Wettable powder for preventing and treating soil-borne diseases and preparation method thereof

Abstract

The invention relates to the technical field of pesticides, in particular to wettable powder for preventing and treating soil-borne diseases and a preparation method of the wettable powder for preventing and treating the soil-borne diseases. Comprising the following raw materials in parts by weight: 3-5 parts of trichoderma harzianum DS-10 bacterial concentrate, 5-8 parts of modified sodium lignin sulfonate, 4-7 parts of fatty alcohol-polyoxyethylene ether and 80-90 parts of modified diatomite. The prepared wettable powder for preventing and treating soil-borne diseases has the advantages of being good in light and heat stability, good in sterilization effect, good in water dispersibility and not prone to causing pesticide resistance to crops.

Description

Technical Field

[0001] The invention relates to the technical field of pesticides, and in particular to a wettable powder for preventing and controlling soil-borne diseases and a preparation method thereof. Background Art

[0002] Hot and rainy weather provides favorable conditions for the reproduction of pathogens such as bacteria, fungi, nematodes and viruses, making summer a high-incidence season for many diseases, especially soil-borne diseases. Common soil-borne diseases include wilt, damping-off, verticillium wilt, root rot, etc. After infection, the roots and stems of plants are first affected, and later the leaves can be transmitted, eventually leading to the death of the entire plant, resulting in a decline in crop quality, a significant reduction in yield, or even a total crop failure. Therefore, pesticides used to prevent and control soil-borne diseases are emerging in an endless stream.

[0003] Pesticides used to control soil-borne diseases include chemical pesticides and biological pesticides. Compared with chemical pesticides, biological pesticides such as Bacillus subtilis and Trichoderma have the advantages of being environmentally friendly, low toxicity, and not easy to cause crop resistance, and are gradually favored in the field of pesticide technology. However, Bacillus subtilis has poor environmental adaptability and a narrow temperature range for use. Its effectiveness is significantly reduced under conditions of high humidity, high temperature, drought, cold, and flooding. Therefore, Trichoderma has become a star product for the prevention and control of soil-borne diseases.

[0004] Among the Trichoderma, Trichoderma harzianum DS-10 can produce antagonistic effects on a variety of plant pathogens through multiple mechanisms such as nutrient competition, heavy parasitism, and cell wall decomposing enzymes, and has both protective and therapeutic effects. Trichoderma harzianum DS-10 can not only effectively inhibit the growth of pathogens, but also produce compounds that stimulate plant growth and induce plant defense responses, improve the microenvironment of soil roots, enhance plant growth and disease resistance, and increase crop yields and benefits.

[0005] Patent CN11820323A discloses a fungicide composition, a preparation containing the same and its application. The preparation prepared by compounding Trichoderma harzianum and Ceropegia lacerata GXMS1 as fungicidal active substances, and adding sodium lignin sulfonate, sodium dodecyl sulfonate, xanthan gum, sodium benzoate, polyvinyl alcohol and other substances has excellent effect in preventing and controlling wheat downy mildew. However, the molecular structure of sodium lignin sulfonate contains a large number of functional groups such as phenolic hydroxyl groups. These functional groups are prone to dehydration and cleavage reactions under high temperature conditions, resulting in degradation of sodium lignin sulfonate and decreased performance, thereby affecting the water dispersibility of the fungicide composition and the use effect of the preparation.

[0006] Patent CN11744733A discloses a biological pesticide for preventing and controlling anthracnose of avocado, which is prepared by compounding 20 billion cfu / g of Trichoderma harzianum mother drug with polyoxin, berberine or difenoconazole. The resulting preparation has a good control effect on anthracnose of avocado, but polyoxin can easily cause drug resistance in crops.

[0007] Therefore, there is an urgent need in the market for a wettable powder for preventing and controlling soil-borne diseases that has good bactericidal effect, good dispersibility and is not likely to cause crops to develop drug resistance. Summary of the invention

[0008] In view of the problems existing in the prior art, the purpose of the present invention is to obtain a wettable powder for preventing and controlling soil-borne diseases, which has good light and heat stability, good bactericidal effect, good dispersibility in water and is not easy to cause crops to develop drug resistance.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0010] On the one hand, the present invention provides a wettable powder for preventing and controlling soil-borne diseases, which comprises the following raw materials, measured by weight: 3-5 parts of Trichoderma harzianum DS-10 stock drug, 5-8 parts of modified sodium lignin sulfonate, 4-7 parts of fatty alcohol polyoxyethylene ether, and 80-90 parts of modified diatomaceous earth.

[0011] The present application compounds the mother drug of Trichoderma harzianum DS-10, modified sodium lignin sulfonate, fatty alcohol polyoxyethylene ether and modified diatomaceous earth, and obtains a wettable powder for preventing and controlling soil-borne diseases, which has good bactericidal effect, good water dispersibility and is not easy to cause crops to develop drug resistance. Modified sodium lignin sulfonate and fatty alcohol polyoxyethylene ether can make the powder evenly dispersed in water, and diatomaceous earth can be used as an inert carrier of Trichoderma harzianum DS-10 bacteria, so that Trichoderma harzianum DS-10 bacteria can be evenly dispersed after dilution, and it is not easy to precipitate and lose activity during use. In addition, diatomaceous earth can protect the molecules of Trichoderma harzianum DS-10 bacteria, reduce chemical reactions, and thus extend the shelf life of the wettable powder.

[0012] In some embodiments, the Trichoderma harzianum DS-10 stock drug is 20 billion CFU / g of Trichoderma harzianum DS-10 stock drug.

[0013] The DS-10 strain of Trichoderma harzianum has been screened for commonly used chemical fungicides, has good drug resistance, strong vitality in the soil, strong parasitic ability on the leaves and roots of plants, and has good prevention and control effects on soil-borne diseases.

[0014] In some embodiments, the preparation method of the modified sodium lignin sulfonate comprises the following steps:

[0015] A1. Add sodium lignin sulfonate and deionized water into a reaction vessel, stir at room temperature for 20-30 min, adjust the pH to 10-12, add 2,2,6,6-tetramethyl-4-piperidinamine, heat to 60-80° C., react for 13-16 h, add 3.5-3.8 wt % formaldehyde aqueous solution, react for 25-35 min, then heat to 85-90° C., react for 2-4 h, cool to room temperature, add anhydrous ethanol, stir for 20-30 min, filter, wash, and dry to obtain hindered amine-grafted sodium lignin sulfonate;

[0016] A2. Add the hindered amine-grafted sodium lignin sulfonate obtained in step A1, 1-bromopropane, 4-dimethylaminopyridine and ethanol into a reaction vessel, heat to 60-80° C. and react for 1-2 hours, wash and dry to obtain modified sodium lignin sulfonate.

[0017] Sodium lignin sulfonate can be used as a filler and emulsifying dispersant for wettable powders, can improve the dispersibility and stability of Trichoderma harzianum DS-10, thereby improving the use effect of Trichoderma harzianum DS-10, and can also be used as a plant growth regulator to promote the growth of crops, and has degradable properties, but its segments are easily broken under light conditions, affecting its use effect. In response to this problem, the present application introduces hindered amine segments on the sodium lignin sulfonate segments, which can not only improve the light stability of sodium lignin sulfonate but also improve the light and heat stability of Trichoderma harzianum DS-10, but after introducing a side chain containing two secondary amine groups, the sulfonate anion and the secondary amine cation produce an interaction force, which will reduce the dispersibility of the sodium lignin sulfonate itself.

[0018] In view of the above problems, the present application can ensure that sodium lignin sulfonate has good emulsification performance while having good light and heat stability performance and good acid and alkali adaptability by reacting some primary amine groups to generate tertiary amine groups. This may be because the quaternary ammonium salt group has strong hydrophilicity, which weakens the influence of the anion-cation interaction force and makes the modified sodium lignin sulfonate have the characteristics of some amphoteric surfactants.

[0019] In some embodiments, the mass ratio of the sodium lignin sulfonate to 2,2,6,6-tetramethyl-4-piperidinamine is 1:(0.1-0.2).

[0020] The present application can make the wettable powder for controlling soil-borne diseases have good light stability by selecting sodium lignin sulfonate and 2,2,6,6-tetramethyl-4-piperidinamine in a specific ratio. This may be because when the content of 2,2,6,6-tetramethyl-4-piperidinamine is appropriate, the grafting rate of sodium lignin sulfonate is higher.

[0021] In some embodiments, the mass ratio of the hindered amine-grafted sodium lignin sulfonate to 1-bromopropane in step A2 is 1:(0.01-0.02).

[0022] The content of 1-bromopropane affects the retention rate of hindered amine side chains. The present application can make the sodium lignin sulfonate have better emulsification properties and better light stability by selecting a specific ratio of hindered amine-grafted sodium lignin sulfonate and 1-bromopropane.

[0023] In some embodiments, the fatty alcohol polyoxyethylene ether is one or more of AEO-9, AEO-15 and AEO-20.

[0024] In some embodiments, the method for preparing the modified diatomaceous earth comprises the following steps:

[0025] B1, adding glucose, 3-isocyanatepropyltriethoxysilane and ethanol into a reaction container, reacting at 60-80° C. for 1.5-2.5 h, and obtaining modified glucose after drying;

[0026] B2. Add the modified glucose, diatomaceous earth, ethanol and water obtained in step B1 into a reaction container, react at 60-70° C. for 1-2 h, and obtain modified diatomaceous earth after drying.

[0027] In some embodiments, the mass ratio of glucose to 3-isocyanatepropyltriethoxysilane is 1:(0.8-1.2).

[0028] This application adds glucose and a silane coupling agent containing an isocyanate group to ethanol for reaction, so that the isocyanate group on the silane coupling agent reacts with the hydroxyl group on the glucose, and obtains a modified glucose containing a large number of siloxane groups by limiting the ratio of 3-isocyanate propyltriethoxysilane, which is reacted with diatomaceous earth to successfully graft glucose onto the diatomaceous earth. After the use of the wettable powder, the reproduction of Trichoderma harzianum DS-10 can be promoted, and the pathogen can be made to "wander toward" the diatomaceous earth containing glucose segments through chemotaxis, making the pathogen more easily captured by Trichoderma harzianum DS-10, thereby improving the bactericidal effect of the wettable powder used to prevent and control soil-borne diseases. In addition, the carbamate group also has a certain bactericidal effect, which further improves the use effect of the wettable powder.

[0029] In some embodiments, the mass ratio of diatomaceous earth to modified glucose in step B2 is 1:(0.2-0.3).

[0030] When the glucose content is excessive, it cannot be consumed in time by Trichoderma harzianum DS-10, which may promote the reproduction of pathogenic bacteria. The present application can make the wettable powder have a better bactericidal effect by selecting a specific ratio of diatomaceous earth and modified glucose.

[0031] Another aspect of the present invention provides a method for preparing a wettable powder for controlling soil-borne diseases, comprising the following steps:

[0032] (1) Adding Trichoderma harzianum DS-10 bacterial stock and modified diatomaceous earth into a mixer, mixing at room temperature for 0.5-1.5 hours, adding modified sodium lignin sulfonate and fatty alcohol polyoxyethylene ether, mixing at room temperature for 20-40 minutes, and obtaining a mixture;

[0033] (2) The mixture obtained in step (1) is added to a low-temperature airflow pulverizer at a pulverizing temperature of 20-30° C. After pulverization, the mixture is sieved through a 200-400 mesh sieve and added to a mixer. The mixture is mixed at room temperature for 20-30 minutes to obtain a wettable powder for controlling soil-borne diseases.

[0034] In some embodiments, the amount of the wettable powder for controlling soil-borne diseases is 70-370 g / mu.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) The present invention prepares a wettable powder for preventing and controlling soil-borne diseases by compounding the mother drug of Trichoderma harzianum DS-10, modified sodium lignin sulfonate, fatty alcohol polyoxyethylene ether and modified diatomaceous earth. The wettable powder has good bactericidal effect, good water dispersibility and is not easy to cause crops to develop drug resistance.

[0037] (2) The present invention can improve the drug resistance of Trichoderma harzianum DS-10 by selecting 20 billion CFU / g of Trichoderma harzianum DS-10 mother drug, so that Trichoderma harzianum DS-10 has strong vitality in the soil and strong parasitic ability on the leaves and roots of plants, and has a better prevention and control effect on soil-borne diseases.

[0038] (3) The present invention introduces a hindered amine segment into the sodium lignin sulfonate segment, which can not only improve the light stability of sodium lignin sulfonate but also improve the light and heat stability of Trichoderma harzianum DS-10. In addition, the present invention reacts some primary amine groups to generate tertiary amine groups, which can ensure that sodium lignin sulfonate has good emulsification properties while having good light stability and good acid and alkali adaptability.

[0039] (4) The present invention reacts glucose with an isocyanate group in ethanol, so that the isocyanate group on the silane coupling agent reacts with the hydroxyl group on the glucose to obtain a modified glucose containing a siloxane group, which is reacted with diatomaceous earth to successfully graft glucose onto the diatomaceous earth to form a carbamate group with a certain bactericidal effect. After the modified diatomaceous earth is used in the wettable powder, the reproduction of Trichoderma harzianum DS-10 can be promoted, and the pathogens can be more easily captured by Trichoderma harzianum DS-10, thereby improving the bactericidal effect of the wettable powder. DETAILED DESCRIPTION

[0040] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following embodiments are examples of the present invention and are only used to illustrate the present invention, but not to limit the present invention. Other combinations and various modifications within the concept of the present invention may be performed without departing from the spirit or scope of the present invention.

[0041] In the following examples and comparative examples, except for modified sodium lignin sulfonate and modified diatomaceous earth, the other polymer monomers and related reagents used can be purchased from the market, among which the mother drug of Trichoderma harzianum DS-10 is 20 billion CFU / g of Trichoderma harzianum DS-10 mother drug independently developed by our company, the strain is a patented strain of Dingsheng Company, deposited in China Microbiological Culture Collection Center, certificate number: CGMCC7.466, mother drug pesticide registration certificate number is PD20230094. Preparation registration certificate number: PD20230092.

[0042] Preparation Example 1

[0043] The preparation method of modified sodium lignin sulfonate-1 comprises the following steps:

[0044] A1. Add 10 g of sodium lignin sulfonate and 50 g of deionized water into a reaction vessel, stir at room temperature for 25 min, adjust the pH to 11 with a 30 wt % sodium hydroxide aqueous solution, add 1.5 g of 2,2,6,6-tetramethyl-4-piperidinamine, heat to 70 ° C, react for 14 h, add 0.3 g of a 3.6 wt % formaldehyde aqueous solution, react for 30 min, then heat to 87 ° C and react for 3 h, cool to room temperature, add 50 g of anhydrous ethanol, stir for 25 min, filter, wash and dry to obtain hindered amine-grafted sodium lignin sulfonate;

[0045] A2. Add 10 g of hindered amine-grafted sodium lignin sulfonate obtained in step A1, 0.15 g of 1-bromopropane, 0.01 g of 4-dimethylaminopyridine and 100 g of anhydrous ethanol into a reaction vessel, heat to 70° C. and react for 1.5 h. After washing and drying, modified sodium lignin sulfonate-1 is obtained.

[0046] Preparation Example 2

[0047] The preparation method of modified sodium lignin sulfonate-2 is the same as that of Preparation Example 1, except that the added amount of 2,2,6,6-tetramethyl-4-piperidinamine is 2.5 g.

[0048] Preparation Example 3

[0049] The preparation method of modified sodium lignin sulfonate-3 is the same as that of Preparation Example 1, except that the added amount of 1-bromopropane is 0.25 g.

[0050] Preparation Example 4

[0051] The preparation method of modified diatomite-1 comprises the following steps:

[0052] B1, adding 1g of glucose, 1g of 3-isocyanatepropyltriethoxysilane and 5g of anhydrous ethanol into a reaction container, reacting at 70°C for 2h, and obtaining modified glucose after drying;

[0053] B2. Add 1 g of modified glucose, 4 g of diatomaceous earth, 10 g of anhydrous ethanol and 1 g of water obtained in step B1 into a reaction container, react at 65° C. for 1.5 h, and obtain modified diatomaceous earth-1 after drying.

[0054] Preparation Example 5

[0055] The preparation method of modified diatomite-2 is the same as that of Preparation Example 4, except that the added amount of 3-isocyanatepropyltriethoxysilane is 0.5 g.

[0056] Preparation Example 6

[0057] The preparation method of modified diatomite-3 is the same as that of Preparation Example 4, except that the amount of modified glucose added in step B2 is 1.5 g.

[0058] Example 1

[0059] A wettable powder for preventing and controlling soil-borne diseases comprises the following raw materials, measured by weight: 4 parts of 20 billion CFU / g of Trichoderma harzianum DS-10 stock drug, 7 parts of modified sodium lignin sulfonate-1, 5 parts of AEO-9, and 85 parts of modified diatomaceous earth-1.

[0060] (1) Add 20 billion CFU / g of Trichoderma harzianum DS-10 stock drug and modified diatomaceous earth-1 into a mixer, mix at room temperature for 1 hour, add modified sodium lignin sulfonate-1 and AEO-9, mix at room temperature for 30 minutes, and obtain a mixture;

[0061] (2) The mixture obtained in step (1) is added to a low-temperature airflow pulverizer at a pulverizing temperature of 25° C. After pulverization, it is sieved through a 300-mesh sieve and added to a mixer. The mixture is mixed at room temperature for 25 minutes to obtain a wettable powder for controlling soil-borne diseases.

[0062] Example 2

[0063] A wettable powder for preventing and controlling soil-borne diseases comprises the following raw materials, measured by weight: 3 parts of 20 billion CFU / g of Trichoderma harzianum DS-10 stock drug, 5 parts of modified sodium lignin sulfonate-1, 4 parts of AEO-9, and 80 parts of modified diatomaceous earth-1.

[0064] (1) Add 20 billion CFU / g of Trichoderma harzianum DS-10 stock drug and modified diatomaceous earth-1 into a mixer, mix at room temperature for 0.5 h, add modified sodium lignin sulfonate-1 and AEO-9, mix at room temperature for 20 min, and obtain a mixture;

[0065] (2) The mixture obtained in step (1) is added to a low-temperature airflow pulverizer at a pulverizing temperature of 20° C. After pulverization, it is sieved through a 200-mesh sieve and added to a mixer. The mixture is mixed at room temperature for 20 minutes to obtain a wettable powder for controlling soil-borne diseases.

[0066] Example 3

[0067] A wettable powder for preventing and controlling soil-borne diseases comprises the following raw materials, measured by weight: 5 parts of 20 billion CFU / g of Trichoderma harzianum DS-10 stock drug, 8 parts of modified sodium lignin sulfonate-1, 7 parts of AEO-9, and 90 parts of modified diatomaceous earth-1.

[0068] (1) Add 20 billion CFU / g of Trichoderma harzianum DS-10 stock drug and modified diatomaceous earth-1 into a mixer, mix at room temperature for 2 hours, add modified sodium lignin sulfonate-1 and AEO-9, mix at room temperature for 40 minutes, and obtain a mixture;

[0069] (2) The mixture obtained in step (1) is added to a low-temperature airflow pulverizer at a pulverizing temperature of 30° C. After pulverization, the mixture is sieved through a 400-mesh sieve and added to a mixer. The mixture is mixed at room temperature for 30 minutes to obtain a wettable powder for controlling soil-borne diseases.

[0070] Example 4

[0071] A wettable powder for preventing and controlling soil-borne diseases and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that an equal amount of modified sodium lignin sulfonate-1 is replaced by modified sodium lignin sulfonate-2.

[0072] Example 5

[0073] A wettable powder for preventing and controlling soil-borne diseases and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that an equal amount of modified sodium lignin sulfonate-1 is replaced by modified sodium lignin sulfonate-3.

[0074] Example 6

[0075] A wettable powder for preventing and controlling soil-borne diseases and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that an equal amount of modified diatomaceous earth-1 is replaced by modified diatomaceous earth-2.

[0076] Example 7

[0077] A wettable powder for preventing and controlling soil-borne diseases and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that an equal amount of modified diatomaceous earth-1 is replaced by modified diatomaceous earth-3.

[0078] Comparative Example 1

[0079] A wettable powder for preventing and controlling soil-borne diseases and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that an equal amount of modified sodium lignin sulfonate-1 is replaced by sodium lignin sulfonate.

[0080] Comparative Example 2

[0081] A wettable powder for preventing and controlling soil-borne diseases and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that an equal amount of modified diatomaceous earth-1 is replaced by diatomaceous earth.

[0082] Performance Testing

[0083] The performance of the wettable powders for preventing and controlling soil-borne diseases obtained in the above embodiments and comparative examples was tested:

[0084] (1) Sample preparation:

[0085] The wettable powder used to prevent and control soil-borne diseases was diluted with water at 80 g / mu, and the treatment without the agent was used as a blank control.

[0086] (2) Performance testing

[0087] Select Jinpeng 8 tomato plants at the 4-5 leaf stage with consistent growth for spraying treatment. Apply the pesticide once and test the growth rate of Jinpeng 8 tomato plants 21 days later according to the Criteria for Safety Assessment of Pesticides for Crops. Record the original plant height and 21-day plant height and calculate the increase in plant height.

[0088] The test results are shown in Table 1:

[0089] Table 1

[0090]

[0091]

[0092] It can be seen from the data in Table 1 that the wettable powders for preventing and controlling soil-borne diseases in Examples 1-3 of the present invention have the advantages of good fungicidal effect, good water dispersibility and not easy to cause crops to develop drug resistance; from the comparison between Example 4 and Example 1, it can be seen that changing the ratio of 2,2,6,6-tetramethyl-4-piperidinamine will reduce the photostability of the wettable powder for preventing and controlling soil-borne diseases, resulting in a decrease in the fungicidal performance of the wettable powder for preventing and controlling soil-borne diseases; from the comparison between Example 5 and Example 1, it can be seen that changing the ratio of 1-bromopropane will reduce the retention rate of the hindered amine side chains, which will reduce the photostability of the wettable powder for preventing and controlling soil-borne diseases, resulting in a decrease in the fungicidal performance of the wettable powder for preventing and controlling soil-borne diseases; from the comparison between Example 6 and Example 1, It can be seen from the comparison of Example 7 and Example 1 that changing the ratio of 3-isocyanatepropyltriethoxysilane will make the isocyanate on glucose insufficient to graft glucose on diatomaceous earth, thereby reducing the bactericidal effect of the wettable powder; from the comparison of Example 7 and Example 1, it can be seen that changing the ratio of modified glucose will prevent the harzianum DS-10 bacteria from consuming glucose in time, which may promote the reproduction of pathogens and reduce the bactericidal effect of the wettable powder; from the comparison of Comparative Example 1 and Example 1, it can be seen that without modifying the sodium lignin sulfonate, the photostability and emulsification effect of the agent are poor, and the bactericidal performance of the wettable powder for preventing and controlling soil-borne diseases is reduced; from the comparison of Comparative Example 2 and Example 1, it can be seen that without modifying the diatomaceous earth, the bactericidal performance of the wettable powder for preventing and controlling soil-borne diseases is reduced.

[0093] The above implementation modes are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A wettable powder for preventing and controlling soil-borne diseases, characterized in that: The preparation method comprises the following raw materials in parts by weight: 3-5 parts of Trichoderma harzianum DS-10 stock drug, 5-8 parts of modified sodium lignin sulfonate, 4-7 parts of fatty alcohol polyoxyethylene ether, and 80-90 parts of modified diatomaceous earth.

2. The wettable powder for controlling soil-borne diseases according to claim 1, characterized in that: The Trichoderma harzianum DS-10 bacterial stock drug is 20 billion CFU / g of the Trichoderma harzianum DS-10 bacterial stock drug.

3. The wettable powder for controlling soil-borne diseases according to claim 1, characterized in that: The preparation method of the modified sodium lignin sulfonate comprises the following steps: A1. Add sodium lignin sulfonate and deionized water into a reaction vessel, stir at room temperature for 20-30 min, adjust the pH to 10-12, add 2,2,6,6-tetramethyl-4-piperidinamine, heat to 60-80° C., react for 13-16 h, add 3.5-3.8 wt % formaldehyde aqueous solution, react for 25-35 min, then heat to 85-90° C., react for 2-4 h, cool to room temperature, add anhydrous ethanol, stir for 20-30 min, filter, wash, and dry to obtain hindered amine-grafted sodium lignin sulfonate; A2. Add the hindered amine-grafted sodium lignin sulfonate obtained in step A1, 1-bromopropane, 4-dimethylaminopyridine and ethanol into a reaction vessel, heat to 60-80° C. and react for 1-2 hours, wash and dry to obtain modified sodium lignin sulfonate.

4. The wettable powder for controlling soil-borne diseases according to claim 3, characterized in that: The mass ratio of the sodium lignin sulfonate to 2,2,6,6-tetramethyl-4-piperidinamine is 1:(0.1-0.2).

5. The wettable powder for controlling soil-borne diseases according to claim 3, characterized in that: The mass ratio of hindered amine-grafted sodium lignin sulfonate and 1-bromopropane in step A2 is 1:(0.01-0.02).

6. The wettable powder for controlling soil-borne diseases according to claim 1, characterized in that: The fatty alcohol polyoxyethylene ether is one or more of AEO-9, AEO-15 and AEO-20.

7. The wettable powder for controlling soil-borne diseases according to claim 1, characterized in that: The preparation method of the modified diatomite comprises the following steps: B1, adding glucose, 3-isocyanatepropyltriethoxysilane and ethanol into a reaction container, reacting at 60-80° C. for 1.5-2.5 h, and obtaining modified glucose after drying; B2. Add the modified glucose, diatomaceous earth, ethanol and water obtained in step B1 into a reaction container, react at 60-70° C. for 1-2 h, and obtain modified diatomaceous earth after drying.

8. The wettable powder for controlling soil-borne diseases according to claim 7, characterized in that: The mass ratio of the glucose to 3-isocyanatepropyltriethoxysilane is 1:(0.8-1.2).

9. The wettable powder for controlling soil-borne diseases according to claim 7, characterized in that: The mass ratio of diatomaceous earth to modified glucose in step B2 is 1:(0.2-0.3).

10. A method for preparing a wettable powder for controlling soil-borne diseases according to any one of claims 1 to 9, characterized in that: The following steps are involved: (1) Adding Trichoderma harzianum DS-10 bacterial stock and modified diatomaceous earth into a mixer, mixing at room temperature for 0.5-1.5 hours, adding modified sodium lignin sulfonate and fatty alcohol polyoxyethylene ether, mixing at room temperature for 20-40 minutes, and obtaining a mixture; (2) The mixture obtained in step (1) is added to a low-temperature airflow pulverizer at a pulverizing temperature of 20-30° C. After pulverization, the mixture is sieved through a 200-400 mesh sieve and added to a mixer. The mixture is mixed at room temperature for 20-30 minutes to obtain a wettable powder for controlling soil-borne diseases.

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