Composite bacteriostatic agent for preventing and treating rice blast and preparation method thereof

Abstract

The application relates to the field of agricultural pesticide technology, and particularly discloses a composite bacteriostatic agent for preventing and treating rice blast and a preparation method thereof. The composite bacteriostatic agent comprises a chemical bactericide, a plant source bacteriostatic agent and a microbial source bacteriostatic agent, and is composed of surfactants, synergistic additives and diatomite carriers. The preparation method comprises the following steps: firstly, modifying the carrier; secondly, respectively performing micronization compounding on the chemical bactericide, activation on the plant bacteriostatic agent and steady-state treatment on the microorganism; thirdly, emulsifying and constructing a multi-phase system by compounding the components after the treatment with the surfactants; and finally, obtaining the finished product through high-pressure homogenization, pH adjustment, low-temperature drying and screening and sterile packaging. The bacteriostatic agent can be used for preventing and treating rice blast, has the advantages of multi-component synergistic effect, wide bacteriostatic spectrum and ecological compatibility. In addition, the preparation method realizes effective integration and function maintenance of active components with different properties by optimizing the technological process, and has the advantages of strong technological coherence and high product stability.

Description

Technical Field

[0001] This application relates to the field of agricultural pesticide technology, and more specifically, to a compound antibacterial agent for the prevention and control of rice blast and its preparation method. Background Technology

[0002] Rice blast is a devastating fungal disease in rice production. Its pathogen can infect leaves, panicles, and other organs, leading to severe yield reductions and posing a significant threat to food security. Current control mainly relies on single types of pesticides: chemical fungicides are fast-acting but easily induce resistance; plant-derived bacteriostatic agents are environmentally friendly but have limited efficacy; and microbial preparations have good persistence but a narrow spectrum of action. Existing technologies are mostly limited to single-mode of action, making it difficult to form a synergistic control system.

[0003] Although current research focuses on improving the combination of chemical agents, it has not yet overcome the limitation of a single mechanism of action. Both traditional tricyclazoles and novel methoxyacrylate agents exert their effects through specific biochemical pathways, lacking multi-level control capabilities. This single mechanism not only accelerates the development of resistance but also fails to activate the plant's own resistance or regulate the field microecology, resulting in unstable control effects and short-lasting efficacy. Summary of the Invention

[0004] To address the problem that existing pesticides for controlling rice blast lack synergistic integration of multiple mechanisms of action, making it difficult to balance broad-spectrum antibacterial activity with ecological compatibility, this application provides a compound antibacterial agent for controlling rice blast and its preparation method.

[0005] Firstly, this application provides a compound antibacterial agent for the prevention and control of rice blast, employing the following technical solution: The compound antibacterial agent for the prevention and control of rice blast consists of the following components in parts by weight: 10-40 parts chemical fungicide, 5-25 parts plant-derived antibacterial agent, 3-15 parts microbial antibacterial agent, 2-10 parts surfactant, 1-8 parts synergist, and 30-60 parts diatomaceous earth.

[0006] By employing the above technical solutions, a basic layer of the control system is constructed using chemical fungicides in specific ratios. Tricyclazole primarily interferes with melanin synthesis, while azoxystrobin exerts its effect by inhibiting the mitochondrial respiratory chain, forming a dual mechanism of action. In plant-derived antibacterial agents, tea polyphenols disrupt cell membrane integrity, and emodin interferes with energy metabolism pathways, jointly enhancing natural antibacterial capabilities. Microbial antibacterial agents establish a biological protective barrier by colonizing plant surfaces and secreting antimicrobial peptides through Bacillus subtilis. The surfactant system utilizes the spreadability of alkyl polysaccharides and the emulsifying properties of polyoxyethylene sorbitan monooleate to improve the adhesion and coverage of the formulation on leaf surfaces. In the synergistic adjuvants, nano-silica provides a porous carrier structure, and sodium alginate forms a protective gel network, jointly maintaining the stability of the active ingredients. Diatomaceous earth serves as the main carrier, and its unique porous structure enables the sustained-release function of the active ingredients, thus constructing a multi-layered control system encompassing chemical antibacterial action, physical barriers, and biological competition.

[0007] Preferably, the chemical fungicide is a combination of tricyclazole and azoxystrobin, wherein the weight ratio of tricyclazole to azoxystrobin is 1:0.5 to 1:1.5.

[0008] By adopting the above technical solution, the two components complement each other by leveraging their different mechanisms of action in inhibiting rice blast fungus, thus avoiding the limitations of a single component. At the same time, this ratio range can optimize the compatibility of the two components, avoid antagonistic effects, and enhance the specificity and synergy of the chemical antibacterial effect, thereby ensuring the efficient and stable performance of the chemical antibacterial link in the composite system.

[0009] Preferably, the plant-derived antibacterial agent is a compound combination of tea polyphenols and emodin, wherein the weight ratio of tea polyphenols to emodin is 1:0.6 to 1:1.6.

[0010] By adopting the above technical solution, and utilizing the synergistic characteristics of the two in natural antibacterial activity, the antibacterial effect of tea polyphenols and the antibacterial and plant resistance-inducing effects of emodin complement each other. This ratio range can optimize the activity compatibility of the two components, avoid the cancellation of activity between components, and play a role in strengthening the specificity and synergistic effect of plant-derived antibacterial activity. In this way, it can ensure the stable performance of the plant-derived antibacterial link in the compound system and help improve the overall control compatibility.

[0011] Preferably, the microbial antibacterial agent is a Bacillus subtilis preparation with a viable bacteria content of 1×10⁻⁶. 10 -2×10 10 CFU / g.

[0012] By adopting the above technical solution, and utilizing the characteristics of Bacillus subtilis competing for nutrient resources and secreting antimicrobial metabolites after colonization, the live bacteria content range can ensure that the number of functional strains in the formulation is sufficient, guaranteeing their colonization and reproduction capabilities in the application environment. This avoids the failure of biological barrier construction due to insufficient live bacteria, thereby enhancing the long-term effectiveness and stability of microbial antimicrobial activity. Ultimately, this ensures the continuous performance of the microbial antimicrobial link in the composite system and helps to build a long-term mechanism for multi-pathway prevention and control.

[0013] Preferably, the synergistic agent comprises nano-silica and sodium alginate, wherein the weight ratio of nano-silica to sodium alginate is 1:1 to 1:10.

[0014] By adopting the above technical solution, the high specific surface area adsorption characteristics of nano-silica and the sustained release and adhesion functions of sodium alginate complement each other. This ratio range can optimize the functional compatibility of the two components, allowing nano-silica to better carry the active components, while sodium alginate extends the action period of the components. This avoids the limitations of a single component in being unable to simultaneously achieve adsorption and sustained release, thereby enhancing the efficiency of each antibacterial component, improving the stability and sustainability of the system, and ultimately ensuring the efficient performance of the synergistic link in the composite system and assisting in the synergistic adaptation of each core antibacterial component.

[0015] Preferably, the surfactant is a compound of alkyl polysaccharide and polyoxyethylene sorbitan monooleate, wherein the weight ratio of alkyl polysaccharide to polyoxyethylene sorbitan monooleate is 1:1 to 1:3.

[0016] By adopting the above technical solution, the natural compatibility of alkyl polysaccharide glycosides and the strong emulsifying and dispersing ability of polyoxyethylene sorbitan monooleate ester are used to form a functional complementarity. This ratio range can optimize the synergistic compatibility of the two components, avoid the limitations of single surfactants in dispersion efficiency or interfacial compatibility, and promote the uniform distribution of each antibacterial component in the system and improve the adhesion of the components to the rice surface. In this way, the dispersion stability of the composite system is guaranteed and the core antibacterial components are able to fully contact the target.

[0017] Secondly, this application provides a method for preparing a compound antibacterial agent for the prevention and control of rice blast, using the following technical solution: A method for preparing a compound antibacterial agent for controlling rice blast includes the following steps: S1. Carrier pretreatment: The diatomaceous earth carrier is dried and then mixed with nano-silica to complete the functional modification of the carrier surface. S2. Micronization and compounding of chemical fungicides: Tricyclazole and azoxystrobin are separately subjected to air jet milling and grinding to a predetermined particle size, and then mixed to form a compound chemical fungicide. S3. Activation of plant antibacterial agents: Tea polyphenols and emodin are synergistically extracted using supercritical carbon dioxide fluid, then dissolved and activated in deionized water, and then stirred to form a uniform activated solution. S4. Microbial stabilization: Bacillus subtilis preparation and sodium alginate solution are mixed under aseptic conditions and then spray-dried to form microcapsule particles. S5. Construction of multiphase system: The functionalized diatomaceous earth obtained in step S1, the composite chemical bactericide obtained in step S2, the activated plant-derived antibacterial agent solution obtained in step S3, the stabilized microbial preparation obtained in step S4, and the surfactant are combined and emulsified to form a uniform multiphase system. S6. High-pressure homogenization and pH adjustment: The multiphase system material obtained in step S5 is subjected to high-pressure homogenization, and then the pH value of the system is adjusted to a predetermined range using citric acid solution. S7. Low-temperature drying and sieving: The material processed in step S6 is dried in a vacuum environment and then sieved to finally obtain the composite antibacterial agent product. S8. Aseptic packaging: The composite antibacterial agent obtained in step S7 is vacuum packaged under aseptic conditions.

[0018] By employing the above technical solution, the surface of the carrier is functionalized by drying diatomaceous earth and mixing it with nano-silica. Tricyclazole and azoxystrobin are ground to predetermined particle sizes using airflow pulverization and then compounded to form a composite chemical bactericide. Supercritical carbon dioxide fluid is used for the synergistic extraction of tea polyphenols and emodin, followed by dissolution and activation to form an activated solution. Under aseptic conditions, Bacillus subtilis preparation is mixed with sodium alginate solution and spray-dried to form microcapsule particles, achieving microbial stabilization. Finally, functionalized diatomaceous earth, the composite chemical bactericide, the activated plant-derived antibacterial agent solution, the stabilized microbial preparation, and a surfactant are compounded and emulsified to construct a multiphase system, which is then homogenized under high pressure. The stability of the system is optimized through quality treatment and pH adjustment with citric acid solution. The product morphology is controlled by vacuum low-temperature drying and sieving. Finally, aseptic packaging ensures storage stability. Each step specifically treats and gradually integrates different components, ensuring that the functional properties of each component are not lost and promoting the homogeneous and stable construction of the multiphase system. This achieves the effect of preparing a composite antibacterial agent product with synergistic component adaptation and stable performance. The synergistic adjuvants consist of nano-silica and sodium alginate, added at different stages during the preparation process: nano-silica is used to functionalize and modify the diatomaceous earth carrier in the carrier pretreatment stage, while sodium alginate is used as a microcapsule wall material in the microbial stabilization treatment stage. Both work together to enhance the final product.

[0019] Preferably, in step S1, the drying temperature is 100-200°C, the drying time is 1-3 hours, the mixing speed is 800-1200 r / min, and the mixing time is 15-30 minutes; in step S2, the predetermined particle size is D 90 For particles smaller than 10 μm, the mixing time is 30-60 min; in step S3, the pressure of the synergistic extraction treatment is 15-35 MPa, the extraction temperature is 40-60°C, the activation temperature is 40-60°C, and the stirring time is 10-30 min.

[0020] By adopting the above technical solution, controlling the drying temperature of diatomaceous earth at 100-200°C and the drying time at 1-3 hours, the moisture and impurities in the carrier are fully removed. Then, mixing is performed at a speed of 800-1200 r / min for 15-30 minutes to ensure that nano-silica is uniformly adhered to the surface of the diatomaceous earth, thus guaranteeing the functional modification effect of the carrier. The tricyclazole and azoxystrobin are then air-jet pulverized to D... 90 Particles smaller than 10 μm are mixed for 30-60 min to improve the dispersibility and uniformity of the chemical bactericide. By controlling the supercritical carbon dioxide synergistic extraction pressure at 15-35 MPa and the temperature at 40-60°C, the active ingredients of tea polyphenols and emodin are fully extracted. Then, the mixture is stirred at an activation temperature of 40-60°C for 10-30 min to promote the full dissolution and activation of the components. This ensures the effectiveness of each step of the process, optimizes the performance of the components, and lays a good foundation for the subsequent construction of a multiphase system.

[0021] Preferably, in step S4, the inlet temperature of the spray drying technology is 120-150°C and the outlet temperature is 60-80°C; in step S5, the emulsification speed is 2000-5000 r / min and the emulsification time is 10-20 min; in step S6, the homogenization pressure is 30-60 MPa, the homogenization times are 2-4 times, and the predetermined pH range is 5.5-6.5.

[0022] By adopting the above technical solution, and controlling the inlet temperature of the spray drying technology to 120-150°C and the outlet temperature to 60-80°C, the viability of Bacillus subtilis is maintained while producing microcapsule particles, avoiding microbial inactivation caused by high temperatures. By setting the emulsification speed to 2000-5000 r / min and the emulsification time to 10-20 min, the functionalized diatomaceous earth, compound chemical bactericide, activated plant-derived antibacterial agent solution, stabilized microbial preparation, and surfactant are fully integrated, avoiding stratification of the multiphase system. By using a homogenization pressure of 30-60 MPa and 2-4 homogenization cycles, the system particles are refined, and the pH value is adjusted to a suitable range of 5.5-6.5 to meet the activity requirements of each component, ensuring the microbial stabilization effect, enhancing the homogeneity and stability of the multiphase system, and thus improving the overall quality of the compound antibacterial agent system.

[0023] Preferably, in step S7, the drying temperature is 50-70°C, the drying time is 2-4 hours, and the mesh size of the sieve is 100-200 mesh.

[0024] By adopting the above technical solution, and controlling the drying temperature at 50-70°C and the drying time at 2-4 hours, the moisture in the multiphase system is fully removed while avoiding high temperature damage to the active ingredients of chemical bactericides and plant-derived antibacterial agents, as well as the stability of Bacillus subtilis viable bacteria. This prevents the product from clumping and deteriorating due to residual moisture during storage. By setting a sieve mesh size of 100-200 mesh, product particles with uniform particle size are selected, ensuring that the product can be evenly dispersed and fully contact the target object during application. This ensures the product's storage stability and suitability for use, thereby optimizing the quality and application effect of the composite antibacterial agent.

[0025] In summary, this application has the following beneficial effects: 1. This application adopts a triple synergistic system of chemical fungicides, plant-derived antibacterial agents, and microbial antibacterial agents, combined with surfactants, synergistic adjuvants, and diatomaceous earth carriers. Due to the complementary mechanism of action of each component, the chemical components provide rapid antibacterial effect, the plant-derived components enhance natural resistance, and the microbial components establish a long-term biological barrier, thereby achieving a multi-pathway comprehensive control effect against rice blast and improving the broad spectrum of antibacterial activity and ecological compatibility.

[0026] 2. In this application, tricyclazole and azoxystrobin are preferably combined in a specific ratio as a chemical fungicide, while tea polyphenols and emodin are combined in an optimized ratio as a plant-derived antibacterial agent, and nano-silica and sodium alginate complex are used as synergistic adjuvants. Because the precise ratio of these components is compatible with each other in terms of physicochemical properties, the nanomaterials enhance the adsorption of the carrier, and the polysaccharide components improve the survival environment of microorganisms, thereby obtaining synergistically enhanced antibacterial activity and physical stability of the formulation.

[0027] 3. The method of this application optimizes the loading performance through carrier functionalization pretreatment, activates plant active ingredients through supercritical fluid extraction, ensures microbial vitality through spray drying technology, and combines multiphase system construction and high-pressure homogenization process. Because the steps are sequentially connected and the parameters are matched with each other, the active components are effectively integrated and protected. Therefore, the product has good uniformity, efficient release of functional components, and strong adaptability to field application. Attached Figure Description

[0028] Figure 1 This is a flowchart of the preparation method of the compound antibacterial agent for the prevention and control of rice blast provided in this application. Detailed Implementation

[0029] The present application will be further described in detail below with reference to embodiments and comparative examples. Unless otherwise specified, the experimental methods used below are conventional methods. Unless otherwise specified, the materials, reagents, methods and instruments used are all conventional materials, reagents, methods and instruments in the art, which can be obtained by those skilled in the art through commercial channels or prepared according to literature methods.

[0030] Technical concept: Existing rice blast control technologies rely on single-type antifungal agents, which have inherent limitations: chemical fungicides, depending on a single mechanism of action, easily induce drug resistance in pathogens and lack ecological compatibility; plant-derived or microbial antifungal agents, when used alone, suffer from low release efficiency of active ingredients and short action cycles, making it difficult to achieve a balance between rapid control and long-term protection. The core reason lies in the lack of synergistic integration design of different types of antifungal components, and the failure to optimize the processing technology for each component during preparation, resulting in poor compatibility between components, inability to fully realize their functions, and an inability to simultaneously achieve broad-spectrum antifungal activity and ecological compatibility.

[0031] This technical solution addresses the aforementioned problems by first constructing a triple synergistic system of chemical bactericides, plant-derived antibacterial agents, and microbial antibacterial agents. By clearly defining the compounding ratio and core parameters of each component, it leverages the complementary mechanisms of rapid antibacterial action by chemical components, enhanced natural resistance by plant-derived ingredients, and the construction of a long-lasting biological barrier by microbial components, thus overcoming the functional limitations of single-type agents. Simultaneously, it designs a targeted preparation process, employing carrier functionalization modification, micronization of chemical bactericides, activation of plant-derived ingredients, and microbial stabilization treatment. Combined with precisely controlled parameters such as emulsification, homogenization, and drying, it ensures the activity and uniform dispersion of each component. Furthermore, it optimizes the system's stability and efficiency through the synergistic effect of surfactants and synergistic adjuvants, ultimately achieving comprehensive multi-pathway control and solving the core problem of existing technologies' inability to simultaneously achieve broad-spectrum antibacterial activity and ecological compatibility.

[0032] The following are the main raw materials and reagents used in the preparation examples, embodiments, and comparative examples, and their sources and specifications are as follows; unless otherwise specified, all reagents are commercially available analytical grade or higher products: 1. Tricyclazole was purchased from Hubei Xinmingtai Chemical Co., Ltd., CAS: 41814-78-2; 2. Azoxystrobin was purchased from Shanghai Yuanye Biotechnology Co., Ltd., product number: S24903; 3. Tea polyphenols were purchased from Shanghai Yuanye Biotechnology Co., Ltd., product number: S18152; 4. Emodin was purchased from Shanghai Yuanye Biotechnology Co., Ltd., product number: S30748; 5. Alkyl polysaccharide was purchased from Wuhan Penglei Biotechnology Co., Ltd., CAS: 157707-88-5; 6. Polyoxyethylene sorbitan monooleate (Tween 80) was purchased from Shanghai Yuanye Biotechnology Co., Ltd., product number: S15020; 7. Sodium alginate was purchased from Shenzhen Jinfuyuan Biotechnology Co., Ltd., CAS: 9005-38-3; 8. Citric acid was purchased from Jingjing Pharmaceutical Co., Ltd., CAS: 77-92-9.

[0033] Example 1 This application provides a compound antibacterial agent for the prevention and control of rice blast, which is composed of the following components in parts by weight: 25 parts of chemical fungicide, 15 parts of plant-derived antibacterial agent, 9 parts of microbial antibacterial agent, 6 parts of surfactant, 4.5 parts of synergist, and 45 parts of diatomaceous earth. The chemical fungicide is a combination of tricyclazole and azoxystrobin, wherein the weight ratio of tricyclazole to azoxystrobin is 1:1. Among them, the plant-derived antibacterial agent is a combination of tea polyphenols and emodin, wherein the weight ratio of tea polyphenols to emodin is 1:1.1. Among them, the microbial antibacterial agent is a Bacillus subtilis preparation with a viable bacterial content of 1.5 × 10¹ 0 CFU / g; The synergistic agent includes nano-silica and sodium alginate, wherein the weight ratio of nano-silica to sodium alginate is 1:5.5. The surfactant is a compound of alkyl polysaccharide and polyoxyethylene sorbitan monooleate, wherein the weight ratio of alkyl polysaccharide to polyoxyethylene sorbitan monooleate is 1:2. The preparation method of the above-mentioned compound antibacterial agent for the prevention and control of rice blast includes the following steps: S1. Carrier pretreatment: The diatomaceous earth carrier is dried and then mixed with nano-silica to complete the functional modification of the carrier surface. The drying temperature was 150°C, the drying time was 2 hours, the mixing speed was 1000 r / min, and the mixing time was 22.5 minutes. S2. Micronization and compounding of chemical fungicides: Tricyclazole and azoxystrobin are separately subjected to air jet milling and grinding to a predetermined particle size, and then mixed to form a compound chemical fungicide. Wherein, the predetermined particle size is D 90 For particles smaller than 10 μm, the mixing time is 45 min. S3. Activation of plant antibacterial agents: Tea polyphenols and emodin are synergistically extracted using supercritical carbon dioxide fluid, then dissolved and activated in deionized water, and then stirred to form a uniform activated solution. The pressure for the synergistic extraction process was 25 MPa, the extraction temperature was 50°C, the activation temperature was 50°C, and the stirring time was 20 min. S4. Microbial stabilization: Bacillus subtilis preparation and sodium alginate solution are mixed under aseptic conditions and then spray-dried to form microcapsule particles. The inlet temperature of the spray drying technology is 135°C, and the outlet temperature is 70°C. S5. Construction of multiphase system: The functionalized diatomaceous earth obtained in step S1, the composite chemical bactericide obtained in step S2, the activated plant-derived antibacterial agent solution obtained in step S3, the stabilized microbial preparation obtained in step S4, and the surfactant are combined and emulsified to form a uniform multiphase system. The emulsification speed was 3500 r / min, and the emulsification time was 15 min. S6. High-pressure homogenization and pH adjustment: The multiphase system material obtained in step S5 is subjected to high-pressure homogenization, and then the pH value of the system is adjusted to a predetermined range using citric acid solution. The homogenization pressure was 45 MPa, the homogenization was performed 3 times, and the predetermined pH range was 6.0. S7. Low-temperature drying and sieving: The material processed in step S6 is dried in a vacuum environment and then sieved to finally obtain the composite antibacterial agent product. The drying temperature was 60°C, the drying time was 3 hours, and the sieve mesh size was 150 mesh. S8. Aseptic packaging: The composite antibacterial agent obtained in step S7 is vacuum packaged under aseptic conditions.

[0034] Example 2 This application provides a compound antibacterial agent for the prevention and control of rice blast, which is composed of the following components in parts by weight: 10 parts of chemical fungicide, 5 parts of plant-derived antibacterial agent, 3 parts of microbial antibacterial agent, 2 parts of surfactant, 1 part of synergist, and 30 parts of diatomaceous earth. The chemical fungicide is a combination of tricyclazole and azoxystrobin, with a weight ratio of 1:0.5 between tricyclazole and azoxystrobin. Among them, the plant-derived antibacterial agent is a combination of tea polyphenols and emodin, wherein the weight ratio of tea polyphenols to emodin is 1:0.6. Among them, the microbial antibacterial agent is a Bacillus subtilis preparation with a viable bacterial content of 1×10¹. 0 CFU / g; The synergistic agent includes nano-silica and sodium alginate, wherein the weight ratio of nano-silica to sodium alginate is 1:1. The surfactant is a compound of alkyl polysaccharide and polyoxyethylene sorbitan monooleate, wherein the weight ratio of alkyl polysaccharide to polyoxyethylene sorbitan monooleate is 1:1. The preparation method of the above-mentioned compound antibacterial agent for the prevention and control of rice blast includes the following steps: S1. Carrier pretreatment: The diatomaceous earth carrier is dried and then mixed with nano-silica to complete the functional modification of the carrier surface. The drying temperature was 100°C, the drying time was 1 hour, the mixing speed was 800 r / min, and the mixing time was 15 minutes. S2. Micronization and compounding of chemical fungicides: Tricyclazole and azoxystrobin are separately subjected to air jet milling and grinding to a predetermined particle size, and then mixed to form a compound chemical fungicide. Wherein, the predetermined particle size is D 90 For particles smaller than 10 μm, the mixing time is 30 min. S3. Activation of plant antibacterial agents: Tea polyphenols and emodin are synergistically extracted using supercritical carbon dioxide fluid, then dissolved and activated in deionized water, and then stirred to form a uniform activated solution. The pressure for the synergistic extraction process was 15 MPa, the extraction temperature was 40°C, the activation temperature was 40°C, and the stirring time was 10 min. S4. Microbial stabilization: Bacillus subtilis preparation and sodium alginate solution are mixed under aseptic conditions and then spray-dried to form microcapsule particles. The inlet temperature of the spray drying technology is 120°C, and the outlet temperature is 60°C. S5. Construction of multiphase system: The functionalized diatomaceous earth obtained in step S1, the composite chemical bactericide obtained in step S2, the activated plant-derived antibacterial agent solution obtained in step S3, the stabilized microbial preparation obtained in step S4, and the surfactant are combined and emulsified to form a uniform multiphase system. The emulsification speed was 2000 r / min, and the emulsification time was 10 min. S6. High-pressure homogenization and pH adjustment: The multiphase system material obtained in step S5 is subjected to high-pressure homogenization, and then the pH value of the system is adjusted to a predetermined range using citric acid solution. The homogenization pressure was 30 MPa, the homogenization was performed twice, and the predetermined pH range was 5.5. S7. Low-temperature drying and sieving: The material processed in step S6 is dried in a vacuum environment and then sieved to finally obtain the composite antibacterial agent product. The drying temperature was 50°C, the drying time was 2 hours, and the sieve mesh size was 100 mesh. S8. Aseptic packaging: The composite antibacterial agent obtained in step S7 is vacuum packaged under aseptic conditions.

[0035] Example 3 This application provides a compound antibacterial agent for the prevention and control of rice blast, which is composed of the following components in parts by weight: 40 parts of chemical fungicide, 25 parts of plant-derived antibacterial agent, 15 parts of microbial antibacterial agent, 10 parts of surfactant, 8 parts of synergist, and 60 parts of diatomaceous earth. The chemical fungicide is a combination of tricyclazole and azoxystrobin, with a weight ratio of 1:1.5 between tricyclazole and azoxystrobin. Among them, the plant-derived antibacterial agent is a combination of tea polyphenols and emodin, wherein the weight ratio of tea polyphenols to emodin is 1:1.6. Among them, the microbial antibacterial agent is a Bacillus subtilis preparation with a viable bacterial content of 2×10¹. 0 CFU / g; The synergistic agent includes nano-silica and sodium alginate, wherein the weight ratio of nano-silica to sodium alginate is 1:10. The surfactant is a compound of alkyl polysaccharide and polyoxyethylene sorbitan monooleate, wherein the weight ratio of alkyl polysaccharide to polyoxyethylene sorbitan monooleate is 1:3. The preparation method of the above-mentioned compound antibacterial agent for the prevention and control of rice blast includes the following steps: S1. Carrier pretreatment: The diatomaceous earth carrier is dried and then mixed with nano-silica to complete the functional modification of the carrier surface. The drying temperature was 200°C, the drying time was 3 hours, the mixing speed was 1200 r / min, and the mixing time was 30 minutes. S2. Micronization and compounding of chemical fungicides: Tricyclazole and azoxystrobin are separately subjected to air jet milling and grinding to a predetermined particle size, and then mixed to form a compound chemical fungicide. Wherein, the predetermined particle size is D 90 For particles smaller than 10 μm, the mixing time is 60 min. S3. Activation of plant antibacterial agents: Tea polyphenols and emodin are synergistically extracted using supercritical carbon dioxide fluid, then dissolved and activated in deionized water, and then stirred to form a uniform activated solution. The pressure for the synergistic extraction process was 35 MPa, the extraction temperature was 60°C, the activation temperature was 60°C, and the stirring time was 30 min. S4. Microbial stabilization: Bacillus subtilis preparation and sodium alginate solution are mixed under aseptic conditions and then spray-dried to form microcapsule particles. The inlet temperature of the spray drying technology is 150°C, and the outlet temperature is 80°C. S5. Construction of multiphase system: The functionalized diatomaceous earth obtained in step S1, the composite chemical bactericide obtained in step S2, the activated plant-derived antibacterial agent solution obtained in step S3, the stabilized microbial preparation obtained in step S4, and the surfactant are combined and emulsified to form a uniform multiphase system. The emulsification speed was 5000 r / min, and the emulsification time was 20 min. S6. High-pressure homogenization and pH adjustment: The multiphase system material obtained in step S5 is subjected to high-pressure homogenization, and then the pH value of the system is adjusted to a predetermined range using citric acid solution. The homogenization pressure was 60 MPa, the homogenization was performed 4 times, and the predetermined pH range was 6.5. S7. Low-temperature drying and sieving: The material processed in step S6 is dried in a vacuum environment and then sieved to finally obtain the composite antibacterial agent product. The drying temperature was 70°C, the drying time was 4 hours, and the sieve mesh size was 200 mesh. S8. Aseptic packaging: The composite antibacterial agent obtained in step S7 is vacuum packaged under aseptic conditions.

[0036] Comparative Example 1 The only difference from Example 1 is that the microbial antibacterial agent component is removed, while the other components and their dosages remain unchanged.

[0037] Comparative Example 2 The only difference from Example 1 is that the synergist component is removed, while the other components and their amounts remain unchanged.

[0038] Comparative Example 3 The only difference from Example 1 is that the addition of nano-silica is omitted in step S1, and only the diatomaceous earth is dried, while other process parameters remain unchanged.

[0039] Comparative Example 4 The only difference from Example 1 is that the antibacterial agent is a commercially available wettable powder containing 40% tricyclazole, and the dosage is as recommended in the product instructions, i.e., 100 grams per acre.

[0040] Experiment 1: Indoor Determination of Inhibition Rate of Rice Blast Pathogen Test Standard: NY / T1156.2-2006 "Guidelines for Indoor Bioassay Testing of Pesticides - Fungicides Part 2: Test for Inhibition of Mycelial Growth" After activating the standard strain of rice blast fungus in PDA medium for 72 hours, it was diluted with sterile water to prepare 1×10⁻⁶ strains. 6 CFU / mL bacterial suspensions were prepared for use. 0.5g of each of the compound antibacterial agents from Examples 1, 2, and 3, and Comparative Examples 1, 2, and 3 were weighed. The commercially available 40% tricyclazole wettable powder from Comparative Example 4 was converted to the recommended dosage according to the instructions. All were diluted with sterile water to a concentration of 50 μg / mL. Using the plate confrontation method, a 5mm diameter rice blast fungus mycelium was inoculated into the center of a 9cm diameter PDA agar plate. Three drops of the test drug solution (20μL each) were evenly added 2cm from the edge of the plate. Sterile water was used as a blank control. Each treatment was replicated five times. The plates were incubated in the dark at 25℃ for 5 days. The colony diameter of each plate was measured using the cross-sectional method, and the inhibition rate was calculated using the following formula: Inhibition rate (%) = (D0 - D1) / D0 × 100; where D0 is the colony diameter of the blank control (cm), and D1 is the colony diameter of the treatment group (cm). Experiment 2: Field test of rice blast control efficacy Testing Standard: GB / T17980.19-2000 "Guidelines for Field Efficacy Tests of Pesticides (I) Fungicides for the Control of Rice Blast" The experimental field, consisting of the conventional rice variety Xiangzaoxian 45, was selected in an area where rice blast is a perennial disease. The experimental field covered 1 mu (approximately 0.067 hectares) and was divided into 28 plots, each 15 m². A 50 cm wide isolation row was placed between plots. A randomized block design was used, with four replicates for each treatment. The pesticide solution was prepared according to the recommended dosages of each example and comparative example. For Examples 1, 2, and 3, and Comparative Examples 1, 2, and 3, 150 g of pesticide was diluted in 30 kg of water per mu. For Comparative Example 4, 100 g of pesticide was diluted in 30 kg of water per mu. The blank control was sprayed with an equal volume of water. The first application was performed at the early stage of rice blast disease during the tillering stage, using a backpack sprayer to evenly spray until the leaves were moist. A second application was performed 7 days later. Disease severity was assessed in each plot 7, 14, and 21 days after the first application of pesticide. Five random sampling points were selected in each plot, and all leaves of 20 rice plants at each point were examined. Disease severity was recorded as follows: 0: no lesions; 1: lesions covering less than 5% of leaf area; 3: lesions covering 6%-15% of leaf area; 5: lesions covering 16%-30% of leaf area; 7: lesions covering 31%-50% of leaf area; 9: lesions covering more than 50% of leaf area. Disease severity index and control efficacy index were calculated. Disease severity index = Σ(number of diseased plants × corresponding disease severity value) / (total number of plants surveyed × highest disease severity value) × 100. Control efficacy = (disease severity index of blank control area - disease severity index of treated area) / disease severity index of blank control area × 100%. Experiment 3: Comprehensive determination of the duration of efficacy and rice safety Testing standards: GB / T17980.19-2000 and NY / T1965.1-2010 "Pesticide Safety Evaluation Part 1: Crop Safety Testing" Following the field trial plot design of Experiment 2, the investigation period was extended to 30 and 45 days after the second application of the pesticide. The disease index was recorded and the control efficacy was calculated according to the disease severity investigation method of Experiment 2. The last investigation time when the control efficacy was ≥60% was taken as the endpoint of the duration of efficacy. The differences in the duration of efficacy between each example and the comparative example were compared. Simultaneously, the growth status of rice in each plot was observed at 7, 14, 21, and 30 days after application, and growth indicators such as plant height, leaf color, and tiller number were recorded. The rice seed setting rate and thousand-grain weight were measured 45 days after application, referring to the phytotoxicity grading standard of NY / T1965.1-2010, where: 0: no phytotoxicity; 1: slight phytotoxicity, no impact on growth; 3: moderate phytotoxicity, growth inhibited; 5: severe phytotoxicity, some plants die; 7: extremely severe phytotoxicity, most plants die. The phytotoxicity was assessed, and the safety factor was calculated: safety factor = maximum dose without phytotoxicity / recommended dose. The persistence and safety of each treatment were comprehensively compared.

[0041] The results of the indoor inhibition rate of rice blast fungus are shown in Table 1.

[0042] Table 1: The field control effect of rice blast is shown in Table 2 (%).

[0043] Table 2: The combined results of the effective period and rice safety test are shown in Table 3.

[0044] Table 3: Based on Examples 1-3 and Comparative Example 1, and referring to Tables 1-3, it can be seen that microbial antibacterial agents are an important component of the compound antibacterial agent system. They exhibit significant synergistic effects with chemical fungicides and plant-derived antibacterial agents. This synergistic effect complements each other at different mechanism levels, helping to improve antibacterial performance and overall performance in field applications. It also has a corresponding impact on the long-term effect of the product. Without this component, the synergistic effect of the various antibacterial components in the system cannot be fully realized, and the relevant performance of the product will show different trends compared to when this component is present. As can be seen from Examples 1-3 and Comparative Example 2, and Tables 1-3, the synergistic agent, as a complex of nano-silica and sodium alginate, plays a key auxiliary role in the composite antibacterial agent system. It can cooperate with the carrier, various antibacterial components and surfactants to promote the uniform dispersion and efficient performance of each component in the system, and enhance the synergistic effect between different components. Without this synergistic agent, the efficiency of each antibacterial component and the stability of the system will be affected, which will lead to a corresponding change in the overall performance of the product.

[0045] As can be seen from Examples 1-3 and Comparative Example 3, and Tables 1-3, the functional modification of diatomaceous earth carriers by nano-silica is a key step in the preparation process. The modified carrier can significantly optimize the carrying capacity of various antibacterial components, improve the adhesion and sustained-release effect of components on the carrier surface, and help to stabilize the multiphase system. If this modification step is omitted, the performance of the carrier cannot be effectively optimized, and it is difficult to give full play to the carrying and synergistic effect of various antibacterial components, thus causing the overall performance of the product to change accordingly.

[0046] As can be seen from Examples 1-3 and Comparative Example 4, and Tables 1-3, there are fundamental differences in the mechanism of action and overall effect between single chemical fungicides and composite antibacterial systems. Traditional single-component systems mainly rely on chemical killing effects, while composite systems exhibit more balanced disease prevention effects and better ecological adaptability through multiple pathways such as chemical antibacterial, plant-derived active substances, and microbial regulation, highlighting the technical advantages of multi-component synergy.

[0047] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A compound bacteriostatic agent for the prevention and control of rice blast, characterized in that: It is composed of the following components in parts by weight: 10-40 parts chemical bactericide, 5-25 parts plant-derived antibacterial agent, 3-15 parts microbial antibacterial agent, 2-10 parts surfactant, 1-8 parts synergist, and 30-60 parts diatomaceous earth.

2. The compound antibacterial agent for controlling rice blast according to claim 1, characterized in that: The chemical fungicide is a compound combination of tricyclazole and azoxystrobin, wherein the weight ratio of tricyclazole to azoxystrobin is 1:0.5 to 1:1.

5.

3. The compound antibacterial agent for controlling rice blast according to claim 1, characterized in that: The plant-derived antibacterial agent is a compound combination of tea polyphenols and emodin, wherein the weight ratio of tea polyphenols to emodin is 1:0.6 to 1:1.

6.

4. The compound antibacterial agent for controlling rice blast according to claim 1, characterized in that: The microbial antibacterial agent is a Bacillus subtilis preparation with a viable bacterial content of 1×10⁻⁶. 10 -2×10 10 CFU / g.

5. The compound antibacterial agent for controlling rice blast according to claim 1, characterized in that: The synergistic agent comprises nano-silica and sodium alginate, wherein the weight ratio of nano-silica to sodium alginate is 1:1 to 1:

10.

6. The compound antibacterial agent for controlling rice blast according to claim 1, characterized in that: The surfactant is a compound of alkyl polysaccharide and polyoxyethylene sorbitan monooleate, wherein the weight ratio of alkyl polysaccharide to polyoxyethylene sorbitan monooleate is 1:1 to 1:

3.

7. A method for preparing a compound antibacterial agent for controlling rice blast, characterized in that, The compound antibacterial agent for controlling rice blast as described in any one of claims 1-6 comprises the following steps: S1. Carrier pretreatment: The diatomaceous earth carrier is dried and then mixed with nano-silica to complete the functional modification of the carrier surface. S2. Micronization and compounding of chemical fungicides: Tricyclazole and azoxystrobin are separately subjected to air jet milling and grinding to a predetermined particle size, and then mixed to form a compound chemical fungicide. S3. Activation of plant antibacterial agents: Tea polyphenols and emodin are synergistically extracted using supercritical carbon dioxide fluid, then dissolved and activated in deionized water, and then stirred to form a uniform activated solution. S4. Microbial stabilization: Bacillus subtilis preparation and sodium alginate solution are mixed under aseptic conditions and then spray-dried to form microcapsule particles. S5. Construction of multiphase system: The functionalized diatomaceous earth obtained in step S1, the composite chemical bactericide obtained in step S2, the activated plant-derived antibacterial agent solution obtained in step S3, the stabilized microbial preparation obtained in step S4, and the surfactant are combined and emulsified to form a uniform multiphase system. S6. High-pressure homogenization and pH adjustment: The multiphase system material obtained in step S5 is subjected to high-pressure homogenization, and then the pH value of the system is adjusted to a predetermined range using citric acid solution. S7. Low-temperature drying and sieving: The material processed in step S6 is dried in a vacuum environment and then sieved to finally obtain the composite antibacterial agent product. S8. Aseptic packaging: The composite antibacterial agent obtained in step S7 is vacuum packaged under aseptic conditions.

8. The method for preparing the compound antibacterial agent for controlling rice blast according to claim 7, characterized in that: In step S1, the drying temperature is 100-200°C, the drying time is 1-3 hours, the mixing speed is 800-1200 r / min, and the mixing time is 15-30 minutes; in step S2, the predetermined particle size is D 90 For particles smaller than 10 μm, the mixing time is 30-60 min; in step S3, the pressure of the synergistic extraction treatment is 15-35 MPa, the extraction temperature is 40-60°C, the activation temperature is 40-60°C, and the stirring time is 10-30 min.

9. The method for preparing the compound antibacterial agent for controlling rice blast according to claim 7, characterized in that: In step S4, the inlet temperature of the spray drying technology is 120-150°C, and the outlet temperature is 60-80°C; in step S5, the emulsification speed is 2000-5000 r / min, and the emulsification time is 10-20 min; in step S6, the homogenization pressure is 30-60 MPa, the homogenization times are 2-4 times, and the predetermined pH range is 5.5-6.

5.

10. The method for preparing the compound antibacterial agent for controlling rice blast according to claim 7, characterized in that: In step S7, the drying temperature is 50-70°C, the drying time is 2-4 hours, and the mesh size of the sieve is 100-200 mesh.

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