Seed coating agent as well as preparation method and application thereof

Abstract

The invention discloses a seed coating agent as well as a preparation method and application thereof, and belongs to the technical field of pesticide mixtures. The active ingredients of the seed coating agent are fluxapyroxad, clothianidin and bacillus subtilis. The seed coating agent has double effects of disease and pest control and growth promotion, can synchronously control seed-borne diseases, soil-borne diseases and seedling-stage pests, and remarkably improves the control effect on diseases and pests of cereal crops; meanwhile, crop root growth and development can be promoted, and the survival rate is increased through rooting and seedling strengthening. The technical defects of insufficient prevention effect, high cost and serious pollution in traditional seed treatment are overcome in a low-toxicity environment-friendly mode, the defect that a traditional seed coating agent is difficult to take both fast-acting property and long-acting property into account is overcome, and an efficient and environment-friendly technical scheme is provided for seed treatment.

Description

Technical Field

[0001] This application belongs to the field of pesticide mixture technology, specifically relating to a seed coating agent, its preparation method, and its application. Background Technology

[0002] Currently, two types of pests and diseases in wheat production are highly specific and difficult to control: one is stem rot, a typical soil-borne and seed-borne complex disease with strong regional adaptability. For example, the Jianghuai type of stem rot is particularly adapted to the local climate conditions of rainy springs and high soil moisture. In recent years, in high-humidity areas, stem rot caused by *Microdochium nivale* has gradually become dominant. Unlike the common *Fusarium graminearum*, *Microdochium nivale* infection progresses more slowly, mainly causing leaf sheath browning and leaf blight; while *Fusarium graminearum* is more likely to cause stem rot, whiteheads, and even death of the entire plant, posing a greater threat to yield. Because traditional foliar or soil application of pesticides cannot penetrate to the infected stem base, the control effect is less than 30%, and the problem of pesticide resistance is prominent. Single chemical agents are difficult to effectively block its infection cycle. The other type is the oriental mole cricket (*Gryllotalpa orientalis*), which has developed behavioral resistance in the Yangtze River basin. The resistant population CJ-R in the clay rice-growing areas of the Chaohu Plain, Jianghan Plain, and Poyang Lake region has evolved significant behavioral resistance due to long-term exposure to traditional insecticides. This resistance manifests as active avoidance of organophosphates and carbamates, such as by altering their activity depth to avoid topsoil pesticides and reducing feeding frequency to lower the risk of poisoning. This has led to a decrease in the effectiveness of traditional contact and stomach poison pesticides to below 50%. The insect, in both nymph and adult forms, feeds on wheat seeds, young roots, and tender stems, causing gaps in the rows and seedlings. Its complex underground movement makes it difficult for conventional spraying or application of pesticides to accurately reach the insects. Furthermore, the warm and humid climate of the Yangtze River basin extends its activity period, resulting in more generations per year than northern populations, and a continuous period of damage lasting 3-4 months, making current pesticide control extremely challenging.

[0003] Seed coating technology achieves slow-release and sustained action of pesticides by forming a protective film on the seed surface. While this can improve control efficiency to some extent, current seed treatment technologies and coating agents have significant shortcomings in controlling the two types of pests and diseases mentioned above, mainly in the following three aspects: (1) Poor compatibility between chemical and biological agents: If chemical bactericides and microbial agents are added to traditional coating agents at the same time, the agents often become inactive due to the inhibitory effect of chemical components on microorganisms. It is difficult to build a synergistic prevention and control system that combines "rapid effect + long-term effect" and cannot effectively resist the continuous infection of resistant fungi and insects.

[0004] (2) Insufficient control spectrum and specificity: Existing single chemical coating agents (such as the combination of thiamethoxam and chemical fungicide used in Chinese patent application CN106614693A) have a certain broad spectrum, but still lack the ability to conduct directionally to the stem base of Microdochium nivale, and cannot overcome the behavioral resistance of mole cricket, resulting in limited control effect on the two types of specific pests and diseases.

[0005] (3) There is a contradiction between environmental safety and persistence: Increasing the dosage of neonicotinoid insecticides to enhance the control effect often increases the exposure risk to pollinating insects. In addition, the release of traditional formulations of pesticides is too fast, which cannot match the infection cycle of wheat stem base rot, nor can it continuously control mole crickets. At the same time, it will also aggravate soil residue and ecological pollution.

[0006] Therefore, developing a seed coating agent that can achieve synergistic effects between chemical agents and microbial agents, while also being targeted, long-lasting, and environmentally friendly, has become a key need for breakthroughs in the field of wheat pest and disease control, specifically targeting the specific damage caused by stem base rot in the Jianghuai region and the behaviorally resistant mole cricket in the Yangtze River Basin. Summary of the Invention

[0007] In view of this, the primary objective of this application is to provide a seed coating agent containing three active ingredients: fluopyram, thiamethoxam, and Bacillus subtilis, which form a synergistic control system of "rapid-acting + long-lasting effect." This achieves a comprehensive effect of "simultaneous prevention of diseases and pests, promotion of growth and increased efficiency, and safety and environmental protection," providing an efficient seed treatment solution for agricultural production.

[0008] To achieve the above objectives, this application adopts the following technical solution: The first aspect of this application discloses a seed coating agent containing active ingredients, namely fluopyram, thiamethoxam, and Bacillus subtilis; wherein the mass ratio of fluopyram to thiamethoxam is (1-10):(0.5-5), and the spore concentration of Bacillus subtilis is 1-10 billion CFU / g.

[0009] Another aspect of this application discloses a method for preparing the seed coating agent described in this application, comprising the following steps: Chemical coating: Mix fluopyram, thiamethoxam and other excipients according to the formula, add water and grind to form a suspension; spray evenly on the seed surface and dry at low temperature; Bio-coating: Bacillus subtilis spore powder is mixed with other excipients according to the formula and attached to the outside of the chemical layer using fluidized bed coating technology, while controlling the temperature to ≤40℃ and the humidity to ≤30%.

[0010] Another aspect of this application discloses the application of the seed coating agent described in this application, or the seed coating agent prepared by the method described, in the prevention and control of underground pests and seedling diseases and pests in crops.

[0011] The beneficial effects of this application are: The active ingredients of the seed coating agent disclosed in this application are fluopyram, Bacillus subtilis, and thiamethoxam. Fluopyram can quickly kill pathogens carried on the seed surface (fast-acting), thiamethoxam controls seedling pests through systemic action, and Bacillus subtilis continuously inhibits soil-borne diseases and secretes auxin to promote growth after colonization in the soil (long-acting). The three form a synergistic control system of "fast-acting + long-acting".

[0012] In this application, a layered coating process is used to achieve physical isolation between chemical and biological components, solving the compatibility problem between chemical agents and microbial agents, avoiding direct contact between fluopyram and Bacillus subtilis, thus solving the problem of poor compatibility between the two and increasing the survival rate of microorganisms to over 80%.

[0013] The seed coating agent described in this application creatively combines pest and disease control with growth promotion. It simultaneously controls seed-borne diseases, soil-borne diseases, and seedling pests, significantly improving efficacy against pests and diseases in cereal crops. Simultaneously, it promotes root growth and development, resulting in stronger seedlings and higher survival rates. This achieves a comprehensive effect of "simultaneous pest and disease control, growth promotion and efficiency enhancement, and safety and environmental friendliness," providing an efficient seed treatment solution for agricultural production. Detailed Implementation

[0014] The embodiments of this application will be clearly and completely described below. The technical solutions in the embodiments described below are exemplary and only possible technical implementations of this application, not all possible implementations. Those skilled in the art can combine the embodiments of this application to obtain other embodiments without creative effort, and these embodiments are also within the protection scope of this application.

[0015] The first aspect of this application discloses a seed coating agent containing active ingredients, said active ingredients being fluopyram, thiamethoxam, and Bacillus subtilis.

[0016] Fluxapyroxad, belonging to the SDHI class of fungicides, has the chemical name 3-(difluoromethyl)-1-methyl-N-(3',4',5'-trifluorobiphenyl-2-yl)-1H-pyrazole-4-carboxamide and the molecular formula C2. 18 H 12 F5N3O, with a molecular weight of 381.31 and CAS number 907204-31-3, has the following molecular structure: ; Fluopyram inhibits succinate dehydrogenase in mitochondrial respiratory chain complex II, thereby suppressing spore germination, germ tube, and mycelial growth of pathogens, thus controlling fungal diseases. It has strong systemic properties, allowing absorption through the roots and upward transport to all parts of the plant; it possesses both protective and curative effects, effective against various higher fungal diseases; it exhibits excellent activity against basidiomycetes, ascomycetes, and deuteromycete pathogens, especially highly effective against Fusarium pathogens.

[0017] Clothiadin is a neonicotinoid insecticide with the chemical name (E)-1-(2-chloro-1,3-thiazolyl-5-ylmethyl)-3-methyl-2-nitroguanidine, molecular formula C6H8ClN5O2S, molecular weight 249.68, CAS number 210880-92-5, and its molecular structure is as follows: ; Its mechanism of action is to act on nicotinic acetylcholine receptors in the insect nervous system, exhibiting contact, stomach poison, and systemic activity. Thiamethoxam is mainly used to control aphids, leafhoppers, thrips, planthoppers, mirid bugs, cabbage caterpillars, and other Hemiptera, Coleoptera, Diptera, and some Lepidoptera pests on crops such as rice, vegetables, and fruit trees.

[0018] Bacillus subtilis is a Gram-positive bacterium widely found in soil, decaying organic matter, and various environments. Its CAS number is 68038-70-0. Its mechanisms of action include: (1) competition: colonizing the plant rhizosphere and competing for the living space of pathogens; (2) secretion of antimicrobial substances: producing lipopeptide antibiotics (such as iturin and fengycin), proteases, etc., to inhibit the growth of pathogens; (3) induction of plant resistance: activating the plant immune system and enhancing resistance to pathogens; (4) growth promotion: secreting auxin-like substances to promote root development. Currently, the main targets of Bacillus subtilis for disease control are soil-borne diseases (such as root rot and stem base rot) and seed-borne diseases (such as wheat scab); it has a significant inhibitory effect on pathogens such as Fusarium and Rhizoctonia, and can also improve the soil microecological environment.

[0019] In this application, the above three agents were combined, and surprisingly, it was found that they could produce good control and pest control effects on crop diseases and pests, especially on cereal crops (such as wheat). Specifically, the seed coating agent in this application utilizes three active ingredients to form a synergistic control system of "fast-acting + long-acting". Fluopyram can quickly kill pathogens carried on the seed surface (fast-acting), thiamethoxam controls seedling pests through systemic action, and Bacillus subtilis continuously inhibits soil-borne diseases and secretes auxin to promote growth after colonization in the soil (long-acting), thereby achieving disease and pest control and enhanced growth promotion.

[0020] It is understood that the content of the three active ingredients in the seed coating agent can be confirmed experimentally, and those skilled in the art possess this capability. In some specific examples of this application, based on the seed coating agent, the mass ratio of fluopyram to thiamethoxam is (1-10):(0.5-5), and the spore concentration of Bacillus subtilis is 1-10 billion CFU / g. By adjusting and optimizing the ratio of active ingredients, better control effects can be obtained. Therefore, as a preferred example, the mass ratio of fluopyram to thiamethoxam is 5:2.5, and the spore concentration of Bacillus subtilis is 2.5 billion CFU / g.

[0021] Similarly, in this application, the proportion of the active ingredient in the seed coating agent can be determined experimentally. As an example, the active ingredient accounts for 0.1%-50% of the total mass of the seed coating agent.

[0022] It is understood that the seed coating agent also includes at least one pesticide-acceptable excipient. The excipient includes, but is not limited to, at least one of the following: dispersants, antifreeze agents, anti-caking agents, suspending agents, film-forming agents, fungicides, pH adjusters, colorants, UV shielding agents, microbial protectants, and media. In actual formulation, those skilled in the art can select one or more excipients from the above categories for compounding according to formulation requirements and agronomic requirements.

[0023] The specific types of excipients can be selected according to the actual situation, without any special restrictions.

[0024] In some specific examples, the dispersant may be selected from at least one of phosphate esters, lignin sulfonates, benzene sulfonates, alkylphenol polyoxyethylene ether methyl ether condensate sulfates, alkyl sulfonate calcium salts, naphthalene sulfonate formaldehyde condensate sodium salts, alkylphenol polyoxyethylene ethers, fatty acid polyoxyethylene esters, fatty amine polyoxyethylene ethers, and glycerol fatty acid ester polyoxyethylene ethers. The antifreeze may be selected from at least one of ethylene glycol, propylene glycol, glycerol, polyethylene glycol, sorbitol, and urea. The anticaking agent may include, but is not limited to, sodium aluminosilicate, tricalcium phosphate, and silica. The antifungal agent may be selected from at least one of benzisothiazolinone, sodium benzoate, sorbic acid, and propylparaben. The pH adjuster may be selected from sodium hydroxide, ammonia, acetic acid, hydrochloric acid, citric acid, and phosphoric acid. The film-forming agent is preferably chitosan. The ultraviolet shielding agent is preferably titanium dioxide. The microbial protectant is preferably trehalose. The colorant (warning color) may be selected from carmine, Acid Red, or Acid Red B. The medium is typically water, which is added to bring the balance to 100% based on the active ingredients and excipients.

[0025] In this application, the seed coating agent preferably has a double-layer structure, comprising an inner chemical agent layer and an outer microbial agent layer. The inner layer contains the active ingredients fluopyram and thiamethoxam, preferably with fluopyram accounting for 0.1% to 10% by mass and thiamethoxam accounting for 0.05% to 5% by mass. The outer layer contains the microbial agent Bacillus subtilis, with an effective viable count preferably between 1 and 10 billion CFU / g. This double-layer structure effectively isolates the chemical and biological components physically, allowing for both the rapid control effect of the chemical agents and the long-term biocontrol induction and root growth promotion achieved through the microbial agents. This synergistic effect significantly enhances the overall control efficacy of the seed coating agent.

[0026] In some specific examples, the inner layer of the seed coating agent comprises the following components by weight percentage: fluopyram 0.1%~10%, thiamethoxam 0.05%~5%, film-forming agent 1%~5%, and UV shielding agent 0.15%~1.5%; the outer layer comprises the following components by weight percentage: Bacillus subtilis 1~10 billion CFU / g, microbial protectant 1%~3%, and warning color 0.01%~1%. It is understood that the weight percentages are based on the total mass of the seed coating agent. In addition to the components mentioned in the examples above, antifreeze agents, anti-caking agents, antifungal agents, dispersants, film-forming agents, pH adjusters, etc., may be added as needed. Those skilled in the art can add these as needed without particular limitation. As a preferred example, the film-forming agent is chitosan, the UV shielding agent is titanium dioxide, the microbial protectant is trehalose, and the warning color is carmine or acid red. This composition effectively ensures the stability and bioactivity of each functional component and facilitates field identification and use.

[0027] In a further embodiment, the method for preparing the seed coating agent includes the following steps: Chemical coating: Fluopyram, thiamethoxam and the excipients in the chemical coating are mixed according to the formula, water is added and the mixture is ground until the D90 particle size does not exceed 5μm to form a uniform suspension; the suspension is evenly sprayed onto the seed surface and dried and shaped under low temperature conditions. Bio-coating: Bacillus subtilis is mixed with the excipients in the bio-coating according to the specified ratio. Fluidized bed coating technology is used to uniformly adhere the mixture to the outside of the chemical layer. During the process, the temperature is controlled to not exceed 40℃ and the relative humidity not exceed 30%. Preferably, the bio-coating weight gain is 2%~4% of the seed weight. This preparation process effectively avoids the inhibition of microbial agents by chemical agents, ensuring the activity of the agents. Furthermore, the double-layer coating significantly improves the stability and effectiveness of the coating agent.

[0028] The seed coating agent provided in this application can be used to control underground pests and seedling diseases and pests, especially in cereal crops. Specifically, the seed coating agent is applied to cereal crops before planting. This seed coating agent has a significant effect on promoting root growth and development, promoting strong seedlings, and improving survival rate. Furthermore, this seed coating agent has a wide range of applications, is highly effective and low in toxicity, and has good environmental compatibility, effectively solving the problems of insufficient efficacy, high cost, and serious pollution in existing control technologies, and has good prospects for widespread application. In particular, the seed coating agent provided in this application is especially suitable for the control of wheat stem rot and the mole cricket, especially as a control of leaf blight pathogens. Microdochium nivale The targeted pesticides for stem base rot caused by the disease in the Jianghuai region and the behaviorally resistant mole cricket in the Yangtze River basin have shown significant effects.

[0029] The present application will be further illustrated below with reference to specific embodiments. It should be noted that the specific embodiments below are for illustrative purposes only and do not limit the scope of the present application in any way.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0031] In addition, unless otherwise specified, methods without detailed conditions or steps are conventional methods, and the reagents and materials used are commercially available.

[0032] Indoor bioactivity experiments Experimental subjects: Snow mold leaf blight fungus Microdochium nivale , Minute The specimens are preserved in the Plant Pathology Laboratory of Anhui Agricultural University.

[0033] Eastern mole crickets in the Yangtze River Basin Gryllotalpa orientali CJ-R, the insect source was preserved by the Entomology Laboratory of Anhui Agricultural University.

[0034] Experimental reagents: Fluopyram technical grade, 95%, PD20230621, Inner Mongolia Zhonggao Chemical Co., Ltd.

[0035] Bacillus subtilis technical material, 1 trillion CF / g, PD20140612, Wuhan Kenuo Biotechnology Co., Ltd.

[0036] Thiamethoxam technical grade, 98%, PD20160044, Jiangsu Zhongqi Technology Co., Ltd.

[0037] 1.1 Indoor activity test of *Pseudomonas aeruginosa* causal agent The indoor toxicity test was conducted in accordance with the People's Republic of China agricultural industry standards "Guidelines for Indoor Bioassay Testing of Pesticides" (NY / T1156.16-2006 - Fungicides - Part 16 - Test for Inhibition of Bacterial Growth) and (NY / T1156.6-2006 - Fungicides - Part 7: Determination of Combined Effects of Mixtures). The specific steps are as follows: Under aseptic conditions, according to the experimental treatment, pre-melted sterile culture medium was quantitatively added to a sterile conical flask. The drug solution was quantitatively drawn from low concentration to high concentration and added to the above conical flasks respectively, and then shaken thoroughly. Then, the solution was poured into four petri dishes with a diameter of 9 cm to prepare drug-containing plates of the corresponding concentration. Under aseptic conditions, the cultured pathogens were cut from the edge of the colony using a sterile punch with a diameter of 5 mm. The mycelial side of the mycelial block was inoculated into the center of the drug-containing plate with an inoculator, and the plate was covered and placed in an incubator at 25°C for cultivation.

[0038] The experiment included a blank control treatment containing an equal volume of acetone in a 0.1% Tween 80 aqueous solution. Each treatment was repeated four times. The growth of pathogenic mycelia was investigated based on the bacterial growth in the blank control culture dishes. Colony diameters were measured using calipers in millimeters (mm). The diameter of each colony was measured vertically once using the cross-sectional method, and the average value was taken.

[0039] Statistical analysis was performed using DPS data processing software to calculate the EC50, standard error of b-value, and 95% confidence limit of each reagent, thereby evaluating the activity of the tested reagents.

[0040] The co-toxicity coefficient (CTC value) of the mixed agents is calculated according to the following formula: ; in, , ; In the formula, CTC is the co-toxicity coefficient; ATI is the measured toxicity index of the mixture; and TTI is the theoretical toxicity index of the mixture. S—EC50 of the standard bactericide, in mg / L; M—EC50 of the mixture, in mg / L; TIA—A drug toxicity index; The mass percentage of PA-A agent in the mixture, expressed as % . TIB-B drug toxicity index; The mass percentage of PB-B reagent in the mixture, in units of %.

[0041] In this experiment, using fluopyram as the standard fungicide, the co-toxicity coefficient (CTC) of the mixed formulation ≥120 indicates a synergistic effect; CTC ≤80 indicates an antagonistic effect; and 80 < CTC < 120 indicates an additive effect. The results are shown in Table 1.

[0042] Table 1. Results of indoor combined toxicity test of fluopyram and Bacillus subtilis against *Cyperus rotundus*.

[0043] Note: In Table 1, the ratio of fluopyram to Bacillus subtilis is the mass / spore concentration ratio. For example, A:B=1:100 means 1g:10 billion CFU / g.

[0044] The results in Table 1 show that the co-toxicity coefficients of the five treatments (C to G) were all significantly greater than 120, indicating that fluopyram and Bacillus subtilis are effective in controlling wheat stem rot and snow mold leaf blight. Microdochium nivale The above treatments showed significant synergistic effects. Among them, treatment E showed the most significant synergistic effect when the mass / spore concentration ratio of fluopyram and Bacillus subtilis was 5:50, and the EC50 was the lowest, indicating the highest toxicity to the pathogen. Therefore, treatment E mixture was subsequently used as the assay agent for the bioassay of the mole cricket.

[0045] 1.2 Indoor activity determination of mole cricket in the Yangtze River Basin According to the People's Republic of China Agricultural Industry Standard "Guidelines for Indoor Bioassay Testing of Pesticides" NY / T1154.15-2009 (Guidelines for Indoor Bioassay Testing of Pesticides - Insecticides - Part 15 - Immersion Method for Soil Pests), for indoor toxicity testing, E refers to the fluopyram-Bacillus subtilis mixture in item 1.1, using thiamethoxam as the standard agent. The specific steps are as follows: The collected egg chambers were placed in rearing boxes filled with sterilized sandy loam soil with a moisture content of 10%–20%. Small nests were made on the soil surface, with one egg chamber placed in each nest. The boxes were covered, and the development of the eggs was observed until the third instar nymphs left the egg chambers. These nymphs were then transferred to rearing boxes filled with sterilized sandy loam soil with a moisture content of 10%–20% and fed with malt for later use. For early third instar nymphs, the pesticide was dissolved in acetone and then diluted with a 0.1% Tween 80 aqueous solution. The target insects were immersed in the pesticide solution for 10 seconds, and excess pesticide was absorbed with filter paper. Each treatment was repeated four times, with 15 insects immersed in each repeat. A control group without pesticide was also included.

[0046] Statistical analysis was performed using DPS data processing software to calculate the EC50, EC90, standard error of the b-value, and their 95% confidence limits for each agent, thereby evaluating the activity of the tested agents. The calculation method can refer to the calculation method for fungicides in section 1.1. The test results are shown in Table 2. Table 2 Results of indoor toxicity tests of the mixture-thiamethoxam

[0047] Note: In Table 2, E:C refers to the ratio of fluopyram-Bacillus subtilis mixture and thiamethoxam. For example, E:C of 5:50:0.5 means that the ratio of fluopyram, Bacillus subtilis and thiamethoxam is 5g:10 billion CFU / g:0.5g.

[0048] The results in Table 2 show that the treatment with mixed pesticides and the treatment with thiamethoxam single agent EC... 50 The difference is not significant; it applies to EC when the E:C ratio is 5:50:2.5. 50 The lowest concentration of thiamethoxam has the highest toxicity to insects. Therefore, the highest toxicity to pests and pathogens occurs when the mass / spore concentration ratio of fluopyram, Bacillus subtilis, and thiamethoxam is 5g:5 billion CFU / g:2.5g.

[0049] Seed coating agent preparation examples Example 1: 0.55% fluopyram·thiamethoxam + 500 million CFU / g Bacillus subtilis seed coating agent The seed coating agent in this embodiment consists of: The seed coating agent consists of the following components: 0.5g fluopyram, 0.05g Bacillus subtilis technical grade, 0.05g thiamethoxam, 3g sodium lignosulfonate dispersant, 2.5g ethylene glycol antifreeze, 3.2g sodium aluminosilicate anticaking agent, 1.3g chitosan film-forming agent, 1.6g sodium benzoate antifungal agent, 1g Acid Red colorant, 1g acetic acid pH adjuster, 1g trehalose bioprotectant, and 0.15g titanium dioxide UV shielding agent, to a final volume of 100g with deionized water. The active ingredients of this seed coating agent are fluopyram, Bacillus subtilis, and thiamethoxam.

[0050] The seed coating agent is prepared as follows: S1, Chemical Coating: Fluopyram technical, thiamethoxam technical, film-forming agent, UV shielding agent, dispersant, antifreeze agent, anti-caking agent, antifungal agent, and pH adjuster are mixed in proportion, and an appropriate amount of water is added. The mixture is then ground in a sand mill until the particle size is ≤5μm (D90≤5μm) to form a uniform suspension. The suspension is then evenly sprayed onto the seed surface using a seed coating machine and dried at 50℃ for 10-15 minutes to form a dense chemical inner layer.

[0051] S2, Bio-coating: Bacillus subtilis spore powder (live count ≥ 1 × 10⁻⁶) 11The mixture of CFU / g with biological protectant and colorant is applied evenly to the outside of the chemical layer using a fluidized bed coating device. During the coating process, the temperature is controlled at ≤40℃ (to avoid killing the spores with high temperature) and the humidity is controlled at ≤30% (to prevent clumping). The final coating weight gain is 2%-4% of the seed weight.

[0052] Example 2: 0.75% fluopyram·thiamethoxam + 500 million CFU / g Bacillus subtilis seed coating agent The seed coating agent in this embodiment consists of: The seed coating agent consists of the following components: 0.5g fluopyram, 0.05g Bacillus subtilis, 0.25g thiamethoxam, 3g sodium lignosulfonate (dispersant), 2.5g ethylene glycol (antifreeze), 3.2g sodium aluminosilicate (anticaking agent), 1.3g chitosan (film-forming agent), 1.6g sodium benzoate (mildew inhibitor), 1g Acid Red (colorant), 1g acetic acid (pH adjuster), 1g trehalose (biological protectant), and 0.15g titanium dioxide (UV shielding agent), to a final volume of 100g with deionized water. The active ingredients are fluopyram, Bacillus subtilis, and thiamethoxam.

[0053] The preparation method of the seed coating agent is the same as in Example 1.

[0054] Example 3: 1% fluopyram·thiamethoxam + 500 million CFU / g Bacillus subtilis seed coating agent The seed coating agent in this embodiment consists of: The seed coating agent consists of the following components: fluopyram 0.5g, Bacillus subtilis 0.05g, thiamethoxam 0.5g, sodium lignosulfonate dispersant 3g, ethylene glycol antifreeze 2.5g, sodium aluminosilicate anticaking agent 3.2g, chitosan film-forming agent 1.3g, sodium benzoate antifungal agent 1.6g, Acid Red colorant 1g, acetic acid pH adjuster 1g, trehalose bioprotectant 1g, and titanium dioxide UV shielding agent 0.15g, to a final volume of 100g with deionized water. The active ingredients of this seed coating agent are fluopyram, Bacillus subtilis, and thiamethoxam.

[0055] The preparation method of the seed coating agent is the same as in Example 1.

[0056] Comparative Example 1: 2% Fluopyram seed coating agent The composition of the fluopyram seed coating agent in this comparative example is as follows: The composition comprises: 2g of fluopyram, 3g of sodium lignosulfonate (dispersant), 2.5g of ethylene glycol (antifreeze), 3.2g of sodium aluminosilicate (anticaking agent), 1.3g of chitosan (film-forming agent), 1.6g of sodium benzoate (mildew inhibitor), 1g of Acid Red (colorant), 0.15g of titanium dioxide (UV shielding agent), and 1g of acetic acid (pH adjuster), to be made up to 100g with deionized water. The active ingredient in this composition is fluopyram.

[0057] The preparation method of the seed coating agent is as described in Example 1.

[0058] Comparative Example 2: 2% Thiamethoxam Seed Coating Agent The composition of the thiamethoxam seed coating agent in this comparative example is as follows: The composition comprises: 2g thiamethoxam, 3g sodium lignosulfonate (dispersant), 2.5g ethylene glycol (antifreeze), 3.2g sodium aluminosilicate (anticaking agent), 1.3g chitosan (film-forming agent), 1.6g sodium benzoate (mildew inhibitor), 1g Acid Red (colorant), 0.15g titanium dioxide (UV shielding agent), and 1g acetic acid (pH adjuster), to be made up to 100g with deionized water. The active ingredient in this composition is thiamethoxam.

[0059] The preparation method of the seed coating agent is as described in Example 1.

[0060] Comparative Example 3: 1 billion CFU / g Bacillus subtilis seed coating agent The composition of the Bacillus subtilis seed coating agent in this comparative example is as follows: The composition comprises: 0.1g of Bacillus subtilis, 3g of sodium lignosulfonate (dispersant), 2.5g of ethylene glycol (antifreeze), 3.2g of sodium aluminosilicate (anticaking agent), 1.3g of chitosan (film-forming agent), 1g of trehalose (bioprotectant), 1.6g of sodium benzoate (mildew inhibitor), 1g of Acid Red (colorant), 0.15g of titanium dioxide (UV shielding agent), and 1g of acetic acid (pH adjuster), to be made up to 100g with deionized water. The active ingredient of this composition is Bacillus subtilis.

[0061] The preparation method of the seed coating agent is as follows (refer to Example 1).

[0062] Field efficacy trials 1. Test location: Hongdian Village, Gaoliu Town, Hefei City, Anhui Province, 31.96°N, 116.91°E.

[0063] 2. Selection of crops and cultivars: Zhenmai 16.

[0064] 3. Test subject: *Pseudomonas aeruginosa* (the pathogen that causes leaf blight) Microdochium nivale; Eastern mole crickets in the Yangtze River Basin Gryllotalpa orientali CJ-R.

[0065] 4. Water and fertilizer management of the experimental plot: The first rotary tillage was carried out on November 10th of the first year, and the second rotary tillage was carried out on November 12th. 30 kg of N:P:K=15:15:15 ternary compound fertilizer was applied as base fertilizer per mu. On February 17th of the second year, 10 kg / mu of urea (N≥46%) was applied as top dressing.

[0066] 5. Test agents: The seed coating agents in Examples 1-3 and Comparative Examples 1-3 were all prepared by Anhui Hefeng Herun Agricultural Technology Co., Ltd.; at the same time, 27% phenyl ether·pyrrolizidine thiamethoxam suspension seed coating agent (registration certificate PD20151131) was used as a conventional control agent.

[0067] 6. Area and duplication: (1) Area: 20m 2 (2) Number of repetitions: 4 times.

[0068] 7. Application method: Before sowing wheat, calculate the seed amount for each plot according to the seeding rate (20 kg / mu) and the experimental design. Coat the seeds according to the treatment. Prepare the pesticide solution according to the amount of water (2 liters / 100 kg of seeds) and mix it thoroughly with the seeds to ensure that it is evenly distributed on the seed surface. Sow the seeds after drying.

[0069] 8. Application time and frequency: Seed coating on November 13th of the first year, once in total.

[0070] 9. Survey time and number of times March 11 of the following year: Survey on the incidence rate of the strain; once in total.

[0071] The prevention and control effect is calculated using the following formula: % (diseases).

[0072] ; (Insect pests).

[0073] The dosage and control effect of each agent are shown in Table 3.

[0074] Table 3. Results of efficacy tests of different pesticides against wheat stem rot and mole cricket.

[0075] As shown in Table 3, the field efficacy test results indicate that when the dosage of each example was 50-100 ml / 100 kg of seeds, the control efficacy against wheat stem rot was over 80%, and when the dosage was 100 ml / 100 kg of seeds, the control efficacy against wheat-resistant mole cricket was over 75%, significantly better than the control efficacy of the comparative example and the conventional control. Among them, Example 2 showed the best efficacy. In terms of safety, none of the examples affected wheat growth, and the safety was guaranteed.

[0076] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A seed coating agent, characterized in that, The seed coating agent contains active ingredients, namely fluopyram, thiamethoxam and Bacillus subtilis; wherein the mass ratio of fluopyram to thiamethoxam is (1-10):(0.5-5), and the spore concentration of Bacillus subtilis is 1-10 billion CFU / g.

2. The seed coating agent as described in claim 1, characterized in that, The mass ratio of fluopyram to thiamethoxam is 5:2.5, and the spore concentration of Bacillus subtilis is 2.5 billion CFU / g.

3. The seed coating agent as described in claim 1, characterized in that, The active ingredient accounts for 0.1%-50% of the total mass of the seed coating agent.

4. The seed coating agent as described in claim 1, characterized in that, The seed coating agent also includes at least one pesticide-acceptable excipient.

5. The seed coating agent as described in claim 4, characterized in that, The excipients include at least one of the following: dispersant, antifreeze, anticaking agent, suspending agent, film-forming agent, antifungal agent, pH adjuster, colorant, ultraviolet shielding agent, microbial protectant, and filler.

6. The seed coating agent according to any one of claims 1-5, characterized in that, The seed coating agent includes: The inner layer is configured as a chemical agent layer, wherein the inner layer comprises 0.1%-10% fluopyram and 0.05%-5% thiamethoxam by mass. And an outer layer, which is configured as a microbial agent layer, the outer layer containing 1-10 billion CFU / g of Bacillus subtilis.

7. The seed coating agent as described in claim 6, characterized in that, The inner layer of the seed coating agent comprises 0.1%-10% fluopyram, 0.05%-5% thiamethoxam, 1%-5% film-forming agent, and 0.15%-1.5% UV shielding agent; The outer layer of the seed coating agent comprises 1-10 billion CFU / g of Bacillus subtilis, 1%-3% of a microbial protectant, and 0.01%-1% of a warning color. Preferably, the film-forming agent is chitosan; and / or, the ultraviolet shielding agent is titanium dioxide; and / or, the microbial protectant is trehalose; and / or, the warning color is carmine or acid red.

8. A method for preparing a seed coating agent as described in any one of claims 1-7, characterized in that, Includes the following steps: Chemical coating: Mix fluopyram, thiamethoxam and other excipients according to the formula, add water and grind to form a suspension; spray evenly on the seed surface and dry at low temperature; Bio-coating: Bacillus subtilis spore powder is mixed with other excipients according to the formula, and then attached to the outside of the chemical layer using fluidized bed coating technology, while controlling the temperature to ≤40℃ and the humidity to ≤30%. Preferably, the D90 of the suspension is ≤5μm; Preferably, the biological coating increases the seed weight by 2%-4%.

9. The application of the seed coating agent as described in any one of claims 1-7, or the seed coating agent prepared by the preparation method described in claim 8, in the prevention and control of underground pests and seedling diseases and pests in crops.

10. The application as described in claim 9, characterized in that, The pests and diseases mentioned are wheat stem base rot and oriental mole cricket; Preferably, the pest or disease is *Pseudomonas aeruginosa*. Microdochium nivale This caused stem rot in the Jianghuai region and behaviorally resistant mole crickets in the Yangtze River basin.

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