Microbial agent for preventing and treating peanut root rot and application thereof

Abstract

The application discloses a microbial agent for preventing and treating peanut root rot and application thereof, and belongs to the technical field of plant disease prevention and treatment. The microbial agent is prepared from raw materials including the following components in parts by weight: 1-5 parts of Trichoderma viride, 1-5 parts of Streptomyces microflavus, 5-8 parts of Paenibacillus polymyxa, 100-180 parts of traditional Chinese medicine extract, 0.5-2 parts of vitamin B1, 25-50 parts of sodium alginate, 10-20 parts of humic acid, 1-5 parts of zinc molybdate, 5-10 parts of copper sulfate, and 5-10 parts of ferrous phosphate. The microbial agent uses Trichoderma viride, Streptomyces microflavus and Paenibacillus polymyxa as biocontrol strains, uses traditional Chinese medicine extract, vitamin B1 and sodium alginate as auxiliary materials, and uses humic acid, zinc molybdate, copper sulfate and ferrous phosphate as nutrient supplements. The microbial agent can inhibit root rot fungi, reduce the incidence of root rot, and improve the peanut resistance and yield.

Description

Technical Field

[0001] The invention relates to the technical field of plant disease prevention and control, in particular to a microbial agent for preventing and controlling peanut root rot and application thereof. Background Art

[0002] Peanut root rot, commonly known as rattail or root rot, is a peanut disease caused by various Fusarium species. It primarily attacks the roots of the plant, but can also damage the needles and pods. Peanut root rot is a worldwide peanut disease that can occur throughout the peanut's growth cycle, causing poor plant growth, seed rot, root rot, fruit rot, and even complete plant death. It typically occurs sporadically, with a disease rate of less than 10% and a yield reduction of 5-8%. In severe cases, the disease can reach 20-30% and lead to a yield reduction of more than 20%.

[0003] Peanut root rot is usually controlled by agricultural and chemical methods. In agricultural control, it is necessary to clean the fields in a timely manner, implement crop rotation and intercropping, drain and irrigate in time, apply fertilizers reasonably, and select high-quality, disease-resistant varieties. In chemical control, on the basis of ensuring seed quality, adopt seed coating or seed mixing; in the early stage of the disease, when the diseased plant (hole) rate in the field reaches 5%, timely chemical control is carried out. However, high-quality, resistant varieties require years of cultivation and screening, field cleaning requires more manpower and material resources, and chemical control mostly uses chemical reagents. Most chemical reagents are environmentally unfriendly. In addition to damaging the ecological environment, they are also prone to drug resistance. In severe cases, they are also prone to contaminating food, causing acute and chronic poisoning of humans and animals, and killing non-target organisms (such as natural enemies).

[0004] Currently, crop disease control measures are gradually moving towards biological control, with an increasing number of biocontrol strains being discovered and developed. During use, the bacterial solution of these strains is directly applied to the field, leveraging the antagonistic effects between strains to achieve control. However, due to the complex field soil environment, the colonization rate of biocontrol strains in the field is not high, resulting in unstable control effects, requiring topdressing, and increasing planting costs. Therefore, it is necessary to provide a microbial agent with a long-lasting control effect, a high colonization rate, and a stable control effect to reduce the incidence of peanut root rot and the cost of peanut cultivation. Summary of the Invention

[0005] The present invention aims to provide a microbial agent for preventing and controlling peanut root rot and its application to address the problems of the prior art. The microbial agent of the present invention uses Trichoderma viride, Streptomyces tenuifolius, and Paenibacillus polymyxa as biocontrol strains, traditional Chinese medicine extracts, vitamin B1, and sodium alginate as auxiliary ingredients, and humic acid, zinc molybdate, copper sulfate, and ferrous phosphate as nutritional supplements. While inhibiting root rot pathogens and reducing the incidence of root rot, it also improves peanut resistance and yield.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The invention provides a microbial agent for preventing and treating peanut root rot. The microbial agent is prepared from the following raw materials in parts by weight: 1-5 parts of Trichoderma viride, 1-5 parts of Streptomyces tenuifolius, 5-8 parts of Paenibacillus polymyxa, 100-180 parts of traditional Chinese medicine extracts, 0.5-2 parts of vitamin B1, 25-50 parts of sodium alginate, 10-20 parts of humic acid, 1-5 parts of zinc molybdate, 5-10 parts of copper sulfate and 5-10 parts of ferrous phosphate.

[0008] Preferably, the preparation method of the Chinese herbal medicine extract comprises the following steps:

[0009] (1) crushing and drying the Chinese medicinal residue, refluxing with an ethanol aqueous solution, and filtering to obtain a filter residue A and a filtrate A;

[0010] (2) soaking the filter residue A in a NaOH solution, neutralizing it with an HCl solution, and filtering to obtain a filter residue B and a filtrate B;

[0011] (3) adding an enzyme preparation to the filter residue B, performing enzymatic hydrolysis, and filtering to obtain filter residue C and filtrate C;

[0012] (4) combining the filtrate B and the filtrate C, drying them, and obtaining extract 1; drying the filter residue C, and obtaining extract 2; and combining extract 1 and extract 2 to obtain the Chinese herbal medicine extract.

[0013] Preferably, in step (1), the volume concentration of the ethanol aqueous solution is 70-90%; the volume ratio of the ethanol aqueous solution to the traditional Chinese medicine residue is (8-10):1; and the reflux time is 8-12 hours.

[0014] Preferably, in step (2), the concentration of the NaOH solution is 1-3 mol / L; the volume ratio of the NaOH solution to the filter residue A is (2-4):1; the soaking time is 2-5 hours, and the temperature is 4°C.

[0015] Preferably, in step (3), the enzyme preparation comprises neutral protease and cellulase; the amount of the enzyme preparation added is 1000-2000 U per g of filter residue B; the ratio of the enzyme activity of the neutral protease to the cellulase is (2-5):1.

[0016] Preferably, in step (3), the enzymatic hydrolysis time is 60 to 90 minutes and the temperature is 40 to 45°C.

[0017] Preferably, in step (1), the Chinese medicine residue includes any one or more of Sophora flavescens residue, Forsythia suspensa residue, Honeysuckle residue, Licorice residue, Polygonatum sibiricum residue, Chuanxiong residue, cinnamon bark residue, clove residue and Magnolia flos residue.

[0018] Preferably, the bacterial content of Trichoderma viride is 2 to 10 billion CFU / g; the bacterial content of Streptomyces tenuifolius is 3 to 8 billion CFU / g; and the bacterial content of Paenibacillus polymyxa is 2 to 5 billion CFU / g.

[0019] The present invention also provides a method for preparing the above-mentioned microbial agent, which comprises mixing the viride, the streptomyces tenuifolius, the polymyxa bacillus, the traditional Chinese medicine extract, the vitamin B1, the sodium alginate, the humic acid, the zinc molybdate, the copper sulfate and the ferrous phosphate to obtain the microbial agent.

[0020] The present invention also provides a use of the microbial agent or the microbial agent prepared by the above preparation method in preventing and treating peanut root rot.

[0021] The present invention discloses the following technical effects:

[0022] The microbial agent of the present invention uses Trichoderma viride, Streptomyces tenuifolius and Paenibacillus polymyxa as biocontrol strains, uses Chinese medicine extract, vitamin B1 and sodium alginate as auxiliary materials, and uses humic acid, zinc molybdate, copper sulfate and ferrous phosphate as nutritional supplements. By selecting three microorganisms, Trichoderma viride, Streptomyces tenuifolius and Paenibacillus polymyxa, which have a significant inhibitory effect on the peanut root rot pathogen, as the main components of the microbial agent, and screening out vitamin B1 and sodium alginate that are conducive to the colonization of the above-mentioned microorganisms, vitamin B1 and sodium alginate are also conducive to improving plant resistance. Utilizing the synergistic effect between vitamin B1, sodium alginate, Trichoderma viride, Streptomyces tenuifolius and Paenibacillus polymyxa, the prevention and control effect of peanut root rot is greatly improved.

[0023] The present invention also adds additional ingredients such as humic acid, zinc molybdate, copper sulfate, and ferrous phosphate, which can supplement the trace elements in the soil, provide the necessary nutrients for peanut growth, and increase peanut yield. The Chinese medicine extract uses Chinese medicine residue as raw material, and is sequentially subjected to crushing treatment, degreasing treatment, alkali treatment, and enzymatic hydrolysis treatment to promote the dissolution of substances such as polysaccharides and polypeptides in the Chinese medicine residue, thereby avoiding the inability of the components to dissolve quickly after the Chinese medicine residue is applied to the soil, resulting in low utilization rate; the treated filter residue maintains a certain size of volume, which can support soil particles, increase soil looseness, and provide colonization space for microorganisms. At the same time, Chinese medicine extracts, as natural plant-derived ingredients, have been proven to have a certain inhibitory effect on a variety of plant pathogens. The present invention combines biocontrol bacteria with Chinese medicine extracts to further improve the prevention and control effect of root rot. The present invention uses Chinese medicine residue as raw material, has low cost, and is also in line with the current green, circular, and sustainable development concepts that are strongly advocated. DETAILED DESCRIPTION

[0024] The following detailed description of various exemplary embodiments of the application will not be considered limiting of the application, but rather a description of certain aspects, features, and embodiments of the application.

[0025] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. Additionally, for a range of values of a parameter, unless otherwise stated, each intervening value of the parameter, as well as any other stated or intervening value of the parameter, is encompassed. The intervening values of the parameter are obtained by simply adding or subtracting the minimum value to and from the maximum value of the range, by each intervening value. These smaller ranges are also encompassed within the application.

[0026] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, the preferred methods and materials are described. All patents, patent applications, publications, and descriptions mentioned herein are incorporated by reference to the extent allowed by law. In the case of conflict between the description herein and the incorporated material, the description herein shall control.

[0027] In the description of the application specific embodiments, numerous specific details are set forth in order to provide a thorough understanding of the application. However, those of ordinary skill in the art will recognize that the application can be practiced without the specific details given herein. In other instances, well-known methods have not been described in detail in order not to unnecessarily obscure aspects of the application.

[0028] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" and the like are open-ended and do not exclude additional elements or steps.

[0029] General Description: The biological materials involved in the present embodiments are as follows: Trichoderma viride, Streptomyces microflavus and Paenibacillus polymyxa were purchased from Guangzhou Zhen Microbial Technology Co., Ltd.; Fusarium oxysporum was purchased from Beijing Kaye Biological Technology Co., Ltd.; neutral protease and cellulase were purchased from Xi'an Musen Biological Engineering Co., Ltd. The above biological materials are publicly available and can be purchased from the above companies through conventional channels.

[0030] The experimental methods in the embodiments of the present application are conventional methods, and are carried out according to the techniques or conditions described in the literature in the art or according to the product instructions, unless otherwise specified. Other materials, reagents, etc. used in the following examples can be obtained from commercial channels, unless otherwise specified.

[0031] Example 1

[0032] This embodiment provides a microbial agent for preventing and treating peanut root rot. The specific preparation process is as follows:

[0033] (1) Forsythia suspensa residue, honeysuckle residue, liquorice residue, polygonatum residue, ligusticum sibiricum residue, chuanxiong residue, and cinnamon bark residue were mixed and dried, crushed into particles of 2 cm in size, and 8 times the volume of the residue was added with a 70% ethanol aqueous solution, refluxed for 10 hours, filtered, and the filtrate A was discarded to recover the residue A. The residue A was soaked in a 2 mol / L NaOH solution at 4°C for 3 hours, stirred every half hour to ensure uniform contact between the solution and the residue. After soaking, HCl solution was added to adjust to neutrality, and filtered to obtain the residue B and filtrate B.

[0034] Mix filter residue B with an enzyme solution at a dosage of 2000 IU per gram of filter residue B. The enzyme solution contains a neutral protease and a cellulase, with the ratio of neutral protease to cellulase activity being 4:1. The mixture is enzymatically hydrolyzed at 42°C for 70 minutes. After completion of the enzymatic hydrolysis, the mixture is filtered to obtain filter residue C and filtrate C.

[0035] Combine filtrate B and filtrate C, and vacuum dry to obtain extract 1; vacuum dry filter residue C to obtain extract 2; combine extract 1 and extract 2 to obtain a traditional Chinese medicine extract;

[0036] (2) Take 1 part of Trichoderma viride (5 billion CFU / g), 1 part of Streptomyces tenuifolius (5 billion CFU / g), 8 parts of Paenibacillus polymyxa (5 billion CFU / g), 180 parts of Chinese herbal medicine extract, 0.5 parts of vitamin B1, 25 parts of sodium alginate, 10 parts of humic acid, 1 part of zinc molybdate, 5 parts of copper sulfate, and 10 parts of ferrous phosphate, mix them evenly to obtain a microbial agent.

[0037] Example 2

[0038] This embodiment provides a microbial agent for preventing and treating peanut root rot. The specific preparation process is as follows:

[0039] (1) Mix honeysuckle residue, liquorice residue, polygonatum residue, chuanxiong residue, cinnamon residue, and clove residue, and dry them. Grind them into particles with a diameter of 2 cm. Add 90% ethanol aqueous solution with a volume concentration of 10 times the volume of the residue, reflux for 10 hours, filter, discard filtrate A, and recover residue A. Soak residue A in 2 mol / L NaOH solution at 4°C for 3 hours, stirring every half hour to ensure uniform contact between the solution and the residue. After soaking, add HCl solution to adjust to neutrality, filter, and obtain residue B and filtrate B.

[0040] The filter residue B is mixed with an enzyme preparation solution, and the enzyme preparation is added at a dose of 2000 U per gram of filter residue B. The enzyme preparation contains neutral protease and cellulase, and the ratio of enzyme activity of the neutral protease to that of the cellulase is 4:1. The mixed material is enzymolyzed at 42°C for 70 min, and after the enzymolysis is completed, filtration is performed to obtain filter residue C and filtrate C.

[0041] The filtrate B and the filtrate C are combined and vacuum dried to obtain extract 1; the filter residue C is vacuum dried to obtain extract 2; and the extract 1 and the extract 2 are combined to obtain the traditional Chinese medicine extract;

[0042] (2) 5 parts of Trichoderma viride (50 billion CFU / g), 5 parts of Streptomyces microflavus (50 billion CFU / g), 5 parts of Paenibacillus polymyxa (50 billion CFU / g), 100 parts of the traditional Chinese medicine extract, 1 part of vitamin B12, 50 parts of sodium alginate, 20 parts of humic acid, 5 parts of zinc molybdate, 10 parts of copper sulfate, and 5 parts of ferrous phosphate are uniformly mixed to obtain a microbial agent.

[0043] Example 3

[0044] The present embodiment provides a microbial agent for preventing and treating peanut root rot, and the specific preparation process is as follows:

[0045] (1) The residues of forsythia, honeysuckle, licorice, polygonatum, chuanxiong, cinnamon, and clove are mixed and dried, and are crushed into particles with a particle size of 2 cm. An 80% ethanol aqueous solution with a volume of 10 times that of the residue is added, and reflux is performed for 10 h. Filtration is performed, and the filtrate A is discarded, and the filter residue A is recovered. The filter residue A is soaked in a 2 mol / L NaOH solution at 4°C for 3 h, and stirring is performed every half hour to ensure uniform contact between the solution and the filter residue. After the soaking is completed, an HCl solution is added to adjust the solution to neutral, and filtration is performed to obtain filter residue B and filtrate B.

[0046] The filter residue B is mixed with an enzyme preparation solution, and the enzyme preparation is added at a dose of 2000 U per gram of filter residue B. The enzyme preparation contains neutral protease and cellulase, and the ratio of enzyme activity of the neutral protease to that of the cellulase is 4:1. The mixed material is enzymolyzed at 42°C for 70 min, and after the enzymolysis is completed, filtration is performed to obtain filter residue C and filtrate C.

[0047] The filtrate B and the filtrate C are combined and vacuum dried to obtain extract 1; the filter residue C is vacuum dried to obtain extract 2; and the extract 1 and the extract 2 are combined to obtain the traditional Chinese medicine extract;

[0048] (2) Take 3 parts of Trichoderma viride (5 billion CFU / g), 3 parts of Streptomyces tenuifolius (5 billion CFU / g), 6 parts of Paenibacillus polymyxa (5 billion CFU / g), 150 parts of Chinese herbal medicine extract, 11 parts of vitamin B1, 40 parts of sodium alginate, 15 parts of humic acid, 4 parts of zinc molybdate, 8 parts of copper sulfate, and 8 parts of ferrous phosphate, mix them evenly to obtain a microbial agent.

[0049] Comparative Example 1

[0050] The only difference between this comparative example and Example 3 is that the Chinese herbal medicine extract and vitamin B1 are omitted, and other operations are the same as those in Example 3.

[0051] Comparative Example 2

[0052] The only difference between this comparative example and Example 3 is that the Chinese herbal medicine extract and sodium alginate are omitted, and other operations are the same as those in Example 3.

[0053] Comparative Example 3

[0054] The only difference between this comparative example and Example 3 is that vitamin B1 and sodium alginate are omitted, and other operations are the same as those in Example 3.

[0055] Comparative Example 4

[0056] The only difference between this comparative example and Example 3 is that vitamin B1, sodium alginate and Chinese herbal medicine extract are omitted, and other operations are the same as those in Example 3.

[0057] Comparative Example 5

[0058] The only difference between this comparative example and Example 3 is that Trichoderma viride and Streptomyces tenuifolius are omitted, and other operations are the same as those in Example 3.

[0059] Comparative Example 6

[0060] The only difference between this comparative example and Example 3 is that Trichoderma viride and Paenibacillus polymyxa are omitted, and other operations are the same as those in Example 3.

[0061] Comparative Example 7

[0062] The only difference between this comparative example and Example 3 is that Streptomyces tenuiflavos and Paenibacillus polymyxa are omitted, and other operations are the same as those in Example 3.

[0063] Test Example 1

[0064] This test example uses an indoor potted plant experiment to test the control effect of microbial agents on peanut root rot and the colonization effect of biocontrol bacteria in each group (Examples 1 to 3 and Comparative Examples 1 to 7). The specific process is as follows:

[0065] The test soil was sterilized at 121℃ for 2h and then dried.5 The root rot pathogen, Fusarium oxysporum, was inoculated at a ratio of 1×10 CFU / g dry soil. The test soil was moved into the pot and the soil humidity was adjusted to 60%. The microbial agent of each group was added at a ratio of 1×10 5 A dose of CFU / g dry soil (the same number of strains of microbial agents was applied in this test example to facilitate result analysis) was applied into the pots, and then 10 Fuhua No. 5 peanut seeds were sown in each tray. In addition, a blank control group and a positive control group were set up. The blank control group was neither inoculated with pathogens nor microbial agents, and the positive control group was only inoculated with pathogens. Each group was set up with 3 replicates, and the peanut emergence rate was counted 20 days after sowing. At the same time, on the 1st, 7th and 20th days after sowing, the soil below 5 cm from the surface of the potted plants was taken, and the dilution plate count method was used to count the number of Fusarium oxysporum and biocontrol bacteria. The statistical results were averaged.

[0066] The statistical results of peanut emergence rate are shown in Table 1.

[0067] Table 1 Peanut germination rate in each group

[0068] Group Seedling emergence rate Blank control group 93.33％ Positive control group 53.33％ Example 1 93.33％ Example 2 90.00％ Example 3 93.33％ Comparative Example 1 70.00％ Comparative Example 2 70.00％ Comparative Example 3 66.67％ Comparative Example 4 60.00％ Comparative Example 5 66.67％ Comparative Example 6 80.00％ Comparative Example 7 76.67％

[0069] Table 1 shows that root rot can reduce the emergence rate of peanuts, while the microbial agents of Examples 1 to 3 can improve the emergence rate of peanuts by inhibiting pathogens, reaching a state similar to that of the blank control group. When one or more raw materials are omitted, the inhibitory effect of the microbial agent on pathogens decreases, and the effect of improving the emergence rate of peanuts decreases. By analyzing Example 3 and Comparative Examples 1 to 3, it can be found that when sodium alginate, vitamin B1, and traditional Chinese medicine extracts are added to the agent alone, their effect on improving the emergence rate is not significant, but when all three are added to the agent, the improvement effect is obvious.

[0070] The statistical numbers of Fusarium oxysporum and biocontrol bacteria are shown in Table 2.

[0071] Table 2 Statistical number of Fusarium oxysporum and biocontrol bacteria in each soil group

[0072]

[0073]

[0074] Table 2 shows that the number of pathogens and biocontrol bacteria showed a downward trend on the first day after inoculation / sowing, while an upward trend was observed on the 7th and 20th days, indicating that microorganisms need to gradually adapt to the complex soil environment. However, according to Examples 1-3 and Comparative Examples 1-4, it can be seen that the addition of either vitamin B1 or sodium alginate can improve the adaptability of biocontrol bacteria and increase their colonization rate; however, the effect of adding either alone is significantly lower than the effect of the three together, indicating a synergistic effect between the two. The addition of traditional Chinese medicine extracts has a strong effect on reducing the number of pathogens, but has little effect on the number of colonized biocontrol bacteria, indicating that traditional Chinese medicine extracts themselves have a certain inhibitory effect on root rot pathogens.

[0075] Test Example 2

[0076] This test example uses field experiments to verify the control effect of microbial agents in each group (Example 3, Comparative Examples 1 to 7) on peanut root rot. The specific process is as follows:

[0077] A field with severe root rot was selected as the experimental field, and 10 plots were randomly divided. The area of ​​each plot was 5m×10m, and they were divided into a blank control group, a positive control group, Example 3, and comparative examples 1 to 7. The blank control group did not apply any pesticides, and the positive control group used 2.5% of the fluazifop seed coating suspension to mix the seeds. The ratio of the suspension to the seeds was 10mL:15kg. Before sowing, Example 3 and comparative examples 1 to 7 applied 5kg / plot of the corresponding microbial agents, and plowed the soil to fully mix the agents with the soil. 40 Fuhua No. 5 seeds were sown in each plot, and other field management measures were the same as those for general peanut fields. When the peanuts were in the full fruit stage, the occurrence of peanut root rot in the field was investigated, the number of diseased plants was counted, and the incidence rate and control effect were calculated. The formula is as follows:

[0078] Incidence rate = number of diseased plants / total number of plants surveyed × 100

[0079] Control effect = (number of diseased plants in the blank control group - number of diseased plants in the treatment group) / number of diseased plants in the blank control group × 100

[0080] The peanut yield of each group was counted and the yield per mu was calculated. The results are shown in Table 3.

[0081] Table 3 Disease incidence and yield of peanuts in each group

[0082] Group Incidence Control effect Yield per mu (kg) Blank control group 30.00％ - 248.52 Positive control group 5.00％ 83.33％ 308.29 Example 3 2.50％ 91.67％ 321.23 Comparative Example 1 12.50％ 58.33％ 277.21 Comparative Example 2 15.00％ 50.00％ 274.67 Comparative Example 3 15.00％ 50.00％ 290.28 Comparative Example 4 20.00％ 33.33％ 265.20 Comparative Example 5 12.50％ 58.33％ 268.67 Comparative Example 6 10.00％ 66.67％ 271.07 Comparative Example 7 10.00％ 66.67％ 271.74

[0083] Table 3 shows that the microbial agent of the present invention has a significant control effect on peanut root rot, comparable to the control effect of chemical agents. In addition, compared with the blank control group and the positive control group, the microbial agent of the present invention also has a significant yield-increasing effect.

[0084] The above described embodiments are only to illustrate the preferred modes of the present application, and are not intended to limit the scope of the present application. Any modification and improvement made by those skilled in the art to the technical solutions of the present application without departing from the design spirit of the present application shall fall within the protection scope of the present application.

Claims

1. A microbial agent for preventing and treating peanut root rot, characterized in that: The microbial agent is prepared from the following raw materials in parts by weight: 1-5 parts of Trichoderma viride, 1-5 parts of Streptomyces tenuifolius, 5-8 parts of Paenibacillus polymyxa, 100-180 parts of Chinese herbal medicine extract, 0.5-2 parts of vitamin B1, 25-50 parts of sodium alginate, 10-20 parts of humic acid, 1-5 parts of zinc molybdate, 5-10 parts of copper sulfate and 5-10 parts of ferrous phosphate; The preparation method of the Chinese medicine extract comprises the following steps: (1) The Chinese medicine residue is crushed and dried, refluxed with ethanol aqueous solution, and filtered to obtain residue A and filtrate A; (2) soaking the filter residue A in a NaOH solution, neutralizing it with an HCl solution, and filtering to obtain a filter residue B and a filtrate B; (3) adding an enzyme preparation to the filter residue B, performing enzymatic hydrolysis, and filtering to obtain filter residue C and filtrate C; (4) combining the filtrate B and the filtrate C, drying them, and obtaining extract 1; drying the filter residue C, and obtaining extract 2; combining extract 1 and extract 2, and obtaining the Chinese herbal medicine extract; In step (1), the Chinese medicine residue includes any one or more of Sophora flavescens residue, Forsythia suspensa residue, Honeysuckle residue, Licorice root residue, Polygonatum sibiricum residue, Chuanxiong root residue, Cinnamon bark residue, Clove residue and Magnolia flos residue.

2. The microbial agent according to claim 1, characterized in that In step (1), the volume concentration of the ethanol aqueous solution is 70-90%; the volume ratio of the ethanol aqueous solution to the Chinese medicinal residue is (8-10):1; and the reflux time is 8-12 hours.

3. The microbial agent according to claim 1, characterized in that In step (2), the concentration of the NaOH solution is 1-3 mol / L; the volume ratio of the NaOH solution to the filter residue A is (2-4):1; the soaking time is 2-5 h, and the temperature is 4°C.

4. The microbial agent according to claim 1, characterized in that In step (3), the enzyme preparation contains neutral protease and cellulase; the amount of the enzyme preparation added is 1000-2000 U per gram of filter residue B; the ratio of the enzyme activity of the neutral protease to the cellulase is (2-5):

1.

5. The microbial agent according to claim 1, characterized in that In step (3), the enzymatic hydrolysis time is 60-90 min and the temperature is 40-45°C.

6. The microbial agent according to claim 1, characterized in that The bacterial content of the Trichoderma viride is 2 to 10 billion CFU / g; the bacterial content of the Streptomyces tenuifolius is 3 to 8 billion CFU / g; and the bacterial content of the Paenibacillus polymyxa is 2 to 5 billion CFU / g.

7. A method for preparing the microbial agent according to any one of claims 1 to 6, characterized in that: The viride, the Streptomyces tenuifolius, the polymyxa bacillus, the traditional Chinese medicine extract, the vitamin B1, the sodium alginate, the humic acid, the zinc molybdate, the copper sulfate and the ferrous phosphate are mixed to obtain the microbial agent.

8. Use of the microbial agent according to any one of claims 1 to 6 or the microbial agent prepared by the preparation method according to claim 7 in preventing and controlling peanut root rot.

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