and Agriculture Organization (FAO) and the World Health Organization (WHO), emphasizes the urgent need for transformative action and improved management of pesticides and fertilizers as global demand and use continue to grow (wedocs.unep.org / xmlui / bitstream / handle / 20.500.11822 / 38409 / pesticides.pdf).

[0024] There is an urgent need to adopt sustainable practices to mitigate the negative impacts of overuse of agrochemicals. In recent years, alternatives to traditional agriculture have been developed to reduce these adverse effects. One such approach is precision agriculture, which aims to optimize agricultural practices by using advanced technologies to collect, analyze, and interpret data on crops, soil, climate, and other factors to make more efficient decisions. The primary goal of precision agriculture is to maximize resource efficiency—such as water, fertilizers, and pesticides—while minimizing environmental impact and increasing productivity.

[0025] Nanotechnology offers innovations and technologies to address these challenges by optimizing resource utilization. Nanotechnology is widely used in modern agriculture to realize the concept of precision agriculture [Duhan, 2017]. It involves a variety of materials, including the development of nanospheres and composite microspheres with one or more dimensions at a scale of 100 nm or smaller. Nanomaterials have wide applications in plant protection, nutrition, and agricultural practices due to their unique properties, such as small size and high surface area to volume ratio [Auffan, 2009].

[0026] Developing controlled-release formulations (CRFs) is ideal for complying with international environmental and biodiversity regulations. The use of polymers for sustained release began in the early 1970s, offering greater efficacy for encapsulated components compared to commercial formulations. To enhance the value of traditional pesticides, many natural molecules, including carrageenan, galactomannan, chitosan, alginate, pectin, cellulose, gum arabic, guar gum, cashew gum, chitin, agar, tamarind seed polysaccharide, and starch, are frequently processed into nanomaterials for the sustained and targeted release of various agrochemicals to specific sites of action [Salgueiro, 2013; Albuquerque, 2016; Sharma, 2019; Slade, 2019; Rashidipour, 2019; Elabasy, 2020].

[0027] Chitosan stands out among commonly used polymers in existing technologies. Chitosan is a polysaccharide composed of repeating D-glucosamine and N-acetyl-D-glucosamine units. It is a major industrial derivative of chitin and can be obtained through the N-deacetylation of chitin. Chitosan is poorly soluble in water; however, when the degree of deacetylation reaches at least 50%, it dissolves as a polyelectrolyte in dilute acidic aqueous solutions [Robert, 1992]. The degree of deacetylation and molecular weight of chitosan significantly affect its physicochemical and biological properties, such as solubility, hydrophobicity, crystallinity, and cellular reactivity.

[0028] In recent decades, chitosan has attracted increasing interest in agriculture. For example, when dissolved in acidic solutions, chitosan activates its antibacterial properties and stimulates plant defense mechanisms, offering the potential to become a novel plant stress protectant [Bautista-Banos, 2006; Sahariah, 2017].

[0029] In Rychter's publication [Rychter, 2019], the herbicidal efficacy and controlled-release properties of chitosan microparticles encapsulating glyphosate were evaluated.

[0030] Another approach to utilizing chitosan in various applications (particularly in agriculture) involves forming three-dimensional structures through the cross-linking of chitosan molecules. These stable structures enable the nanoencapsulation of active components and offer the characteristic of providing more controlled release of the encapsulated components. Slow release, prevention of degradation, and low solubility of encapsulated pesticides are the most important characteristics of polymer nanoformulations, making them the preferred choice for nanoencapsulation. This valuable information paves the way for the development and practical application of polymer nanoparticles with great potential. Furthermore, various types of nanoformulations, including polymer-based and non-polymer-based ones such as nanospheres, nanocapsules, nanogels, micelles, nanofibers, nanometals, and nanoemulsions, have been proposed for pesticide encapsulation. Among these, nanocapsules are most commonly used for controlled release of pesticides. Recently, a novel hybrid nanoformulation concept (nanoemulsion encapsulation or liposome coating) for the controlled release of certain pesticides has been proposed. However, the efficacy of this innovative approach needs to be tested in a wide range of pesticides [Das, 2014].

[0031] In Grenha's (2012) paper, methods for preparing chitosan-based nanostructure systems are described, primarily through emulsification, various types of aggregation, or slight modifications of both. Specifically, these methods include emulsion droplet aggregation [Tokumitsu et al., 1999], solvent diffusion in emulsions [El-Shabouri, 2002], reverse micelles [Mitra et al., 2001], ionogelation, polyelectrolyte complexation [Calvo et al., 1997; Sarmento et al., 2006], and desolvation [Tian & Groves, 1999]. All these methods involve bottom-up fabrication processes that require the assembly of molecules in solution to form defined structures [Chan & Kwok, 2011]. In this context, composite nanospheres were obtained.

[0032] Release systems produced by bottom-up technologies often exhibit size polydispersity [Wang et al., 2011], which in some cases limits the utility of nanoparticles. Indeed, in polydisperse systems, it is assumed that larger nanoparticles may have a greater capacity to load active ingredients, while smaller nanoparticles are expected to be more effective in delivering agrochemicals to tissues or cells [Fan et al., 2012].

[0033] Chitosan microparticles and nanoparticles have been prepared by chemical crosslinking with glutaraldehyde, glyoxal, and polyethylene glycol diglyceride. While these are highly effective crosslinking agents, they are not the preferred choice due to their physiological toxicity. Chitosan exhibits polycationicity in acidic media (pKa 6.5) and can interact with negatively charged substances such as crosslinking agents TPP (sodium tripolyphosphate) and sodium sulfate. This property can be used to prepare crosslinked chitosan nanoparticles. The interaction between chitosan and TPP leads to the formation of biocompatible crosslinked chitosan nanoparticles, which can be effectively used for the delivery of proteins, vaccines, and various other compounds. The crosslinking density, crystallinity, and hydrophilicity of crosslinked chitosan can modulate the release of encapsulated drugs and expand its potential applications in drug delivery [Bhumkar, 2006].

[0034] Chitosan, with its highly protonated amino groups, possesses the ability to form hydrogen gels in the presence of specific polyanions. This process originates from intermolecular and intramolecular crosslinking mediated by anionic molecules [Janes et al., 2001; Terbojevich & Muzzarelli, 2009], and is termed ionic gelation or polyelectrolyte complexation. It has been used to produce chitosan nanoparticles. This method involves the ionic interaction between the positively charged amino groups of chitosan and the polyanionic sodium tripolyphosphate (TPP) acting as a chitosan crosslinking agent. Notably, the term ionic gelation is preferred when chitosan gelation is induced by small anionic molecules such as phosphates, citrates, or sulfates. In contrast, polyelectrolyte complexation refers to the use of large anionic molecules instead of small molecules [Bhattarai et al., 2010].

[0035] The formation of nanoparticles via ionogelation is described in the work of Carvalho [Carvalho et al., 2009]. Several prior art studies have demonstrated cross-linked chitosan nanoparticles with TPP or other biopolymers containing encapsulating active compounds, wherein their antifungal or herbicidal activities are described based on the encapsulating compounds.

[0036] Furthermore, several existing studies have incorporated chitosan nanoparticles loaded or encapsulated with herbicides. For example, in the work of Dos Santos Silva and collaborators (2011), alginate / chitosan nanoparticles with a size of 635 ± 12 nm, a zeta potential of -22.8 ± 2.3 mV, and an association efficiency of 74.2% were prepared as an environmentally friendly carrier system for encapsulating the herbicide paraquat. The nanoparticles (NPs) conjugated with paraquat improved the herbicide release profile and its interaction with the soil, demonstrating that the formulation can effectively reduce the adverse effects of paraquat [Dos Santos Silva, 2011].

[0037] Using a similar approach, Grillo et al. (2014) conducted a similar comparative study using chitosan / tripolyphosphate (CSTPP) nanoparticles loaded with paraquat. They achieved an encapsulation efficiency of 62.66 ± 0.77%, indicating a strong affinity between CSTPP NPs and the herbicide active ingredient. In corn (… Corn ) and mustard greens ( Brassica sp. Herbicidal activity was evaluated in [the study]. Both free and encapsulated forms of paraquat caused leaf necrosis within 48 hours, which is typical of the herbicide's effect in both plants. Z. maysIn this study, the use of nano-herbicides resulted in more significant necrosis, which may be due to the better adhesion of nanoparticles to leaves, as their higher surface area to volume ratio enhances the interaction.

[0038] Finally, in a study by Butstraen and collaborators [Butstraen, 2014], microcapsules loaded with commercially available Miglyol 812 N chitosan and gum arabic were cross-linked with TPP. The microcapsules were obtained using a coagulation method, and different chitosan to gum arabic mass ratios (1:4 and 1:5) were evaluated in the presence of Miglyol as a cross-linking agent during synthesis. The physicochemical parameters of the microparticles, their encapsulation capacity, and the zeta potential of the particles were evaluated. This study aimed to determine the optimal encapsulation conditions for Miglyol but did not describe or imply a correlation between TPP concentration and the zeta potential of the formed particles. The study suggested an optimal chitosan to gum arabic mass ratio of 1:4, while this invention proposes a wider range from 5:1 to 20:1. This wider range allows for easier redispersibility of the herbicides of this invention (containing composite microspheres) in aqueous solutions of agrochemicals and prevents nozzle clogging during field application.

[0039] No prior art reference discloses or implies a composite microsphere like the one described in this invention, which does not encapsulate the active substances of agrochemicals but is added to the herbicidal active ingredient to enhance its efficacy. This enhancement allows for a reduction in the concentration of the herbicide used while maintaining its effectiveness.

[0040] Furthermore, no prior art reference demonstrates that adjusting the concentration of the crosslinking agent (preferably TPP) during the synthesis process can regulate the surface charge or zeta potential of the composite microspheres. Additionally, no prior art reference suggests using resin (a preferred embodiment of this invention) to improve the redispersibility stability of the chitosan-based composite microspheres when mixed with herbicide solutions.

[0041] The resuspension capability of the microspheres described in this invention is a key property for ensuring their agronomic applications. Without this feature, their poor aggregation and dispersion can clog the filters of nozzles in various applicators or sprayers.

[0042] While existing technologies propose using resins as dispersants in the synthesis of microparticles made from natural polymers such as chitosan, there are no reports of using resins to enhance the redispersibility stability of these particles when added to pesticide formulations (including herbicides). In agronomic practice, the function of the resins in this invention is to prevent nozzle clogging during the application of agricultural chemicals.

[0043] This invention provides composite microspheres comprising chitosan and a crosslinking agent, and in a preferred embodiment, a dispersant such as a resin. The composite microspheres of this invention can be synthesized by adjusting their zeta potential using tunable concentrations of TPP, which allows for fine-tuning of the zeta potential in aqueous solutions. This unique feature of the invention enables the design and selection of desired compositions, allowing for their integration with a wide variety of chemical compounds.

[0044] When formulated with herbicidal active ingredients, the particles of the present invention enhance the effectiveness of the herbicide.

[0045] The ability to modulate zeta potential allows microspheres to be tailored for different pH levels, salinity conditions, and soil types. This versatility enables the application of microspheres to a wide range of crops and agricultural systems. The ability to modulate zeta potential through crosslinking agent concentration indicates that microspheres can control surface charge, thereby influencing the release of active compounds (fertilizers, pesticides, or trace elements) in aqueous solutions. Zeta potential control allows for the design of microspheres that selectively interact with specific surfaces or ions to meet the needs of crops and / or soils. This facilitates the targeted delivery of active ingredients to specific sites of action (plants, pathogens, or soil), thereby optimizing the use of agricultural inputs.

[0046] From an application perspective, these microspheres enable the continuous and efficient delivery of agrochemicals and fertilizers (both chemical and biological) and phytosanitary products, reducing losses due to leaching or evaporation and increasing the utilization of biological targets (plants, fungi, insects). Furthermore, the preferred components (chitosan, gum arabic, and TPP) are biodegradable and non-toxic, making the microspheres environmentally friendly. Therefore, compared to synthetic matrices, they reduce environmental impact, promote sustainable agriculture, and protect soil biodiversity. In addition, chitosan possesses antibacterial properties, protecting plants from pathogens and fungal diseases.

[0047] This invention provides composite microspheres that can be used as adjuvants in agrochemical formulations. In general, these properties make composite microspheres an innovative and promising tool for improving the efficiency of agricultural inputs, reducing environmental impact, and promoting sustainable development in modern agriculture.

[0048] The difference between this invention and related prior art is that it can be mixed with herbicides before application, without the need for encapsulation during granule synthesis. Furthermore, the agrochemical formulation of this invention comprises granules at concentrations that do not exhibit herbicidal activity on their own.

[0049] Convincing evidence of the agricultural application of the herbicides of this invention has been demonstrated through laboratory and field trials. These formulations, which combine herbicides (such as glyphosate) with the composite microspheres described herein, exhibit enhanced herbicidal activity. These trials show that the chitosan:resin:TPP particles of this invention are non-toxic and exhibit an increase in herbicidal activity of more than 10%. Furthermore, they maintain the same herbicidal effect when applied at only 48% of the standard dosage.

[0050] Therefore, this invention addresses the problems posed by the prior art by reducing the use of agrochemicals through a biocompatible and biodegradable solution. It allows for the application of lower doses of active ingredients, which are often high-risk, toxic, and expensive commercial components.

[0051] Therefore, this invention solves the problems found in the prior art by reducing the use of agricultural chemicals through a harmless, safe, biocompatible and biodegradable solution. Summary of the Invention

[0052] This invention relates to a composite microsphere designed to enhance the efficacy of herbicides, preferably for agronomic applications. The composite microsphere comprises chitosan with an average molecular weight ranging from 190,000 to 310,000 g / mol and a cross-linking agent, and contains no herbicidal active ingredient. The composite microsphere of this invention has an adjustable surface charge (zeta potential) in an aqueous medium, which is adjusted by the concentration of the cross-linking agent. The mass ratio of chitosan to cross-linking agent is 1:X, where X varies from 0.08 to 1.5, and this ratio defines the zeta potential of the microsphere in aqueous solution. Preferably, X varies from 0.08 to 0.4, and most preferably, X is 0.08.

[0053] In a preferred embodiment, the crosslinking agent is selected from the group consisting of sodium tripolyphosphate (TPP), sodium hexametaphosphate and its derivatives; most preferably, sodium tripolyphosphate (TPP) is selected.

[0054] In another preferred embodiment, the invention further comprises a dispersant that improves the redispersibility of the microspheres when mixed with an aqueous herbicide solution. The dispersant is selected from the group consisting of gum arabic, xanthan gum, guar gum, carrageenan, pectin, alginate, dextrin, cyclodextrin, maltodextrin, astragalus gum, mesquite gum, polyethylene glycol, and mixtures thereof; gum arabic is preferred. The mass ratio of chitosan to the dispersant is Y:1, where Y ranges from 5 to 20, meaning that the gum is added to the microspheres of the invention in an amount up to 20% of the chitosan mass.

[0055] A primary objective of this invention is to provide a herbicide formulation comprising a herbicidal active ingredient and the composite microspheres described herein, which enhances the herbicidal efficacy against crops. The formulation is characterized in that the composite microspheres are added at a concentration ranging from 2% to 200% w / w relative to the herbicidal active ingredient, preferably between 2% and 100%.

[0056] In a preferred embodiment of the present invention, the herbicidal active ingredient is selected from the group consisting of glyphosate, fenbendazim, imazalil ethanoic acid, atrazine, simazine, diuron, pendimethalin, trifluralin, quizalofop-P-ethyl, quizalofop-P-ethyl, dicamba, paraquat, glufosinate, clethodim, quizalofop-P-ethyl, flusulfanilamide, 2,4-dichlorophenoxyacetic acid, thiamethoxam, pyraclostrobin, glufosinate-ammonium, methoxyfenozide, imazalil, flurfluthrin, clethodim, quizalofop-P-ethyl, quizalofop-P-ethyl, pyrfluthrin, metolachlor, S-metolachlor, propyzoxystrobin, sulfonylpyrazosulfuron, MCPA, pyrimisulfuron, bromobenzonitrile, their derivatives, and mixtures thereof; preferably glyphosate or glufosinate-ammonium.

[0057] In a preferred embodiment of the herbicide formulation, the composite microspheres comprise chitosan with an average molecular weight ranging from 190,000 to 310,000 g / mol, a dispersant, and a crosslinking agent, wherein the mass ratio of chitosan to the crosslinking agent is 1:X, where X varies from 0.08 to 1.5, and defines the zeta potential of the microspheres in aqueous solution. In one embodiment of the invention, the composite microspheres comprise chitosan, gum arabic, and sodium tripolyphosphate, and are free of agrochemical active substances.

[0058] The composite microspheres of this invention exhibit a zeta potential ranging from +30 mV to -30 mV in aqueous solution, which can be adjusted by the concentration of the crosslinking agent. At low crosslinking agent concentrations (e.g., 8% by mass of chitosan), the potential is approximately +30 mV. As the crosslinking agent concentration increases, the zeta potential decreases, reaching zero when the crosslinking agent accounts for approximately 40% of the chitosan mass. With further increases in crosslinking agent concentration, the zeta potential becomes more negative, reaching a value of approximately -30 mV when the concentration exceeds 80% by mass of chitosan.

[0059] In a preferred embodiment, the herbicide formulation of the present invention further comprises an adjuvant selected from the group consisting of adhesives, surfactants, stabilizers, defoamers, pH buffers, chelating agents and their derivatives and combinations thereof.

[0060] In a preferred embodiment of the herbicide formulation, the concentration of the herbicidal active ingredient is equal to or less than the recommended field application rate. This means that the herbicide formulation of the present invention can reduce the amount of herbicides used in agriculture.

[0061] A key feature of the herbicide formulation is that the concentration of the compound microspheres ranges from 5% to 200% w / w relative to the herbicide, more preferably from 5% to 100%, and most preferably from 5% to 10%. The mixture of the herbicide and the compound microspheres is prepared in the field prior to application.

[0062] In a preferred embodiment, the herbicide formulation of the present invention is an aqueous composition comprising a herbicidal active ingredient and composite microspheres encapsulated in a container, because these components are pre-mixed and packaged together at a manufacturing plant for sale and distribution.

[0063] In another alternative preferred embodiment, the herbicide formulation of the present invention is a composite microsphere in the form of an aqueous composition (containing a herbicidal active ingredient) and powder, which is mixed before use.

[0064] Another object of the present invention is to provide a method for preparing the herbicide formulation of the present invention, comprising the following steps: a) Prepare an aqueous solution of the herbicidal active ingredient at the required concentration; b) Add dried composite microspheres at a concentration of up to 100% w / w relative to the herbicidal active ingredient.

[0065] In one embodiment, an adjuvant is also added to the formulation, the adjuvant being selected from the group consisting of adhesives, surfactants, stabilizers, defoamers, pH buffers, masking agents, and their derivatives and combinations.

[0066] Another object of the present invention is a method for preventing or reducing the growth of unwanted plants, which includes applying the herbicide of the present invention to the crop or soil before sowing. The crops are selected from grains, oilseeds, forest trees, fruit trees, trees, ornamental plants, vegetables, wheat, barley, rye, triticale, oats, corn, sunflower, rice, soybeans, peas, broad beans, legumes, peanuts, rapeseed, cabbage, cotton, lentils, potatoes, beets, sugarcane, grass, sorghum, rapeseed, flax, legumes, tomatoes, peppers, pumpkins, lettuce, beets, carrots, beetroot, radishes, apple trees, pear trees, plum trees, bananas, mangoes, citrus trees, walnut trees, almond trees, coffee, cocoa, grapes, orange trees, lemon trees, grasses, alfalfa, forage crops, red clover, fescue, ryegrass, camellia, moringa, miscanthus, sweet corn, chamomile, lavender, mint, aloe vera, stevia, pepper, nutmeg, saffron, hemp, agave, jute, and moringa, etc. Herbicides are applied at concentrations of the active herbicidal ingredient lower than those indicated on the label and are up to 70% more effective than herbicides without microspheres.

[0067] In summary, in a preferred embodiment, the present invention comprises a herbicide formulation that enhances the efficacy of a herbicidal active ingredient by at least 10%. The formulation comprises a herbicidal active ingredient and composite microspheres, wherein the microspheres comprise chitosan and a cross-linking agent. The microspheres comprise chitosan with an average molecular weight in the range of 190,000 to 310,000 g / mol, and the mass ratio of chitosan to cross-linking agent is 1:X, where X varies between 0.08 and 1.5. The concentration of the composite microspheres ranges from 2% to 100% w / w relative to the herbicide in the aqueous phase.

[0068] The composite microspheres also contain a dispersant selected from the group consisting of gum arabic, xanthan gum, guar gum, carrageenan, pectin, alginate, dextrin, cyclodextrin, maltodextrin, astragalus gum, mesquite gum, polyethylene glycol, and mixtures thereof; preferably, gums. The composite microspheres have an tunable surface charge or zeta potential adjustable by the concentration of the crosslinking agent, wherein X ranges from 0.08 to 0.8. The crosslinking agent is TPP.

[0069] In a preferred embodiment of the herbicide formulation, the herbicidal active ingredient is located in an aqueous composition within a container, while the composite microspheres are in powder form and configured to be added to the container.

[0070] Another object of the present invention is to provide a method for obtaining composite microspheres, comprising the following steps: mixing acetic acid, chitosan, and water, and stirring; adding a dispersant and stirring; adding a crosslinking agent solution dropwise; allowing the mixture to stand; and drying the resulting microspheres. Preferably, the method comprises the following steps: a. Dissolve chitosan in 1% v / v acetic acid at 20°C with constant stirring until no clumping is observed; b. Add dispersant and stir until completely dissolved, achieving a chitosan to dispersant mass ratio of Y:1, where Y can vary between 5 and 20; c. Without the presence of herbicidal active ingredients, add dropwise a crosslinking agent solution at a mass ratio of 1:X, where X can vary between 0.08 and 1.2; d. Adjust the pH to approximately 6.5; e. Dry the composite microspheres.

[0071] In a preferred embodiment, step e) involves freeze-drying using a 220 V freeze dryer at -45°C and 10 Pa pressure, followed by grinding in a mortar and filtration through a 100-mesh sieve. Alternatively, step e) involves spray drying at an inlet temperature of 200°C.

[0072] Finally, a preferred embodiment of the method for obtaining the fungicidal formulation of the present invention includes the following steps: a. Preparation of aqueous solutions of fungicides; b. Add dried composite microspheres to an aqueous solution of the fungicide. Attached Figure Description

[0073] Figure 1 Scanning electron microscope (SEM) images of MCS 0.08-0.1, MCS 0.3-0.1, MCS 0.5-0.1, MCS 0.8-0.1, MCS 1.2-0.1 and MCS 1.5-0.1.

[0074] Figure 2 Transmission electron microscopy (TEM) images of MCS 0.08–0.1, MCS 0.3–0.1, MCS 0.8–0.1, and MCS 1.2–0.1.

[0075] Figure 3 Herbicidal activity assay of glyphosate mixed with MCS 0.8–0.1. Representative plants for each treatment are shown.

[0076] Figure 4 Herbicidal activity determination of glyphosate mixed with MCS 0.8–0.1. Bars represent the average fresh leaf biomass (in grams) for each treatment.

[0077] Figure 5 The herbicidal activity of glyphosate mixed with 5% MCS 0.08–0.1 and MCS 0.8–0.1 on leaf biomass was determined in wheat plants grown on plates for 14 days. Plants were treated after 8 days of growth and observed 6 days after application (6DAA). Bar height represents the mean for each group, and error bars represent the standard error (n = 4).

[0078] Figure 6 Glyphosate mixed with MCS 0.8-0.1% for bermudagrass ( Cynodon dactylon Field trial of herbicidal activity against weeds. The height of the bar represents the mean of each group (n = 3). Solid black bars correspond to results measured 7 days after application (7 DAA), and white bars correspond to results measured 14 days after application (14 DAA).

[0079] Figure 7 Glyphosate mixed MCS 0.8-0.1 against "long" turnips ( Turnip cabbage "elongated") weeds Elongated noblewoman Field trials of herbicidal activity were conducted. The bar height represents the mean of each group (n = 3). Solid black bars correspond to results measured 7 days after application (7 DAA), and white bars correspond to results measured 14 days after application (14 DAA).

[0080] Figure 8 A photograph shows how the microspheres of this invention, which do not contain resin, cause clogging of herbicide sprayer filters.

[0081] Figure 9 Scanning electron microscope (SEM) images of MCS 0.8 without gum (left) and with gum arabic (right). Invention Details

[0083] For the purposes of this invention, the term "agricultural chemicals" means any natural or synthetic substance or mixture of substances used to prevent, eliminate and / or control pests, diseases or weeds in agricultural activities, and / or maintain or enhance soil fertility, and / or improve crop quality and / or yield.

[0084] In this article, such agrochemicals include fertilizers, plant growth regulators, biostimulants, pesticides, pest control agents, herbicides, fungicides, nematicides, insecticides, rodenticides, agricultural biochemical compounds, and phytosanitary products.

[0085] For the purposes of this invention, the terms "adjuvant" or "auxiliary agent" or "agricultural adjuvant" refer to products of natural or synthetic origin that enhance or promote the action of agrochemicals (phytosanitary products, fertilizers, or biostimulants) by altering certain properties of a solution and whose properties can improve the activity of the agrochemicals.

[0086] In this document, the term "herbicide" refers to a natural, artificial, or modified chemical or biological product used to control and / or eliminate weeds.

[0087] For the purposes of this article, the terms “unwanted plant,” “useless plant,” “weed,” “invasive plant,” and “herb” are used interchangeably.

[0088] In this document, the term “microsphere” refers to micrometer-sized particles, which may include microparticles, microspheres, nanoparticles or nanospheres, and have various shapes, wherein the size of such microspheres is referred to as particle diameter or size.

[0089] For the purposes of this invention, the term "MCS" refers to the composite microspheres of this invention made of chitosan: gum: TPP.

[0090] The term "MCS0.08" refers to the composite microspheres of the present invention made from chitosan: gum: TPP in a mass ratio of 1:0.1:0.08.

[0091] The term "MCS0.3" refers to the composite microspheres of the present invention made from chitosan: gum: TPP in a mass ratio of 1:0.1:0.3.

[0092] The term "MCS0.5" refers to the composite microspheres of the present invention made from chitosan: gum: TPP in a mass ratio of 1:0.1:0.5.

[0093] The term "MCS0.8" refers to the composite microspheres of the present invention made from chitosan: gum: TPP in a mass ratio of 1:0.1:0.8.

[0094] The term "MCS1.2" refers to the composite microspheres of the present invention made from chitosan: gum: TPP in a mass ratio of 1:0.1:1.2.

[0095] In this document, "ea ha -1 "" refers to the glyphosate equivalent applied per hectare of land. This is a commonly used unit for specifying dosages in agricultural applications.

[0096] One of the major challenges in agricultural activities is the overuse of agrochemicals, which can have adverse effects on human health and the environment, and lead to the emergence of resistant crops. This invention provides a solution to the problems existing in the prior art.

[0097] This invention provides chitosan-based cross-linked composite microspheres, preferably spherical, with a size between 100 and 200 nanometers. These microspheres can aggregate into micron-scale structures and exhibit a synergistic effect of enhancing herbicide efficacy when mixed with herbicides at low concentrations. This allows for maintaining the same weed-control effect while reducing the dosage.

[0098] The composite microspheres provided as the main objective of this invention reduce the use of agrochemicals in agriculture. They comprise chitosan, a crosslinking agent, and preferably a dispersant, wherein the microspheres exhibit a positive, neutral, or negative surface charge. This surface charge can be adjusted by the concentration of the crosslinking agent within the microspheres.

[0099] The chitosan used in this invention preferably has a degree of deacetylation of at least 90%.

[0100] In a preferred embodiment of the invention, the crosslinking agent comprises TPP (tripolyphosphate) with a chitosan / crosslinking agent / dispersant weight ratio of 100 / 8 / 15 and 100 / 80 / 10.

[0101] This invention provides hierarchical composite microspheres made of chitosan, possessing precisely defined and tunable chemical composition, size, shape, and charge distribution. These microspheres, acting as formulation adjuvants, can reduce the dosage of herbicides in agrochemical formulations. These microspheres exhibit a well-defined microstructure and have tunable positive, neutral, or negative surface charges.

[0102] The amount of crosslinking agent (preferably sodium tripolyphosphate) is strategically determined based on the desired charge distribution of the particles, ranging from 3% to 150% w / w relative to chitosan. The dispersant (typically a natural polymer) imparts rapid dispersibility to the microspheres and enables their use under a wide range of salinity, pH, and temperature conditions. The dispersant is selected from the group consisting of gum arabic (and its derivatives), xanthan gum (and its derivatives), guar gum (and its derivatives), poly(ethylene glycol)-poly(propylene glycol) triblock copolymers, polyacrylamide derivatives, microcrystalline cellulose (and its derivatives), and carboxymethyl cellulose (and its derivatives). The concentration of the dispersant can reach up to 20% w / w relative to the mass of chitosan.

[0103] Herbicidal active substances that may be included in this invention include, but are not limited to: glyphosate, fenbendazim, imidacloprid, atrazine, simazine, diuron, pendimethalin, trifluralin, quizalofop-p-ethyl, quizalofop-p-ethyl, dicamba, paraquat, glufosinate, clethodim, quizalofop-p-ethyl, flufenoxuron, 2,4-dichlorophenoxyacetic acid, thiamethoxam, pyraclostrobin, glufosinate-ammonium, methoxyfenozide, imidacloprid, fluroxypyr, clethodim, quizalofop-p-ethyl, quizalofop-p-ethyl, pyrfluthrin, metolachlor, S-metolachlor, propyzoxystrobin, sulfonylpyrazosulfuron, MCPA, pyrimisulfuron, bromobenzonitrile, their derivatives and mixtures thereof.

[0104] The composite microspheres of this invention differ from existing microspheres in that they possess tunable physicochemical properties, particularly their zeta potential and charge distribution. The inventors have been able to adjust and define the zeta potential of the particles described in this invention based on the amount of TPP added during the synthesis process.

[0105] Particles with a chitosan TPP content ranging from 0.03 to 1.5 per unit were developed, achieving tunable zeta potentials in the range of +30 mV to -30 mV. This allows for the synthesis of particles with optimal physicochemical properties for integration with a wide range of agrochemicals.

[0106] In one embodiment of the invention, the microspheres are composed of a positive surface charge, and the amount of sodium tripolyphosphate is less than 40% w / w relative to chitosan.

[0107] In another embodiment of the invention, the microspheres are composed of a negative surface charge, and the amount of sodium tripolyphosphate is at least 50% w / w relative to chitosan.

[0108] In a preferred embodiment, the microspheres of the present invention comprise a medium molecular weight chitosan ranging from 190,000 to 310,000 g / mol and having a degree of deacetylation greater than 90%.

[0109] The present invention also provides an agricultural chemical formulation, particularly a herbicide formulation, comprising a combination of the composite microspheres of the present invention and a herbicide. When added at low concentrations, these composite microspheres do not exhibit herbicidal activity on their own, but enhance the herbicidal effect, which allows for the application of reduced dosages—up to 52% less herbicide—while maintaining similar efficacy to the recommended dosage of the herbicide used alone.

[0110] Compelling and surprising evidence has been observed that formulations of glyphosate mixed with the composite microspheres of this invention (constituting the formulations of this invention) exhibit 15-21% higher herbicidal activity in laboratory plant studies than glyphosate alone. Notably, the concentration range of the composite microspheres used in this invention can be from 2% to 100% w / w relative to the herbicide concentration. Excellent results have been achieved even within a narrow range of 5% to 10%.

[0111] Field trials have shown that agrochemical formulations incorporating the composite microspheres of this invention (at a ratio of 5% w / w relative to the active ingredient) can reduce the application dose of glyphosate by up to 52%, while maintaining similar herbicidal efficacy as glyphosate applied alone at the recommended dose. In this document, the formula for calculating the enhancing effect of the composite microspheres of this invention on the herbicidal active ingredient is defined as follows: Enhancement (%) = ((Effect of this invention - Effect of herbicide alone) / Effect of herbicide alone) × 100 In this case, the effect can be measured by herbicidal activity. However, other variables can also be used for evaluation, such as when yield depends on the control applied by the agrochemical in question.

[0112] Unlike similar particles identified in the prior art, characterized by encapsulating agrochemicals within granules during synthesis, the composite microspheres of this invention are combined with the active ingredient after synthesis, preferably before field application. The most significant advantages include compatibility with a wide range of agrochemicals and enhanced efficacy when co-formulated. By increasing efficiency, this invention allows for the recommendation of lower application doses than the commercially recommended dosage of the product.

[0113] The fact that the composite microspheres of this invention are dried and bound upon application ensures an extended shelf life for the stable product under normal environmental conditions. Because they are biodegradable, these composite microspheres do not accumulate and therefore do not cause environmental damage. No cytotoxicity markers were detected in human cells.

[0114] This invention provides a manufacturing process for these composite microspheres, involving a strategically designed physical gelation process consisting of three essential components: chitosan, a crosslinking agent, and a dispersant.

[0115] The production process has been successfully scaled up to a reaction volume of 20 liters. Throughout the process, the pH was maintained at 4.5 by adjusting with acetic acid, while stirring and temperature were kept constant at 130 rpm and 20°C, respectively. At the end of the process, the pH was adjusted to 6.5, and the microspheres were allowed to settle naturally. They were then dried using spray drying and filtered through a 100-mesh sieve.

[0116] The present invention also provides a method for synthesizing the composite microspheres of the present invention, which includes the following steps: a. Dissolve chitosan in acetic acid at 1% v / v at 20°C with constant stirring until no clumping is observed; b. Add gum arabic and stir until completely dissolved, achieving a chitosan to gum arabic mass ratio of Y:1, where Y can vary between 5 and 20; c. Without the presence of herbicidal active ingredients, add TPP solution dropwise to the mixture until the desired TPP concentration is reached, achieving a chitosan to TPP mass ratio of 1:X, where X can vary between 0.03 and 1.2; d. Adjust the pH to approximately 6.5; e. Dry granules.

[0117] In a preferred embodiment of the present invention: Step e) involves freeze-drying using a 220 V freeze dryer at -45°C and 10 Pa pressure, followed by grinding in a mortar and pestle and filtering through a 100-mesh sieve; or Step e) involves spray drying at an inlet temperature of 200°C.

[0118] The present invention also provides a method for preventing weed growth, comprising applying the herbicide of the present invention to crops or soil before sowing, wherein the crops are selected from grains, trees, oil crops, vegetables, fruits, ornamental plants, sugar beets (…). Beta common ), chili peppers (Capsicum spp.), garlic and onions ( Allium spp. .),celery( Sweet celery ),eggplant( Solanum aubergine ),pumpkin( Musk gourd ), Chayote Eat the Sechium ),cabbage( Brassica oleracea Spinach (Spinacia oleracea), green beans ( Common bean ),lettuce( Green lettuce ),corn( Corn ),peanut( Peanut ),tomato( Nightshade tomato),cucumber( Cucumber okra Hibiscus esculentum ),radish( Radish agricultural ), beetroot ( Beetroot ),carrot( Carrot ),avocado( American Persea ), custard apple ( Scaly food ), Star Apple ( Chrysophyllum cainito Eggfruit () Pouteria Campeche Acerola cherry ( Malpighia punicifolia ), oxheart custard apple ( Netted annona ),Plum( Sweet Spondias ),coconut( Cocos nucifera ),pawpaw( Papaya ), Soursop ( Muricada annona ), guava ( Psidium guajava ),Pomegranate( Pomegranate ),lime( Citrus golden-leaved ),lemon( Citrus limon ),apple( Domestic apple ), Ma Mi Xing ( Calocarpus mammoth ), Mammillen apple ( American mammal Spanish lime () Two-spotted honeysuckle ),Tangerine( Citrus reticulata ),mango( Mangosteen ),passion fruit( Passionflower laurel ),watermelon( Citrullus woolly bitter orange () Citrus aurantium ), sweet orange ( Citrus sinensis ),pear( Pear common ),Pineapple( Pineapple is delicious. ),banana( Paradise banana ), plantain ( Musa balbisiana Tamarind ( Tamarind ), grapefruit Citrus paradisi ),Grapefruit( Citrus grandis ), grape (Vitis) wine-producing ), rice White rice ),coffee( Arabic coffee ),sugar cane( Sugar factories ),cotton( Gossypium hirsutum ), small cucumber Melothria guadalupeensis ),sweet potato( Ipomoea batatas ),potato( Solanum tuberosum Andean potatoes SolanumpHureja ), Physalis peruviana, cassava ( Manihot esculenta ), soybeans Glycine max ),strawberry( Fragaria spp.), Mulberry ( Morusspp .),blackberries( Rubus spp Palm family plants, oil palm (.), palm trees, oil palm ( Elaeis guineen s is), Cocoa Theobroma cacao Tree tomato Solanum betaceum ), Lulu fruit ( Solanum quitoense ), chickpeas Cicer arietinum Other species, such as )

[0119] The present invention is further described through the following embodiments, which should not be considered as limiting the scope of the invention. The present invention is not limited to the illustrative embodiments provided below.

[0120] Example

[0121] Example 1: Laboratory-scale synthesis and production method of chitosan: gum arabic: tripolyphosphate (TPP) composite microspheres

[0122] The following materials were used to synthesize the composite microspheres: chitosan (95% deacetylation, Mw 275,000), gum arabic (Mw 70,000), TPP, 1% acetic acid, 1 M sodium hydroxide, distilled water, 600 ml and 250 ml beakers, DragonLab mechanical stirrer, peristaltic pump, pH meter, and 100 mesh and 450 mesh sieves.

[0123] Chitosan, gum arabic, and TPP composite microspheres were obtained in 0.6- and 20-liter reactors using an iontophoresis method, following the procedure described below: a) For a 600 ml reactor: Prepare 200 ml of 1% w / v acetic acid (10 mL / L) solution and add 4 g of chitosan while stirring at a constant 1300 RPM using a DragonLab mechanical stirrer. Stir until the solution is completely dissolved and reaches a uniform, clear color without visible lumps, and stir for 10 minutes at room temperature.

[0124] Add 0.4 g of gum arabic (10% of the weight of chitosan). Stir for 10 minutes until completely dissolved.

[0125] Prepare a 1.6% w / v sodium tripolyphosphate aqueous solution.

[0126] Using a peristaltic pump, begin adding TPP solution dropwise to the beaker until 200 mL of TPP has been added to the reactor. After the addition is complete, maintain stirring for 30 minutes. Keep the reactor stirred at 1300 RPM.

[0127] Measure and adjust the pH to 6.5 using 1 M sodium hydroxide.

[0128] Centrifuge at 1200 RPM for 10 minutes and discard the supernatant.

[0129] The composite microspheres were frozen in a freezer for 24 hours.

[0130] The composite microspheres were dried using a PeetLab BK-FD10PT freeze dryer at 220 V, -18°C, and 10 Pa.

[0131] The composite microspheres were ground and first passed through a 100-mesh sieve, then through a 450-mesh sieve.

[0132] b) For a 20-liter reactor: The same procedure was followed, except that the material dosage was adjusted for the size of a 20-liter reactor equipped with a DragonLab 4-blade mechanical stirrer (Figmay), and the drying step was modified to spray drying, as shown below: In short, 5 L of 1% acetic acid (10 mL / L) and 100 g of chitosan (95% deacetylation, Mw 275,000) were added to a 20 L borosilicate glass reactor (Figmay) equipped with four flat paddle stirrers (unheated), and stirred at 130 RPM for 10 minutes. The reactor temperature was maintained at 21 ± 2°C. Complete dissolution was achieved, and the solution was homogeneous, clear, and free of visible lumps. Subsequently, 15 g of gum arabic was added as a dispersant, and the mixture was stirred for 10 minutes.

[0133] In the second 10-liter reactor, a TPP solution (sodium tripolyphosphate) with a concentration of 16 g / L was prepared by adding 5 L of distilled water and 80 g of TPP, and stirring until completely dissolved, and stirring for 5 minutes at room temperature.

[0134] A 20-liter reactor containing chitosan solution was stirred at 130 rpm, and TPP solution was added dropwise at a rate of 2 L / h using two peristaltic pumps. Once all TPP had been added, stirring was maintained for 30 minutes. The pH was then adjusted to 6.5 using 1 M NaOH.

[0135] The reactor was then emptied into a 20-liter container and allowed to stand overnight (12 hours) at room temperature. The supernatant was discarded. The particles were dried using a JISL LSD-48 benchtop spray dryer with a drying capacity of 1 L / h at an inlet temperature of 200°C and a feed rate of 60% (600 mL / h). The particles were kept in suspension by stirring during the drying process.

[0136] Example 2: Preparation of chitosan composite microspheres with different proportions of gum arabic and tripolyphosphate

[0137] Composite microspheres were obtained according to the procedure described in Example 1, adjusting the amount of gum arabic relative to the weight of chitosan and modifying the volume of TPP added dropwise relative to the amount of chitosan. This produced composite microspheres with different chitosan:gum arabic:TPP mass ratios.

[0138] The following composite microspheres with the mass ratios shown in Table 1 were prepared.

[0139] Table 1. Composite microspheres containing different mass ratios of gum arabic and TPP relative to 1 part chitosan.

[0140]

[0141] Example 3: Preparation of composite microspheres using chitosan and sodium hexametaphosphate (HMP) as crosslinking agents, and xanthan gum and polyethylene glycol as dispersants.

[0142] In a 20 L reactor (Fignnay brand) made of 3.3 borosilicate glass and equipped with a 4-blade stirrer (unheated), 5 L of 15% citric acid solution (10 mL / L) and 100 g of chitosan (92% deacetylation, Mw 210,000) were added. The mixture was stirred at 150 RPM for 10 minutes, maintaining the reactor temperature at 21 ± 2 °C. Complete dissolution was achieved, producing a homogeneous, clear solution free of visible lumps. Subsequently, 5 g of xanthan gum and 10 g of polyethylene glycol were added as dispersants, and the mixture was stirred for 10 minutes.

[0143] In the second 10 L reactor, a sodium hexametaphosphate (HMP) solution with a concentration of 25 g / L was prepared by adding 5 L of distilled water and 125 g of HMP, and stirring for 10 minutes until completely dissolved at room temperature.

[0144] The 20 L reactor containing the chitosan solution was stirred at 150 RPM, and HMP was added dropwise at a rate of 0.5 L / h using a peristaltic pump (over 10 hours). Stirring was maintained for an additional 60 minutes after all HMP was added.

[0145] The reactor contents were then transferred to a 20 L container and allowed to stand overnight (12 hours) at room temperature. The supernatant was poured into another container, ensuring no material loss during the process, and then centrifuged at 1500 RPM for 15 minutes using a Rolco MOD.CM-2036 laboratory centrifuge. The sample was then frozen at -24 °C for 24 hours. The sample was then freeze-dried for 72 hours using a benchtop multi-collector freeze dryer. Finally, the sample was ground and passed through a 450-mesh sieve.

[0146] Example 4: Determination of the size and morphology of chitosan: gum arabic: tripolyphosphate composite microspheres

[0147] The composite microspheres obtained according to the procedure in Example 1 and the chemical composition described in Example 2 were subjected to comprehensive physicochemical characterization to define their structure and properties.

[0148] Three techniques were used to study and define the size and morphology of the composite microspheres: 1. Dynamic light scattering (DLS).

[0149] Three measurements were performed at 25°C using a Malvern zetasizer Nano S90, each lasting 60 seconds with a 10-second interval. The Brownian motion of the composite microspheres in the suspension was analyzed. The light scattered by the composite microspheres provided information about the diffusion coefficient, from which the hydrodynamic radius and size distribution of the material could be determined.

[0150] Table 2. Physicochemical parameters of composite microspheres (MCS) with different TPP / CS ratios. All samples contained 10% gum arabic.

[0151]

[0152] 2. Transmission electron microscope (TEM).

[0153] This technique was performed using a JEOL JEM 2100 microscope with a 200 kV and B6La filament. Images were taken at 50,000x or higher magnification to analyze the morphology and size of the particles.

[0154] 3. Scanning electron microscope (SEM).

[0155] (FESEM) ZEISS Crossbeam 350. Samples with Cr or Au coatings were prepared. Images were taken at magnifications of 30x, 500x, 1500x, 6000x, 20,000x, and 40,000x. General appearance, particle size, and morphology were analyzed.

[0156] Characterizing particle size using DLS allowed us to conclude that populations with different size distributions exist (Table 2). In many cases, up to three different hydrodynamic diameters were observed, ranging from approximately 200–300 nm, 600–1000 nm, and 2000–5000 nm.

[0157] When using more precise techniques such as SEM and TEM to study particle morphology and size, it was observed that spherical particles with a diameter of approximately 20-30 nm interacted to form larger aggregates, some of which were amorphous and others spherical. Figure 1 and 2 These aggregates range from hundreds of nanometers to several micrometers, thus confirming the size distribution results obtained by DLS during synthesis.

[0158] Example 5: Determination of charge distribution in chitosan: gum arabic: tripolyphosphate composite microspheres

[0159] To determine the zeta potential, three measurements were performed at 25°C using a Horiba-SZ 100 instrument, each lasting 100 seconds with a 10-second interval. The results were averaged and reported. The results obtained for different composite microspheres (MCS) are shown in Table 2.

[0160] Characterization results show that composite microspheres containing resin (10% w / w relative to chitosan) with TPP / CS ratios between 0.08 and 0.3 (inclusive) (MCS 0.08–0.1 and MCS 0.3–0.1) exhibit positive Zeta potential values, while those with TPP / CS ratios between 0.5 and 1.5 (MCS 0.5–0.1, MCS 0.8–0.1, MCS 1.2–0.1, and MCS 1.5–0.1) exhibit negative values ​​(Table 2). The inflection point appears to correspond to a TPP / CS ratio of 0.4, at which point the particle surface charge is close to neutral, as the Zeta potential value is around 0 considering measurement errors (between ±5 and ±10 mV). These results demonstrate that increasing the TPP concentration increases the negative Zeta potential of the particles, thus enabling the design of composite microspheres with desired Zeta potentials based on the amount of TPP added.

[0161] Example 6: Study on the interaction between composite microspheres and glyphosate

[0162] A study was conducted to evaluate the interaction between the composite microspheres and different agrochemicals in aqueous solution, and the amount of active ingredients bound to the material was determined.

[0163] Nuclear magnetic resonance (NMR)

[0164] Following the technique described in "Probing interactions by means of pulsed field gradient nuclear magnetic resonance spectroscopy" S. Cozzolino, et al. Magn. Reson. Chem. 2008, 46, S16-S23 DOI 10.1002 / mrc.2345, diffusion coefficients were calculated using NMR. These coefficients can be used to determine the percentage of physicochemical binding of different analytes to the composite microspheres (MCS).

[0165] In their free state, analytes and particles possess their own diffusion coefficients, reflecting their molecular weight and shape. However, when a complex is formed and the analyte is strongly bound to the particle, they should have the same diffusion coefficient because they diffuse as a single molecular entity. In cases of weak binding or no significant binding, the diffusion coefficients of the analyte and particle remain unchanged. In other cases, assuming rapid exchange on the NMR timescale, the observed (measured) diffusion coefficient is a weighted average of the free and bound diffusion coefficients, and can therefore be used to calculate the binding ratio.

[0166] The diffusion coefficient was determined using the PFGSTE26 sequence on a Spinsolve80 Ultra from Magritek GmbH, with the membrane strip placed in a 5 mm tube and operated at 26°C.

[0167] The study used MCS 0.8-0.1 (with resin), MCS 0.8-0 (without resin) samples from Example 2 and glyphosate to investigate the binding percentages between them. The components were added to laboratory tubes containing distilled water and stirred manually for 1 minute. Suspensions of individual components and mixtures of each microparticle with glyphosate at a glyphosate / microsphere mass ratio of 1:5 were prepared.

[0168] In the second study, a mixture of glyphosate and microspheres MCS 0.08-0.1, MCS 0.8-0.1 and MCS 1.2-0.1 from Example 2 was prepared at a glyphosate / microsphere mass ratio of 10:1.

[0169] Table 3. Percentage of glyphosate (negative charge) binding to composite microspheres (MCS). Percentages were obtained based on diffusion coefficients determined by NMR techniques.

[0170]

[0171] This table highlights that, due to the negative charge of glyphosate, the highest binding rate occurred on composite microspheres exhibiting a positive zeta potential. It also shows that the presence of resin reduces the binding affinity between glyphosate and the microspheres, which is a factor limiting the amount of resin used.

[0172] Example 7: Glyphosate-infused composite microspheres (MCS) on lettuce plants ( Lactuca sativa Herbicidal activity assay

[0173] To evaluate whether chitosan: gum arabic: TPP composite microspheres have a herbicidal enhancement effect when formulated with glyphosate, the following experimental protocol was used to apply different concentrations of commercial herbicides to lettuce plants in conjunction with the determination of the composite microspheres: Lettuce plants ( Lactuca sativa *Growmantecosas* var. *mantecosas* was grown for two weeks in 7 x 9.5 x 4 cm pots, each containing 25 g of the commercial substrate Grow Mix Multipro, under controlled light (16:8 photoperiod), temperature (25°C), and humidity (60% relative humidity). After 14 days of growth, the plants were divided into five experimental groups, each containing 10 plants (5 x 10), and treated by foliar spraying with the treatments described in Table 4.

[0174] The application volume per plant is 0.2 ml. A water-sensing card is used to control and calibrate the spray. Spraying is performed using a plastic sprayer (PVC-EPA).

[0175] Table 4. Treatments for evaluating the herbicidal efficacy of different concentrations of glyphosate combined with MCS 0.8-0.1.

[0176]

[0177] To prepare the application solution, an initial aqueous solution of 5 mg / ml MCS was first prepared. The required amount of MCS solution for glyphosate herbicide was calculated to ensure that the composite microspheres (MCS) of the present invention maintained a 5% by weight ratio of the glyphosate active acid equivalent (ea) present in the mixture, under specified proportions of composite microspheres. These proportions are expressed as 5% (w / ea glyphosate) or 10% (w / ea glyphosate) according to the treatment. The application solution was prepared in 15 or 50 ml Falcon tubes (Bio-Plast) according to the required volume. Each formulation was shaken in a vicking (model M23) for 2 hours until application.

[0178] Ten days after each treatment (10 DDA), 10 plants from each experimental group were collected, and the biomass of fresh leaves was quantified using an analytical balance (OHAUS, model Traveler TA302).

[0179] Figure 3 Representative plants for each treatment are shown, while Figure 4 The average weight (with standard deviation) of 10 plants for each treatment test is shown.

[0180] Apply full dose of herbicide (1 L ha) -1 Glyphosate caused a 62% reduction in fresh biomass relative to the water control (H2O). Using 0.5 L ha -1 Plants treated with glyphosate showed a 30% reduction in biomass compared to the same control. Figure 4 In contrast, using 0.5 L ha -1 Plants treated with glyphosate + 5% MCS 0.8-0.1 showed a 51% reduction in biomass compared to the control. This indicates that combining MCS 0.8-0.1 with a reduced dose of glyphosate enhances weed control efficacy by 21% compared to treatments using the same herbicide concentration but without MCS 0.8-0.1.

[0181] On a percentage basis, the formulation of this invention containing 5% chitosan complex microspheres (MCS) enhanced the herbicidal efficacy of glyphosate by 70%. The percentage of biomass reduction increased from 30% without MCS (0.8-0.1%) to 51% with MCS (0.8-0.1%). The formula for calculating the enhancement is as follows: Enhancement (%) = ((51-30) / 30) × 100 In this article, this indicator of increased herbicidal efficacy is referred to as "enhancement". In this test, the use of MCS 0.8-0.1 increased the efficacy of the herbicide by 70% compared to the use of herbicides without the complex microspheres alone.

[0182] Control plants treated with 5% MCS at 0.8–0.1 glyphosate but without glyphosate did not show significant phytotoxicity or biomass reduction.

[0183] This study demonstrates that adding 0.8-0.1 MCS (which itself has no herbicidal activity) at a concentration of 5% can improve herbicidal efficacy, thereby allowing for a reduction in application dosage by up to 50%. This is evidence of a surprising synergistic effect that has never been previously suggested.

[0184] Example 8: Glyphosate combined with composite microspheres with different TPP concentrations on wheat (as a target plant, simulated weed) Triticum aestivum Herbicidal activity assay

[0185] An evaluation was conducted to determine whether the surface charge (Zeta potential) of chitosan composite microspheres had a differential effect on the glyphosate efficacy of wheat plants grown on plates under controlled environmental conditions.

[0186] The following experimental design was used: Wheat seeds were sterilized with 20% (v / v) bleach and evenly sown in sterile Petri dishes (90 mm x 15 mm, Bio-Plast) containing filter paper moistened with 5 ml of sterile water. The seeds germinated and grew for 8 days under controlled light, temperature, and humidity conditions.

[0187] After this period, each treatment was performed by foliar spraying with the solutions described in Table 5. Application was carried out using a PVC-EPA sprayer. The application volume for each solution was 0.8 ml per dish.

[0188] Table 5. Treatments for evaluating the enhancement of glyphosate efficacy applied to wheat plants by composite microspheres MCS 0.8-0.1 and MCS 0.08-0.1.

[0189]

[0190] An aqueous solution of 5 mg / ml MCS was initially prepared. The required volume of MCS solution (depending on the case) was combined with the test dose of glyphosate. The solution was treated in a track shaker (Vicking, model M23) for 2 hours. Six days after the start of treatment (6DDA), plants were harvested and weighed on an analytical balance (OHAUS, model Traveler TA302) to quantify the fresh biomass of the aboveground parts. The biomass per leaf was estimated. Figure 5 ).

[0191] Use 1 L ha -1 Plants treated with glyphosate showed a 28% (w / w) reduction in dry leaf biomass relative to the water control (H2O). Figure 5 ). Using 5% MCS 0.08-0.1 + 1 L ha -1 When plants were treated with glyphosate, the biomass reduction rate relative to the same control (H2O) was 40.56% (w / w). This means that, on a percentage basis, the herbicidal efficacy of glyphosate was increased by 45% using the formulation of this invention containing 5% chitosan complex microspheres. The percentage reduction in biomass increased from 28% (w / w) without MCS 0.08-0.1 to 40.56% (w / w) with MCS 0.08-0.1.

[0192] Enhancement Formula: Enhancement (%) = ((40.56-28) / 28) x 100 This article refers to this increase in herbicidal efficacy as "enhancement". In this study, the use of MCS 0.08-0.1 resulted in a 45% enhancement of herbicide efficacy compared to using the herbicidal active ingredient alone (without the addition of composite microspheres (MCS)).

[0193] In addition, when using 5% MCS 0.8-0.1 + 1 L ha -1 In plants treated with glyphosate, the biomass reduction rate relative to the H2O control was 32.24% (w / w). This indicates that applying 5% MCS at 0.08–0.1 g / L with 1 L of H2O significantly reduced biomass. -1 The combination of glyphosate and MCS increased herbicidal efficacy by 12.2% (w / w) compared to the same glyphosate dosage without MCS. Meanwhile, the addition of 5% MCS at 0.8-0.1% resulted in a 3.9% (w / w) increase in glyphosate efficacy. Figure 5 ).

[0194] On a percentage basis, the formulation of this invention containing 5% chitosan complex microspheres increased the herbicidal efficacy of glyphosate by 15%. The percentage of biomass reduction increased from 32.24% (w / w) without MCS 0.08 to 40.56% (w / w) containing MCS 0.8-0.1. Enhancement (%) = ((32.24-28) / 28) x 100 This article refers to this increase in herbicidal efficacy as "enhancement". In this assay, the use of MCS 0.8 provided a 15% enhancement in efficacy for the herbicide formulation of this invention.

[0195] Example 9: Field trials of glyphosate combined with composite microspheres against different weeds

[0196] Independent field trials were conducted at various locations in the Republic of Argentina. In all trials, glyphosate was formulated at different concentrations, always in combination with spray-dried MCS 0.8–0.1 composite microspheres. Different weeds were tested, and measurements were taken at different days after treatment.

[0197] The experiment adopted the following general scheme: The experiment was conducted in Argentina during the summer (2023 / 2024). The herbicidal activity of glyphosate in chemical fallow was evaluated. The design consisted of microplots 3 meters wide and 8 meters long, with three randomized replicates. Different solutions were applied to the fallow land using a CO2 backpack sprayer under constant pressure.

[0198] Table 6 describes the different treatments evaluated. Treatments were completely randomized to fairly represent each experimental group (n = 3). The percentage of weed control was quantified at different days after treatment application (DDA). To determine the percentage of weed control, the percentage of control of each treatment relative to the untreated weed treatment was estimated. These determinations were performed regularly according to the guidelines of the EWRS (European Weed Research Society).

[0199] It recorded the monthly and cumulative rainfall during the election year.

[0200] Table 6. Treatments for evaluating the efficacy of glyphosate-binding composite microspheres MCS 0.8-0.1.

[0201]

[0202] 1- Location: Adolfo Gonzales Chaves

[0203] Field location: 38°09'39.93"S / 59°45'42.70"W

[0204] Application conditions: Use a backpack CO2 sprayer equipped with a 2-meter spray boom and a fan-shaped nozzle. The application rate is 110 L / ha and the pressure is 2 bar.

[0205] The weeds tested: Bermuda grass ( Cynodon dactylon Gramon)

[0206] exist Figure 6 The table shows the average results for each treatment (n=3), illustrating the percentage of control relative to untreated plots at two intervals (7 days and 14 days) after treatment. Glyphosate full dose 1500 ea ha -1 Treatments combining composite microspheres (5% and 10% w / ea) showed slightly higher percentages of control than glyphosate administered alone at the same dose. Furthermore, treatments using 900 ea ha... -1 Treatments combining glyphosate with composite microspheres (5% and 10% w / ea) (treatments 4 and 5, respectively) achieved similar percentages of control as the recommended glyphosate dose (treatment 1).

[0207] The weed tested: long turnip ( Brassica rapa, "elongated" Nobolza)

[0208] exist Figure 7 The table shows the average results for each treatment (n=3), illustrating the percentage of control relative to untreated plots at two intervals (7 days and 14 days) after treatment. Treatments 4, 5, 6, and 7 show the percentage of weed control compared to applying 1500 ea ha alone. -1Similar to glyphosate (treatment 1).

[0209] Both trials demonstrated that the combination of the composite microspheres with the herbicide allowed for a dosage reduction of at least 40%, as the combination enhanced the herbicide's efficacy, matching it to the highest dosage tested.

[0210] 2- Location: Tres Arroyos

[0211] Field location: -38.602085°, -59.960860°

[0212] Application conditions: A constant pressure backpack sprayer equipped with a carbon fiber side spray bar with four hollow conical nozzles spaced 52 cm apart, applied at a flow rate of 100 L / ha under a pressure of 3 bar.

[0213] The weed tested: Datura ( Datura ferox Chamico)

[0214] Apply glyphosate as indicated on the label: 1500 ea ha -1 glyphosate

[0215] The formulation of the present invention was applied in the field under the same conditions as follows: 900 ea ha -1 Glyphosate + 5% MCS 0.8 Nineteen days after treatment, the same weed control effect was observed, indicating that glyphosate application can be reduced by 40% while maintaining the same weed control efficacy.

[0216] 900 ea ha -1 Glyphosate + 10% w / w MCS 0.8

[0217] At 19 and 28 days post-treatment, the herbicidal effect of the formulation of the present invention was observed to be 15% stronger than that of glyphosate (#1) applied in the conventional manner.

[0218] 1500 ea ha -1 Glyphosate + 10% w / w MCS 0.8

[0219] Nineteen days after treatment, the weed control efficacy was increased by 40%, and at 28 days, an increase of 15% was observed.

[0220] The weed tested: lambsquarters ( Chenopodium album Quinoa)

[0221] Apply glyphosate as indicated on the label: 1500 ea ha-1 glyphosate

[0222] The formulation of the present invention was applied in the field under the same conditions as follows: 720 ea ha -1 Glyphosate + 5% w / w MCS 0.8 Seven days after treatment, a 5% increase in weed control was observed, with the glyphosate dosage being 48% lower than the label recommended. This demonstrates that a 52% reduction in glyphosate application can be achieved while maintaining higher weed control efficacy.

[0223] 1500 ea ha -1 Glyphosate + 10% w / w MCS 0.8

[0224] Seven days after treatment, the weed control efficacy increased by 10%.

[0225] 3- Location: 9 de Julio

[0226] Field location: 35°23'12.86"S; 61°0'41.64"W

[0227] Application conditions: CO2 manual constant pressure backpack sprayer, spray bar equipped with four nozzles spaced 52 cm apart, using hollow cone 80015 nozzles, flow rate of 100 L / ha, pressure of 2.5 bar.

[0228] The weeds tested: Goosegrass ( ) Eleusyne sp. )

[0229] Apply glyphosate as indicated on the label: 1500 ea ha -1 glyphosate

[0230] The formulation of the present invention was applied in the field under the same conditions as follows: 900 ea ha -1 Glyphosate + 5% w / w MCS 0.8 900 ea ha -1 Glyphosate + 10% w / w MCS 0.8 Fourteen days after treatment, a 24% increase in weed control was observed, with the glyphosate dosage at 60% of the label-recommended amount. This demonstrates that glyphosate application can be reduced by 40% while achieving higher weed control efficacy.

[0231] During chemical fallow, apply 1500 ea ha -1Glyphosate resulted in 63% weed control (Eleusine indica) 21 days after treatment (21 DDA). Eleusine indica At this herbicide concentration, the addition of 5% (w / ea) MCS 0.8 resulted in 72% weed control at 21 DDA, representing a 9% increase in glyphosate efficacy (Figure 11). Furthermore, the addition of 5% (w / ea) MCS 0.8 to a reduced dose of glyphosate (40% lower than the full dose) achieved 70% weed control, demonstrating that the addition of MCS allows for a reduction of at least 40% in glyphosate application under field conditions.

[0232] Example 10: Field trial of the herbicidal activity of glyphosate + 2,4-D choline salt combined microspheres against weeds.

[0233] Independent field trials were conducted at various locations in the Republic of Argentina. In all trials, glyphosate and / or 2,4-D choline salts were formulated at different concentrations, always in combination with spray-dried MCS 0.8–0.15 composite microspheres. The trials targeted Sumatran white wine grass (… Conyza sumatrensis (Rama Negra), and measurements were taken at different number of days after treatment.

[0234] The experiment followed the following general protocol: The experiment was conducted during the Argentine summer. The herbicidal activity of glyphosate in chemical fallow was evaluated. The design consisted of microplots 3 meters wide and 8 meters long, with three randomized replicates. Different solutions were applied to the fallow land using a constant-pressure CO2 backpack sprayer.

[0235] Table 7 describes the different treatments evaluated. Treatments were completely randomized to fairly represent each experimental group (n = 3). The percentage of weed control was quantified at different days after treatment application (DDA). To determine the percentage of weed control, the percentage of control of each treatment relative to the untreated weed treatment was estimated. These determinations were performed regularly according to the guidelines of the EWRS (European Weed Research Society).

[0236] It recorded the monthly and cumulative rainfall during the election year.

[0237] Table 7. Evaluation of the herbicidal activity of glyphosate formulations and treatments combining glyphosate with 2,4-D choline salt (2,4-D) and MCS microspheres 0.8–0.15.

[0238]

[0239] Location: Tres Arroyos

[0240] Field location: -38.388612; -60.346111

[0241] Application conditions: A manual backpack sprayer with a working width of 2 meters, equipped with a TeeJet 80015 nozzle, was used to apply CO2 at a constant pressure of 2.5 bar at a rate of 126 L / ha. Visual control measurements were taken at 10, 20, 30, and 50 days (DDA) after application. Data were analyzed by ANOVA, and means were compared using Fisher's LSD test (p < 0.05).

[0242] The weed tested: Sumatran white wine grass ( Conyza sumatrensis Rama Negra)

[0243] Table 8 presents the average percentage of control values ​​for the four treatments at 10, 20, 30, and 50 DDA.

[0244] Table 8. Control of Rama Negra by glyphosate formulations and glyphosate-conjugated 2,4-D choline salt (2,4-D) and composite microspheres MCS 0.8–0.15.

[0245]

[0246] This demonstrates the residual effectiveness of the invention.

[0247] Example 11: Field trial evaluating the herbicidal efficacy of glufosinate-phosphonate combined with microspheres against the weed Rama Negra.

[0248] A field trial was conducted to evaluate the herbicidal efficacy of using different concentrations of glufosinate-ammonium alone, or in combination with spray-dried compound microspheres MCS 0.8–0.15. The trial targeted Sumatran white wine grass (… Conyza sumatrensis (Rama Negra), and measurements were taken at different number of days after treatment.

[0249] The experiment followed the following general protocol: The experiment was conducted during the Argentine summer. The herbicidal activity of glufosinate-phosphonate in chemical fallow was evaluated. The design consisted of microplots 3 meters wide and 8 meters long, with three randomized replicates. Different solutions were applied to the fallow land using a constant-pressure CO2 backpack sprayer.

[0250] Table 9 describes the different treatments evaluated. Treatments were completely randomized to fairly represent each experimental group (n = 3). The percentage of weed control was quantified at different days after treatment application (DDA). To determine the percentage of weed control, the percentage of control of each treatment relative to the untreated weed treatment was estimated. These determinations were performed regularly according to the guidelines of the EWRS (European Weed Research Society).

[0251] It recorded the monthly and cumulative rainfall during the election year.

[0252] Location: Bragado, field position: -35.08043°S; -60.33043°W

[0253] Application conditions: A manual backpack sprayer with a working width of 2 meters, equipped with a TeeJet 80015 nozzle, was used to apply CO2 at a constant pressure of 2.5 bar at a rate of 126 L / ha. Visual control measurements were taken at 7 and 25 days post-application (DDA). Data were analyzed by ANOVA, and means were compared using Fisher's LSD test (p < 0.05).

[0254] The weed tested: Sumatran white wine grass ( Conyza sumatrensis Rama Negra)

[0255] Table 8. Control of Rama Negra by different formulations of glufosinate-phosphonate combined microspheres MCS 0.8–0.15. Percentage of control for different treatments tested.

[0256]

[0257] In this experiment, the addition of microspheres (maintaining a weight ratio of microspheres to active ingredient, i.e., w / wMCS / Glufosinate Ammonium, in each mixture) demonstrated higher efficacy, faster weed wilt, and lower weed regrowth rates. Even at doses lower than the commercially recommended full dose (2 L / ha), treatments containing the composite microspheres of this invention showed increased efficacy compared to glufosinate-ammonium treatment alone.

[0258] Example 12: Field trial of the herbicidal activity of glyphosate + 2,4-D choline salt combined microspheres against weeds.

[0259] Treatment 3 from Table 7 of Example 10, comprising equal parts glyphosate + 2,4-D choline salt, and 5% and 10% of the composite microspheres of the present invention as defined in Test 4 of Table 1 of Example 2, specifically MCS 0.8-0 microspheres in a chitosan:resin:TPP mass ratio of 1:0:0.8 (i.e., without resin), was applied using a handheld backpack sprayer. Clogged nozzle filters were observed, such as… Figure 8 As shown. This is because the redispersibility of the microspheres of the present invention is low when resin is not present.

[0260] In a similar test subsequently conducted using microspheres MCS 0.8-0.1 (containing a resin concentration of 10% relative to the chitosan mass) from Test 4 of Table 1 in Example 2, the nozzles did not become clogged and there was no need to clean their filters.

[0261] Figure 9 It has been demonstrated that resin concentrations between 5% and 20% improve the formation of the microspheres described in this invention.

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Claims

1. A herbicide formulation comprising a herbicidal active ingredient and composite microspheres, said herbicidal active ingredient being in an aqueous solution, said composite microspheres being used to enhance the herbicidal efficacy against weeds in crops, wherein, when mixed with said aqueous solution, the composite microspheres in powder form are present at a concentration in the range of 2% to 200% w / w relative to the herbicidal active ingredient; wherein said composite microspheres comprise chitosan with an average molecular weight in the range of 190,000 to 310,000 g / mol, and further comprise a crosslinking agent.

2. The herbicide formulation according to claim 1, wherein the herbicidal active ingredient is selected from glyphosate, fenbendazim, imazalil ethanoic acid, atrazine, simazine, diuron, pendimethalin, trifluralin, quizalofop-p-ethyl, quizalofop-p-ethyl, dicamba, paraquat, glufosinate, clethodim, quizalofop-p-ethyl, flusulfanilamide, 2,4-dichlorophenoxyacetic acid, thiamethoxam, pyraclostrobin, glufosinate-ammonium, methoxyfenozide, imazalil, fluroxypyr, clethodim, quizalofop-p-ethyl, quizalofop-p-ethyl, pyrfluthrin, mesotrione, S-metolachlor, propyzoxystrobin, sulfonylpyrazosulfuron, MCPA, pyrimisulfuron, bromobenzonitrile, their derivatives, and mixtures thereof.

3. The herbicide formulation according to claim 1, wherein the herbicidal active ingredient is glyphosate.

4. The herbicide formulation according to claim 1, wherein the herbicidal active ingredient is glufosinate.

5. The herbicide formulation according to claim 1, wherein the composite microspheres comprise chitosan, a dispersant, and a crosslinking agent with an average molecular weight in the range of 190,000 to 310,000 g / mol, and have a zeta potential in aqueous solution in the range of +30 to -30, the potential being determined by a chitosan / crosslinking agent mass ratio of 1:X, wherein X ranges from 0.08 to 1.

5.

6. The herbicide formulation according to claim 1, wherein the composite microspheres contain chitosan, gum arabic, and tripolyphosphate without the presence of agrochemical active substances.

7. The herbicide formulation according to claim 1 further comprises an adjuvant selected from binders, surfactants, stabilizers, defoamers, pH buffers, masking agents, derivatives thereof, and combinations thereof.

8. The herbicide formulation according to claim 1, wherein the concentration of the herbicidal active ingredient is equal to or less than the field application amount indicated on the product label when the herbicide is used alone.

9. The herbicide formulation according to claim 1, wherein the concentration of the composite microspheres ranges from 5% to 100% w / w relative to the herbicidal active ingredient.

10. The herbicide formulation according to claim 1, wherein the concentration of the composite microspheres ranges from 5% to 10% w / w relative to the herbicidal active ingredient.

11. The herbicide formulation according to claim 1, wherein the mixture of the herbicidal active ingredient and the composite microspheres is prepared in the field before use.

12. The herbicide formulation of claim 1, wherein the mixture of the herbicidal active ingredient and the composite microspheres is contained in a package for commercialization and distribution.

13. A method for obtaining the herbicidal formulation of claim 1, comprising the steps of: a) preparing an aqueous solution of the herbicidal active ingredient at a desired concentration; and b) adding dried composite microspheres at a concentration of up to 100% by weight relative to the herbicidal active ingredient, and stirring.

14. The method of claim 13, further comprising adding an adjuvant.

15. A method for preventing or reducing unwanted plant growth, comprising applying the herbicide of claim 1 to the crop or soil prior to planting.

16. The method according to claim 15, wherein the crop is selected from cereals, oilseeds, forest crops, fruits, trees, ornamental plants, vegetables, wheat, barley, rye, triticale, oats, corn, sunflower, rice, soybeans, peas, beans, peanuts, rapeseed, cabbage, cotton, lentils, potatoes, beets, sugarcane, grass, sorghum, flax, legumes, tomatoes, peppers, pumpkins, lettuce, beets, carrots, radishes, apples, pears, plums, bananas, mangoes, citrus fruits, walnuts, almonds, coffee, cocoa, grapevines, etc.

17. The method of claim 15, wherein the herbicide is applied at a concentration of herbicide active ingredient lower than that indicated on the product label.

18. The method of claim 15, wherein the herbicidal effect is enhanced by up to 70% compared to herbicides without composite microspheres.

19. A herbicide formulation that enhances the efficacy of a herbicidal active ingredient by at least 10%, said herbicide formulation comprising the herbicidal active ingredient and composite microspheres; wherein the composite microspheres comprise chitosan with an average molecular weight in the range of 190,000 to 310,000 g / mol, and further comprise a crosslinking agent, wherein the chitosan / crosslinking agent mass ratio is 1:X, wherein X ranges from 0.08 to 1.5; and wherein the concentration of the composite microspheres relative to the herbicidal active ingredient in the aqueous phase ranges from 2% to 100% w / w.

20. The formulation according to claim 1 or 19, wherein the composite microspheres further comprise a dispersant selected from gum arabic, xanthan gum, guar gum, carrageenan, pectin, alginate, dextrin, cyclodextrin, maltodextrin, astragalus gum, mesquite gum, and mixtures thereof.

21. The formulation of claim 20, wherein the composite microspheres comprise a surface charge or zeta potential adjustable by the concentration of the crosslinking agent, wherein X is 0.08 to 0.8, and wherein the crosslinking agent is TPP.

22. The formulation according to claim 19, wherein the herbicidal active ingredient is in an aqueous composition within a container, and the composite microspheres are powders added to the container.

23. The formulation according to claim 1 or 19, wherein the composite microspheres comprise a crosslinking agent selected from sodium tripolyphosphate (TPP), sodium hexametaphosphate, and derivatives thereof.

24. The formulation according to claim 1 or 19, wherein the composite microspheres comprise a crosslinking agent, the crosslinking agent being sodium tripolyphosphate (TPP).

25. The formulation according to claim 1 or 19, wherein the composite microspheres further comprise a dispersant that improves the redispersibility of the microspheres mixed with the herbicide aqueous solution, wherein the dispersant is selected from gum arabic, xanthan gum, guar gum, carrageenan, pectin, alginate, dextrin, cyclodextrin, maltodextrin, astragalus gum, mesquite gum, polyethylene glycol, and mixtures thereof, and wherein the dispersant comprises a chitosan / dispersant in a mass ratio of Y:1, wherein Y is 5 to 20.

26. The formulation according to claim 25, wherein the dispersant is gum arabic.

27. A composite microsphere for preparing the formulation of claim 1 or 19 and enhancing the herbicidal efficacy against weeds in crops, said composite microsphere comprising chitosan with an average molecular weight in the range of 190,000 to 310,000 g / mol, and comprising a crosslinking agent, without the presence of herbicidal active ingredients.

28. The composite microspheres according to claim 27, comprising a surface charge (zeta potential) adjustable in an aqueous medium by the concentration of a crosslinking agent; wherein the chitosan / crosslinking agent mass ratio is 1:X, where X is from 0.08 to 1.5, and the chitosan / crosslinking agent mass ratio defines the zeta potential of the microspheres in an aqueous solution.

29. The composite microspheres according to claim 27, wherein the crosslinking agent is selected from sodium tripolyphosphate (TPP), sodium hexametaphosphate and its derivatives.

30. The composite microspheres according to claim 27, wherein the crosslinking agent is sodium tripolyphosphate (TPP).

31. The composite microspheres according to claim 27, further comprising a dispersant that improves the redispersibility of the microspheres when mixed with an aqueous herbicide solution, wherein the dispersant is selected from gum arabic, xanthan gum, guar gum, carrageenan, pectin, alginate, dextrin, cyclodextrin, maltodextrin, astragalus gum, mesquite gum, polyethylene glycol, and mixtures thereof.

32. The composite microspheres according to claim 31, wherein the dispersant comprises chitosan / dispersant in a mass ratio of Y:1, wherein Y is 5 to 20.

33. The composite microspheres according to claim 31, wherein the dispersant is gum arabic.

34. A method for obtaining the composite microspheres of claim 27, comprising the steps of: a) mixing acetic acid, chitosan and water and stirring; b) adding a dispersant and stirring; c) adding a crosslinking agent solution dropwise; d) allowing the mixture to stand; and e) drying the resulting microspheres.

35. The method of claim 34, comprising the steps of: a) dissolving chitosan in 1% v / v acetic acid at 20°C with constant stirring until no clumping is observed; b) adding a dispersant and stirring until completely dissolved to achieve a chitosan / dispersant mass ratio of Y:1, wherein Y is 5 to 20; c) adding a crosslinking agent solution dropwise to the mixture at a chitosan / crosslinking agent mass ratio of 1:X, wherein X is 0.08 to 1.2, in the absence of herbicidal active ingredients; d) adjusting the pH to approximately 6.5; and e) drying the composite microspheres.

36. The method according to claim 35, characterized in that, Step e) involves freeze-drying at -45°C and 10 Pa using a 220 V freeze dryer, followed by grinding with a mortar and filtration through a 100-mesh sieve to obtain composite microspheres.

37. The method according to claim 34, characterized in that, Step e) involves spray drying at an inlet temperature of 200°C.

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