Complex microbial inoculant for preventing and treating tobacco root knot nematode disease as well as preparation method and application of complex microbial inoculant

Abstract

The invention belongs to the technical field of biopesticides, and particularly discloses a complex microbial inoculant for preventing and treating tobacco root knot nematode disease as well as a preparation method and application of the complex microbial inoculant. The complex microbial inoculant is prepared by compounding a bacillus subtilis fermentation broth with the preservation number of CGMCC NO.19784 and a bacillus sorola fermentation broth with the preservation number of CGMCC NO.1.15888 according to a certain volume ratio, and can be prepared into dosage forms such as liquid or powder. Field tests show that the complex microbial inoculant can effectively prevent and treat tobacco root knot nematode disease, the prevention effect is obviously higher than that of a single microbial inoculant and a chemical pesticide control, the two strains have obvious synergistic effect, are stable and reliable, are green and environment-friendly, and are not easy to induce nematodes to generate resistance. The invention provides an effective technical means for green prevention and control of the tobacco root knot nematode disease.

Description

Technical Field

[0001] This invention belongs to the field of biological pesticide technology, specifically relating to a compound microbial agent for the prevention and control of tobacco root-knot nematode disease, its preparation method, and its application. Background Technology

[0002] Tobacco root-knot nematodes are highly destructive plant pathogens with a unique infection method. During infection, the second-instar larvae actively seek out tobacco roots and use their stylets to pierce the root tissue, feeding and developing within the roots. This process directly damages the normal structure and physiological functions of the tobacco roots, hindering the absorption and transport of water and nutrients, leading to stunted growth, yellowing leaves, and dwarfed plants, ultimately causing severe yield reduction and significantly impacting both the quantity and quality of tobacco.

[0003] More seriously, the wounds caused by tobacco root-knot nematodes on the plant roots provide convenient entry points for other pathogens. This makes tobacco plants more susceptible to various diseases such as tobacco root rot and bacterial wilt. The concurrent occurrence of multiple diseases often accelerates the death of tobacco plants, further exacerbating losses in tobacco production. Without reasonable and effective control measures, as the area under tobacco cultivation expands and the number of years of cultivation increases, the scope and severity of tobacco root-knot nematode disease will continue to expand, and it is highly likely to become a major factor restricting tobacco production in the future.

[0004] Currently, chemical pesticides remain the primary means of controlling tobacco root-knot nematode disease. Chemical nematicides, with their rapid and significant effects, can control the spread of the disease to some extent. However, long-term, continuous, and irrational overuse of chemical pesticides can lead to problems such as nematodes developing resistance, pesticide residues in tobacco leaves exceeding safety limits, posing health and safety risks, and causing ecological damage. The green control strategy of replacing chemical pesticides with microbial inoculants is gradually becoming the main development direction for tobacco root-knot nematode disease control.

[0005] For the prevention and control of tobacco root-knot nematode disease, the use of microbial agents can effectively control the development and spread of root-knot nematode disease while also effectively controlling the problem of harmful substance residues in tobacco products. However, the microbial agents for the prevention and control of tobacco root-knot nematodes on the market are mainly composed of single strains.

[0006] Single-strain microbial inoculants have several limitations. Firstly, the mechanism of action of a single strain is relatively simple, and its control efficacy is often greatly influenced by environmental factors. Under different soil conditions, climate conditions, and planting patterns, the activity and control efficacy of a single strain may fluctuate significantly, making it difficult to maintain stable and effective control under varying environments. Secondly, the biological characteristics and ecological habits of tobacco root-knot nematodes are complex and diverse, making it difficult for a single strain to comprehensively address the control needs of root-knot nematodes at different growth stages. For example, some strains may have good control effects on second-instar larvae of root-knot nematodes, but poor control effects on adults or eggs, failing to achieve control throughout the entire life cycle of root-knot nematodes. Furthermore, long-term use of single-strain microbial inoculants may lead to resistance development in root-knot nematodes, resulting in a gradual decline in control efficacy.

[0007] Therefore, developing compound microbial agents to leverage the synergistic effects between different strains and improve the control efficacy and stability against tobacco root-knot nematodes has become an urgent problem to be solved in the field of tobacco root-knot nematode control. Summary of the Invention

[0008] The present invention aims to provide a compound microbial agent for the prevention and control of tobacco root-knot nematode disease, its preparation method and application, so as to solve the problems existing in the prior art and provide a new technical means for the green prevention and control of tobacco root-knot nematode disease.

[0009] On the one hand, the present invention provides a compound microbial agent for preventing and controlling tobacco root-knot nematode disease, the compound microbial agent containing Bacillus subtilis. Bacillus subtilis Fermentation broth and Sonora desert Bacillus Bacillus sonorensis The fermentation broth, containing Bacillus subtilis Bacillus subtilis The accession number is CGMCC NO.19784, and the described Sonora desert Bacillus is... Bacillus sonorensis The accession number is CGMCC NO. 1.15888.

[0010] Furthermore, the Bacillus subtilis in the compound microbial agent Bacillus subtilis The fermentation broth and the Sonora desert Bacillus Bacillus sonorensis The volume ratio of the fermentation broth is 5:1 to 1:2.

[0011] Furthermore, the compound microbial agent is a liquid microbial agent.

[0012] Furthermore, the compound microbial agent is in powder form.

[0013] As will be readily apparent to those skilled in the art, to fully realize the efficacy of the compound microbial agent, it can be prepared into a formulation suitable for easy application, depending on the specific needs. The compound microbial agent is processed into an industrially and agriculturally acceptable formulation using conventional techniques, and this formulation contains adjuvants that enhance the efficacy of the compound microbial agent. The microbial agent can be formulated into various dosage forms, including soluble liquids, water-dispersible granules, wettable powders, dispersible oil suspensions, suspensions, microemulsions, granules, and microcapsules with a certain sustained-release effect. When formulating these different dosage forms, those skilled in the art, in addition to using the selected compound microbial agent, also need to select various adjuvants, and different formulation auxiliary components (adjuvants) can be selected as needed. These auxiliary components can be one or more of the following: dispersion media, dispersants, emulsifiers, wetting agents, thickeners, defoamers, antifreeze agents, disintegrants, binders, fillers, and carriers.

[0014] In another aspect, a method for preparing the compound microbial agent described in this invention is also provided, comprising the following steps: Bacillus subtilis Bacillus subtilis Fermentation broth with Sonora desert Bacillus Bacillus sonoran The fermentation broth was mixed evenly in proportion.

[0015] Thirdly, it also provides Bacillus subtilis. Bacillus subtilis The application of Bacillus subtilis in the control of tobacco root-knot nematode disease. Bacillus subtilis The accession number is CGMCC NO.19784.

[0016] Fourthly, a method for preventing and controlling tobacco root-knot nematode disease is also provided, the method comprising applying the compound microbial agent described in this invention to the soil or plant roots.

[0017] Furthermore, in the method described above, the compound microbial agent is applied by applying it to the planting hole during transplanting.

[0018] Fifthly, pesticides containing the compound microbial agent described in this invention are also provided.

[0019] Finally, the application of the aforementioned pesticide in the control of tobacco root-knot nematode disease is also provided.

[0020] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages: (1) The compound microbial agent provided by the present invention has excellent control effect on tobacco root-knot nematode disease, with a field control efficacy of over 90%, which is significantly better than chemical pesticides and single microbial agents.

[0021] By combining Bacillus subtilis CGMCC NO.19784 with Sonora desert Bacillus CGMCC NO.1.15888, a significant synergistic effect was achieved, solving the technical problems of single bacterial agents having a single mechanism of action, unstable efficacy, and easy development of resistance.

[0022] (2) This compound microbial agent is a microbial preparation, which is environmentally friendly, safe for non-target organisms, and is not likely to cause pesticide residues in tobacco leaves, which meets the development needs of green agriculture.

[0023] (3) The microbial agent of the present invention is easy to use, can be adapted to various formulations and application methods, and has good application prospects and promotion value.

[0024] In summary, this invention provides a new technical solution for the integrated management of tobacco root-knot nematode disease, which helps to reduce the use of chemical pesticides and protect the agricultural ecological environment. Detailed Implementation

[0025] The technical solution of the present invention will be described below with reference to the embodiments. However, the present invention is not limited to the following embodiments.

[0026] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below with reference to specific embodiments, but the embodiments are not intended to limit the present invention.

[0027] Unless otherwise specified, the experimental and detection methods described in the following embodiments are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0028] Bacillus sonorensis, accession number: CGMCC NO 1.15888 (hereinafter referred to as Bacillus sonorensis CGMCC NO 1.15888), was purchased from the China General Microbiological Culture Collection Center.

[0029] Bacillus subtilis, accession number: CGMCC NO.19784 (hereinafter referred to as Bacillus subtilis CGMCC NO.19784), is a strain that the applicant deposited at the China General Microbiological Culture Collection Center on May 8, 2020, and this strain has been disclosed in patent CN112359084A.

[0030] Example 1 This example describes the preparation of fermentation broth for Bacillus subtilis CGMCC NO.19784.

[0031] Bacillus subtilis CGMCC NO.19784, stored at -4℃, was retrieved and inoculated onto LB agar plates using an inoculation loop. The plates were then incubated at 30℃ for 48 hours to activate the strain. The activated strain was then transferred to a 250mL Erlenmeyer flask containing 100mL of LB liquid medium and incubated at 30℃ and 180rpm for 48 hours using a shaking incubator to obtain the Bacillus subtilis CGMCC NO.19784 fermentation seed culture. The bacterial concentration in the seed fermentation broth was adjusted to OD0.05. 600 =0.1. The Bacillus subtilis CGMCC NO.19784 fermentation seed liquid was inoculated at 5% in LB medium and cultured at 30℃ and 200 r / min for 3 days to obtain the Bacillus subtilis CGMCC NO.19784 fermentation broth.

[0032] Example 2 This example describes the preparation of fermentation broth for Sonora desert Bacillus CGMCC NO 1.15888.

[0033] Sonora desert Bacillus CGMCC NO 1.15888, stored at -4℃, was inoculated into LB liquid medium and cultured at 37℃ and 180 rpm for 12 h to obtain the seed fermentation broth. The bacterial cell concentration in the seed fermentation broth was adjusted to OD. 600 =0.1, the seed fermentation broth was inoculated into liquid LB medium at 1%, and cultured at 30℃ and 150rpm for 60h to obtain Sonora desert Bacillus CGMCC NO 1.15888 fermentation broth.

[0034] Example 3 This embodiment describes the preparation of a compound microbial agent using Bacillus subtilis CGMCC NO.19784 fermentation broth and Sonora desert Bacillus CGMCC NO 1.15888 fermentation broth.

[0035] The fermentation broth of Bacillus subtilis CGMCC NO.19784 prepared in Example 1 and the fermentation broth of Bacillus desertis CGMCC NO 1.15888 prepared in Example 2 were mixed evenly at a volume ratio of 5:1 to obtain a compound bacterial agent, which was marked as No. 1 compound bacterial agent for later use.

[0036] Example 4 This embodiment describes the preparation of a compound microbial agent using Bacillus subtilis CGMCC NO.19784 fermentation broth and Sonora desert Bacillus CGMCC NO 1.15888 fermentation broth.

[0037] The fermentation broth of Bacillus subtilis CGMCC NO.19784 prepared in Example 1 and the fermentation broth of Bacillus desertica CGMCC NO 1.15888 prepared in Example 2 were mixed evenly at a volume ratio of 3:1 to obtain a compound bacterial agent, which was marked as Compound Bacillus Agent No. 2 for later use.

[0038] Example 5 This embodiment describes the preparation of a compound microbial agent using Bacillus subtilis CGMCC NO.19784 fermentation broth and Sonora desert Bacillus CGMCC NO 1.15888 fermentation broth.

[0039] The Bacillus subtilis CGMCC NO.19784 fermentation broth prepared in Example 1 and the Sonora desert Bacillus CGMCC NO 1.15888 fermentation broth prepared in Example 2 were mixed evenly at a volume ratio of 1:1 to obtain a compound bacterial agent, which was marked as No. 3 compound bacterial agent for later use.

[0040] Example 6 This embodiment describes the preparation of a compound microbial agent using Bacillus subtilis CGMCC NO.19784 fermentation broth and Sonora desert Bacillus CGMCC NO 1.15888 fermentation broth.

[0041] The Bacillus subtilis CGMCC NO.19784 fermentation broth prepared in Example 1 and the Sonora desert Bacillus CGMCC NO 1.15888 fermentation broth prepared in Example 2 were mixed evenly at a volume ratio of 1:2 to obtain a compound bacterial agent, which was marked as No. 4 compound bacterial agent for later use.

[0042] Example 7 This example is a field trial of a compound microbial agent.

[0043] Experiment location: Tobacco-growing areas in Nanzheng County, Hanzhong City, Shaanxi Province, where root-knot nematode disease has been prevalent for many years.

[0044] Experimental crop: Yunyan 99 Experimental groups: The fermentation broth of Bacillus subtilis CGMCC NO.19784 prepared in Example 1 served as control group 1; the fermentation broth of Sonora desert Bacillus CGMCC NO.15888 prepared in Example 2 served as control group 2; the compound bacterial agents 1#-4# prepared in Examples 3-6 served as experimental groups 1#-4#; and water served as the blank control group. 0.5% abamectin granules served as the positive control group (CK).

[0045] A randomized block design was adopted. Based on the principle of local control, the experimental plots were divided into 8 blocks according to fertility, light, and topographic slope. Within each block, 4 replicate plots were set up, and the plots were randomly arranged. Fermentation broth from control groups 1 and 2, compound microbial agents from experimental groups 1-4, and water (blank control) were applied at transplanting holes at a dosage of 1 kg / mu. The positive control, 0.5% abamectin granules, was mixed with soil at a dosage of 4 kg / mu and applied at transplanting holes. Within each plot, Yunyan 99 plants were spaced 0.55 m apart × 1.1 m apart. Other field management was standard. Disease surveys were conducted at tobacco maturity according to GB / 23222—2008, "Classification and Survey Methods of Tobacco Diseases and Pests."

[0046] The grading standards for tobacco root-knot nematode disease are as follows: Grade 0: Roots are normal, with no visible root knots; Level 1: A small number of root knots are present on the lower 1 / 4 of the root; Grade 3: A small number of root knots on 1 / 4 to 1 / 3 of the root; Level 5: Root knots are present on 1 / 3 to 1 / 2 of the root; Level 7: Root knots are present on more than 1 / 2 of the roots, and a small number of secondary roots produce root knots; Level 9: All roots, including secondary roots, are covered with root knots.

[0047] Based on the above grading standards, the disease index and prevention and control effectiveness are calculated using the following formulas: Disease index = 100 × ∑ (number of plants at each disease level × representative value at each level) / (total number of plants surveyed × highest representative value) Prevention and control effect = (Disease index of blank control group - Disease index of treatment group) / Disease index of blank control group × 100 The field test results are shown in Table 1. The disease index of the blank control group was 47.96%, consistent with the long-standing high incidence of root-knot nematode disease in this tobacco-growing area. The single-strain Bacillus subtilis (control group 1) had a control efficacy of 77.34%, slightly higher than the 73.67% control efficacy of the positive control (0.5% abamectin granules), indicating that the Bacillus subtilis CGMCC NO.19784 strain provided by this invention has a good control effect on root-knot nematode disease. However, the single-strain Sonora desert Bacillus CGMCC NO 1.15888 strain had a control efficacy of only 5.98%, almost ineffective, indicating that this strain does not have a significant control ability against nematodes in this region.

[0048] The control efficacy of compound microbial agents 1#–4# was higher than that of the positive control (CK) and the single microbial agent control group. Moreover, the control efficacy of compound microbial agents 1#–4# was greater than the sum of the control efficacy of single strain Bacillus subtilis CGMCC NO.19784 and single strain Sonora desert Bacillus CGMCC NO 1.15888, indicating that compound microbial agents may enhance the control effect through synergistic effect.

[0049] Table 1. Control effects of different treatment agents on root-knot nematode disease in Yunyan 99 tobacco.

[0050] In summary, this invention has found that the single bacterial agent Bacillus subtilis CGMCC NO.19784 has a good control effect on root-knot nematode disease, and its control effect is slightly better than that of the chemical pesticide 0.5% abamectin granules. More importantly, the bacterial agent composed of fermentation broth of Bacillus subtilis CGMCC NO.19784 and fermentation broth of Bacillus desertica CGMCC NO 1.15888 has a significantly better control effect on root-knot nematode disease than the single bacterial agent. Although the single strain of Bacillus desertica CGMCC NO.1.15888 has limited control effect on root-knot nematode disease, when it is combined with Bacillus subtilis CGMCC NO.19784, the chitinase and protease secreted by Bacillus desertica may complement the bactericidal active substances produced by Bacillus subtilis, thereby synergistically killing bacteria. In addition, the compound bacterial agent usually works through multiple targets and mechanisms, which greatly reduces the risk of nematodes developing adaptive resistance, making the control effect reliable and sustained.

[0051] Example 8 This embodiment describes the preparation of a compound bacterial agent powder using Bacillus subtilis CGMCC NO.19784 fermentation broth and Sonora desert Bacillus CGMCC NO 1.15888 fermentation broth.

[0052] The Bacillus subtilis CGMCC NO.19784 fermentation broth prepared in Example 1 and the Sonora desert Bacillus CGMCC NO 1.15888 fermentation broth prepared in Example 2 were mixed evenly at a volume ratio of 1:2. 5 wt% trehalose was added, and after stirring and mixing, the mixture was freeze-dried using a freeze dryer to obtain a compound microbial agent frozen product. The freeze-dried compound microbial agent product was then pulverized using a pulverizer to obtain compound microbial agent powder, which was labeled as No. 1 compound microbial agent powder.

[0053] Example 9 This embodiment describes the preparation of a compound bacterial agent powder using Bacillus subtilis CGMCC NO.19784 fermentation broth and Sonora desert Bacillus CGMCC NO 1.15888 fermentation broth.

[0054] The Bacillus subtilis CGMCC NO.19784 fermentation broth prepared in Example 1 and the Sonora desert Bacillus CGMCC NO 1.15888 fermentation broth prepared in Example 2 were mixed evenly at a volume ratio of 1:1. 5 wt% trehalose was added, and after stirring and mixing, the mixture was freeze-dried using a freeze dryer to obtain a compound bacterial agent frozen product. The freeze-dried compound bacterial agent product was then pulverized using a pulverizer to obtain compound bacterial agent powder, which was labeled as No. 2 compound bacterial agent powder.

[0055] Example 10 This embodiment describes the preparation of a compound bacterial agent powder using Bacillus subtilis CGMCC NO.19784 fermentation broth and Sonora desert Bacillus CGMCC NO 1.15888 fermentation broth.

[0056] The Bacillus subtilis CGMCC NO.19784 fermentation broth prepared in Example 1 and the Sonora desert Bacillus CGMCC NO 1.15888 fermentation broth prepared in Example 2 were mixed evenly at a volume ratio of 2:1. 5 wt% trehalose was added, and after stirring and mixing, the mixture was freeze-dried using a freeze dryer to obtain a compound bacterial agent frozen product. The freeze-dried compound bacterial agent product was then pulverized using a pulverizer to obtain compound bacterial agent powder, which was labeled as No. 3 compound bacterial agent powder.

[0057] Example 11 This embodiment describes the preparation of a compound bacterial agent powder using Bacillus subtilis CGMCC NO.19784 fermentation broth and Sonora desert Bacillus CGMCC NO 1.15888 fermentation broth.

[0058] The Bacillus subtilis CGMCC NO.19784 fermentation broth prepared in Example 1 and the Sonora desert Bacillus CGMCC NO 1.15888 fermentation broth prepared in Example 2 were mixed evenly at a volume ratio of 5:1. 5 wt% trehalose was added, and after stirring and mixing, the mixture was freeze-dried using a freeze dryer to obtain a compound bacterial agent frozen product. The freeze-dried compound bacterial agent product was then pulverized using a pulverizer to obtain compound bacterial agent powder, which was labeled as No. 4 compound bacterial agent powder.

[0059] Example 12 This example is a field trial of the compound microbial agent powder.

[0060] Experiment location: Tobacco-growing areas in Luonan County, Shangluo City, Shaanxi Province, where root-knot nematode disease has been prevalent for many years.

[0061] Experimental crop: Qinyan 99 Experimental groups: Control group 1 consisted of Bacillus subtilis CGMCC NO.19784 fermentation broth prepared in Example 1, which was mixed with 5 wt% trehalose, freeze-dried, and pulverized. Control group 2 consisted of Bacillus subtilis CGMCC NO.19784 fermentation broth prepared in Example 2, which was mixed with 5 wt% trehalose, freeze-dried, and pulverized. Experimental group 3 consisted of the 1#-4# compound bacterial agent powder prepared in Examples 8-11. Water was used as the blank control group. 0.5% abamectin granules were used as the positive control group (CK).

[0062] A randomized block design was adopted. Based on the principle of local control, the experimental plots were divided into 8 blocks according to fertility, light, and topographic slope. Within each block, 4 replicate plots were set up, and the plots were randomly arranged. Inoculum powder from control groups 1 and 2, compound inoculum powder from experimental groups 1-4, and water (for the blank control) were applied at transplanting holes at a dosage of 1 kg / mu. The positive control, 0.5% abamectin granules, was mixed with soil at a dosage of 4 kg / mu and applied at transplanting holes. Within each plot, Yunyan 99 plants were spaced 0.55 m apart × 1.1 m apart. Other field management was standard. Disease surveys were conducted at tobacco maturity according to GB / 23222—2008, "Classification and Survey Methods of Tobacco Diseases and Pests." The survey methods were the same as in Example 7. The field test results are shown in Table 2.

[0063] Table 2. Control effects of different treatments on root-knot nematode disease in Qinyan 99 tobacco.

[0064] Table 2 shows that the control efficacy of the compound microbial agents 1#–4# was higher than that of the positive control (CK) and the single microbial powder control group. Furthermore, the control efficacy of the compound microbial agents 1#–4# was greater than the sum of the control efficacies of the single-strain Bacillus subtilis CGMCC NO.19784 microbial powder and the single-strain Sonora desert Bacillus CGMCC NO 1.15888 microbial powder, indicating that the compound microbial agents may enhance the control effect through synergistic effects. The control efficacy of the single-strain Bacillus subtilis CGMCC NO.19784 microbial powder was comparable to that of the positive control chemical pesticide 0.5% abamectin granules. This indicates that the single-strain Bacillus subtilis CGMCC NO.19784 microbial powder provided by this invention has a good control effect on root-knot nematode disease; and that the microbial powder prepared by combining Bacillus subtilis CGMCC NO.19784 and Sonora desert Bacillus CGMCC NO 1.15888 has a synergistic effect on the control of tobacco root-knot nematode disease. This invention provides an environmentally friendly, non-resistant, and highly effective control solution for tobacco root-knot nematode disease.

[0065] As described above, the basic principles, main features, and advantages of the present invention have been well described. The above embodiments and specifications are merely descriptions of preferred embodiments of the present invention, and the present invention is not limited to the above embodiments. Various changes and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit and scope of the present invention should fall within the protection scope defined by the present invention.

Claims

1. A compound microbial agent for controlling tobacco root-knot nematode disease, characterized in that, The compound microbial agent contains Bacillus subtilis. Bacillus subtilis Fermentation broth and Sonora desert Bacillus Bacillus sonorensis The fermentation broth, containing Bacillus subtilis Bacillus subtilis The accession number is CGMCC NO.19784, and the described Sonora desert Bacillus is... Bacillus sonorensis The accession number is CGMCC NO. 1.15888.

2. The compound microbial agent according to claim 1, characterized in that, Bacillus subtilis Bacillus subtilis Fermentation broth and the aforementioned Sonora desert Bacillus Bacillus sonorensis The volume ratio of the fermentation broth is 5:1 to 1:

2.

3. The compound microbial agent according to any one of claims 1-2, characterized in that, The compound microbial agent is a liquid microbial agent.

4. The compound microbial agent according to any one of claims 1-2, characterized in that, The compound microbial agent is in powder form.

5. A method for preparing the compound microbial agent as described in any one of claims 1-2, characterized in that, Includes the following steps: Bacillus subtilis Bacillus subtilis Fermentation broth with Sonora desert Bacillus Bacillus sonorensis The fermentation broth was mixed evenly in proportion.

6. Bacillus subtilis Bacillus subtilis Its application in the control of tobacco root-knot nematode disease is characterized by... Bacillus subtilis Bacillus subtilis The accession number is CGMCC NO.19784.

7. A method for controlling tobacco root-knot nematode disease, characterized in that, This includes applying the compound microbial agent as described in any one of claims 1-2 to the soil or plant roots.

8. The method according to claim 5, characterized in that, The compound microbial agent is applied by applying it to the planting hole during transplanting.

9. A pesticide containing the compound microbial agent as described in claim 1.

10. The application of the pesticide according to claim 9 in the control of tobacco root-knot nematode disease.

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