Fmoxadone-containing agricultural bactericidal composition

Abstract

The invention discloses an agricultural bactericidal composition containing famoxadone, and belongs to the technical field of pesticides. The agricultural bactericidal composition containing famoxadone is prepared from the following raw materials in percentage by weight: 3 to 4 percent of famoxadone, 3 to 4 percent of hymexazol, 10 to 12 percent of enhancer, 20 to 30 percent of guanidyl chitosan quaternary ammonium salt, 20 to 30 percent of modified beta-cyclodextrin and 30 to 34 percent of water, wherein the modified beta-cyclodextrin is beta-cyclodextrin treated by a modified silane coupling agent, and the modified silane coupling agent contains a disulfide bond and a sulfonic acid group. The agricultural bactericidal composition prepared by the invention has excellent slow release performance and bactericidal performance, and can solve the problem that hymexazol in the prior art loses the bactericidal effect within a short time due to too high biodegradation speed.

Description

Technical Field

[0001] The present invention relates to the technical field of pesticides, and particularly relates to an agricultural fungicidal composition containing famoxadone. Background Art

[0002] Famoxadone is a broad-spectrum fungicide, mainly used for controlling important diseases caused by ascomycetes, basidiomycetes, and oomycetes, such as powdery mildew, rust, glume blotch, net blotch, downy mildew, late blight, etc. Famoxadone is a mitochondrial respiration inhibitor, but its inhibitory site for mitochondrial electron transport is very single, and it is easy for pathogens to develop adaptive mutations to the agent, resulting in a reduction or even invalidation of the efficacy of the agent. Currently, there are relevant reports on drug resistance abroad, and there are greater risks in the long-term use of single agents. Combining different active ingredients of pesticides, a composition with synergistic effects can not only significantly improve the actual control effect, reduce the dosage and cost of pesticides, but also help to avoid the occurrence of pathogen resistance and delay the generation rate of drug resistance. It is an effective way to solve the problems such as high cost, narrow fungicidal spectrum, and easy generation of resistance in the application of single pesticides. Developing an agricultural fungicidal composition containing famoxadone is necessary and has great practical application value.

[0003] Hymexazol is a fungicide with a large dosage in China at present. Its English name is Hymexazol, and its chemical name is 3-hydroxy-5-methylisoxazole, belonging to the oxazole fungicides. This agent is a highly efficient, low-toxic, environmentally friendly, and broad-spectrum fungicide, and has good control effects on plant diseases caused by various pathogenic fungi. It has good therapeutic effects on Pythium, Fusarium, Rhizoctonia, Corticiella, Typhula, etc. of oomycetes, ascomycetes, basidiomycetes, and deuteromycetes. Hymexazol has systemic and conductive effects, and its bactericidal mechanism is to inhibit the mitochondrial respiration of pathogens, but it is different from β-methoxyacrylate fungicides. At the same time, Hymexazol is also a soil disinfectant, which is highly effective against Pythium in the soil and can combine with inorganic aluminum ions in the soil to improve the ability to inhibit the germination of pathogen spores. Hymexazol is also used as a plant growth regulator. Its metabolites in plants are two glucosides, which can improve the physiological activity of plants, thereby promoting plant growth, root tillering, increasing root hairs, and enhancing root activity. Hymexazol has no impact on the ecology of microorganisms in the soil and can be decomposed into compounds with very low toxicity in the soil, being safe and residue-free. However, the biodegradation rate of Hymexazol is too fast, and its bactericidal effect will be lost in a short time. Therefore, it is necessary to prepare a sustained-release Hymexazol bactericidal preparation. Summary of the Invention

[0004] The present invention provides an agricultural fungicidal composition containing famoxadone, which can solve the problem that the biodegradation rate of Hymexazol in the prior art is too fast and its bactericidal effect will be lost in a short time.

[0005] The object of the present invention can be achieved by the following technical solutions:

[0006] An agricultural bactericidal composition containing famoxadone, by weight percentage, comprises the following raw materials: 3-4% of famoxadone, 3-4% of hymexazol, 10-12% of a strengthening agent, 20-30% of guanidyl chitosan quaternary ammonium salt, 20-30% of modified β-cyclodextrin, and 30-34% of water; wherein, the modified β-cyclodextrin is β-cyclodextrin treated with a modified silane coupling agent, and the modified silane coupling agent contains a disulfide bond and a sulfonic acid group.

[0007] Further, the strengthening agent is any one of aluminum sulfate, copper sulfate or ferrous sulfate.

[0008] Further, the preparation method of the guanidyl chitosan quaternary ammonium salt is as follows:

[0009] A1: Dispersing chitosan in isopropanol, slowly dropping a NaOH solution with a mass concentration of 40%, stirring at 50-60 °C for 1-2 h, then adding an aqueous solution of chloroacetic acid, stirring at 50-60 °C for 3-4 h, after the reaction is completed, precipitating with absolute ethanol, and freeze-drying for 48 h to obtain carboxymethyl chitosan;

[0010] Wherein, the dosage ratio of chitosan, isopropanol, NaOH solution, and aqueous solution of chloroacetic acid is 1 g: 10-12 mL: 3 mL: 5 mL; the dosage ratio of chloroacetic acid to deionized water in the aqueous solution of chloroacetic acid is 0.58 g: 5 mL.

[0011] A2: Dispersing carboxymethyl chitosan in 1-methyl-2-pyrrolidone, sequentially adding sodium iodide, a sodium hydroxide solution with a mass fraction of 15%, and iodomethane under stirring at room temperature, refluxing and reacting at 60 °C for 2 h, then adding an excessive amount of ethanol for precipitation, and after washing and suction filtration, obtaining carboxymethyl chitosan quaternary ammonium salt;

[0012] Wherein, the dosage ratio of carboxymethyl chitosan, 1-methyl-2-pyrrolidone, sodium iodide, sodium hydroxide solution, and iodomethane is 1 g: 30-40 mL: 1.5 g: 20 mL: 5 mL.

[0013] A3: Dissolving carboxymethyl chitosan quaternary ammonium salt in deionized water, adding aminoguanidine phosphate, stirring at room temperature for 10-12 h, dialyzing, and freeze-drying to obtain guanidyl chitosan quaternary ammonium salt.

[0014] Wherein, the dosage ratio of carboxymethyl chitosan quaternary ammonium salt, deionized water, and aminoguanidine phosphate is 1 g: 30-40 mL: 1.07 g.

[0015] Through the above reaction steps, the guanidine chitosan quaternary ammonium salt containing both guanidine groups and quaternary ammonium salt groups is prepared in the present invention. Chitosan itself has antibacterial properties and can improve the bactericidal performance of the agricultural bactericidal composition. Both the guanidine groups and quaternary ammonium salt groups in the guanidine chitosan quaternary ammonium salt carry positive charges, which can increase the positive charge content of chitosan. Moreover, both the guanidine groups and quaternary ammonium salt groups have antibacterial properties and can synergistically enhance the antibacterial effect of chitosan, thereby improving the bactericidal performance of the agricultural bactericidal composition. In addition, the phosphorus element in the guanidine chitosan quaternary ammonium salt can also promote crop growth.

[0016] Further, in step A1, the molecular weight of chitosan is 60KDa and the degree of deacetylation is 90%.

[0017] Further, the preparation method of the modified β-cyclodextrin is as follows:

[0018] S1: Add calcium hydride-dried dichloromethane to 2,2-dithiopyridine, stir and dissolve to obtain solution a; dissolve 3-mercaptopropyltriethoxysilane in calcium hydride-dried dichloromethane to obtain solution b, and dropwise add this solution b to solution a. After the addition is complete, stir magnetically at room temperature for 48 hours, evaporate the solvent, wash, and dry under vacuum to obtain an intermediate;

[0019] Among them, the dosage ratio of 2,2-dithiopyridine to dichloromethane is 4.6 g: 200 mL; the dosage ratio of 3-mercaptopropyltriethoxysilane to dichloromethane is 10 g: 300 mL; the volume ratio of solution a to solution b is 2:3.

[0020] S2: Add the intermediate to dichloromethane, stir for 20 - 30 min to obtain solution c; add sodium 2-mercaptoethylsulfonate to dichloromethane to obtain solution d; dropwise add solution d to solution c, react at room temperature for 48 h, wash, and dry under vacuum to obtain a modified silane coupling agent;

[0021] Among them, the dosage ratio of the intermediate to dichloromethane is 253 mg: 100 mL; the dosage ratio of sodium 2-mercaptoethylsulfonate to dichloromethane is 216 mg: 10 mL; the volume ratio of solution c to solution d is 10:1.

[0022] S3: Add β-cyclodextrin to water and absolute ethanol, stir, then add the modified silane coupling agent, heat to 50 - 60 °C and stir for 1 - 2 h, then cool to room temperature, wash, and dry under vacuum to obtain the modified β-cyclodextrin;

[0023] Among them, the dosage ratio of β-cyclodextrin, water, absolute ethanol, and N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride is 10 g: 10 - 20 mL: 80 - 90 mL: 0.4 - 0.8 g.

[0024] β-cyclodextrin is a natural cyclic oligosaccharide, which is conical in shape, with hydrophilic groups on the outer surface and a hydrophobic cavity inside. Therefore, it can encapsulate the hydrophobic fungicide, namely famoxadone, in the cavity to increase the water solubility and stability of famoxadone. However, β-cyclodextrin does not carry a charge, and there is a problem of poor compatibility between β-cyclodextrin and quaternary ammonium salt of guanidyl chitosan due to the charge difference, which affects the sustained-release performance and stability of the bactericidal composition.

[0025] Through the above reaction steps, the present invention obtains a modified silane coupling agent, and the modified silane coupling agent contains disulfide bonds and sodium sulfonate. The low bond energy of the disulfide bond can promote the slippage of the molecular chain. Using this property, when the modified β-cyclodextrin is used as a sustained-release material for the bactericidal composition, it can be repaired in time after being damaged, thereby improving the sustained-release performance of the agricultural bactericidal composition. The sulfonic acid group in sodium sulfonate contains a negative charge, which can increase the negative charge content on the surface of the modified β-cyclodextrin, and the S element in the sulfonic acid group can also be used as a nutrient element to promote the growth of crops.

[0026] The beneficial effects of the present invention:

[0027] 1. The present invention uses quaternary ammonium salt of guanidyl chitosan and modified β-cyclodextrin as the sustained-release materials for the bactericidal composition. The quaternary ammonium salt of guanidyl chitosan has a large number of positive charges, and the modified β-cyclodextrin has negative charges. The two can be tightly combined, thereby improving the stability of the sustained-release material and enhancing the sustained-release performance of the agricultural bactericidal composition.

[0028] 2. The quaternary ammonium salt of guanidyl chitosan has broad-spectrum antibacterial properties and can synergistically improve the bactericidal performance of the bactericidal composition; the modified β-cyclodextrin contains disulfide bonds, which can improve the sustained-release performance of the agricultural bactericidal composition. Moreover, the quaternary ammonium salt of guanidyl chitosan and the modified β-cyclodextrin contain elements such as nitrogen, phosphorus, and silicon, which can promote the growth of crops while sterilizing. Specific embodiments

[0029] The following describes the specific embodiments of the present invention in detail, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0030] Example 1

[0031] An agricultural bactericidal composition containing famoxadone, by weight percentage, comprises the following raw materials: 3% famoxadone, 3% hymexazol, 10% aluminum sulfate, 25% quaternary ammonium salt of guanidyl chitosan, 25% modified β-cyclodextrin, and 34% water.

[0032] The preparation method of the quaternary ammonium salt of guanidyl chitosan is:

[0033] A1: Dissolve 1 g of chitosan (with a molecular weight of 60 kDa and a deacetylation degree of 90%) in 10 - 12 mL of isopropanol. Slowly add 3 mL of a 40% NaOH solution dropwise, and stir at 55 °C for 1 h. Then add 5 mL of an aqueous chloroacetic acid solution (the dosage ratio of chloroacetic acid to deionized water is 0.58 g : 5 mL), and stir at 50 °C for 3 h. After the reaction, precipitate with absolute ethanol and freeze-dry for 48 h to obtain carboxymethyl chitosan;

[0034] A2: Dissolve 1 g of carboxymethyl chitosan in 40 mL of 1-methyl-2-pyrrolidone. Sequentially add 1.5 g of sodium iodide, 20 mL of a 15% sodium hydroxide solution, and 5 mL of iodomethane under stirring at room temperature. Reflux and react at 60 °C for 2 h, then add an excess of ethanol for precipitation. After washing and suction filtration, obtain carboxymethyl chitosan quaternary ammonium salt;

[0035] A3: Dissolve 1 g of carboxymethyl chitosan quaternary ammonium salt in 40 mL of deionized water, add 1.07 g of aminoguanidine phosphate, stir at room temperature for 12 h, dialyze, and freeze-dry to obtain guanidyl chitosan quaternary ammonium salt.

[0036] The preparation method of modified β-cyclodextrin is as follows:

[0037] S1: Add 4.6 g of 2,2'-dipyridyl disulfide to 200 mL of dichloromethane dried with calcium hydride, stir to dissolve to obtain solution a; dissolve 10 g of 3-mercaptopropyltriethoxysilane in 300 mL of dichloromethane dried with calcium hydride to obtain solution b. Slowly add 300 mL of this solution b dropwise to 200 mL of solution a. After the addition, stir magnetically at room temperature for 48 h, evaporate the solvent, wash, and dry in vacuum to obtain an intermediate;

[0038] S2: Add 253 mg of the intermediate to 100 mL of dichloromethane, stir for 30 min to obtain solution c; add 216 mg of 2-mercaptoethyl sulfonate sodium salt to 10 mL of dichloromethane to obtain solution d; add 10 mL of solution d dropwise to 100 mL of solution c, react at room temperature for 48 h, wash, and dry in vacuum to obtain a modified silane coupling agent.

[0039] S3: Add 10 g of β-cyclodextrin to 10 mL of water and 90 mL of absolute ethanol, stir, then add 0.4 g of the modified silane coupling agent, heat to 60 °C and stir for 2 h, then cool to room temperature, wash, and dry in vacuum to obtain modified β-cyclodextrin;

[0040] Example 2

[0041] The difference between this example and Example 1 is as follows:

[0042] An agricultural bactericidal composition containing famoxadone, by weight percentage, comprises the following raw materials: 3.5% famoxadone, 3.5% hymexazol, 11% aluminum sulfate, 25% guanidyl chitosan quaternary ammonium salt, 25% modified β-cyclodextrin, 32% water.

[0043] The remaining raw materials and steps are the same as those in Example 1.

[0044] Example 3

[0045] The difference between this example and Example 1 is as follows:

[0046] An agricultural bactericidal composition containing famoxadone, by weight percentage, comprises the following raw materials: 4% famoxadone, 4% hymexazol, 12% aluminum sulfate, 25% guanidyl chitosan quaternary ammonium salt, 25% modified β-cyclodextrin, 30% water.

[0047] The remaining raw materials and steps are the same as those in Example 1.

[0048] Example 4

[0049] The difference between this example and Example 3 is as follows:

[0050] Replace "0.4 g of modified silane coupling agent" in the preparation process of modified β-cyclodextrin in Example 1 with "0.6 g of modified silane coupling agent", and the remaining raw materials and steps are the same as those in Example 3.

[0051] Example 5

[0052] The difference between this example and Example 3 is as follows:

[0053] Replace "0.4 g of modified silane coupling agent" in the preparation process of modified β-cyclodextrin in Example 1 with "0.8 g of modified silane coupling agent", and the remaining raw materials and steps are the same as those in Example 3.

[0054] Comparative Example 1

[0055] The difference between this comparative example and Example 1 is as follows:

[0056] An agricultural bactericidal composition containing famoxadone, by weight percentage, comprises the following raw materials: 3% famoxadone, 3% hymexazol, 10% aluminum sulfate, 25% carboxymethyl chitosan quaternary ammonium salt, 25% modified β-cyclodextrin, 34% water.

[0057] The preparation method of carboxymethyl chitosan quaternary ammonium salt is as follows:

[0058] A1: Disperse 1g chitosan (molecular weight of chitosan is 60KDa, degree of deacetylation is 90%) in 10-12mL isopropanol, slowly add 3mL of 40% NaOH solution, stir at 55℃ for 1h, then add 5mL of chloroacetic acid aqueous solution (the ratio of chloroacetic acid to deionized water is 0.58g:5mL), stir at 50℃ for 3h, precipitate with anhydrous ethanol after the reaction, freeze-dry for 48h, and obtain carboxymethyl chitosan;

[0059] A2: Disperse 1 g of carboxymethyl chitosan in 40 mL of 1-methyl-2-pyrrolidone, add 1.5 g of sodium iodide, 20 mL of 15% sodium hydroxide solution and 5 mL of methyl iodide in sequence under stirring at room temperature, reflux at 60°C for 2 h, then add excess ethanol for precipitation, wash and filter to obtain carboxymethyl chitosan quaternary ammonium salt.

[0060] The remaining materials and steps are the same as in Example 1.

[0061] Comparative Example 2

[0062] Compared with Example 1, this comparative example is different in that:

[0063] The guanidino chitosan quaternary ammonium salt in Example 1 was replaced by chitosan, the molecular weight of chitosan was 60 KDa, and the degree of deacetylation was 90%. The remaining raw materials and steps were the same as in Example 1.

[0064] Comparative Example 3

[0065] Compared with Example 1, this comparative example is different in that:

[0066] The β-cyclodextrin is not modified by using a modified silane coupling agent, and the other raw materials and steps are the same as those in Example 1.

[0067] The corresponding weight percentages of oxadone, oxadone and aluminum sulfate of Examples 1 to 5 and Comparative Examples 1 to 3 were added to water and stirred evenly, and then guanidyl chitosan quaternary ammonium salt and modified β-cyclodextrin were added, and the mixture was stirred evenly to fully blend the mixture into a paste colloid to prepare the sample to be tested. The sample was tested for performance, and the test items were as follows:

[0068] The experimental crop was cucumber, and the control target was cucumber downy mildew (Pseudoperonospora cubens is). Field efficacy tests were conducted. The plots of experimental agents, control agents, and blank controls were arranged in random blocks, with a plot area of ​​30m 2, Repeated 4 times. The disease base number was investigated before applying the medicine. The medicine was applied once, with 45 kg of liquid medicine per mu. The control effects 10 days and 15 days after applying the medicine were investigated, for a total of 4 investigations. Four points were randomly selected in each plot for investigation. Two plants were investigated at each point, and all the leaves of each plant were investigated. Each leaf was graded and recorded according to the percentage of the lesion area occupying the leaf area. Grading method (taking the leaf as the unit):

[0069] Grade 0: No lesion;

[0070] Grade 1: The lesion area accounts for less than 5% of the entire leaf area;

[0071] Grade 3: The lesion area accounts for 6%-10% of the entire leaf area;

[0072] Grade 5: The lesion area accounts for 11%-25% of the entire leaf area;

[0073] Grade 7: The lesion area accounts for 26%-50% of the entire leaf area;

[0074] Grade 9: The lesion area accounts for more than 50% of the entire leaf area.

[0075] Disease index = [∑(number of diseased leaves at each level × relative level value) / (total number of investigated leaves × 9)] × 100; Control effect (%) = [1 - (disease index before applying medicine in the control × disease index after applying medicine in the treatment) / (disease index after applying medicine in the control × disease index before applying medicine in the treatment)] × 100

[0076] Table 1

[0077]

[0078]

[0079] It can be seen from Table 1 that both the bactericidal performance and the slow-release performance of the agricultural bactericidal compositions prepared in Examples 1-5 are superior to those of the agricultural bactericidal compositions prepared in Comparative Examples 1-3. The bactericidal performance of Examples 1-3 increases with the increase of the drug loading amount.

[0080] The dosage of the modified silane coupling agent in Examples 4 and 5 is higher than that in Example 3. The content of disulfide bonds in the bactericidal composition is high, the self-repair performance is good, and the slow-release performance is improved. It can still reach more than 98% 15 days after applying the medicine.

[0081] Compared with Example 1, Comparative Example 1 does not contain guanidine groups, and its antibacterial performance and slow-release performance are both lower than those of Example 1. It shows that guanidine groups have antibacterial properties, can improve the bactericidal performance of the agricultural bactericidal composition, and can increase the positive charge content of chitosan, thereby enabling chitosan to be tightly combined with modified β-cyclodextrin and improving the slow-release performance of the bactericidal composition.

[0082] Comparative Example 2, compared with Example 1, does not contain guanidine group and quaternary ammonium salt. The positive charge content of chitosan decreases, the binding force with modified β-cyclodextrin is weaker than that in Example 1, and the sustained-release performance decreases; moreover, the antibacterial groups decrease, and the bactericidal performance also decreases to some extent.

[0083] Comparative Example 3, compared with Example 1, does not contain modified silane coupling agent. β-cyclodextrin does not contain negative charge, the binding ability with guanidine chitosan quaternary ammonium salt decreases, the sustained-release performance decreases to some extent, and β-cyclodextrin does not contain disulfide bond, the self-healing performance becomes poor, and the sustained-release performance further decreases.

[0084] The above only discloses several specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any changes that can be thought of by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. An agricultural bactericidal composition containing famoxadone, characterized in that: The following raw materials are included by weight percentage: 3-4% oxadipamide, 3-4% meconazole, 10-12% enhancer, 20-30% guanidino chitosan quaternary ammonium salt, 20-30% modified β-cyclodextrin, 30-34% water; wherein the modified β-cyclodextrin is β-cyclodextrin treated with a modified silane coupling agent, and the modified silane coupling agent contains a disulfide bond and a sulfonic acid group.

2. The agricultural bactericidal composition containing famoxadone according to claim 1, characterized in that: The strengthening agent is any one of aluminum sulfate, copper sulfate or ferrous sulfate.

3. The agricultural bactericidal composition containing famoxadone according to claim 1, characterized in that: The preparation method of guanidine chitosan quaternary ammonium salt is: A1: Disperse chitosan in isopropanol, slowly add 40% NaOH solution, stir at 50-60°C for 1-2h, then add chloroacetic acid aqueous solution, stir at 50-60°C for 3-4h, precipitate after the reaction, freeze-dry for 48h, and obtain carboxymethyl chitosan; A2: Disperse carboxymethyl chitosan in 1-methyl-2-pyrrolidone, add sodium iodide, 15% sodium hydroxide solution and iodomethane in sequence under stirring at room temperature, reflux at 60°C for 2h, then precipitate, wash and filter to obtain carboxymethyl chitosan quaternary ammonium salt; A3: Dissolve carboxymethyl chitosan quaternary ammonium salt in deionized water, add aminoguanidine phosphate, stir at room temperature for 10-12 hours, dialyze, and freeze-dry to obtain guanidine chitosan quaternary ammonium salt.

4. The agricultural bactericidal composition containing famoxadone according to claim 3, characterized in that: In step A1, the usage ratio of chitosan, isopropanol, NaOH solution, and chloroacetic acid aqueous solution is 1 g:10-12 mL:3 mL:5 mL; the usage ratio of chloroacetic acid to deionized water in the chloroacetic acid aqueous solution is 0.58 g:5 mL.

5. The agricultural fungicidal composition containing famoxadone according to claim 3, characterized in that: In step A2, the usage ratio of carboxymethyl chitosan, 1-methyl-2-pyrrolidone, sodium iodide, sodium hydroxide solution and iodomethane is 1 g: 30-40 mL: 1.5 g: 20 mL: 5 mL.

6. The agricultural fungicidal composition containing famoxadone according to claim 3, characterized in that: In step A3, the usage ratio of carboxymethyl chitosan quaternary ammonium salt, deionized water, and aminoguanidine phosphate is 1 g: 30-40 mL: 1.07 g.

7. The agricultural bactericidal composition containing famoxadone according to claim 1, characterized in that: The preparation method of modified β-cyclodextrin is: S1: Add dichloromethane to 2,2-disulfide dipyridine, stir and dissolve to obtain solution a; dissolve 3-mercaptopropyltriethoxysilane in dichloromethane to obtain solution b, add solution b dropwise to solution a, after the addition is complete, stir magnetically at room temperature for 48 hours, spin dry the solvent, wash, and vacuum dry to obtain an intermediate; S2: adding the intermediate to dichloromethane and stirring for 20-30 min to obtain solution c; adding sodium 2-mercaptoethyl sulfonate to dichloromethane to obtain solution d; adding solution d dropwise to solution c, reacting at room temperature for 48 h, washing, and vacuum drying to obtain a modified silane coupling agent; S3: Add β-cyclodextrin to water and anhydrous ethanol, stir, then add modified silane coupling agent, heat to 50-60°C and stir for 1-2h, then cool to room temperature, wash, and vacuum dry to obtain modified β-cyclodextrin.

8. The agricultural fungicidal composition containing famoxadone according to claim 7, characterized in that: In step S1, the usage ratio of 2,2-disulfide dipyridine to dichloromethane is 4.6 g:200 mL; the usage ratio of 3-mercaptopropyltriethoxysilane to dichloromethane is 10 g:300 mL; and the volume ratio of solution a to solution b is 2:

3.

9. The agricultural fungicidal composition containing famoxadone according to claim 7, characterized in that: In step S2, the usage ratio of the intermediate to dichloromethane is 253 mg:100 mL; the usage ratio of 2-mercaptoethylsulfonic acid sodium salt to dichloromethane is 216 mg:10 mL; and the volume ratio of solution c to solution d is 10:

1.

10. The agricultural fungicidal composition containing famoxadone according to claim 7, characterized in that: In step S3, the usage ratio of β-cyclodextrin, water, anhydrous ethanol, and N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride is 10 g: 10-20 mL: 80-90 mL: 0.4-0.8 g.

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