An agricultural bactericidal slow-release granule and a preparation method thereof

Abstract

The application discloses an agricultural bactericidal slow-release granule and a preparation method thereof, and belongs to the technical field of pesticides. According to the application, component B is used to wrap component A, forming a double slow-release structure, and modified porous diatomite and porous starch with different pore diameters are mixed to achieve the purpose of gradient slow release. Furthermore, the application is crosslinked with polyvinyl alcohol and crosslinking agent A, forming a stable three-dimensional network structure, so that the loading is more stable and the application mechanical property is better. In addition, D-tyrosine is added to component A, which can strengthen the bactericidal effect. Component B adopts a degradable material, and aminopropyl oligosiloxane and crosslinking agent B are introduced into polylactic acid-polyethylene glycol block copolymer, so that the adhesion of component B on the surface of component A is enhanced. Furthermore, crosslinking agent B can also form a chemical bond with crosslinking agent A, polyvinyl alcohol and modified porous diatomite, so that the bond network delays the rupture of the film layer, and the storage property and slow-release property are better. Furthermore, the addition of an antibacterial agent can synergistically kill bacteria and prolong the persistence.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pesticides, in particular to an agricultural fungicide sustained-release granule and a preparation method thereof. BACKGROUND

[0002] Pesticides are widely used in agriculture to ensure crop yield and quality. However, the original pesticide generally has the disadvantages of poor water solubility and stability, and most of them cannot be directly applied and need to be processed into various dosage forms. However, some toxic organic solvents and adjuvants are often added in traditional dosage forms, which has a large negative impact on the ecological system, low utilization rate of active ingredients and causes irreversible toxicity to non-target species. In addition, plant pathogens pose a great threat to crop growth and are the main cause of crop yield and quality decline. With the increasing risk of pesticide resistance, there is an urgent need for safer and more effective fungicides.

[0003] At the same time, the traditional pesticide application method also has many problems, such as short duration of efficacy, low drug utilization rate, and greater negative impact on the environment. In order to solve these problems, the sustained-release preparation technology has gradually been valued. By wrapping the active ingredients in appropriate carrier materials, slow release of the drug can be achieved, achieving the purposes of prolonging the effective period, reducing the frequency of pesticide application, and improving the utilization rate of the drug. There are also many studies on pesticide sustained-release granules in the prior art, such as the patent with the patent application number CN202410468454.5, which discloses a drug carrier, a drug-loaded particle and a preparation method thereof. The drug carrier comprises Fe3O4 nanoparticles and a CuMn2O4 shell wrapping the Fe3O4 nanoparticles. The drug carrier can achieve synergistic fungicidal effect of photo-thermal and chemical pesticides after loading pesticides, and has a sustained-release effect, which can reduce the frequency of pesticide application, reduce pesticide resistance and improve the control effect. However, the existing technology still has the problems of poor application stability and poor fungicidal effect of the prepared agricultural sustained-release granule. Therefore, it is urgent to develop or improve an agricultural fungicide sustained-release granule and a preparation method thereof for sustainable development of agriculture. SUMMARY

[0004] Therefore, in order to solve one of the above technical problems, the present application provides an agricultural fungicide sustained-release granule and a preparation method thereof, and the specific technical solutions are as follows:

[0005] An agricultural fungicide sustained-release granule, which comprises component A and component B, and the weight ratio of the component A to the component B is (5-20):(1-9).

[0006] The component A comprises the following raw materials by weight: 25-40 parts of modified porous diatomite, 15-20 parts of porous starch, 8-13 parts of polyvinyl alcohol, 7-12 parts of disintegrant, 0.01-5 parts of fungicide, 0.5-10 parts of D-tyrosine, 1-3 parts of crosslinking agent A, 0.1-0.8 parts of wetting agent, and 50-100 parts of solvent A.

[0007] The component B comprises the following raw materials by weight: 45-50 parts of polylactic acid-polyethylene glycol block copolymer, 9-12 parts of aminopropyl oligosiloxane, 10-15 parts of sodium carboxymethyl cellulose, 0.01-9 parts of antibacterial agent, 1-3 parts of plasticizer, 5-7 parts of crosslinking agent B, and 30-100 parts of solvent B.

[0008] Preferably, the modified porous diatomite is prepared by the following method:

[0009] The porous diatomite is added to 3-aminopropyl triethoxysilane, stirred at a speed of 50-100 r / min at 60-65°C for 20-60 min, then 1-hydroxymethyl pyrazole-3-carboxylic acid is added, and stirring is continued for 20-30 min to obtain the modified porous diatomite.

[0010] Preferably, the fungicide is at least one of carbendazim, tebuconazole, azoxystrobin, and metalaxyl-M.

[0011] Preferably, the disintegrant is at least one of calcium chloride, calcium stearate, and magnesium chloride.

[0012] Preferably, the crosslinking agent A is at least one of citric acid and glutaraldehyde.

[0013] Preferably, the wetting agent is at least one of cocamidopropyl betaine and sodium lignosulfonate.

[0014] Preferably, the polylactic acid-polyethylene glycol block copolymer has a molecular weight in the range of 5000-20000 Da, and the ratio of polylactic acid to polyethylene glycol is (5-9) to (1-5).

[0015] Preferably, the antibacterial agent is at least one of chitosan, nano-zinc oxide, and nano-magnesium oxide.

[0016] Preferably, the plasticizer is glycerol.

[0017] Preferably, the crosslinking agent B is at least one of polyethylene glycol dimethacrylate, β-cyclodextrin, and dextran.

[0018] In addition, the application further provides a preparation method of the agricultural bactericidal slow-release granule, and the preparation method comprises the following steps:

[0019] dispersing the bactericide in the solvent A to obtain a bactericide solution;

[0020] mixing the modified porous diatomite and porous starch, then adding the bactericide solution, stirring at a stirring speed of 50 r / min-100 r / min for 1 h-3 h, then adding polyvinyl alcohol, a crosslinking agent A, a disintegrating agent and a wetting agent, stirring at a stirring speed of 100 r / min-200 r / min under the condition of 65 DEG C-75 DEG C for 1 h-2 h, then adding D-tyrosine, stirring for 10 min-30 min, granulating to obtain component A;

[0021] adding the polylactic acid-polyethylene glycol block copolymer into the solvent B, stirring uniformly, then adding the aminopropyl oligosiloxane, sodium carboxymethyl cellulose, a plasticizer and the crosslinking agent B, stirring under the condition of 50 DEG C-70 DEG C for 1 h-3 h, then adding the antibacterial agent, continuing to stir for 20 min-30 min to obtain component B;

[0022] spraying the component B on the surface of the component A, and then treating under the condition of 50 DEG C-70 DEG C for 30 min-60 min to obtain the agricultural bactericidal slow-release granule.

[0023] Compared with the prior art, the application has the following beneficial effects:

[0024] 1. The component B is used for wrapping the component A to form an internal and external double slow-release structure, and the stability and uniformity of the whole are more excellent after the components and the ratio of the component A are optimized, the slow-release effect of the granule is positively affected, and due to the wrapping of the component B, the rapid loss of the effective component can be reduced after rainwater washing or ultraviolet irradiation, which is also helpful to achieve the slow-release purpose, and the environmental protection is more excellent, and the application has good application and promotion prospect.

[0025] 2. The modified porous diatomite and the porous starch with different pore diameters are mixed as the slow-release matrix to achieve the purpose of gradient slow-release, and the system formed under the interaction of the polyvinyl alcohol and the crosslinking agent A has more load crosslinking sites and forms a stable three-dimensional network structure, which improves the load stability of the effective component and also ensures the application mechanical properties of the agricultural bactericidal slow-release granule, and the agricultural bactericidal slow-release granule is not easy to be broken and the loss rate is reduced.

[0026] 3. The component B of the present application adopts a degradable material, and introduces an aminopropyl oligomeric siloxane and a crosslinking agent B in the polylactic acid-polyethylene glycol block copolymer, so as to not only form a crosslinking structure and enhance the adhesion on the surface of the component A, but also form a chemical bonding action with the crosslinking agent A, polyvinyl alcohol and modified porous diatomite in the component A, so that the adhesion is more excellent, the bonding network delays the film layer from being broken, and the storage is more excellent. In the soil environment, the component B is gradually degraded, and the slow-release performance is further ensured. In addition, the antibacterial agent is added in the component B, so as to achieve the purpose of synergistically enhancing the sterilization effect, achieving the broad-spectrum sterilization and antibacterial effect, reducing the use amount of the pesticide, and prolonging the persistence. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 A structural schematic diagram of the component A obtained from the embodiment 1 of the present application is shown in the figure.

[0028] Figure 2 A structural schematic diagram of the agricultural bactericidal slow-release particle of the embodiment 1 of the present application is shown in the figure. DETAILED DESCRIPTION

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terminology used in the description of the present application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application.

[0030] An agricultural bactericidal slow-release particle in an embodiment of the present application comprises a component A and a component B, and the weight ratio of the component A to the component B is (5-20):(1-9).

[0031] The component A comprises the following raw materials by weight: modified porous diatomite 25-40 parts, porous starch 15-20 parts, polyvinyl alcohol 8-13 parts, disintegrating agent 7-12 parts, bactericide 0.01-5 parts, D-tyrosine 0.5-10 parts, crosslinking agent A 1-3 parts, wetting agent 0.1-0.8 parts, and solvent A 50-100 parts.

[0032] The component B comprises the following raw materials by weight: polylactic acid-polyethylene glycol block copolymer 45-50 parts, aminopropyl oligomeric siloxane 9-12 parts, sodium carboxymethyl cellulose 10-15 parts, antibacterial agent 0.01-9 parts, plasticizer 1-3 parts, crosslinking agent B 5-7 parts, and solvent B 30-100 parts.

[0033] In some embodiments, the preparation method of the modified porous diatomite is as follows:

[0034] The porous diatomite is added to 3-aminopropyl triethoxysilane, stirred at a speed of 50r / min~100r / min at 60℃~65℃ for 20min~60min, then 1-hydroxymethyl pyrazole-3-carboxylic acid is added, and stirring is continued for 20min~30min to obtain the modified porous diatomite.

[0035] In some embodiments, the ratio of the porous diatomite, 3-aminopropyl triethoxysilane, and 1-hydroxymethyl pyrazole-3-carboxylic acid is (20~35):(30~55):(1~5) by weight.

[0036] In some embodiments, the average pore size of the modified porous diatomite is 30nm~100nm.

[0037] In some embodiments, the average pore size of the porous starch is 20nm~30nm.

[0038] In some embodiments, the fungicide is at least one of carbendazim, tebuconazole, azoxystrobin, and metalaxyl-M.

[0039] In some embodiments, the disintegrant is at least one of calcium chloride, calcium stearate, and magnesium chloride.

[0040] In some embodiments, the crosslinking agent A is at least one of citric acid and glutaraldehyde.

[0041] In some embodiments, the wetting agent is at least one of cocamidopropyl betaine and sodium lignosulfonate.

[0042] In some embodiments, the solvent A is at least one of methanol, ethyl acetate, chloroform, ethanol, and acetone.

[0043] In some embodiments, the molecular weight of the polylactic acid-polyethylene glycol block copolymer ranges from 5000~20000 Da, and the ratio of polylactic acid to polyethylene glycol is (5~9):(1~5).

[0044] In some embodiments, the antibacterial agent is at least one of chitosan, nano-zinc oxide, and nano-magnesium oxide.

[0045] In some embodiments, the plasticizer is glycerol.

[0046] In some embodiments, the crosslinking agent B is at least one of polyethylene glycol dimethacrylate, β-cyclodextrin, and dextran.

[0047] In some embodiments, solvent B is at least one of ethyl acetate and dichloromethane.

[0048] In addition, the present invention also provides a method for preparing agricultural bactericidal slow-release granules, the preparation method comprising the following steps:

[0049] The bactericide is dispersed in solvent A to obtain a bactericide solution;

[0050] Modified porous diatomaceous earth and porous starch are mixed, and then the bactericide solution is added. The mixture is stirred at a speed of 50 r / min to 100 r / min for 1 h to 3 h. Then, polyvinyl alcohol, crosslinking agent A, disintegrant and wetting agent are added. The mixture is stirred at a speed of 100 r / min to 200 r / min at 65 ℃ to 75 ℃ for 1 h to 2 h. D-tyrosine is then added and the mixture is stirred for 10 min to 30 min. The mixture is then granulated to obtain component A.

[0051] Polylactic acid-polyethylene glycol block copolymer was added to solvent B and stirred evenly. Then, aminopropyl oligosiloxane, sodium carboxymethyl cellulose, plasticizer and crosslinking agent B were added. The mixture was stirred at 50℃~70℃ for 1h~3h. Then, antibacterial agent was added and stirring was continued for 20min~30min to obtain component B.

[0052] Component B is sprayed onto the surface of component A, and then treated at 50℃~70℃ for 30min~60min to obtain agricultural bactericidal slow-release granules.

[0053] In some embodiments, the average particle size of the agricultural bactericidal slow-release granules is 2mm to 5mm.

[0054] The above method produces agricultural bactericidal slow-release granules that form a dual slow-release structure with high structural stability and uniformity, achieving significant slow-release bactericidal properties, and exhibiting excellent degradability and environmental friendliness.

[0055] The implementation scheme of the present invention will be described in detail below with reference to specific embodiments. Unless otherwise specified, the raw materials and reagents used in the embodiments are commercially available.

[0056] Example 1:

[0057] A method for preparing agricultural bactericidal slow-release granules, the method comprising the following steps:

[0058] By weight, 30 parts of porous diatomaceous earth were added to 48 parts of 3-aminopropyltriethoxysilane and stirred at 50 r / min at 65 °C for 50 min. Then, 3 parts of 1-hydroxymethylpyrazole-3-carboxylic acid were added and stirred for another 30 min to obtain modified porous diatomaceous earth with an average pore size of 62 nm.

[0059] By weight, 1 part of metalaxyl was dispersed in 50 parts of ethanol to obtain a bactericide solution; then 27 parts of modified porous diatomaceous earth and 19 parts of porous starch (pore size 25 nm) were mixed, and the bactericide solution was added. The mixture was stirred at 50 r / min for 2 h, then 9 parts of polyvinyl alcohol, 3 parts of citric acid, 9 parts of calcium chloride and 0.5 parts of cocamidopropyl betaine were added. The mixture was stirred at 100 r / min at 65 °C for 1 h, then 2 parts of D-tyrosine were added and stirred for 20 min. The mixture was then granulated to obtain component A.

[0060] By weight, 46 parts of polylactic acid-polyethylene glycol block copolymer were added to 67 parts of ethyl acetate and stirred evenly. Then, 9 parts of aminopropyl oligosiloxane, 11 parts of sodium carboxymethyl cellulose, 3 parts of glycerol and 5 parts of polyethylene glycol dimethacrylate were added and stirred at 55°C for 2 hours. Then, 5 parts of chitosan were added and stirred for another 25 minutes to obtain component B.

[0061] By weight, 7 parts of component B were sprayed onto the surface of 15 parts of component A, and then treated at 65°C for 30 minutes to obtain agricultural bactericidal slow-release granules with an average particle size of 5 mm.

[0062] Example 2:

[0063] A method for preparing agricultural bactericidal slow-release granules, the method comprising the following steps:

[0064] By weight, 31 parts of porous diatomaceous earth were added to 49 parts of 3-aminopropyltriethoxysilane and stirred at 50 r / min at 65 °C for 45 min. Then, 4 parts of 1-hydroxymethylpyrazole-3-carboxylic acid were added and stirred for another 25 min to obtain modified porous diatomaceous earth with an average pore size of 63 nm.

[0065] By weight, 0.09 parts of metalaxyl were dispersed in 50 parts of ethanol to obtain a bactericide solution; then 26 parts of modified porous diatomaceous earth and 20 parts of porous starch (pore size 25 nm) were mixed, and the bactericide solution was added. The mixture was stirred at 50 r / min for 2 h. Then, 8 parts of polyvinyl alcohol, 3 parts of citric acid, 10 parts of calcium chloride and 0.6 parts of cocamidopropyl betaine were added. The mixture was stirred at 100 r / min at 65 °C for 1 h. Finally, 3 parts of D-tyrosine were added and stirred for 20 min. The mixture was then granulated to obtain component A.

[0066] By weight, 45 parts of polylactic acid-polyethylene glycol block copolymer were added to 65 parts of ethyl acetate and stirred evenly. Then, 10 parts of aminopropyl oligosiloxane, 10 parts of sodium carboxymethyl cellulose, 3 parts of glycerol and 6 parts of polyethylene glycol dimethacrylate were added and stirred at 55°C for 2 hours. Then, 6 parts of chitosan were added and stirred for another 25 minutes to obtain component B.

[0067] By weight, 7 parts of component B were sprayed onto the surface of 15 parts of component A, and then treated at 65°C for 30 minutes to obtain agricultural bactericidal slow-release granules with an average particle size of 5 mm.

[0068] Example 3:

[0069] A method for preparing agricultural bactericidal slow-release granules, the method comprising the following steps:

[0070] By weight, 30 parts of porous diatomaceous earth were added to 50 parts of 3-aminopropyltriethoxysilane and stirred at 50 r / min at 65 °C for 60 min. Then, 3 parts of 1-hydroxymethylpyrazole-3-carboxylic acid were added and stirred for another 30 min to obtain modified porous diatomaceous earth with an average pore size of 61 nm.

[0071] By weight, 1 part of metalaxyl was dispersed in 50 parts of ethanol to obtain a bactericide solution; then 25 parts of modified porous diatomaceous earth and 18 parts of porous starch (pore size 25 nm) were mixed, and the bactericide solution was added. The mixture was stirred at 50 r / min for 2 h. Then, 9 parts of polyvinyl alcohol, 3 parts of citric acid, 11 parts of calcium chloride and 0.8 parts of cocamidopropyl betaine were added. The mixture was stirred at 100 r / min at 65 °C for 1 h. Finally, 5 parts of D-tyrosine were added and stirred for 20 min. The mixture was then granulated to obtain component A.

[0072] By weight, 45 parts of polylactic acid-polyethylene glycol block copolymer were added to 65 parts of ethyl acetate and stirred evenly. Then, 12 parts of aminopropyl oligosiloxane, 11 parts of sodium carboxymethyl cellulose, 3 parts of glycerol and 7 parts of polyethylene glycol dimethacrylate were added and stirred at 60°C for 2 hours. Then, 9 parts of chitosan were added and stirred for another 30 minutes to obtain component B.

[0073] By weight, 7 parts of component B were sprayed onto the surface of 15 parts of component A, and then treated at 65°C for 30 minutes to obtain agricultural bactericidal slow-release granules with an average particle size of 5 mm.

[0074] Comparative Example 1:

[0075] The difference between Comparative Example 1 and Example 3 is that ordinary porous diatomaceous earth (unmodified and with an average pore size of 45 nm) was used in Comparative Example 1 instead of the modified porous diatomaceous earth in Example 3, while the rest is the same as in Example 3.

[0076] Comparative Example 2:

[0077] The difference between Comparative Example 2 and Example 3 is that porous starch was not added in Comparative Example 2, but otherwise the same as in Example 3.

[0078] Comparative Example 3:

[0079] The difference between Comparative Example 3 and Example 3 is that D-tyrosine was not added in Comparative Example 3, but otherwise the same as in Example 3.

[0080] Comparative Example 4:

[0081] The difference between Comparative Example 4 and Example 3 is that citric acid (crosslinking agent A) was not added in Comparative Example 4, but otherwise it was the same as Example 3.

[0082] Comparative Example 5:

[0083] The difference between Comparative Example 5 and Example 3 is that polylactic acid was used instead of polylactic acid-polyethylene glycol block copolymer in Comparative Example 5, while the rest is the same as in Example 3.

[0084] Comparative Example 6:

[0085] The difference between Comparative Example 6 and Example 3 is that polyethylene glycol dimethacrylate (crosslinking agent B) was not added in Comparative Example 6, but otherwise it was the same as Example 3.

[0086] Comparative Example 7:

[0087] The difference between Comparative Example 7 and Example 3 is that chitosan (antibacterial agent) was not added in Comparative Example 7, but otherwise it was the same as Example 3.

[0088] Comparative Example 8:

[0089] The difference between Comparative Example 8 and Example 3 is that Comparative Example 8 only has component A, that is, the process of spraying component B onto the surface of component A is not performed. Otherwise, it is the same as Example 3.

[0090] I. Adhesion tests were conducted on the samples prepared in Examples 1-3 and the comparative samples prepared in Comparative Examples 1-8. The test method was as follows: The original mass M1 of the sample and the comparative sample were weighed by those skilled in the art, and then placed in the drum of a friability tester with a sweeping plate. The rotation speed and rotation time were set. During the continuous rotation of the drum, the sample or comparative sample was repeatedly rotated, rolled, impacted and slid under the driving principle of the baffle. The particles were constantly subjected to friction. If the adhesion of component A and component B is not strong, the film formed by component B will be incomplete and will slowly fall off. The particles were sieved using a sieve with a particle size of 1.00 mm. The material under the sieve was the material with poor adhesion. The mass of the material under the sieve was accurately weighed as M2. The particle stability was judged according to W% = M2 / M1 × 100%. If necessary, the morphology of the agricultural bactericidal slow-release particles could be observed with the help of magnifying glasses and other tools. The results are shown in Table 1 below.

[0091] Table 1: Judgment Results

[0092] Group RPM, Time W% Agricultural fungicide slow-release granule state Example 1 20 r / min, 30 min 0.48% 99% or more of the granules were uniform, the surface was intact, no breakage, no shedding. Example 2 20 r / min, 30 min 0.45% 99% or more of the granules were uniform, the surface was intact, no breakage, no shedding. Example 3 20 r / min, 30 min 0.47% 99% or more of the granules were uniform, the surface was intact, no breakage, no shedding. Comparative Example 1 20 r / min, 30 min 1.26% 95% or more of the granules were uniform, the surface was intact, no breakage, no shedding. Comparative Example 2 20 r / min, 30 min 1.38% 95% or more of the granules were uniform, the surface was intact, no breakage, no shedding. Comparative Example 3 20 r / min, 30 min 0.48% 99% or more of the granules were uniform, the surface was intact, no breakage, no shedding. Comparative Example 4 20 r / min, 30 min 16.7% 60% or more of the granules were uniform, the surface was intact, no breakage, no shedding. Comparative Example 5 20 r / min, 30 min 8.2% 81% or more of the granules were uniform, the surface was intact, no breakage, no shedding. Comparative Example 6 20 r / min, 30 min 13.6% 56% or more of the granules were uniform, the surface was intact, no breakage, no shedding. Comparative Example 7 20 r / min, 30 min 5.1% 98% or more of the granules were uniform, the surface was intact, no breakage, no shedding. Comparative Example 8 20 r / min, 30 min 24.7% 39% or more of the granules were uniform, 100% no surface film layer.

[0093] Analysis of the data in Table 1 shows that the agricultural bactericidal slow-release granules prepared by this invention have excellent overall application stability. Through the interaction between component B and component A, the granules exhibit higher integrity, thus ensuring their application quality. Compared to Example 3, Comparative Example 1 uses a different porous diatomaceous earth, which has poorer applicability than Example 3. The lack of modification reduces the adhesion between components A and B. Comparative Example 2 did not add porous starch, which acts as both a load-bearing agent and a binder; without it, the adhesion between components decreases. Comparative Example 3 did not add D-tyrosine, resulting in a lower impact on the physical properties of the agricultural bactericidal slow-release granules. Comparative Example 4 did not add citric acid, leading to a significant decrease in cross-linking activity, indicating that the addition of a certain amount of cross-linking agent is necessary. The addition of polylactic acid (PLA) to the polylactic acid-polyethylene glycol block copolymer in Comparative Example 5 increases the stability of the network structure within the system. In Comparative Example 6, the absence of PLA (crosslinking agent B) also affects the crosslinking and film-forming properties of the components, and weakens the hydrogen bonding with component A, leading to decreased adhesion. In Comparative Example 7, the absence of chitosan (antibacterial agent) has a relatively small impact on particle integrity. In Comparative Example 8, the lack of film-forming protection from component B results in varying degrees of breakage. This demonstrates that the present invention, through the synergistic effect of its components, helps to obtain agricultural bactericidal slow-release granules with higher stability and integrity.

[0094] II. Sustained-release effect

[0095] Test method: Acetonitrile and water were mixed in a volume ratio of 60:40 to prepare the release medium. The samples obtained in Examples 1 to 3 and the comparative samples in Comparative Examples 1 to 8 were placed in 200 mL of the release medium. 1 mL of the sample was taken at intervals and detected by high performance liquid chromatography (a conventional technique, which will not be described in detail here). The results are shown in Table 2 below.

[0096] Table 2: Sustained-release effect (%)

[0097] Group 0.5h 2h 6h 24h 48h 72h 168h Example 1 3.1 8.4 18.4 41.6 62.3 74.6 88.9 Example 2 3.2 8.7 18.7 42.1 62.5 74.8 89.2 Example 3 3.2 8.5 18.6 41.7 62.4 74.5 89.3 Comparative Example 1 2.9 28.9 50.6 75.6 80.6 86.2 90.5 Comparative Example 2 10.8 22.6 41.2 69.7 89.1 91.4 94.7 Comparative Example 3 3.5 8.9 18.7 42.5 59.8 71.6 89.1 Comparative Example 4 15.1 30.1 56.9 83.4 95.3 97.6 99.0 Comparative Example 5 2.5 6.3 30.2 65.7 79.3 86.1 90.4 Comparative Example 6 15.9 28.9 50.9 77.1 90.2 93.5 96.8 Comparative Example 7 3.7 8.9 18.2 42.7 63.4 74.6 90.2 Comparative Example 8 22.8 36.7 67.6 75.9 96.7 97.8 99.2

[0098] Analysis of the data in Table 2 shows that the present invention achieves a superior sustained-release effect through the interaction of its components. Compared with Example 3, Comparative Example 1 uses ordinary diatomaceous earth with a smaller pore size than Example 3. It has not undergone modification and has poor compatibility in the system, resulting in inferior performance of the prepared agricultural bactericidal granules compared to Example 3. Comparative Example 2 does not add porous starch, leading to a decrease in system performance and a gradient in pore size, affecting the sustained-release effect. Comparative Example 3 does not add D-tyrosine, so its effect on the sustained-release effect is not significant. Comparative Examples 4 and 6 do not add crosslinking agents, resulting in a decrease in the degree of crosslinking in the system structure, affecting the release effect. Comparative Example 5 uses polylactic acid instead of polylactic acid-polyethylene glycol block copolymer, which cannot balance hydrophilicity and hydrophobicity. The use of polylactic acid results in low initial release efficiency, followed by gradual penetration and rapid release. Comparative Example 7 does not add chitosan, which affects the film-forming properties of component B, thus making its sustained-release effect inferior to Example 3, but the impact is not significant. Comparative Example 8 does not encapsulate component A, resulting in rapid release.

[0099] III. Field Trials

[0100] The bactericidal and antibacterial effects of the samples in Examples 1-3 and the comparative samples in Comparative Examples 1-8 were tested and compared through indoor greenhouse experiments. The experimental area for each group was 20m². 2 Each treatment group was repeated 3 times. The application time was when cucumber seedlings were transplanted and the dosage was 1 kg / mu. The control effect of soil-borne diseases was recorded at each time interval. The results are shown in Table 3 below.

[0101] Table 3: Prevention and control efficacy (%)

[0102] Group 20d 30d 40d 60d Example 1 85.8 96.7 94.2 92.3 Example 2 86.2 98.4 94.7 91.7 Example 3 88.9 99.5 95.5 93.2 Comparative Example 1 85.4 90.9 92.3 86.5 Comparative Example 2 84.9 92.5 93.5 90.2 Comparative Example 3 75.2 85.6 86.7 87.3 Comparative Example 4 80.2 83.7 87.6 88.3 Comparative Example 5 72.4 78.0 80.4 78.4 Comparative Example 6 81.3 84.6 86.7 87.1 Comparative Example 7 85.6 97.3 94.1 91.0 Comparative Example 8 78.3 81.0 82.4 76.4

[0103] Analysis of the data in Table 3 shows that the agricultural bactericidal slow-release granules of this invention have excellent control effects on soil-borne diseases and can achieve control for a relatively long period of time. Furthermore, the addition of D-tyrosine and antibacterial agents has a certain synergistic effect, resulting in even better performance. In addition, the raw materials used in the preparation of this invention are biodegradable, and the agricultural bactericidal granules have a certain degree of degradability, making them more environmentally friendly.

[0104] To further illustrate the agricultural bactericidal granules of the present invention, combined with Figure 1 as well as Figure 2 Further analysis of the agricultural bactericidal slow-release granules of the present invention, wherein, Figure 1 This is a schematic diagram of the structure of component A obtained in Example 1 of the present invention. Figure 1 It can be seen that the components in component A are cross-linked to form a relatively stable network structure and have a porous structure; Figure 2 This is a schematic diagram of the structure of the agricultural bactericidal slow-release granules of Embodiment 1 of the present invention, wherein, Figure 2As can be seen from Figure a, the agricultural bactericidal slow-release granules of the present invention exhibit relatively uniform dispersion and integrity. Figure 2 Figure 2 As shown in Figure b, the agricultural bactericidal slow-release granules of the present invention have a core-shell structure, with component A acting as the core and component B acting as the shell. Component B can effectively encapsulate component A, forming a double slow-release structure inside and outside. No cracking or particle collapse was observed, which further demonstrates that the agricultural bactericidal slow-release granules prepared by the present invention have excellent application performance and can achieve the purpose of long-term prevention and control.

[0105] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. An agricultural bactericidal slow-release granule, characterized in that, The agricultural bactericidal slow-release granules include component A and component B, and the weight ratio of component A to component B is (5~20):(1~9). Component A comprises the following raw materials in parts by weight: 25-40 parts modified porous diatomaceous earth, 15-20 parts porous starch, 8-13 parts polyvinyl alcohol, 7-12 parts disintegrant, 0.01-5 parts bactericide, 0.5-10 parts D-tyrosine, 1-3 parts crosslinking agent A, 0.1-0.8 parts wetting agent, and 50-100 parts solvent A; wherein crosslinking agent A is at least one of citric acid and glutaraldehyde. Component B comprises the following raw materials in parts by weight: 45-50 parts of polylactic acid-polyethylene glycol block copolymer, 9-12 parts of aminopropyl oligosiloxane, 10-15 parts of sodium carboxymethyl cellulose, 0.01-9 parts of antibacterial agent, 1-3 parts of plasticizer, 5-7 parts of crosslinking agent B, and 30-100 parts of solvent B; wherein the crosslinking agent B is at least one of polyethylene glycol dimethacrylate, β-cyclodextrin, and dextran. The modified porous diatomaceous earth is prepared as follows: Porous diatomaceous earth was added to 3-aminopropyltriethoxysilane and stirred at 50 r / min to 100 r / min at 60℃ to 65℃ for 20 min to 60 min. Then 1-hydroxymethylpyrazole-3-carboxylic acid was added and stirring was continued for 20 min to 30 min to obtain modified porous diatomaceous earth.

2. The bactericidal sustained-release granules according to claim 1, characterized in that, The fungicide is at least one of carbendazim, tebuconazole, azoxystrobin, and metalaxyl.

3. The bactericidal sustained-release granules according to claim 1, characterized in that, The disintegrant is at least one of calcium chloride, calcium stearate, and magnesium chloride.

4. The bactericidal sustained-release granules according to claim 1, characterized in that, The molecular weight range of the polylactic acid-polyethylene glycol block copolymer is 5000~20000 Da, and the ratio of polylactic acid to polyethylene glycol is (5~9)~(1~5).

5. The bactericidal sustained-release granules according to claim 1, characterized in that, The antibacterial agent is at least one of chitosan, nano zinc oxide, and nano magnesium oxide.

6. The bactericidal sustained-release granules according to claim 1, characterized in that, The plasticizer is glycerin.

7. A method for preparing agricultural bactericidal slow-release granules, characterized in that, The preparation method is used to prepare agricultural bactericidal slow-release granules as described in any one of claims 1 to 6, and the preparation method includes the following steps: The bactericide is dispersed in solvent A to obtain a bactericide solution; Modified porous diatomaceous earth and porous starch are mixed, and then the bactericide solution is added. The mixture is stirred at a speed of 50 r / min to 100 r / min for 1 h to 3 h. Then, polyvinyl alcohol, crosslinking agent A, disintegrant and wetting agent are added. The mixture is stirred at a speed of 100 r / min to 200 r / min at 65 ℃ to 75 ℃ for 1 h to 2 h. D-tyrosine is then added and the mixture is stirred for 10 min to 30 min. The mixture is then granulated to obtain component A. Polylactic acid-polyethylene glycol block copolymer was added to solvent B and stirred evenly. Then, aminopropyl oligosiloxane, sodium carboxymethyl cellulose, plasticizer and crosslinking agent B were added. The mixture was stirred at 50℃~70℃ for 1h~3h. Then, antibacterial agent was added and stirring was continued for 20min~30min to obtain component B. Component B is sprayed onto the surface of component A, and then treated at 50℃~70℃ for 30min~60min to obtain agricultural bactericidal slow-release granules.

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