A fludioxonil · thifluzamide · thiamethoxam seed treatment suspension agent and a preparation method thereof

Abstract

The application discloses a kind of seed treatment suspending agent field and preparation method of fludioxonil • thiflumeamide • thiamethoxam seed treatment suspending agent, including the following weight parts of components: fludioxonil 0.8-1.2 parts, thiflumeamide 1-2 parts, thiamethoxam 0.5-1.5 parts, film forming agent 2-6 parts, modified drug-loading particle 1.5-4.5 parts, warning agent 1-5 parts, dispersing agent 5-8 parts, preservative 0.1-0.5 parts, thickening agent 0.1-0.5 parts, water 75-100 parts.The application proposes to load pesticide active substance by metal organic framework, realizes the improvement of pesticide active substance loading capacity, simultaneously combines metal organic framework and film forming, can improve the slow-release ability of pesticide active substance, improve the air permeability and water permeability of seed coating, promote seed germination.

Description

Technical Field

[0001] This invention belongs to the field of seed treatment suspension technology, specifically referring to a fludioxonil·thifluzamide·thiamethoxam seed treatment suspension and its preparation method. Background Technology

[0002] Seed treatment suspensions, also known as seed coating agents, mainly consist of pesticide active ingredients, film-forming agents, stabilizers, warning colors, and other substances. The main components are ground and dispersed in water, then coated onto the seed surface to form a film containing the active ingredients. This allows the pesticide to directly target the target substance, improving pesticide utilization and thus increasing crop yield. Seed treatment suspensions can be used on various important crops, including grain crops and cash crops such as corn, wheat, and soybeans. They also include adjuvants such as dispersants, thickeners, preservatives, and antifreeze agents. Seed treatment suspensions form a protective film on the seed surface, physically blocking contact between the seed and the external environment, reducing pathogen infection. After sowing, the outer protective film swells by absorbing water, releasing pesticides and other active substances, creating a sterile and harmless environment around the seed. Simultaneously, the water absorption of the protective film promotes seed germination. After rooting, the active pesticide substances are systemically absorbed by the roots and diffused to all parts of the plant, preventing crop diseases and pests. Fludioxonil is a novel pyrrole-based, non-systemic, broad-spectrum fungicide that effectively controls diseases caused by pathogens such as *Aspergillus* and *Trichoderma*. It is mainly used to control wheat smut, snow rot, and sheath blight; cotton damping-off and anthracnose; soybean root rot; and rice bakanae disease. Its main mechanism of action is through inhibiting glucose phosphorylation-related translocations and simultaneously inhibiting fungal mycelial growth, ultimately leading to pathogen death. Thifluzamide belongs to the thiazole amide class of fungicides and is characterized by strong systemic activity and long-lasting effect, effectively controlling mycelial diseases. Thiaflutamide is highly effective against diseases caused by pathogenic fungi such as Sclerotium, Stylostella, and Ustilago, especially against sheath blight and damping-off caused by Basidiomycetes. The mechanism of action of thiaflutamide is mainly to inhibit succinate dehydrogenase, thereby blocking the tricarboxylic acid cycle of pathogens and leading to the death of the pathogens. Thiamethoxam is a neonicotinoid insecticide with stomach poison, contact, and systemic activity against pests. It can be applied through soil drenching. After being absorbed by the roots, thiamethoxam is transported to all parts of the plant and can effectively control piercing-sucking pests such as aphids, planthoppers, and leafhoppers.

[0003] The existing technologies currently have the following main problems: First, the film-forming agent in the seed treatment suspension forms a coating on the seed surface, which is easily leached by rainwater in the soil and has poor durability; Second, the coating on the seed surface has poor water and air permeability, which reduces the germination rate of the seeds. Summary of the Invention

[0004] To address the above issues and overcome the shortcomings of existing technologies, this invention provides a fludioxonil-thifluzamide-thiamethoxam seed treatment suspension and its preparation method. To solve the problems of poor seed coating durability and low air and water permeability, this invention proposes to increase the loading capacity of pesticide active substances by loading pesticide active substances onto a metal-organic framework. Furthermore, combining the metal-organic framework with film formation enhances the ability to slowly release pesticide active substances, while also improving the air and water permeability of the seed coating and promoting seed germination.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The present invention proposes a fludioxonil•thifluzamide•thiamethoxam seed treatment suspension, wherein the seed treatment suspension comprises the following components in parts by weight: fludioxonil 0.8-1.2 parts, thifluzamide 1-2 parts, thiamethoxam 0.5-1.5 parts, film-forming agent 2-6 parts, modified drug-loaded particles 1.5-4.5 parts, warning agent 1-5 parts, dispersant 5-8 parts, preservative 0.1-0.5 parts, thickener 0.1-0.5 parts, and water 75-100 parts.

[0006] The modified drug-loaded particles are Ti 2+ OH-MIL-125 nanoparticles, formed with 2,5-dihydroxyterephthalic acid as the organic ligand and iodine as the central ion, were further modified with a dicarboxylic acid to obtain modified drug-loaded particles.

[0007] The preparation method of the modified drug-loaded particles specifically includes the following steps:

[0008] S1. Add the titanium source to N,N-dimethylformamide, add 2,5-dihydroxyterephthalic acid, and mix evenly by ultrasonic treatment to obtain the reaction solution;

[0009] S2. Transfer the reaction solution prepared in step S1 into a sealed reaction vessel, heat the reaction, cool to room temperature after the reaction is completed, filter, remove the solvent, and dry to obtain OH-MIL-125 nano-drug-loaded particles.

[0010] S3. Add the OH-MIL-125 nanoparticles prepared in step S2 to a dicarboxylic acid solution, and microwave heat for 30-45 minutes to obtain modified nanoparticles.

[0011] Preferably, in step S1, the titanium source is tetrabutyl titanate, and the molar ratio between the titanium source and 2,5-dihydroxyterephthalic acid is 1:1.5-2.

[0012] Preferably, in step S1, the concentration of tetrabutyl titanate in N,N-dimethylformamide is 20-5 mmol / L.

[0013] Preferably, in step S2, the microwave power in the microwave heating reaction is 150-200W, the heating temperature is 100-150℃, and the reaction time is 5-10h.

[0014] Preferably, in step S3, the dicarboxylic acid is at least one selected from oxalic acid, malonic acid, succinic acid, glutaric acid, and citric acid.

[0015] Preferably, in step S3, the mass ratio of the OH-MIL-125 nanoparticles to the dicarboxylic acid is 3-7:1.

[0016] Preferably, in step S3, the mass concentration of the dicarboxylic acid solution is 10%-30%.

[0017] Preferably, the film-forming agent is polyvinyl alcohol.

[0018] Preferably, the warning agent is at least one of gentian violet dye, iron oxide yellow, and basic rose essence.

[0019] Preferably, the dispersant is at least one of sodium dodecylbenzene sulfonate, desaccharified lignin sulfonate, desaccharified condensed lignin sulfonate, and sodium succinate sulfonate.

[0020] Preferably, the preservative is at least one of Kathon, sodium benzoate, and Bropol.

[0021] Preferably, the thickener is at least one of magnesium aluminum silicate, xanthan gum, and carboxymethyl cellulose.

[0022] This invention also provides a method for preparing a seed treatment suspension of fludioxonil•thifluzamide•thiamethoxam, specifically including the following steps:

[0023] (1) Dissolve fludioxonil, thifluzamide and thiamethoxam in ethanol solution, add modified drug-loaded particles, shake in a sealed environment at room temperature for 10-16 h, add dispersant, stir until completely dissolved, remove ethanol by rotary evaporation to obtain active ingredient suspension;

[0024] (2) The film-forming agent, preservative, thickener and warning agent are subjected to high-speed shearing treatment, and the active ingredient suspension prepared in step (1) and water are added and homogenized to obtain the seed treatment suspension.

[0025] Preferably, in step (1), the volume fraction of ethanol in the ethanol solution is 20-40%, and the volume of the ethanol solution is 80-100 mL.

[0026] Preferably, in step (2), the high-speed shearing process has a shearing speed of 10,000-12,000 rpm and a processing time of 15-20 min.

[0027] The beneficial effects achieved by this invention are as follows:

[0028] This invention utilizes metal-organic frameworks as pesticide-loaded particles, with their surfaces modified with diacids. After seed treatment, this effectively improves the durability and permeability of the seed coating film, without affecting seed germination after sowing. The pesticide-loaded particles release active pesticide components into the surrounding environment, maintaining its resistance to pests and diseases over a long period. The modified particles use titanium ions as the central ion and 2,5-dihydroxyterephthalic acid as the organic ligand. The titanium ions complex with the carboxyl groups in the organic ligand, forming a porous carrier structure. The hydroxyl groups in the organic ligand esterify with the carboxyl groups in the diacid, grafting the diacid onto the outside of the particles and increasing their hydrophilicity. Polyvinyl alcohol is used as a film-forming agent, and the water content of polyvinyl alcohol... With high solubility and high film-forming toughness, it can undergo cross-linking reaction through the carboxyl groups grafted onto the modified drug-loaded particles, which can improve the durability of polyvinyl alcohol film. The metal-organic framework structure in the modified drug-loaded particles enhances the mechanical properties of the polyvinyl alcohol film, making it less prone to leaching by rainwater. This invention overcomes the problems of poor slow-release ability and low air and water permeability of single synthetic polymer film-forming agents, which are not conducive to seed germination. It proposes a fludioxonil·thifluzamide·thiamethoxam seed treatment suspension, which can suspend seeds before sowing and form a thin film structure with slow-release properties of pesticide active ingredients on the outside of the seed. The film structure has good water absorption and air permeability, does not inhibit seed germination, can promote seed germination, and at the same time avoids the invasion of diseases and pests in the soil environment. Attached Figure Description

[0029] Figure 1 The graphs show the performance results of seed coating after seed coating treatment with the seed coating suspensions described in Examples 1-4 and Comparative Examples 1-2 of this invention.

[0030] Figure 2 SEM image of the modified drug-loaded particles prepared in Example 1;

[0031] Figure 3 The graph shows the results of pesticide active ingredient retention rate after wheat seeds were treated with the seed treatment suspensions described in Examples 1-4 and Comparative Examples 1-2;

[0032] Figure 4 The graph shows the results of the seed treatment suspensions described in Examples 1-4 and Comparative Examples 1-2 on the germination rate of wheat seeds and the inhibitory effect on wheat sheath blight.

[0033] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. Detailed Implementation

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0036] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; unless otherwise specified, the experimental materials and test strains used in the following examples were purchased from commercial channels.

[0037] Example 1

[0038] A fludioxonil-thifluzamide-thiamethoxam seed treatment suspension, wherein the seed treatment suspension comprises the following components in parts by weight: 1.2 parts fludioxonil, 2 parts thifluzamide, 0.5 parts thiamethoxam, 2 parts polyvinyl alcohol, 1.5 parts modified drug-loaded particles, 5 parts gentian violet dye, 5 parts sodium dodecylbenzenesulfonate, 0.1 parts sodium benzoate, 0.5 parts xanthan gum, and 75 parts water.

[0039] The preparation method of the modified drug-loaded particles specifically includes the following steps:

[0040] S1. Dissolve 68 mg of tetrabutyl titanate and 60 mg of 2,5-dihydroxyterephthalic acid in 3 mL of N,N-dimethylformamide, respectively. Add the DMF solution of 2,5-dihydroxyterephthalic acid dropwise to the tetrabutyl titanate solution. After ultrasonic treatment at 400 W for 5 min at room temperature, the reaction solution is obtained.

[0041] S2. The reaction solution prepared in step S1 is transferred into a polytetrafluoroethylene-lined reaction vessel, sealed, and microwave-heated to 130°C for 8 hours with a microwave power of 150W. After the reaction is completed, the mixture is allowed to cool naturally to room temperature. After filtration, the precipitate is collected, centrifuged at 10,000 rpm for 5 minutes to remove excess DMF, and dried to obtain OH-MIL-125 nanoparticles.

[0042] S3. Add the OH-MIL-125 nanoparticles prepared in step S2 to a 40% glutaric acid solution. The mass ratio of OH-MIL-125 nanoparticles to dicarboxylic acid is 3:1. Heat the solution to 100°C with microwave power of 150W and react for 30 minutes to obtain modified nanoparticles.

[0043] This invention also provides a method for preparing a seed treatment suspension of fludioxonil•thifluzamide•thiamethoxam, specifically including the following steps:

[0044] (1) Dissolve fludioxonil, thifluzamide and thiamethoxam in 80 mL of 40% ethanol solution, add modified drug-loaded particles, shake in a sealed environment at room temperature for 12 h, add sodium dodecylbenzenesulfonate, stir until completely dissolved, remove ethanol by rotary evaporation to obtain active ingredient suspension.

[0045] (2) Mix polyvinyl alcohol, xanthan gum and sodium benzoate in water, dissolve them and add gentian violet dye. Shear at 10,000 rpm for 15 min, add the active ingredient suspension prepared in step (1) and water for homogenization to obtain seed treatment suspension.

[0046] Example 2

[0047] A fludioxonil-thifluzamide-thiamethoxam seed treatment suspension, wherein the seed treatment suspension comprises the following components in parts by weight: 0.8 parts fludioxonil, 1 part thifluzamide, 1.5 parts thiamethoxam, 6 parts polyvinyl alcohol, 3 parts modified drug-loaded particles, 1 part iron oxide yellow, 8 parts desaccharified lignin sulfonate, 0.1 parts Kathon, 0.4 parts sodium benzoate, 0.1 parts magnesium aluminum silicate, 0.1 parts xanthan gum, and 80 parts water.

[0048] The preparation method of the modified drug-loaded particles specifically includes the following steps:

[0049] S1. Dissolve 68 mg of tetrabutyl titanate and 80 mg of 2,5-dihydroxyterephthalic acid in 2 mL of N,N-dimethylformamide. Add the DMF solution of 2,5-dihydroxyterephthalic acid dropwise to the tetrabutyl titanate solution. After ultrasonic treatment at 400 W for 5 min at room temperature, the reaction solution is obtained.

[0050] S2. The reaction solution prepared in step S1 is transferred into a polytetrafluoroethylene-lined reaction vessel, sealed, and microwave-heated to 150°C for 5 hours with a microwave power of 200W. After the reaction is completed, the mixture is naturally cooled to room temperature, filtered, and the precipitate is collected. The precipitate is centrifuged at 10,000 rpm for 5 minutes to remove excess DMF. After drying, OH-MIL-125 nanoparticles are obtained.

[0051] S3. Add the OH-MIL-125 nanoparticles prepared in step S2 to a 20% glutaric acid solution with a mass ratio of OH-MIL-125 nanoparticles to dicarboxylic acid of 5:1. Heat the solution to 100°C with microwave power of 150W and react for 30 minutes to obtain modified nanoparticles.

[0052] This invention also provides a method for preparing a seed treatment suspension of fludioxonil•thifluzamide•thiamethoxam, specifically including the following steps:

[0053] (1) Dissolve fludioxonil, thifluzamide and thiamethoxam in 100 mL of 20 wt% ethanol solution, add modified drug-loaded particles, shake in a sealed environment at room temperature for 10 h, add desugared sodium lignin sulfonate, stir until completely dissolved, remove ethanol by rotary evaporation to obtain active ingredient suspension.

[0054] (2) Mix polyvinyl alcohol, Kathon, sodium benzoate, magnesium aluminum silicate and xanthan gum in water, dissolve them, add iron oxide yellow, and shear at 12000 rpm for 20 min. Add the active ingredient suspension prepared in step (1) and homogenize to obtain seed treatment suspension.

[0055] Example 3

[0056] A fludioxonil-thifluzamide-thiamethoxam seed treatment suspension, the seed treatment suspension comprising the following components in parts by weight: 1 part fludioxonil, 1.5 parts thifluzamide, 1 part thiamethoxam, 4 parts polyvinyl alcohol, 3 parts modified drug-loaded particles, 2.5 parts gentian violet dye, 3 parts sodium dodecylbenzene sulfonate, 3 parts desaccharified lignin sulfonate, 0.2 parts sodium benzoate, 0.3 parts bropol, 0.1 parts magnesium aluminum silicate, 0.3 parts xanthan gum, and 100 parts water.

[0057] The preparation method of the modified drug-loaded particles specifically includes the following steps:

[0058] S1. Dissolve 68 mg of tetrabutyl titanate and 70 mg of 2,5-dihydroxyterephthalic acid in 5 mL of N,N-dimethylformamide, respectively. Add the DMF solution of 2,5-dihydroxyterephthalic acid dropwise to the tetrabutyl titanate solution. After ultrasonic treatment at 400 W for 5 min at room temperature, the reaction solution is obtained.

[0059] S2. The reaction solution prepared in step S1 is transferred into a polytetrafluoroethylene-lined reaction vessel, sealed, and microwave-heated to 100°C for 10 hours with a microwave power of 150W. After the reaction is completed, the mixture is naturally cooled to room temperature, filtered, and the precipitate is collected. The precipitate is centrifuged at 10,000 rpm for 5 minutes to remove excess DMF. After drying, OH-MIL-125 nanoparticles are obtained.

[0060] S3. Add the OH-MIL-125 nanoparticles prepared in step S2 to a 20% glutaric acid solution with a mass ratio of OH-MIL-125 nanoparticles to dicarboxylic acid of 7:1. Heat the solution to 100°C with microwave power of 150W and react for 30 minutes to obtain modified nanoparticles.

[0061] This invention also provides a method for preparing a seed treatment suspension of fludioxonil•thifluzamide•thiamethoxam, specifically including the following steps:

[0062] (1) Dissolve fludioxonil, thifluzamide and thiamethoxam in 100 mL of 30% ethanol solution, add modified drug-loaded particles, shake in a sealed environment at room temperature for 16 h, add sodium dodecylbenzene sulfonate and desugared lignin sulfonate, stir until completely dissolved, remove ethanol by rotary evaporation to obtain active ingredient suspension.

[0063] (2) Mix polyvinyl alcohol, sodium bropol benzoate, magnesium aluminum silicate and xanthan gum in water, dissolve them and add gentian violet dye. Perform high-speed shearing at 10,000 rpm for 15 min, add the active ingredient suspension prepared in step (1) and homogenize to obtain seed treatment suspension.

[0064] Example 4

[0065] A fludioxonil-thifluzamide-thiamethoxam seed treatment suspension, wherein the seed treatment suspension comprises the following components in parts by weight: 1 part fludioxonil, 2 parts thifluzamide, 1 part thiamethoxam, 6 parts polyvinyl alcohol, 4.5 parts modified drug-loaded particles, 5 parts gentian violet dye, 4 parts sodium dodecylbenzene sulfonate, 4 parts desaccharified lignin sulfonate, 0.5 parts sodium benzoate, 0.5 parts xanthan gum, and 100 parts water.

[0066] The preparation method of the modified drug-loaded particles specifically includes the following steps:

[0067] S1. Dissolve 68 mg of tetrabutyl titanate and 70 mg of 2,5-dihydroxyterephthalic acid in 4 mL of N,N-dimethylformamide, respectively. Add the DMF solution of 2,5-dihydroxyterephthalic acid dropwise to the tetrabutyl titanate solution. After ultrasonic treatment at 400 W for 5 min at room temperature, the reaction solution is obtained.

[0068] S2. The reaction solution prepared in step S1 is transferred into a polytetrafluoroethylene-lined reaction vessel, sealed, and microwave-heated to 130°C for 12 hours with a microwave power of 200W. After the reaction is completed, the mixture is allowed to cool naturally to room temperature. After filtration, the precipitate is collected and centrifuged at 10,000 rpm for 5 minutes to remove excess DMF. After drying, OH-MIL-125 nanoparticles are obtained.

[0069] S3. Add the OH-MIL-125 nanoparticles prepared in step S2 to a 30% glutaric acid solution. The mass ratio of OH-MIL-125 nanoparticles to dicarboxylic acid is 5:1. Heat the solution to 100°C with microwave power of 150W and react for 45 minutes to obtain modified nanoparticles.

[0070] This invention also provides a method for preparing a seed treatment suspension of fludioxonil•thifluzamide•thiamethoxam, specifically including the following steps:

[0071] (1) Dissolve fludioxonil, thifluzamide and thiamethoxam in 100 mL of 30% ethanol solution, add modified drug-loaded particles, shake in a sealed environment at room temperature for 16 h, add sodium dodecylbenzene sulfonate and desugared lignin sulfonate, stir until completely dissolved, remove ethanol by rotary evaporation to obtain active ingredient suspension.

[0072] (2) Mix polyvinyl alcohol, sodium benzoate and xanthan gum in water, dissolve them, add gentian violet dye, shear at 12000 rpm for 15 min, add the active ingredient suspension prepared in step (1) for homogenization, and obtain seed treatment suspension.

[0073] Comparative Example 1

[0074] This comparative example provides a fludioxonil-thifluzamide-thiamethoxam seed treatment suspension, which differs from Example 1 only in that it does not contain modified drug-loaded particles in any of its components, while the remaining components and their contents are the same as in Example 1.

[0075] Comparative Example 2

[0076] This comparative example provides a fludioxonil-thifluzamide-thiamethoxam seed treatment suspension, which differs from Example 1 only in that the drug-loaded particles are not modified with dicarboxylic acid, while the other components and component contents are the same as in Example 1.

[0077] Experimental Example

[0078] This experiment tested the physicochemical properties of the seed treatment suspensions described in Examples 1-4 and Comparative Examples 1-2. The tested performance indicators included the solubility, swelling rate, and water absorption rate of the seed membrane formed after seed treatment. The above indicators were determined using a gravimetric method. Specifically, 1.00 mL (V0) of the seed treatment suspension was accurately pipetted into a petri dish, naturally cast to form a film, allowed to stand at room temperature for 1 hour, and then dried in a 45°C oven to constant weight. The weight of the dried film and petri dish was recorded as M1, and the weight of the dried petri dish as M0. The petri dish was then filled with distilled water, and the dried film was completely immersed in the water. After 8 hours and 72 hours, the distilled water was removed from the petri dish, and excess water was absorbed with absorbent paper. The weights of the film and petri dish at these times were measured and recorded as M8 and M1, respectively.72 After the culture dishes sampled at 72h were air-dried to remove moisture, they were dried at 45℃ until constant weight, and the weight of the membrane and the culture dish was measured as M2. The performance indicators of the seed coating were calculated according to the following formula:

[0079] Swelling rate (%) = (M8-M1) / (M1-M0) × 100%;

[0080] Water absorption rate (%) = (M) 72 -M1) / (M1-M0)×100%;

[0081] Solubility (%) = (M1-M2) / (M1-M0)×100%.

[0082] Figure 1 The figures show the performance results of seed coating after seed coating treatment with the seed coating suspensions described in Examples 1-4 and Comparative Examples 1-2 of this invention. As shown, the swelling rate of the seed coatings formed in Examples 1-4 after immersion in distilled water for 8 hours is between 30% and 40%, while the swelling rate of the seed coatings formed in Comparative Examples 1 and 2 is higher, around 60%. The seed coating suspensions described in Examples 1-4 form a coating on the seed surface after seed treatment. The modified drug-carrying particles in the components have a diacid-modified surface structure, which can form interaction forces with polyvinyl alcohol, improving the crosslinking degree of polyvinyl alcohol after film formation. The swelling rate of the coating can characterize the water permeability and air permeability of the coating. Comparative Examples 1 and 2... In Comparative Example 2, the film-forming agent polyvinyl alcohol has strong hydrophilicity, and water molecules have strong diffusion and penetration capabilities in the polyvinyl alcohol network structure. The swelling rates of Examples 1-4 are lower than those of the comparative example. However, in the comparative example, the polyvinyl alcohol coating dissolves in water within 72 hours. After the polyvinyl alcohol film is formed, it is immersed in water, and water molecules quickly penetrate and diffuse into the cross-linked network structure of the polyvinyl alcohol polymer, which lengthens the distance between polyvinyl alcohol molecules and causes the volume of the polyvinyl alcohol film to expand. In the comparative example, the polyvinyl alcohol molecules lack a stable cross-linked structure. As water molecules penetrate, the distance between the polyvinyl alcohol molecular chains exceeds the length limited by the intermolecular forces. Therefore, the polyvinyl alcohol film in the comparative example has high swelling performance but poor water resistance.

[0083] Experimental Example 2

[0084] In this experimental example, scanning electron microscopy was used to observe the microstructure of the modified drug-loaded particles prepared in Example 1. Figure 2 This is an SEM image of the modified drug-loaded particles prepared in Example 1.

[0085] Experimental Example 3

[0086] This experiment measures the retention rate of pesticide active substances in seed coatings. The specific method includes the following steps:

[0087] 1. Seed treatment: 100g of wheat seeds were coated evenly with the seed treatment suspensions described in Examples 1-4 and Comparative Examples 1-2, respectively. The amount of seed treatment suspension used was 5mL. The seeds were then dried in a seed dressing bag to obtain coated wheat seeds.

[0088] 2. Seed soaking treatment: Take 5g of evenly coated wheat seeds and place them in 500mL of distilled water. After sealing, place them in a dark incubator at 25℃. Take samples of the distilled water for soaking the seeds at 1d, 2d, 4d, 8d, 12d, 20d, 30d, and 40d respectively, determine the concentration of pesticide active ingredients, and calculate the retention rate of pesticide active ingredients.

[0089] Figure 3 The graph shows the retention rates of pesticide active ingredients after treating wheat seeds with the seed treatment suspensions described in Examples 1-4 and Comparative Examples 1-2. After the seed coating is formed, the active ingredients of the three pesticides (fludioxonil, thifluzamide, and thiamethoxam) undergo slow-release diffusion in the environment. As shown in the graph, after the seed coating is formed, the retention rate of pesticide active substances in the seed treatment suspensions described in Examples 1-4 is 15%-20% after 40 days. In Comparative Example 1, the retention rate of pesticide active ingredients drops to 20% after only 2-4 days. Comparative Example 1 is a seed treatment suspension without modified pesticide-loaded particles; the film-forming agent polyvinyl alcohol alone cannot effectively retain the active pesticide substances. To achieve a sustained-release effect, polyvinyl alcohol (PVA) is easily decomposed in water, and its polymer network structure is easily damaged. In Comparative Example 2, the retention rate of the pesticide active ingredient dropped to below 10% after 5-8 days. Comparative Example 2 involved the addition of unmodified pesticide-loaded particles. Unmodified pesticide-loaded particles are difficult to cross-link with PVA, and the polymer network structure of PVA is not further strengthened. It is also easily decomposed in water. Without the polymer structure on the surface of the pesticide-loaded particles, the large concentration difference easily causes the pesticide active substances in the pesticide-loaded particles to be released. The release rate is relatively fast in the early stage, but when the release reaches a certain level, it reaches equilibrium. At this equilibrium, it is difficult to maintain a good sustained-release effect.

[0090] Experiment Example 4

[0091] This experimental example demonstrates the effects of the seed treatment suspensions described in Examples 1-4 and Comparative Examples 1-2 on wheat emergence rate and inhibition of wheat sheath blight. The specific testing method includes the following steps:

[0092] 1. Seed treatment: Take 50 mL of the seed treatment suspension described in Examples 1-4 and Comparative Examples 1-2 and mix it with 1 kg of wheat seeds. After mixing evenly, dry the mixture.

[0093] 2. Inoculation with wheat sheath blight: The pathogen causing wheat sheath blight is Rhizoctonia solani, purchased from CICC, preservation number: [insert number here]. Inoculate Rhizoctonia solani into the culture medium and dilute stepwise with sterile water to prepare a spore suspension. The spore concentration in the spore suspension is 1×10⁸ to 1×10⁹ spores / mL. Use the soil mixing method to mix the spore suspension evenly with dry sandy loam soil free of any pesticide residues. Add 10mL of spore suspension to every 1kg of dry sandy loam soil. Continuously spray water into the sandy loam soil and mix until the moisture content of the sandy loam soil reaches 20%. Let it stand overnight in a dark room temperature environment for later use.

[0094] 3. Pot experiment: Fill 2L flower pots with inoculated sandy loam soil to two-thirds full. Sow 5 wheat seeds evenly in each pot using the five-point method. Set up a control group of wheat without seed treatment. Cultivate in a greenhouse at 25℃ for 7 days and count the emergence rate of wheat. Continue to cultivate wheat for 60 days and count the number of diseased wheat plants to calculate the incidence of wheat sheath blight.

[0095] Figure 4 The figures show the results of the seed treatment suspensions described in Examples 1-4 and Comparative Examples 1-2 on the emergence rate of wheat seeds and their inhibitory effect on wheat sheath blight. As shown in the figures, the wheat seeds treated with the seed treatment suspensions described in Examples 1-4 showed no significant difference in emergence rate compared to those treated in Comparative Examples 1 and 2. This indicates that the suspensions with added drug-loaded particles in the examples do not affect the germination and emergence of wheat seeds. Furthermore, the wheat seeds treated in Examples 1-4 showed a protective effect against wheat sheath blight infection after emergence, with the incidence rate reduced by more than 20% compared to Comparative Examples 1 and 2. This demonstrates that the seed treatment suspensions described in this invention have a high control effect on the occurrence of wheat sheath blight.

[0096] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0097] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention. The actual application is not limited to this. In conclusion, if those skilled in the art are inspired by this description and design similar methods and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A seed treatment suspension of fludioxonil•thifluzamide•thiamethoxam, characterized in that: The seed treatment suspension comprises the following components in parts by weight: 0.8-1.2 parts fludioxonil, 1-2 parts thifluzamide, 0.5-1.5 parts thiamethoxam, 2-6 parts film-forming agent, 1.5-4.5 parts modified drug-loaded particles, 1-5 parts warning agent, 5-8 parts dispersant, 0.1-0.5 parts preservative, 0.1-0.5 parts thickener, and 75-100 parts water; wherein the film-forming agent is polyvinyl alcohol. The modified drug-loaded particles are Ti 2+ OH-MIL-125 nanoparticles, formed with 2,5-dihydroxyterephthalic acid as the organic ligand and OH-MIL-125 nanoparticles as the central ion, were modified with a dicarboxylic acid to obtain modified drug-loaded particles. The preparation method of the modified drug-loaded particles specifically includes the following steps: S1. Add the titanium source to N,N-dimethylformamide, add 2,5-dihydroxyterephthalic acid, and mix evenly by ultrasonic treatment to obtain the reaction solution; S2. Transfer the reaction solution prepared in step S1 into a sealed reaction vessel, heat the reaction, cool to room temperature after the reaction is completed, filter, remove the solvent, and dry to obtain OH-MIL-125 nano-drug-loaded particles. S3. Add the OH-MIL-125 nanoparticles prepared in step S2 to a dicarboxylic acid solution, and microwave heat for 30-45 min to obtain modified nanoparticles. In step S3, the dicarboxylic acid is at least one selected from oxalic acid, malonic acid, succinic acid, glutaric acid, and citric acid.

2. The fludioxonil•thifluzamide•thiamethoxam seed treatment suspension according to claim 1, characterized in that: In step S1, the titanium source is tetrabutyl titanate, and the molar ratio between the titanium source and 2,5-dihydroxyterephthalic acid is 1:1.5-2; the concentration of tetrabutyl titanate in N,N-dimethylformamide is 20-5 mmol / L.

3. The fludioxonil•thifluzamide•thiamethoxam seed treatment suspension according to claim 2, characterized in that: In step S2, the microwave heating reaction has a microwave power of 150-200W, a heating temperature of 100-150℃, and a reaction time of 5-10h.

4. The fludioxonil•thifluzamide•thiamethoxam seed treatment suspension according to claim 3, characterized in that: In step S3, the mass ratio of the OH-MIL-125 nanoparticles to the dicarboxylic acid is 3-7:1; the mass concentration of the dicarboxylic acid solution is 10%-30%.

5. A method for preparing a seed treatment suspension of fludioxonil•thifluzamide•thiamethoxam according to any one of claims 1-4, characterized in that: Specifically, the following steps are included: (1) Dissolve fludioxonil, thifluzamide and thiamethoxam in ethanol solution, add modified drug-loaded particles, shake in a sealed environment at room temperature for 10-16 h, add dispersant, stir until completely dissolved, remove ethanol by rotary evaporation to obtain active ingredient suspension; (2) The film-forming agent, preservative, thickener and warning agent are subjected to high-speed shearing treatment, and the active ingredient suspension prepared in step (1) and water are added and homogenized to obtain the seed treatment suspension.

6. The method for preparing the fludioxonil•thifluzamide•thiamethoxam seed treatment suspension according to claim 5, characterized in that: The warning agent is at least one of gentian violet dye, iron oxide yellow, and basic rose essence; the thickener is at least one of magnesium aluminum silicate, xanthan gum, and carboxymethyl cellulose.

7. The method for preparing the fludioxonil•thifluzamide•thiamethoxam seed treatment suspension according to claim 6, characterized in that: The dispersant is at least one of sodium dodecylbenzene sulfonate, desaccharified lignin sulfonate, desaccharified condensed lignin sulfonate, and sodium succinate sulfonate; the preservative is at least one of Kathon, sodium benzoate, and Bropol.

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