Plant pathogenic soil biological control agent, preparation method, application and application method

Abstract

The present application provides a kind of plant pathogenic soil biological control agent and its preparation method and application technology, which is composed of multiple different genera of biocontrol strains and their metabolite concentrated solid 70-90% and auxiliary materials 10-30% with complementary mechanism and target.The fermentation concentrated liquid of multiple strains is mixed with carrier, and then spray dried to obtain the compound bacteria fermentation liquid concentrated solid;Then it is mixed with auxiliary materials to granulate to obtain the present application.The present application is used for the prevention and control of plant diseases caused by one or several of fusarium, pythium, pathogenic streptomyces, rhizoctonia solani, raoultella, erwinia carotovora and other plant pathogenic bacteria and nematodes that can survive in soil and its pathogenic soil.The present application effectively improves the microecological environment of pathogenic soil, induces plant disease resistance effect, constructs a good plant soil ecosystem and promotes plant growth and development.

Description

Plant-borne pathogenic soil biocontrol agents, preparation methods, applications and application methods Technical Field

[0001] This invention belongs to the field of biological pesticides, specifically relating to a plant pathogenic soil biological control agent with multiple biocontrol strains of different genera and their metabolite concentrates as the main active components, the preparation method, application and application method. Background Technology

[0002] Soil is the substrate for crop growth and the fundamental resource supporting crop development. Soil health largely determines plant health; an unhealthy soil ecosystem makes plants susceptible to harmful soil organisms, especially soil-borne diseases and pests. However, with rapid population growth and socio-economic development, the demand for food, vegetables, and fruits is constantly increasing. The long-term excessive use of chemical fertilizers and pesticides, along with continuous cropping, in an effort to increase crop yields, has caused irreparable damage to the soil, resulting in soil structure degradation, reduced productivity, exacerbated pesticide and fertilizer damage, and severe alterations to the soil microbiome. This leads to the accumulation of large numbers of pathogenic microorganisms in the soil, forming a microbial community dominated by pathogens, which is detrimental to crop growth and makes various soil-borne plant diseases more likely to break out. Soil microorganisms are the main regulators of the dynamic balance of various biochemical processes in the soil, playing a crucial role in soil fertility formation. The proportion of fungi and bacteria in the microbial community is an important biological indicator of soil quality. Soils with a higher proportion of bacteria indicate high soil quality and fertility, while soils with a higher proportion of fungi indicate soil depletion, accumulation of plant pathogens and nematodes, and the formation of pathogenic soil. Such pathogenic soils easily lead to various plant diseases and pests, reduced crop yield and quality, seriously hindering sustainable agricultural development and threatening agricultural product safety.

[0003] Currently, the main control measures for pathogenic soils include chemical control and biological control. Chemical control, primarily using chemical pesticides, has long been a widely used technology due to its advantages such as good short-term effects, low cost, simple application, and a wide variety of available pesticides. However, long-term, irrational use of chemical pesticides can severely pollute the environment, reduce the soil's self-repair capacity, and lead to pesticide resistance in pathogens, affecting control effectiveness. Furthermore, it can easily cause a vicious cycle of altered soil physical, chemical, and biological properties, resulting in a severe decline in soil quality, failing to meet the demands of modern green agricultural control that addresses both the symptoms and root causes. Biological control, characterized by its non-polluting, pollution-free, and comprehensive approach, has been widely recognized in recent years as the most effective technology for controlling pathogenic soils, overcoming the drawbacks of chemical control. It includes organic matter control and biocontrol. Organic matter control involves the rational use of crop residues, which can, to some extent, mimic the effects of non-host plants to suppress harmful soil organisms. It has a mild effect, can fundamentally improve the soil ecosystem, and has a long-lasting effect. However, it is labor-intensive, complex to operate, costly, and slow to produce significant results, requiring a long application period. It also carries the risk of introducing new harmful hosts, making its widespread application difficult. Biocontrol utilizes functional microorganisms with antagonistic properties against pathogens and their metabolites to inhibit or kill harmful soil organisms, stimulate plant protective enzymes and growth hormones, thereby improving the rhizosphere microbiome and controlling pathogenic soil. Biocontrol technology has a clear target, is less likely to induce drug resistance in pathogens, has relatively simple production and application processes, is generally safe and non-toxic to humans and animals, does not pollute the environment, helps maintain ecological balance, promotes crop growth, has good application effects, and is relatively low in cost, making it the most important technical means for controlling pathogenic soil in the future. However, the vast majority of registered and widely used biocontrol agents are single-strain formulations, primarily in wettable powder form. Pathogenic soils already have established dominant indigenous microbial communities. Single biocontrol microorganisms have a narrow control spectrum and, after application, struggle to establish a dominant community in competition with these native microorganisms, resulting in unstable control efficacy. Furthermore, for control requirements in pathogenic soils, wettable powders are inconvenient to use, difficult to control dosage, pose safety risks due to dust dispersion, and are wasteful. Additionally, biocontrol monotypic bacteria and other non-resilience-resistant organisms present in wettable powder formulations of biocontrol microorganisms have a short shelf life. Summary of the Invention

[0004] This invention provides a soil-based biological control agent for plant pathogens. Through the complementary action of multiple biocontrol strains of different genera and their metabolites with complementary mechanisms of action and targets, the biocontrol effect is better and faster than that of a single strain.

[0005] Another objective of this invention is to provide a method for preparing a soil-based biocontrol agent for plant pathogens, which uses organic matter and effective adjuvants to form granules, thereby improving its application stability, safety, operability, and versatility.

[0006] The third objective of this invention is to provide an application technology for a plant pathogenic soil biological control agent, used for the control of plant diseases and their pathogenic soil caused by one or more of the following pathogenic fungi: Fusarium, Phytophthora, Streptomyces, Botrytis cinerea, Rhizoctonia solani, Raulella, Erwinia carotenoides, other plant pathogens that can survive in soil, and nematodes.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A soil-based biological control agent for plant pathogens is formulated from the following raw materials by weight percentage: 70.0%–90.0% effective active ingredient, 3.0%–6.0% dispersant, 1.0%–4.0% wetting agent, 1.0%–3.0% binder, and 5.0%–17.0% filler. The effective active ingredient is a concentrated and solidified fermentation broth of a compound bacterial strain comprising Bacillus subtilis, Bacillus amyloliquefaciens, Bacillus cereus, Bacillus thuringiensis, and Streptomyces urophylla in equal proportions. The Bacillus subtilis is Bacillus subtilis, with accession number CGMCC No. 24484; the Bacillus amyloliquefaciens is Bacillus amyloliquefaciens, with accession number CGMCC No. 24481; and the Bacillus cereus is Bacillus cereus, with accession number CGMCC. No. 24485; the Bacillus thuringiensis is Bacillus thuringiensis, with accession number CGMCC No. 24483; the Streptomyces atroolivaceus is Streptomyces atroolivaceus, with accession number CGMCC No. 24482.

[0009] Further:

[0010] The dispersant is one or a mixture of several of the following in any proportion: lignin sulfonate, naphthalene sulfonate formaldehyde condensate, dispersant BX, dodecyl sulfonate, ammonium sulfate, alkyl succinate sulfonate, dibutylnaphthalene sulfonate, Morwet D-425, sodium low-substituted hydroxypropyl cellulose, and dry starch.

[0011] The wetting agent is one or a mixture of several of the following in any proportion: MorwetEFW, chitosan, sodium alginate, Tween-80, Span-80, monoglyceride, monolaurate, tea seed cake, soapberry, and polyvinyl alcohol.

[0012] The adhesive is one of 3%–8% starch paste, 1%–4% polyvinylpyrrolidone solution, and 1%–5% hydroxypropyl methylcellulose solution.

[0013] The filler is one or a mixture of several of the following in any proportion: diatomaceous earth, bentonite, attapulgite, clay, kaolin, peat moss, silica, humus, dextrin, microcrystalline cellulose (MCC), treated agar, and calcium carbonate.

[0014] A method for preparing a soil-based biocontrol agent for plant pathogens includes the following steps: Fermentation concentrates of Bacillus subtilis, Bacillus amyloliquefaciens, Bacillus cereus, Bacillus thuringiensis, and Streptomyces urophylla are mixed with a carrier and spray-dried at below 70°C to obtain a concentrated solidified compound fermentation broth. Then, 70.0%–90.0% of the concentrated solidified compound fermentation broth, 1.0%–4.0% of a wetting agent, and 5.0%–17.0% of a filler are mixed thoroughly. Next, 3.0%–6.0% of a dispersant is added and mixed well. Finally, 8%–20% of the compound fermentation supernatant is added in 3–5 portions and mixed thoroughly. The mixture is made into a soft material, and finally 1.0% to 3.0% binder is added to granulate it. The wet granules are immediately placed in a clean environment of 25 to 30°C or above and dried. The moisture content of the granules is 5% to 7%. The granules are then passed through sieves with apertures of 0.10 mm and 2.50 mm to remove oversized particles and powder, resulting in a compound bacterial granule preparation, which is a soil biological control preparation for plant diseases. The carrier is one or a mixture of several of the following in any proportion: humic acid, peat, sphagnum moss, alginate, polyacrylamide, clay, corn flour, soybean meal, trehalose, monosodium glutamate, maltodextrin, milk powder, soluble starch, sorbitol D, and gum arabic.

[0015] The application of a plant pathogenic soil biological control agent for the control of plant diseases and their pathogenic soil caused by one or more of the following plant pathogens: Fusarium, Phytophthora, Streptomyces, Botrytis cinerea, Rhizoctonia solani, Raulella, Erwinia carotenoides, Alternaria alternata, nematodes, and other plant pathogens that can survive in the soil.

[0016] A method for applying a soil-based biocontrol agent for plant pathogens, characterized by the following:

[0017] The types and severity of crop diseases were investigated using both seasonal field surveys and harvest surveys, and the appropriate pesticide application methods were determined based on the severity of the diseases.

[0018] A. When the same plant or plants of the same family are first continuously cropped, or when it is the first time to rotate crops, apply this preparation twice as a preventative measure; that is: after the previous crop is harvested, spread it on the ground with organic base fertilizer, and plow deeply, 3.0-5.0 kg / mu; when sowing, apply it in furrows, 2.5-3.5 kg / mu, or spread it with base fertilizer, 3.5-4.5 kg / mu.

[0019] B. When the incidence of various diseases is low, i.e., when the disease incidence rate of plants is less than 10%, apply this preparation twice; that is: after the previous crop is harvested, spread it on the ground with organic base fertilizer, plow deeply, 4.0-6.0 kg / mu; at the time of sowing, apply it in furrows with base fertilizer, 3.0-5.0 kg / mu, or spread it with base fertilizer, 4.0-5.5 kg / mu.

[0020] C. When various diseases occur, i.e., when 10% to 20% of the plants are diseased, apply this preparation three or four times; that is: after harvest, spread it on the ground with organic base fertilizer, and plow deeply, at 6.0 to 8.0 kg / mu; at sowing, apply it in furrows with base fertilizer, at 4.0 to 6.0 kg / mu, or spread it together with base fertilizer at 5.0 to 6.5 kg / mu; during the growth process, when encountering wet and cold or hot and humid climates, spread it on the ground, or dissolve it in irrigation water and apply it, at 6.0 to 8.0 kg / mu. If such climates last for a long time, apply it again in the same amount and method after ten days.

[0021] D. When various diseases occur severely, i.e., when the disease incidence rate of plants exceeds 20%, apply this preparation four or five times; that is: after harvest, spread it on the ground with organic base fertilizer, deep plow, 8.0-10.0 kg / mu; at sowing, apply it in furrows with base fertilizer, 5.0-7.0 kg / mu, or spread it together with base fertilizer, 6.0-8.0 kg / mu; during the growth process, when encountering wet and cold or hot and humid climate, spread it on the ground, or dissolve it in irrigation water and apply, 8.0-10.0 kg / mu. If such climate lasts for a long time, apply it again 1-2 times with the same amount and method after ten days.

[0022] This invention addresses the current state of pathogenic soils and the shortcomings of existing control technologies. It leverages the advantages of probiotic communities, using different biocontrol bacteria species with complementary antagonistic mechanisms and metabolites as the main active ingredients. These bacteria act through different mechanisms during their entry into the soil and competition for ecological niches with pathogens, broadening their spectrum of action, enhancing their competitive colonization ability, and stabilizing control effects. Simultaneously, organic matter and effective adjuvants are incorporated to formulate granules, improving their application stability, safety, operability, and versatility. This provides an effective and green new approach to controlling pathogenic soils. Details are as follows:

[0023] 1. A well-balanced microbial community leads to superior application effects. The main effective active ingredients of this invention consist of five different genera of biocontrol strains and their metabolites with complementary mechanisms of action and target mechanisms. These strains inhibit the growth, reproduction, or infection capacity of target plant pathogens through various mechanisms, including inhibiting protein synthesis, suppressing ergosterol biosynthesis, disrupting cell wall and cell membrane structure and stability, inhibiting cell wall degrading enzyme activity, and nematicidal activity. This effectively controls the spread and damage of corresponding plant diseases. This rationally combined biocontrol microbial community works synergistically in the complex soil environment, resulting in a better and faster biocontrol effect than single-strain formulations, with a control efficacy 11.62%–63.95% higher than that of single-strain preparations.

[0024] 2. Broad spectrum of control. The five different biocontrol bacteria used in the soil-borne biological control agent for plant pathogens have different mechanisms of action and metabolites, resulting in varying degrees of effectiveness against plant pathogens and nematodes with different structural characteristics. This leads to differences in their effective control spectrum. By forming a bacterial community, they complement each other's strengths and weaknesses, effectively expanding the control spectrum of the agent. The control efficacy against pathogenic Fusarium, Phytophthora, pathogenic Streptomyces, Rhizoctonia solani, Raulella, Erwinia carotenoides, nematodes, and other plant pathogens that can survive in the soil is all above 74%.

[0025] 3. Diverse Functions. The application of rational biocontrol bacteria not only effectively controls target plant pathogens in the soil, but also interacts with the soil micro-ecosystem through their reproduction, growth, and metabolic products. This inhibits the number of pathogens, increases the proportion of beneficial bacteria in the soil, effectively improves the micro-ecological environment of pathogenic soil, thereby increasing soil enzyme activity, enhancing soil available nutrients, inducing plant disease resistance, strengthening their disease resistance, constructing a healthy plant-soil ecosystem, and promoting plant growth and development.

[0026] 4. Easy to use, wide applicable range, and long shelf life. The plant pathogenic soil biocontrol agent provided by this invention is a nearly spherical granular preparation with an average particle size of 0.5mm to 2.5mm and a bacterial count greater than 10. 9 CFU / g is an ideal formulation for controlling soil-borne diseases. It can be applied by broadcasting, furrowing or hole application with tillage machinery, or dissolved and applied by root drenching or watering. Compared to liquid formulations, it has a longer shelf life and is convenient to store and transport. It does not disperse during use, is safe for humans, animals, natural enemies, and the environment, and is suitable for traditional planting methods, but even more so for large-scale fully mechanized planting methods. Detailed Implementation

[0027] The present invention will be further described in detail below through principles and specific implementations, so that those skilled in the art can have a more comprehensive understanding of the present invention, but it is not intended to limit the present invention in any way.

[0028] The principle of this invention is explained as follows:

[0029] The main active ingredients of this invention are composed of five different genera of biocontrol bacteria and their metabolites. Because they have different mechanisms of action and targets, they complement each other and enhance each other in application, thereby achieving a broad-spectrum, high-efficiency, and wider-ranging composite target.

[0030] Streptomyces atroolivaceus is rich in metabolically active substances, including compounds such as strychnine, androstenone monosulfate, salvia miltiorrhizin, furanyltetrahydropyrrole, aminotrimethylimidazoquinoline, methylquinoline, ethoxymethylcoumarin, arecoline, pyrimethanil, isodesin, isopiclin, isonicotinic acid, protodiosgenin, and myristic acid. These compounds inhibit the biosynthesis of ergosterol in the cell membrane of pathogenic fungi, disrupting cell membrane structure and stability. Simultaneously, they inhibit the activity of protective enzymes in pathogenic fungi, exacerbating lipid peroxidation and causing rapid cell death. This results in the inhibition of pathogenic Fusarium, Rhizoctonia solani, Phytophthora, Pythium spp., Pseudomonas aeruginosa, Cladosporium, and pathogenic monotyphi. Furthermore, its metabolically active substances also include amino acids and plant hormones, which, in synergistic with these active compounds, activate the resistance system of protected plants, enhancing their stress resistance and synergistically improving the antibacterial effect.

[0031] Bacillus amyloliquefaciens is rich in metabolically active substances, including organic acids, alkaloids, and bacteriostatic agents such as acrylic acid, rhein, pyridylic acid, quinic acid, isocobacterium, isochoryl glycoside, ephemeralin, isopyroxin, piracetamine, demethoxycurcumin, and anestheticin. These fermentation broth active substances increase the lipid peroxidation level of pathogens (leading to a decrease in intracellular malondialdehyde content), disrupting the cell membrane stability of pathogens and strongly inhibiting fungal spore germination and hyphal growth. This achieves the goal of inhibiting plant pathogenic fungi diseases caused by Fusarium oxysporum, Erwinia carotenoides soft rot type, Verticillium dahliae, Rhizoctonia solani, Pseudomonas syringae, and Pseudomonas xanthoides, as well as diseases caused by Cyclosporium and Peronospora. In addition, metabolically active substances include amino acids and melatonin, which enhance plant photosynthesis and carbon assimilation, increase chlorophyll content, and activate the plant's stress resistance system, significantly increasing the activity of its disease-fighting and defense enzymes. This improves the protected plant's ability to resist pathogen infection and stress, and synergistically enhances the antibacterial effect.

[0032] Bacillus subtilis contains metabolically active substances such as indole acids, cytokinins, plant hormones, sugars, and various amino acids, which promote plant growth and development and have a significant growth-promoting effect on protected plants. It also contains antibacterial substances such as epoxyoctadecanoic acid, itaconic acid, styracidin, benapralli, hydroxyphenylcarvedilol, hydroxyfurandan, furanone, methylfuranaldehyde, and nitrosothiazolidinecarboxylic acid. It inhibits the growth of pathogenic fungal cell wall chitinases and related protective enzymes, promotes lipid peroxidation in pathogenic cells, and disrupts the stability of the cell wall and cell membrane, leading to protoplasmic leakage and cell death. Simultaneously, it inhibits the activity of cell wall degrading enzymes in pathogenic fungi, reducing their infectivity to host plants, thus achieving the goal of inhibiting plant pathogens such as Botrytis cinerea, Fusarium oxysporum, Fusarium solani, Rhizoctonia solani, Pseudomonas pathogenica, Rhizoctonia solani, and Pseudomonas nigra.

[0033] Bacillus cereus contains bacteriocinoids and organic acids such as isotetracycline, ethylcarboxamide, methylmalonic acid, methoxyphenol, and ricinoleic acid in its metabolically active substances, acting as an antibacterial agent. Bacillus cereus has high reproductive capacity and spreads rapidly. It inhibits plant pathogens by competing with pathogens for space and suppressing their cell membrane protein synthesis, thus severely damaging the cell membrane. These pathogens include Streptomyces scabica, Ralstonia solanacearum, Erwinia carotenoidea (soft rot type), Erwinia carotenoidea (black rot type), Corynebacterium circumferentiale, Pseudomonas syringae (pathogenic type), Pseudomonas aeruginosa, Fusarium oxysporum, Fusarium sulfide, and Alternaria solanacearum. In addition, its fermentation metabolites include plant growth regulators such as indoleacetic acid, cytokinins, and amino acids, promoting the growth and development of protected plants.

[0034] Bacillus thuringiensis contains a variety of insecticidal and bacteriostatic compounds in its metabolically active substances, including dihydroxycinnamic acid, homovanillic acid, aminobutyraldehyde, ethyl dimethylpyrazine, methyldeoxyrhezin, pyridine bases, peptides, complex amino acids, rotenone, carbapenem dehydropiperazine, and tetrahydropyrrole. These compounds exert their killing or inhibitory effects on lepidopteran pests such as armyworms and diamondback moths, homopteran pests such as aphids, and crop nematodes such as root-knot nematodes and root-rot nematodes through stomach poisoning, contact killing, and growth inhibition. Furthermore, its metabolites also contain monoamino acid groups and phytokinins, which promote robust growth in protected plants and enhance their resistance to diseases and pests.

[0035] Of the five biocontrol bacteria mentioned above, four synergistically attack the cell membranes or cell walls of different or the same target pathogens through different mechanisms, disrupting their structure and stability, or inhibiting the activity of cell wall degrading enzymes. This leads to the cessation of mycelial growth, spore germination, and infection capacity of the target pathogens, achieving a broad-spectrum and highly effective bactericidal effect through combined application. Bacillus thuringiensis, primarily effective against nematodes and other underground pests, compensates for the shortcomings of the other four antibacterial strains, achieving a broad-spectrum target of controlling both diseases and pests. Furthermore, their metabolites contain specific amino acids, phytokinins, and plant growth regulators, which can effectively increase the chlorophyll content of protected plants, activate the plant's stress resistance system, and promote the growth and development of protected plants, synergistically enhancing their antibacterial and insecticidal effects, thereby achieving highly effective control of the spread and damage of corresponding plant diseases and pests.

[0036] The present invention and its beneficial effects are further illustrated below through examples and test cases.

[0037] I. Examples 1-10: The proportions of each group in a plant-pathogenic soil biocontrol agent are shown in Table 1.

[0038] Table 1. Distribution ratio of each component in soil-based biological control agents for plant pathogens

[0039]

[0040]

[0041]

[0042] Note: Prepare 100 kg of plant-pathogenic soil biological control agent.

[0043] II. Examples 11-13: Preparation method of a soil biocontrol agent for plant pathogens

[0044] Example 11, a method for preparing a plant-pathogenic soil biocontrol agent (Formulation of Example 1), comprising the following steps:

[0045] Fermentation concentrates of Bacillus subtilis, Bacillus amyloliquefaciens, Bacillus cereus, Bacillus thuringiensis, and Streptomyces urophylla were mixed with a carrier and spray-dried at below 70°C to obtain a concentrated solidified compound bacterial fermentation broth. Then, 70.0% of the concentrated solidified compound bacterial fermentation broth, 4.0% wetting agent, and 17.0% filler were mixed evenly, followed by the addition of 6.0% dispersant. 20% of the compound bacterial fermentation supernatant was added in five portions and mixed thoroughly to form a soft mass. Finally, 3.0% binder was added dropwise for granulation. The wet granules were immediately placed in a clean environment of 30°C or higher (Class 100,000 or higher) for drying. The granules had a moisture content of 5%. They were then passed through 0.1mm and 2.50mm sieves to remove oversized particles and powder, yielding a compound bacterial granule preparation, i.e., a soil-based biocontrol agent for plant pathogens. The carrier was a 3:2:1:1 mixture of humic acid, polyacrylamide, monosodium glutamate, and maltodextrin.

[0046] Example 12, a method for preparing a plant-pathogenic soil biocontrol agent (formulation of Example 5), comprising the following steps:

[0047] Fermentation concentrates of Bacillus subtilis, Bacillus amyloliquefaciens, Bacillus cereus, Bacillus thuringiensis, and Streptomyces urophylla were mixed with a carrier and spray-dried at below 70°C to obtain a concentrated solidified compound bacterial fermentation broth. Then, 80.0% of the concentrated solidified compound bacterial fermentation broth, 3.0% wetting agent, and 11.5% filler were mixed evenly, followed by the addition of 4.0% dispersant. The supernatant of the compound bacterial fermentation broth was added in four portions and mixed thoroughly to form a soft mass. Finally, 1.5% binder was added dropwise for granulation. The wet granules were immediately placed in a clean environment of 28°C or higher (Class 100,000 or higher) for drying. The granules had a moisture content of 6%. They were then passed through 0.1mm and 2.50mm sieves to remove oversized particles and powder, yielding a compound bacterial granule preparation, i.e., a soil-based biocontrol agent for plant pathogens. The carrier was a mixture of peat, clay, soybean meal, milk powder, and sorbitol D in a 5:2:1:1:0.5 ratio.

[0048] Example 13, a method for preparing a plant-pathogenic soil biocontrol agent (formulation of Example 10), comprising the following steps:

[0049] Fermentation concentrates of Bacillus subtilis, Bacillus amyloliquefaciens, Bacillus cereus, Bacillus thuringiensis, and Streptomyces urophylla were mixed with a carrier and spray-dried at below 70°C to obtain a concentrated solidified compound bacterial fermentation broth. Then, 90.0% of the concentrated solidified compound bacterial fermentation broth, 1.0% wetting agent, and 5.0% filler were mixed evenly, followed by the addition of 3.0% dispersant. The 8% supernatant of the compound bacterial fermentation broth was added in three portions and mixed thoroughly to form a soft mass. Finally, 1.0% binder was added dropwise for granulation. The wet granules were immediately placed in a clean environment of 25°C or higher (Class 100,000 or higher) for drying. The granules had a moisture content of 7%. They were then passed through 0.1mm and 2.50mm sieves to remove oversized particles and powder, yielding a compound bacterial granule preparation, i.e., a soil-based biocontrol agent for plant pathogens. The carrier was a mixture of sodium alginate, corn flour, trehalose, soluble starch, and gum arabic in a 3:2:1:1:0.3 ratio.

[0050] The quality of the products obtained by the preparation methods in Examples 11 to 13: The products are dry, uniformly colored, round or oval granules with a bacterial count greater than 10. 9 CFU / g; uniform particle size, with an average particle size of 0.5mm to 2.5mm; good solubility, 5g of the preparation can be completely dissolved by adding 200ml of hot water and stirring continuously for 3 to 4 minutes; stable properties, 5g of the preparation can be stored in a constant temperature incubator at (54±2)℃ for 14 days or in a low temperature freezer at (-15±1)℃ for 24 hours, and then left to thaw at room temperature for 8 hours. This process can be repeated 3 times, and the viable count is greater than 10. 9 cfu / g.

[0051] III. Application Technology of Soil-Based Biological Control Agents for Plant Pathogens

[0052] 1. Application objectives: For the control of plant diseases caused by one or more of the following pathogenic fungi: Fusarium, Phytophthora, Streptomyces, Rhizoctonia solani, Raulella, Erwinia carotenoides, other plant pathogens that can survive in soil, and nematodes, as well as the control of their pathogenic soils.

[0053] 2. Application method:

[0054] The types and severity of crop diseases were investigated using both seasonal field surveys and harvest surveys. The appropriate pesticide application method was determined based on the severity of the disease.

[0055] 1) When the same plant or plants of the same family are first continuously cropped, or when the first crop rotation is performed, apply the preparation twice as a preventive measure; that is: after the previous crop is harvested, spread it on the ground with organic base fertilizer, and plow deeply, 3-5 kg / mu; when sowing, apply it in furrows, 2.5-3.5 kg / mu, or spread it with base fertilizer, 3.5-4.5 kg / mu.

[0056] 2) When the incidence of various diseases is low, i.e., when the disease incidence rate of plants is less than 10%, apply this preparation twice; that is: after the previous crop is harvested, spread it on the ground with organic base fertilizer, plow deeply, 4-6 kg / mu; when sowing, apply it in furrows with base fertilizer, 3-5 kg / mu, or spread it together with base fertilizer, 4-5.5 kg / mu.

[0057] 3) When various diseases occur, i.e., when 10% to 20% of the plants are diseased, apply this preparation three to four times; that is: after harvest, spread it on the ground with organic base fertilizer and plow deeply, 6 to 8 kg / mu; at sowing, apply it in furrows with base fertilizer, 4 to 6 kg / mu, or spread it together with base fertilizer, 5 to 6.5 kg / mu; during the growth process, when encountering wet and cold or hot and humid climate, spread it on the ground, or dissolve it in irrigation water and apply it, 6 to 8 kg / mu. If this climate lasts for a long time, apply it again in the same amount and method after ten days.

[0058] 4) When various diseases occur severely, i.e., when the disease incidence rate of plants is greater than 20%, apply this preparation four to five times; that is: after harvest, spread it on the ground with organic base fertilizer and plow deeply, 8-10 kg / mu; at sowing, apply it in furrows with base fertilizer, 5-7 kg / mu, or spread it together with base fertilizer, 6-8 kg / mu; during the growth process, when encountering wet and cold or hot and humid climate, spread it on the ground, or dissolve it in irrigation water and apply it, 8-10 kg / mu. If this climate lasts for a long time, apply it again 1-2 times with the same amount and method after ten days.

[0059] IV. Experimental Verification of the Plant-Pathogenic Soil Biocontrol Agent of the Present Invention

[0060] Experimental Example 1: The effect of this invention on the prevention and control of cucumber wilt and damping-off and its influence on plant growth.

[0061] Test agents: Plant pathogenic soil biological control agents and various single-strain preparations were used as test agents, 50% carbendazim wettable powder was used as a positive control, and no treatment was used as a blank control.

[0062] Sporotypes with a spore content greater than 1×10 8Cucumber-specific Fusarium oxysporum and Rhizoctonia solani spore suspensions (cuf / mL) were inoculated at 5 ml / g into a 2:1 mixture of coconut coir and black soil. The mixture was kept moist by spraying water, covered with a thin film, and kept at (26±1)℃ for 5 days under constant temperature and humidity. Then, each test agent was mixed with the treatment substrate at a mass ratio of 1:200, and the mixture was placed in small flowerpots, with water sprayed to ensure humidity greater than 75%. Positive control 1 (1:500) was treated in the same way. Plump cucumber seeds were selected, disinfected with 70% alcohol for 1 min, then disinfected with 0.5% sodium hypochlorite for 1 min, rinsed 5–6 times with sterile water, and then soaked in sterile water at 40℃ for 2 h. Germination was carried out at (30±1)℃ in the dark. After most seeds germinated, seeds with consistent germination were selected and sown in small flowerpots containing the treatment substrate, 10 seeds per pot, for a total of 6 pots per treatment. The plants were cultured under a 10h / 14h photoperiod and managed normally. Emergence, plant growth, and disease incidence were observed and recorded daily. Thirty days after emergence (when the number of diseased plants in the blank control exceeded 10%), the treated plants were removed, and the number of diseased plants and their disease severity were recorded. The disease incidence rate was calculated, and the control effect was assessed. Simultaneously, plant height, root weight, and stem and leaf weight were measured to evaluate the growth-promoting effect. The experimental results are shown in Table 2.

[0063] Calculation formula: Disease incidence rate % = Number of diseased plants / Total number of plants surveyed × 100

[0064] Control efficacy % = (Control disease incidence rate - Treatment disease incidence rate) / Control disease incidence rate × 100

[0065] Table 2. The control effect of this invention on cucumber wilt and damping-off and its growth-promoting effect.

[0066]

[0067] Notes: 1. BAS, BAC, BAT, BSS, and STRA formulations are single-strain preparations for controlling plant pathogens in soil, prepared according to the formulation of Example 1, using the strains Bacillus subtilis, Bacillus cereus, Bacillus thuringiensis, Bacillus amyloliquefaciens, and Streptomyces urophylla preserved in this invention; 2. The positive control is 50% carbendazim wettable powder; 3. Plant height, root weight, and stem and leaf weight in the table are the average values ​​of all tested plants; 4. Different lowercase letters in the same column in the table indicate significant differences at the 0.05 level (p≤0.05).

[0068] Example 2: The effect of this invention on the control of wilt disease in cabbage and its influence on plant growth.

[0069] Test agents: Plant pathogenic soil biological control agents and various single-strain preparations were used as test agents, 64% cymoxanil-mancozeb wettable powder was used as a positive control, and no treatment was used as a blank control.

[0070] Sporotypes with a spore content greater than 1×10 8 A 5 ml / g inoculation of *Fusarium oxysporum* spore suspension (cuf / mL) and *Fusarium solani* spore suspension was inoculated into a 2:1 mixture of coconut coir and black soil. The mixture was kept moist by spraying water, covered with a thin film, and kept at (26±1)℃ for 5 days under constant temperature and humidity. The test agent was then mixed with the treatment substrate at a mass ratio of 1:300, and the mixture was placed in small flowerpots, with water sprayed to ensure humidity greater than 75%. A positive control (1:500) was treated in the same manner. Plump cabbage seeds were selected, disinfected with 70% alcohol for 1 min, then with 0.5% sodium hypochlorite for 1 min, rinsed 5–6 times with sterile water, and then soaked in sterile water at 40℃ for 2 h. Germination was carried out at (27±1)℃ in the dark. After most seeds germinated, seeds with consistent germination were selected and sown in small flowerpots containing the treatment substrate, 12 seeds per pot, 5 pots per treatment. Seedlings were cultured under a 10h / 14h photoperiod and managed normally. Seedling survival, plant growth, and disease incidence were observed and recorded daily. After 40 days (when the number of diseased plants in the blank control exceeded 10%), the treated plants were removed, and the number of diseased plants and their disease severity were measured. The disease incidence rate was calculated, and the control effect was evaluated. Simultaneously, plant height, root weight, and fresh plant weight were measured to assess the growth-promoting effect. The experimental results are shown in Table 3.

[0071] Calculation formula: Disease incidence rate % = Number of diseased plants / Total number of plants surveyed × 100

[0072] Control efficacy % = (Control disease incidence rate - Treatment disease incidence rate) / Control disease incidence rate × 100

[0073] Table 3. The control effect of this invention on wilt disease of cabbage and its growth-promoting effect.

[0074]

[0075] Notes: 1. BAS, BAC, BAT, BSS, and STRA formulations are single-strain formulations for controlling plant pathogens in soil, prepared according to the formulation of Example 6 using the strains Bacillus subtilis, Bacillus cereus, Bacillus thuringiensis, Bacillus amyloliquefaciens, and Streptomyces urophylla preserved in this invention; 2. The positive control is 64% cymoxanil-mancozeb wettable powder; 3. Plant height, root weight, and stem and leaf weight in the table are the average values ​​of all tested plants; 4. Different lowercase letters in the same column in the table indicate significant differences at the 0.05 level (p≤0.05).

[0076] Example 3: The effect of this invention on the control of bacterial wilt in tomatoes and its influence on plant growth.

[0077] Test agents: Plant pathogenic soil biological control agents and various single-strain preparations were used as test agents, 50% carbendazim wettable powder was used as a positive control, and no treatment was used as a blank control.

[0078] Sporotypes with a spore content greater than 1×10 8 A 6 ml / g suspension of *Raurus solanaceae* bacterial suspension was inoculated into a 2:1 mixture of coconut coir and black soil. The mixture was kept moist by spraying water, covered with a thin film, and incubated at (26±1) ℃ for 2 days. The test agent was then mixed with the treatment substrate at a ratio of 1:300 and placed in small flowerpots, maintaining a humidity greater than 75%. A positive control (1:500) was treated in the same manner. Plump tomato seeds were selected and disinfected by soaking in 70% alcohol for 1 min, then in 0.5% sodium hypochlorite solution for 1 min, and rinsed 3–4 times with sterile water. The disinfected tomato seeds were placed on sterile petri dishes lined with filter paper, 5 mL of sterile water was added, the dishes were sealed, and the dishes were incubated in the dark at 28±1 ℃ for 48–60 h. Healthy, uniformly sprouted tomato seeds were selected and sown in small flowerpots containing the treatment substrate, with 8 seedlings per pot, for a total of 8 treatments. The seedlings were cultured under a 10h / 14h photoperiod and managed routinely. Seedling survival, plant growth, and disease incidence were observed and recorded daily. 25–30 days after emergence (when the number of diseased plants in the blank control exceeded 10%), the treated plants were removed, and the number and severity of disease were measured. The disease incidence rate was calculated, and the control effect was assessed. Simultaneously, plant height, root weight, and fresh weight were measured to evaluate the growth-promoting effect. The experimental results are shown in Table 4.

[0079] Calculation formula: Disease incidence rate % = Number of diseased plants / Total number of plants surveyed × 100

[0080] Control efficacy % = (Control disease incidence rate - Treatment disease incidence rate) / Control disease incidence rate × 100

[0081] Table 4. The control effect and growth-promoting effect of this invention on bacterial wilt of tomato.

[0082]

[0083] Notes: 1. BAS, BAC, BAT, BSS, and STRA preparations are single-strain preparations for controlling plant pathogens in soil, prepared according to the proportions of Bacillus subtilis, Bacillus cereus, Bacillus thuringiensis, Bacillus amyloliquefaciens, and Streptomyces urophylla preserved in this invention, respectively; 2. The positive control is 50% carbendazim wettable powder; 3. Plant height, root weight, and stem and leaf weight in the table are the average values ​​of all tested plants; 4. Different lowercase letters in the same column in the table indicate significant differences at the 0.05 level (p≤0.05).

[0084] Example 4: The effect of this invention on the prevention and control of soil diseases in continuously cropped cabbage.

[0085] The experimental plot was an irrigated field that had been continuously cropped with cruciferous vegetables for two years. Rainfall and temperature were slightly higher than in previous years during the experimental year. The cabbage variety used in the experiment was Zhonggan 21. This experiment was a summer crop; a disease-resistant variety was planted in the spring crop, and no disease was observed. At harvest, the main pathogens found in the soil and rhizosphere were Fusarium, Pseudomonas aeruginosa, Rhizoctonia solani, and Erwinia carotene. Soil pests were treated with biological insecticides.

[0086] The experiment consisted of three treatments: one test agent (a soil-based biocontrol agent for plant pathogens), one positive control (64% cymoxanil·mancozeb wettable powder), and one blank control (no treatment). Each treatment was replicated five times, resulting in 15 experimental plots, each plot measuring 20 m². 2 The plants were randomly assigned to blocks. A flat, unmulched planting model was adopted. Four applications of pesticides were used: after the previous crop harvest, before transplanting, and during the growing season. Each treatment pesticide was mixed with the substrate or sprinkled on the ground according to the dosages in Table 5, followed by sowing, land preparation or irrigation, and routine management. Seedling emergence, plant growth, and disease occurrence were observed and recorded throughout the growth period and at harvest. Disease types, disease incidence, and control effectiveness were statistically analyzed. The experimental results are shown in Table 5.

[0087] Calculation formula: Disease incidence rate (%) = (Number of diseased plants / Total number of plants surveyed) × 100

[0088] Control efficacy (%) = (Disease rate in control area - Disease rate in treatment area) / Disease rate in control area × 100

[0089] Table 5. The control effect of this invention on soil diseases of continuously cropped cabbage.

[0090]

[0091] Notes: 1. This invention is prepared according to the formulation of Example 9; 2. Different lowercase letters in the same column of the table indicate significant differences at the 0.05 level (p≤0.05).

[0092] Example 5: The effect of this invention on the control of soil-borne diseases in potatoes and its impact on yield.

[0093] The experimental plot had been continuously cropped with potatoes for 5 years, with abundant rainfall and high temperatures in the year of the experiment. The potato variety used was Longshu No. 7. A survey conducted the year prior to the experiment using the growing season field survey and harvest inspection methods revealed that the potatoes in the experimental plot were mainly affected by scab, early blight, wilt, dry rot, soft rot, root rot, and nematodes. The disease rate of potatoes was 14.35%, and the disease rate of plants was 12.70%. Soil pathogen detection also revealed Phytophthora. Underground pests were controlled by collection and treatment with biological insecticides.

[0094] The experiment consisted of three treatments: one test agent (a soil-based biocontrol agent for plant pathogens), one positive control (50% carbendazim wettable powder), and one blank control (no treatment). Each treatment was replicated three times, resulting in a total of nine experimental plots, each with an area of ​​35 m². 2 The potato plants were randomly assigned to blocks. A raised-ridge, mulched planting method was adopted, with mechanized planting throughout. Two rows were planted per ridge, with each ridge being 120cm wide (including furrows), 2cm high, 70cm wide, and 30cm plant spacing. Four applications of pesticides were used: after the previous crop harvest, at sowing in the same year, and during periods of high rainfall and temperature in the growing season. The pesticides for each treatment were applied to the ground, ridge surface, or furrow according to the dosages in Table 6, followed by land preparation, sowing, and covering with soil. Cultivation and management were the same as for other cultivated land. Throughout the potato growth period and at harvest, seedling emergence, plant growth, disease occurrence, and yield were observed and recorded. Disease types, disease incidence, diseased tuber incidence, and yield were statistically analyzed. The experimental results are shown in Table 6.

[0095] Calculation formula:

[0096] Disease incidence rate (%) = (Number of diseased plants / Total number of plants surveyed) × 100

[0097] Control efficacy (%) = (Disease rate in control area - Disease rate in treatment area) / Disease rate in control area × 100

[0098] Disease incidence rate (%) = (Number of diseased tubers / Total number of tubers surveyed) × 100

[0099] Control efficacy (%) = (Disease rate in control area - Disease rate in treatment area) / Disease rate in control area × 100

[0100] Table 6. The control effect and yield impact of this invention on soil diseases of potatoes grown in arid areas under continuous cropping for many years.

[0101]

[0102] Notes: 1. This invention is prepared according to the formula in Example 10; 2. In the disease survey in the table, early blight and wilt plants showed typical diseased plants on the above-ground parts, while other diseases mainly affected the tubers. The control effect is calculated based on the percentage of infected plants for early blight and wilt, and the percentage of infected tubers for other diseases; 3. The yield of the blank control was 1538.26 kg / 667 m². 2 4. If the lowercase letters in the same row of the table are different, it indicates that there is a significant difference at the 0.05 level (p≤0.05).

[0103] Data analysis: The results of potted and field trials in Examples 1-5 show that the plant pathogenic soil biological control agent provided by this invention has a good control effect on plant diseases caused by plant pathogens such as Fusarium, Phytophthora, Streptomyces, Rhizoctonia solani, Raulella, Erwinia carotenoides, Pseudomonas thunbergii, and nematodes that survive in the soil, as well as the pathogenic soil. At the same time, it also has a significant effect on promoting growth and increasing yield of the protected plants (Tables 2, 3, 4, 5, 6), demonstrating its advantages. The pot experiment results of Examples 1-3 showed (Tables 2, 3, 4) that the plant pathogenic soil biological control agent provided by the present invention had a control effect of 82.35%-87.64% on soil-borne diseases such as Fusarium wilt, damping-off, and bacterial wilt caused by Fusarium, Rhizoctonia solani, and Raulella ovale, which are common, highly damaging, and difficult to control. The control effect was much stronger than that of each single-strain agent, with a significant difference (p≤0.05). The control effect was slightly stronger than that of the positive control (50% carbendazim wettable powder and 64% cymoxanil-mancozeb wettable powder), but there was no significant difference (p>0.05). The field trial results of Examples 4 and 5 (Tables 5 and 6) show that the plant pathogenic soil biological control agent provided by this invention has a control effect of 74.46%–78.84% on diseases caused by pathogens such as Fusarium, Phytophthora, Streptomyces, Rhizoctonia solani, Erwinia carota soft rot, Pseudomonas aeruginosa, and nematodes, which are common and cause serious damage in soils where cabbage and potato are continuously cropped for many years. Most of these effects are comparable to the positive controls (64% cymoxanil·mancozeb wettable powder and 50% carbendazim wettable powder), with no significant difference (p > 0.05). The control effect on Fusarium wilt, damping-off, soft rot, and root rot is 76.31%–78.84%. The efficacy of the plant pathogen control agent provided in this invention was significantly better than that of the positive control (64% carbendazim-mancozeb wettable powder and 50% thiophanate-methyl wettable powder), with a statistically significant difference (p≤0.05). Furthermore, all experimental results (Tables 2-6) showed that the agent significantly promoted the emergence and growth of protected plants (cucumber, tomato, and cabbage) and significantly increased potato yield by 15.83%, while the positive control (50% thiophanate-methyl wettable powder and 64% carbendazim-mancozeb wettable powder) showed weaker growth-promoting and yield-increasing effects, with a statistically significant difference between the two (p≤0.05).

Claims

1. A soil-based biological control agent for plant pathogens, characterized in that, It is formulated from the following raw materials by weight percentage: 70.0%–90.0% effective active ingredient, 3.0%–6.0% dispersant, 1.0%–4.0% wetting agent, 1.0%–3.0% binder, and 5.0%–17.0% filler; the effective active ingredient is a concentrated solidified product of fermentation broth of a compound bacteria of Bacillus subtilis, Bacillus amyloliquefaciens, Bacillus cereus, Bacillus thuringiensis, and Streptomyces urophylla in equal proportions; the Bacillus subtilis is Bacillus subtilis, with accession number CGMCC No. 24484; the Bacillus amyloliquefaciens is Bacillus amyloliquefaciens, with accession number CGMCC No. 24481; the Bacillus cereus is Bacillus cereus, with accession number CGMCC No. 24485; the Bacillus thuringiensis is Bacillus thuringiensis. The fungus *Streptomyces thuringiensis*, with accession number CGMCC No. 24483, is described; the *Streptomyces atroolivaceus*, with accession number CGMCC No. 24482, is also described; the plant pathogenic soil biocontrol agent has a bacterial content greater than 10. 9 The dispersant is one or a mixture of several of the following in any proportion: lignin sulfonate, naphthalene sulfonate formaldehyde condensate, separating powder BX, dodecyl sulfonate, ammonium sulfate, alkyl succinate sulfonate, dibutylnaphthalene sulfonate, Morwet D-425, sodium low-substituted hydroxypropyl cellulose, and dry starch; the wetting agent is one or a mixture of several of the following in any proportion: Morwet EFW, chitosan, sodium alginate, Tween-80, Span-80, monoglyceride, monolaurate, tea seed cake, soapberry, and polyvinyl alcohol; the binder is one of the following: 3%–8% starch paste, 1%–4% polyvinylpyrrolidone solution, and 1%–5% hydroxypropyl methylcellulose solution; the filler is one or a mixture of several of the following in any proportion: diatomaceous earth, bentonite, attapulgite, clay, kaolin, peat moss, silica, humus, dextrin, microcrystalline cellulose MCC, treated agar, and calcium carbonate.

2. The method for preparing a plant-pathogenic soil biocontrol agent as described in claim 1, characterized in that, The specific steps are as follows: The fermentation concentrates of Bacillus subtilis, Bacillus amyloliquefaciens, Bacillus cereus, Bacillus thuringiensis, and Streptomyces urophylla are mixed with a carrier and spray-dried at below 70°C to obtain a concentrated solidified compound fermentation broth. Then, 70.0%–90.0% of the concentrated solidified compound fermentation broth, 1.0%–4.0% of the wetting agent, and 5.0%–17.0% of the filler are mixed evenly. Next, 3.0%–6.0% of the dispersant is added and mixed thoroughly. Then, 8%–20% of the compound fermentation supernatant is added in 3–5 portions and mixed thoroughly to form a soft material. Finally, the mixture is dripped... 1.0%–3.0% binder, granulation; wet granules are immediately placed in a clean environment of 25–30℃ or higher (Class 100,000 or higher) for drying, with a granule moisture content of 5%–7%, and passed through sieves with apertures of 0.10 mm and 2.50 mm to remove oversized particles and powder, yielding a compound bacterial granule preparation, i.e., a soil biological control agent for plant pathogens; the carrier is one or a mixture of several of the following in any proportion: humic acid, peat, sphagnum moss, alginate, polyacrylamide, clay, corn flour, soybean meal, trehalose, monosodium glutamate, maltodextrin, milk powder, soluble starch, sorbitol D, and gum arabic.

3. The application of the plant pathogenic soil biological control agent as described in claim 1, characterized in that: The application is for the prevention and control of cucumber wilt, cucumber damping-off, cabbage wilt, cabbage blackleg, cabbage soft rot, cabbage damping-off, tomato bacterial wilt, potato wilt, potato dry rot, potato early blight, potato scab, potato root rot and potato soft rot.

4. The application of the plant pathogenic soil biological control agent as described in claim 3, characterized in that, Specifically, the following methods are used: During the growing season, a field survey and a harvest inspection are employed to investigate the types and severity of crop diseases. The method of application is determined based on the severity of the disease: A. When the same plant or plant of the same family is first continuously cropped, or during the first crop rotation, the agent is applied preventatively twice; that is: after the previous crop is harvested, it is spread on the ground with organic base fertilizer, and after deep plowing, at a rate of 3.0–5.0 kg / mu; at sowing, it is applied in furrows at a rate of 2.5–3.5 kg / mu, or spread with base fertilizer at a rate of 3.5–4.5 kg / mu. A. For mild outbreaks of various diseases, i.e., when the disease incidence rate of plants is less than 10%, apply this preparation twice; that is: after the previous crop harvest, spread it on the ground with organic base fertilizer, deep plow, 4.0-6.0 kg / mu; at sowing, apply it in furrows with base fertilizer, 3.0-5.0 kg / mu, or spread it with base fertilizer, 4.0-5.5 kg / mu; C. For moderate outbreaks of various diseases, i.e., when the disease incidence rate of plants is 10%-20%, apply this preparation three or four times; that is: after harvest, apply it with organic base fertilizer... Spread on the ground, deep plow, 6.0–8.0 kg / mu; at sowing, apply with base fertilizer in furrows, 4.0–6.0 kg / mu, or spread with base fertilizer, 5.0–6.5 kg / mu; during the growing season, in damp and cold or hot and humid weather, spread on the ground, or dissolve in irrigation water and apply, 6.0–8.0 kg / mu. If this weather lasts for a long time, apply again in the same amount and method after ten days; D. When various diseases occur severely, i.e., when the disease incidence rate of plants is greater than 20%, Apply the preparation four or five times: after harvest, spread it on the ground with organic base fertilizer, and plow deeply, at a rate of 8.0–10.0 kg / mu; at sowing, apply it in furrows with base fertilizer at a rate of 5.0–7.0 kg / mu, or spread it together with base fertilizer at a rate of 6.0–8.0 kg / mu; during the growth process, if encountering damp and cold or hot and humid weather, spread it on the ground or dissolve it in irrigation water and apply it, at a rate of 8.0–10.0 kg / mu. If such weather lasts for a long time, apply it again 1–2 times with the same amount and method after ten days.

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