Mixed microbial agent for preventing and treating soil-borne diseases of vegetables as well as preparation method and application of mixed microbial agent

Abstract

The invention relates to the field of agricultural microorganisms, in particular to a mixed microbial agent for preventing and treating soil-borne diseases of vegetables as well as a preparation method and application of the mixed microbial agent. The mixed bacterial agent is prepared from bacillus cereus BC1, bacillus subtilis BS2 and bacillus pumilus BC3; the preservation number of the bacillus cereus is CGMCC (China General Microbiological Culture Collection Center) NO.32167, the preservation number of the bacillus subtilis is CGMCC NO.32165, and the preservation number of the bacillus pumilus is CGMCC NO.32166; when the mixed microbial agent is applied to soil, the number of microorganisms in the soil can be remarkably increased, the activity of the increased microorganisms can promote the enhancement of the enzyme activity of the soil, and insoluble mineral nutrients in the soil can be decomposed and released. Meanwhile, the microorganisms can secrete plant hormones, so that the growth of crops is promoted. The mixed microbial agent disclosed by the invention has important significance on production of green and pollution-free organic vegetables, potatoes and melons.

Description

Technical Field

[0001] The invention relates to the field of agricultural microorganisms and biological control, and in particular to a mixed microbial agent for preventing and controlling soil-borne vegetable diseases, and a preparation method and application thereof. Background Art

[0002] Vegetable soil-borne diseases are the biggest enemy of vegetable production. As the number of consecutive cropping years increases, the problem becomes more prominent, with the highest incidence rate reaching 40%-50%. Research and analysis show that crop consecutive cropping obstacles are caused by the joint action of plants, soil and microorganisms. The main reasons include changes in soil physical and chemical properties, soil ecological environment variations and plant self-toxicity. These three mechanisms interact with each other and jointly limit the increase and stability of crop yields. Literature analysis shows that plants account for 34%, soil accounts for 22% and microorganisms account for 44% of the above three reasons, so biological factors have become the key factor in consecutive cropping obstacles. Summary of the invention

[0003] The present invention overcomes the deficiencies of the prior art and provides a mixed microbial agent for preventing and controlling soil-borne vegetable diseases, which has a broad-spectrum growth-promoting effect, has an inhibitory effect on a variety of vegetables and soil-borne pathogens, and has a growth-promoting effect on leafy vegetables, melon vegetables, and potatoes.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A mixed microbial agent for preventing and controlling soil-borne diseases of vegetables, wherein the mixed agent contains Bacillus cereus BC1, Bacillus subtilis BS2 and Bacillus pumilus BC3;

[0006] The deposit number of Bacillus cereus BC1 is CGMCC NO.32167, the deposit number of Bacillus subtilis BS2 is CGMCC NO.32165, and the deposit number of Bacillus pumilus BC3 is CGMCC NO.32166.

[0007] The Bacillus cereus BC1 of the present invention is separated and screened from 230 bacterial strains in the soil of a vegetable field in Ying County, Shanxi Province.

[0008] The strain was selected and deposited in the General Microbiology Center (CGMCC) of China Microbiological Culture Collection Committee on October 10, 2024. Its address is: No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences; its deposit number is CGMCC NO.32167. Bacillus subtilis BS2 was isolated and screened from organic fertilizer soil in vegetable fields in Xiaodian District, Taiyuan, Shanxi, and was screened from more than 200 bacterial strains.

[0009] It was screened out and deposited in the General Microbiology Center (CGMCC) of China Microorganism Culture Collection Administration on October 10, 2024. Its address is: No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences; its deposit number is CGMCC NO.32165.

[0010] The Bacillus pumilus BC3 of the present invention is separated from organic fertilizer soil in a vegetable field in Taiyuan, Shanxi Province, and is screened from 200 bacterial strains.

[0011] It was screened out and deposited in the General Microbiology Center (CGMCC) of China Microorganism Culture Collection Administration on October 10, 2024. Its address is: No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences; its deposit number is CGMCC NO.32166.

[0012] The present invention also provides a method for preparing the above-mentioned mixed microbial agent for preventing and controlling soil-borne diseases of vegetables, comprising the following steps:

[0013] (1) subjecting Bacillus cereus BC1 with a deposit number of CGMCC NO.32167, Bacillus subtilis BS2 with a deposit number of CGMCC NO.32165, and Bacillus pumilus BC3 with a deposit number of CGMCC NO.32166 to liquid fermentation to obtain Bacillus cereus BC1 fermentation liquid, Bacillus subtilis BS2 fermentation liquid, and Bacillus pumilus BC3 fermentation liquid, respectively;

[0014] (2) Before use, the Bacillus cereus BC1 fermentation liquid, the Bacillus subtilis BS2 fermentation liquid and the Bacillus pumilus BC3 fermentation liquid obtained in step (1) are mixed in a mass ratio of 0.5:2:0.5 to obtain a mixed microbial agent.

[0015] The liquid fermentation medium of Bacillus cereus BC1 is: 3g corn flour, 3g peptone, 2g potassium dihydrogen phosphate, 3g sodium chloride, 4g ammonium sulfate, 0.5g calcium carbonate, 0.2g magnesium sulfate, 0.2g zinc sulfate, 3g yeast extract, 30g glucose, 1000mL water, sterilized at 121℃ for 30 minutes, and the liquid fermentation conditions are: fermentation temperature 30℃, speed: 160 rpm, time: 48 hours, inoculation amount is 7%, pH is set to 7.5. The concentration of Bacillus cereus BC1 fermentation liquid is, 10 11 cfu / mL is about 10%.

[0016] The liquid fermentation medium of Bacillus subtilis BS2 is: 3.5g corn flour, 3.5g soybean flour, 3g peptone, 2g potassium dihydrogen phosphate, 3g sodium chloride, 4g ammonium sulfate, 2g calcium carbonate, 0.6g magnesium sulfate, 0.6g manganese chloride, 3g yeast extract, 40g glucose, 1000mL water, sterilized at 121°C for 20 minutes, and the liquid fermentation conditions are: fermentation temperature 32°C, rotation speed: 160 rpm, time: 48 hours, inoculation amount 8%, pH setting 8 (initial), the concentration of Bacillus subtilis BS2 fermentation liquid is: 10 11 cfu / mL about 10%

[0017] The liquid fermentation medium of Bacillus pumilus BC3 is: 3g corn flour, 3g peptone, 2g potassium dihydrogen phosphate, 3g sodium chloride, 3g ammonium sulfate, 0.8g calcium carbonate, 0.4g magnesium sulfate, 0.4g zinc sulfate, 4g yeast extract, 35g glucose, 1000mL water, sterilized at 121°C for 20 minutes, and the liquid fermentation conditions are: fermentation temperature 30°C, rotation speed: 155 rpm, time: 48 hours, inoculation amount is 8%, pH is set to 7, and the concentration of Bacillus pumilus BC3 fermentation liquid is: 10 10 -10 11 cfu / Ml.

[0018] The present invention also provides the disease prevention and growth promotion effect and application of the mixed microbial agent on soil-borne diseases in vegetable planting.

[0019] Furthermore, the vegetables are peppers, zucchini, radish, rapeseed, sweet potatoes, celery and the like.

[0020] Furthermore, the application comprises the following steps:

[0021] (1) One to two weeks before vegetable transplanting or sowing, treat the soil with a mixed microbial solution. Dilute the mixed microbial solution 50 to 300 times and spray it evenly on the surface, or spray it evenly on organic fertilizer. Then mix and plow it evenly, and then plow it into 10 to 20 cm of soil to allow the microorganisms to grow and colonize naturally, which has a good inhibitory effect on pathogens that overwinter in the soil.

[0022] (2) Dip the roots of vegetable seedlings in a mixed microbial solution diluted 50 times before transplanting for 10-30 minutes before transplanting. After dipping the roots, the seedlings are effectively protected by antagonistic bacteria, reducing infection by soil pathogens;

[0023] (3) Before the disease occurs, irrigate the roots with a mixed microbial solution. Dilute the mixed microbial solution 200-300 times and irrigate each plant with 0.5 catties to 1 catties. Irrigate 1-2 times in total to effectively reduce the incidence of disease in the field.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The mixed microbial agent of the present invention has a broad-spectrum growth-promoting effect, has an inhibitory effect on a variety of soil-borne pathogenic bacteria of vegetables, and has a growth-promoting effect on leafy vegetables, melon vegetables, and potatoes.

[0026] The mixed microbial agent of the present invention is applied to the soil, which can significantly increase the number of microorganisms in the soil, and the increased activities of these microorganisms can promote the enhancement of soil enzyme activity, and can decompose and release the insoluble mineral nutrients in the soil. At the same time, these microorganisms can also secrete plant hormones, thereby promoting crop growth. The mixed microbial agent of the present invention is of great significance to the production of green, pollution-free and organic vegetables, potatoes and melons. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a photograph of a field test of the mixed microbial agent of the present invention in Example 1 on the disease prevention and growth promotion of pepper.

[0028] Figure 2 This is a photograph of the field test of the mixed microbial agent of the present invention in Example 3 on the disease prevention and growth promotion of radish.

[0029] Figure 3 This is a photograph of the yield measurement of radish after the mixed microbial agent of the present invention was tested in Example 3.

[0030] Figure 4 This is a photograph of the disease prevention and growth-promoting effect of the mixed microbial agent of the present invention on sweet potatoes in Example 4.

[0031] Figure 5 These are photos showing the antibacterial effect of Bacillus cereus of the present invention on various pathogens.

[0032] Figure 6 These are photos showing the antibacterial effect of Bacillus subtilis of the present invention on various pathogens.

[0033] Figure 7 These are pictures showing the effects of the three bacteria of the present invention on tomato early blight.

[0034] Figure 8This is a picture showing the effect of a mixture of Bacillus cereus and Bacillus subtilis on Botrytis cinerea of ​​green pepper.

[0035] Fig. 9 This is a microscope picture showing the effect of Bacillus cereus of the present invention on cucumber wilt pathogen.

[0036] Fig.10 These are photos of the field test on the disease prevention and growth promotion effect of the mixed microbial agent of the present invention on zucchini in Example 2.

[0037] Fig.11 These are photos of the field test on the disease prevention and growth promotion effect of the mixed microbial agent of the present invention on celery in Example 5.

[0038] Fig.12 This is a photograph of the yield measurement of zucchini after the mixed microbial agent of the present invention was tested in Example 2. DETAILED DESCRIPTION

[0039] The present invention is further described below in conjunction with specific embodiments.

[0040] The strain of Bacillus cereus BC1 has disease prevention and growth promotion effects on a variety of vegetables, especially peppers, zucchini, radish, celery, rapeseed, sweet potatoes, etc. In the following implementation, Bacillus cereus BC1 is marked as biocontrol bacteria No. 1.

[0041] Bacillus subtilis BS2 strain has a broad-spectrum growth-promoting effect on a variety of vegetables such as peppers, tomatoes, zucchini, celery, rapeseed, cucumber, watermelon, melon and other vegetable soil-borne diseases. It has a strong inhibitory effect on a variety of pathogens such as wilt, blight, root rot, gray mold, early blight, damping-off, etc., and is a broad-spectrum antagonistic bacterium. In the following examples, Bacillus subtilis BS2 is marked as biocontrol bacteria No. 2.

[0042] Bacillus pumilus BC3 strain has a significant inhibitory effect on a variety of vegetable pathogens such as tomato early blight Alternaria, gray mold, and apple rot. The rational combination of three antagonistic bacteria has a significant preventive and control effect on a variety of vegetable and potato soil-borne diseases. See some antibacterial pictures. In the following implementation, Bacillus pumilus BC3 is marked as biocontrol bacteria No. 3.

[0043] The three bacteria are fermented in liquid separately. When used, the three bacterial liquids are mixed in proportion. The best ratio of No. 1: No. 2: No. 3 is 0.5: 2: 0.5, and the dosage is 3 kg / mu. The above ratio is based on the characteristic ratio of each bacteria. After trials and demonstrations on a variety of vegetables and potato crops in recent years, the best combination is selected from multiple ratio combinations.

[0044] The liquid fermentation processes of the above three bacteria are:

[0045] 1. Preparation of Bacillus cereus BC1 fermentation broth with a deposit number of CGMCC NO.32167:

[0046] Preparation of slant strains: Inoculate the original strain of Bacillus cereus BC1 numbered CGMCC NO.32167 on a slant culture medium (the culture medium components are as described above, solid culture medium plus agar), and culture in a 30°C incubator for 48 hours to obtain a slant strain. Preparation of fermentation broth: Inoculate the slant strain into the corresponding liquid culture medium, and inoculate one slant into one triangular flask.

[0047] 200mL / 500mL, 30℃, 160 rpm, shaker culture for 48 hours to obtain Bacillus cereus BC1 fermentation liquid. This bacterial liquid can be used directly in the field or as seed liquid for expanded culture and large-scale production.

[0048] 2. Preparation of Bacillus subtilis BS2 fermentation broth with a deposit number of CGMCC NO.32165:

[0049] Preparation of slant strains: Inoculate the original strain of Bacillus subtilis BS2, numbered CGMCC NO.32165, on a slant culture medium (the culture medium components are as described above, solid culture medium plus agar), and culture in a 32°C constant temperature box for 48 hours to obtain a slant strain. Preparation of fermentation liquid: Inoculate the slant strain into the corresponding liquid culture medium, one slant inoculated with one triangle, 200mL / 500mL, 32°C, 160 rpm, and culture in a shaking table for 48 hours to obtain the fermentation liquid of Bacillus subtilis BS2, numbered CGMCC NO.32165. This liquid can be used directly in the field, or as a seed liquid for expanded culture and large-scale production.

[0050] 3. Preparation of Bacillus pumilus BC3 fermentation broth with a deposit number of CGMCC NO.32166:

[0051] Preparation of slant strains: Inoculate the original strain of Bacillus pumilus BC3 numbered CGMCC NO.32166 on the slant culture medium (the culture medium components are as described above, solid culture medium plus agar), and culture in a 30℃ incubator for 48 hours. Preparation of liquid fermentation liquid: Inoculate the slant strains into the corresponding liquid culture medium, one slant inoculated with one triangle, 200mL / 500mL, 30℃, 155 rpm, and culture in a shaking table for 48 hours, which is the fermentation liquid of Bacillus pumilus BC3 numbered CGMCC NO.32166. It can be used directly in the field, or as a seed liquid for expanded culture and large-scale production.

[0052] The fermentation broth of Bacillus cereus BC1, Bacillus subtilis BS2 and Bacillus pumilus BC3 were prepared separately.

[0053] The fermentation broth was mixed according to the proportion before use.

[0054] Field use:

[0055] The following three key usage times and methods have a positive and effective effect on the prevention and control of soil-borne vegetable diseases.

[0056] (1) Inoculate the soil with mixed microbial solution in spring April-May

[0057] In spring, from late April to early May, it is the time for transplanting or sowing open-field vegetables in the north. One to two weeks before that, the soil is treated with mixed microbial agents to colonize and reproduce, which has a good inhibitory effect on overwintering pathogens in the soil. Between mid-to-late April, when the air and ground temperatures gradually rise, the average daily temperature reaches about 18-20°C, and the mixed microbial liquid is inoculated into the soil, with an inoculation amount of 3-4 kg of stock liquid per mu. The specific method is to first mix the three bacterial liquids in proportion, then dilute them 50-300 times (depending on the dryness and wetness of the soil), spray them evenly on the surface, or spray them evenly on organic fertilizers, then mix and turn them evenly, and then turn them into 10-20 cm of soil to allow them to grow and colonize naturally. Soil samples were measured 1-2 weeks after treatment, and the total amount of soil microorganisms increased, and the pathogenic fungi decreased relatively, effectively controlling the growth and reproduction of overwintering pathogens and reducing the source of initial infection.

[0058] (2) Dip the roots in mixed microbial solution before transplanting:

[0059] In early May, before transplanting vegetable seedlings, dip the roots in 50 times the mixed microbial solution for 10-30 minutes before transplanting. After dipping the roots, the seedlings are effectively protected by antagonistic bacteria, reducing infection by soil pathogens. After dipping the roots, the seedlings grow vigorously and seedling diseases are reduced. If you grow seedlings in nutrient pots, spray the bacterial solution around the nutrient pots. After transplanting, the seedlings will recover quickly and seedling diseases will be reduced.

[0060] (3) Irrigate the roots with mixed microbial solution before the disease occurs:

[0061] From early June to early July, before the onset of disease in open-field vegetables and potatoes, use the combination of biocontrol bacteria No. 1, 2, and 3 to irrigate the roots. After 200-300 times dilution, irrigate 0.5 catties to 1 catties per plant, irrigate 1-2 times in total, and effectively reduce the incidence of field diseases.

[0062] According to the above method, soil-borne diseases of vegetables and potatoes are significantly reduced, the number of chemical pesticide applications can be reduced by 3-4 times, and pesticide residues in vegetables can be reduced. Root irrigation with a combination of biocontrol agents can effectively increase the activity of 3-4 kinds of vegetable resistance enzymes and enhance vegetable disease resistance.

[0063] Example 1

[0064] From 2023 to 2024, a study on the effect of biocontrol bacteria combination No. 1, 2, and 3 on pepper disease prevention and growth promotion was conducted in Jiyi Township, Qingxu County, Taiyuan City. There were five treatments in the experiment, namely (1) blank control (2) chemical pesticide oxadipate (3) biocontrol bacteria combination No. 1 and No. 2, the mass ratio of biocontrol bacteria No. 1 and No. 2 liquid was 1:2 (4) biocontrol bacteria combination No. 1, 2, and No. 3, the mass ratio of biocontrol bacteria No. 1, 2, and No. 3 liquid was 0.5:2:0.5 (5) commercially available compound microbial fertilizer, each treatment occupied 0.8 mu of land. The above experiment adopted the above-mentioned field application method, that is, all treatments were applied to the soil according to the instructions before land preparation 2 weeks before pepper transplanting, that is, from April 23 to 25, 2023, according to the test area, and (3) and (4) were diluted 100 times and sprayed on the ground, then plowed 15 cm underground, raked and ridged, and covered with film on May 2 before transplanting. When transplanting on May 5, peppers were treated with the combination of biocontrol agents No. 1 and No. 2 and the combination of biocontrol agents No. 1, No. 2, No. 3 for 30 minutes, and then transplanted to the corresponding treatment area. The roots were irrigated twice on June 1 and July 1 before the disease occurred (the concentration and method were as mentioned above). No pesticides were used for the following three months, July, August, and September. Surveys and sampling were conducted in the early September of the harvest period to measure yield in the laboratory. The combination of biocontrol agents No. 1 and No. 2 and the combination of biocontrol agents No. 1, No. 2, No. 3 have a good disease prevention and growth promotion effect on peppers. In particular, the combination of biocontrol agents No. 1, No. 2, No. 3 has a significant effect on the prevention and control of soil-borne diseases such as pepper wilt, blight, and gray mold, which is significantly better than chemical pesticides and similar commercially available compound microbial fertilizers, and better than the blank control. See Table 1.

[0065] Table 1 Results of the combined application of biocontrol bacteria to prevent pepper diseases

[0066]

[0067] Jiyi Township, Qingxu County is an old pepper planting area with a history of more than 20 years. Every year, peppers are seriously diseased in the late growth period of August-September. In this test site, the test results in 2023 showed that the combination of biocontrol bacteria 1, 2 and biocontrol 1, 2, 3 was significantly better than other treatments, especially the combination of biocontrol 1, 2, 3, with a low disease pepper rate. Compared with the blank control, the control effect reached 62.70%. The growth-promoting effect is significant, as shown in Table 2.

[0068] Table 2 Biocontrol bacteria combination application - pepper growth promotion experiment

[0069]

[0070]

[0071] As can be seen from Table 2, the combination of biocontrol bacteria 1, 2, and 3 has a significant growth-promoting effect on peppers. Compared with the blank control, the growth-promoting effect on branches and leaves is 28.24%, and the growth-promoting effect on fruit peppers is 36.14%. The effects are better than the chemical agent oxadipamide and compound microbial fertilizer. Based on the 2023 experiment, the biocontrol bacteria combination 1, 2 and the biocontrol bacteria combination 1, 2, 3 on pepper disease prevention and growth promotion experiments were repeated in the base in 2024. The results are shown in Table 3.

[0072] Table 3 Biocontrol bacteria combination application - test on pepper growth promotion and disease prevention

[0073]

[0074] The results of the two-year test show that the combination of biocontrol bacteria 1, 2, and 3 used in accordance with the technology of the present invention has a good control effect on pepper diseases and has a strong growth-promoting effect on pepper plants and pepper fruits. Figure 1 As shown, these are photos of the field trial of the Qingxu Jiyi biocontrol bacteria combination in preventing diseases and promoting growth in peppers. The peppers grown with the biocontrol bacteria combinations 1, 2, and 3 have dense, tall leaves and few diseases.

[0075] Example 2

[0076] In 2017, the experiment was conducted in the zucchini field in Jiyi, Qingxu. The combination of biocontrol bacteria No. 1, 2, and 3 (the mass ratio of No. 1, 2, and 3 was 0.5:2:0.5) was used to irrigate the zucchini twice at a concentration of 200 times. It was discovered that the combination was not only effective against wilt and gray mold, but also had a good control effect on zucchini virus disease. Fig.10 . Fig.10 The left side shows a zucchini field treated with a combination of biocontrol bacteria. Viral diseases occurred sporadically, with a disease rate of about 10%. Fig.10 On the right is an untreated zucchini field owned by a neighboring farmer. The incidence of viral disease is as high as 60%. The leaves in the entire field are shaped like chicken claws, and the zucchini produced are mottled.

[0077] In 2024, in Jiyi Township, Qingxu, in response to the increasing trend of wilt, powdery mildew, gray mold and viral diseases of open-field zucchini, a disease prevention and growth promotion experiment was carried out on zucchini using a combination of biocontrol bacteria 1, 2 and 3. After two root irrigation treatments before and at the beginning of the disease, compared with the blank control, better results were achieved in both growth promotion and disease prevention. The farmer's yield measurement record on July 29, 2024 is shown in Table 4.

[0078] Table 4 Experimental demonstration of biocontrol bacteria combination for preventing disease and promoting growth of zucchini

[0079]

[0080] Compared with the blank control, the combination of biocontrol bacteria 1, 2, and 3 increased yield by 36.82%; the control effect on zucchini diseases reached 68.75%. In this experiment, no chemical fungicides were used during the growth period of zucchini. In 2024, due to the drought, powdery mildew and downy mildew occurred seriously in zucchini fields. Two months later, most of the leaves in the blank area dried up or the whole plant died. In the treatment area of ​​biocontrol bacteria 1, 2, and 3, only some of the outer leaves of the plants dried up, and most of the heart leaves of the plants were green and still growing.

[0081] Example 3

[0082] In 2023, a disease prevention and growth promotion test of radish was carried out in Dongyang, Yuci using a combination of biocontrol agents No. 1, 2, and 3 (the mass ratio of No. 1, 2, and 3 agents was 200 times). Due to the short growth period of radish, only two root irrigation treatments were carried out with a combination of biocontrol agents No. 1, 2, and 3 before the onset of the disease. The diseases were investigated and the yield was measured at harvest. According to statistics, the prevention and control effect of radish diseases was 83.20%, and the growth promotion effect of radish was 24.68%. On this basis, a demonstration was carried out in Jiyi Township, Qingxu, Taiyuan in 2024. The roots of open-field white radish were irrigated twice in the middle of its growth period, on June 23 and July 7, at 200 times, and harvested on July 29. In 2024, due to the dry climate, radish virus diseases were common. Two months later, in the blank area, most of the leaves of the whole plant were short. In the biological pesticide treatment area, the leaves of the plants grew vigorously, the ridges were closed early, and virus diseases were rare. The results are shown in Table 5. And if Figure 2 As shown, the radish leaves of the biocontrol bacteria combinations 1, 2, and 3 were dense, tall, and had few diseases, while the radish leaves of the blank control were sparse, short, and had many viral diseases.

[0083] Table 5 Experimental demonstration of biocontrol bacteria combination for radish disease prevention and growth promotion (2024 Jiyi)

[0084]

[0085] Analysis shows that the root irrigation time in 2024 should be at the early stage of the disease, that is, around June 10. Due to drought and water shortage, the root irrigation was delayed for 2 weeks to June 23, which was slightly later. The prevention and control effect was 70.97%, which was different from the prevention and control effect of 83.20% in 2023. This shows that the selection of the appropriate prevention and control period is very critical for the control of the disease.

[0086] Example 4

[0087] Xi Village, Pingyao County, Shanxi Province is a sweet potato production base. The main varieties grown are "Da Hong Pao" and "Hong Mei Ren". The sweet potatoes are of good quality and taste, but for many years, diseases mainly caused by nematodes have become the main problem in sweet potato production. Since 2020, a three-step disease prevention test has been carried out on sweet potatoes using a combination of biocontrol bacteria No. 1, 2, and 3 (the mass ratio of No. 1, 2, and 3 is 0.5:2:0.5), including soil treatment before transplanting, root dipping treatment of seedlings during transplanting, and root irrigation before disease onset. Significant prevention and control effects have been achieved, and the rational use technology of biocontrol bacteria combination has been summarized. For example, in the sweet potato field of Mr. Liang, a farmer in the experiment, this product has been used every year for the past five years, that is, the soil is treated around April 20; the root of the sweet potato seedlings is dipped with this product before transplanting around May 1; the root of the sweet potato is irrigated in early June before the disease occurs. Basically, no chemical pesticides are used in the later stage of the sweet potato field. From the seedling stage to the middle and late stages of growth, the leaves of the sweet potatoes are dark green, and the branches are long and stretched vigorously, laying a solid foundation for the expansion and growth of the sweet potato tubers in the later stage. Almost no diseased plants or leaves can be seen in the field during the entire growth period. The sweet potatoes produced are smooth, disease-free, uniform and neat, with good commercial quality and are very popular, as shown in Table 6 below.

[0088] Table 6 Statistics of sweet potato field survey

[0089]

[0090] The results show that fewer sweet potatoes rot during storage. In the past, rotten potatoes were dumped out in truckloads, but now only 1-2 small buckets are rotten. More importantly, the seedlings grown with this potato in spring grow vigorously, with fewer diseased seedlings. The seedlings are sold well every year, and the province has become the exclusive purchasing base for experimental seedlings of the Provincial Academy of Agricultural Sciences. However, the seedlings of neighboring farmers died in large numbers, which is still serious. The application of this combination and this technology has reduced the rotten rate of sweet potatoes year by year, which is a fact that is obvious to all farmers in Xi Village, Pingyao.

[0091] Example 5

[0092] The results of the greenhouse test in Xia Ge Township, Yuci in 2016 showed that after two irrigations with the combination of biocontrol bacteria No. 1, 2, and 3 at 300 times the water concentration, the control effect on celery leaf spot and other diseases was 70%, and the growth promotion effect was 35%. Fig.12 .

Claims

1. A mixed microbial agent for preventing and controlling soil-borne diseases of vegetables, characterized in that: The mixed bacterial agent contains Bacillus cereus ( Bacillus cereus )BC1, Bacillus subtilis ( Bacillus subtilis )BS2 and Bacillus pumilus ( Bacillus pumilus )BC3; Bacillus cereus ( Bacillus cereus )BC1 is deposited in CGMCC NO.32167, Bacillus subtilis ( Bacillus subtilis )BS2 is deposited in CGMCC NO.32165, Bacillus pumilus ( Bacillus pumilus ) The preservation number of BC3 is CGMCC NO.32166.

2. The method for preparing a mixed microbial agent for preventing and controlling soil-borne diseases of vegetables according to claim 1, characterized in that: The following steps are involved: (1) subjecting Bacillus cereus BC1 with a preservation number of CGMCC NO.32167, Bacillus subtilis BS2 with a preservation number of CGMCC NO.32165, and Bacillus pumilus BC3 with a preservation number of CGMCC NO.32166 to liquid fermentation to obtain Bacillus cereus BC1 fermentation liquid, Bacillus subtilis BS2 fermentation liquid, and Bacillus pumilus BC3 fermentation liquid, respectively; (2) The fermentation liquid of Bacillus cereus BC1, the fermentation liquid of Bacillus subtilis BS2 and the fermentation liquid of Bacillus pumilus BC3 obtained in step (1) are mixed in a mass ratio of 0.5:2:0.5 to obtain a mixed microbial agent.

3. The method for preparing a mixed microbial agent for preventing and controlling soil-borne diseases of vegetables according to claim 2, characterized in that: The liquid fermentation medium of the Bacillus cereus BC1 is: 3g corn flour, 3g peptone, 2g potassium dihydrogen phosphate, 3g sodium chloride, 4g ammonium sulfate, 0.5g calcium carbonate, 0.2g magnesium sulfate, 0.2g zinc sulfate, 3g yeast extract, 30g glucose, 1000mL water, sterilized at 121°C for 30 minutes, and the liquid fermentation conditions are: fermentation temperature 30°C, rotation speed: 160 rpm, time: 48 hours, inoculation amount 7%, pH setting 7.

5. The concentration of the Bacillus cereus BC1 fermentation liquid is, 10 11 cfu / mL is about 10%.

4. The method for preparing a mixed microbial agent for preventing and controlling soil-borne diseases of vegetables according to claim 2, characterized in that: The liquid fermentation medium of Bacillus subtilis BS2 is: 3.5g corn flour, 3.5g soybean flour, 3g peptone, 2g potassium dihydrogen phosphate, 3g sodium chloride, 5g ammonium sulfate, 2g calcium carbonate, 0.6g magnesium sulfate, 0.6g manganese chloride, 3g yeast extract, 40g glucose, 1000mL water, sterilized at 121℃ for 20 minutes; the liquid fermentation conditions are: fermentation temperature 32℃, speed: 160 rpm, time: 48 hours, inoculation amount is 8%, initial pH setting is 8. The concentration of Bacillus subtilis BS2 fermentation liquid is: 10 11 cfu / mL is about 10%.

5. The method for preparing a mixed microbial agent for preventing and controlling soil-borne diseases of vegetables according to claim 2, characterized in that: The liquid fermentation medium of the Bacillus pumilus BC3 is: 3g corn flour, 3g peptone, 2g potassium dihydrogen phosphate, 3g sodium chloride, 3g ammonium sulfate, 1.5g calcium carbonate, 0.4g magnesium sulfate, 0.4g zinc sulfate, 4g yeast extract, 35g glucose, 1000mL water, sterilized at 121°C for 20 minutes, and the liquid fermentation conditions are: fermentation temperature 30°C, rotation speed: 155 rpm, time: 48 hours, inoculation amount is 8%, pH is set to 7, and the concentration of the Bacillus pumilus BC3 fermentation liquid is: 10 10 -10 11 cfu / Ml.

6. The mixed microbial agent as claimed in claim 1 has the effect of preventing diseases and promoting growth in vegetable planting and its application.

7. The use according to claim 6, characterized in that: The vegetables are peppers, zucchini, radish, rapeseed, sweet potatoes, celery and the like.

8. The use according to claim 6, characterized in that: The following steps are involved: (1) 1-2 weeks before vegetable transplanting or sowing, treat the soil with a mixed microbial solution. Dilute the mixed microbial solution 50-300 times and spray it evenly on the surface, or spray it evenly on organic fertilizer, then mix it evenly and plow it into 10-20 cm of soil to allow the microorganisms to grow and colonize naturally, which has a good inhibitory effect on pathogens that overwinter in the soil; (2) Dip the roots of vegetable seedlings in a mixed microbial solution diluted 50 times before transplanting for 10-30 minutes before transplanting. After dipping the roots, the seedlings are effectively protected by antagonistic bacteria, reducing infection by soil pathogens; (3) Before the disease occurs, irrigate the roots with a mixed microbial solution. Dilute the mixed microbial solution 200-300 times and irrigate each plant with 0.5 catties to 1 catties. Irrigate 1-2 times in total. This can effectively reduce the incidence of field diseases and the number of times chemical pesticides are used.

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