Composite bactericide and application thereof

Abstract

This invention discloses a composite bactericide and its application. The composite bactericide, by mass percentage, comprises the following components: 20-40% alkylamidine, 1-5% a 1000 ppm nano-copper solution, 3-9% milk thistle extract, 4-8% tartaric acid, and the balance being sterile deionized water with a pH of 4.5-5.5; the nano-copper in the nano-copper solution has a particle size of 50-100 nm. This invention achieves a triple-action mechanism of "direct killing + physical protection + active immunization." Through the synergistic effect of the components, the product not only takes effect rapidly but also provides long-lasting protection, effectively balancing high efficiency and environmental safety.

Description

Technical Field

[0001] This invention relates to the field of bactericides, specifically to a compound bactericide and its application. Background Technology

[0002] In modern agricultural plant protection systems, the research and application of fungicides have always been a core element in ensuring high and stable crop yields. For a long time, chemically synthesized fungicides have dominated the market due to their rapid action and economic efficiency, but their inherent defects are becoming increasingly apparent. Take the widely used triazole fungicides as an example; they work by inhibiting ergosterol synthesis, but because their target is too singular, pathogens easily develop resistance through target site mutations under continuous selection pressure, leading to a rapid decline in the effectiveness of the pesticide. More seriously, these fungicides can easily cause phytotoxicity such as growth inhibition and leaf stiffness at specific crop growth stages or under adverse environmental conditions, greatly limiting their safe application. Another class of fungicides with different mechanisms of action, methoxyacrylates, although once considered a solution, have also become unreliable in field use due to the rapid spread of resistance risks. This resistance cycle caused by a single mode of action has become a difficult predicament to overcome in the current chemical pesticide technology path.

[0003] In search of breakthroughs, research has turned to emerging fields such as bioactive substances and nanotechnology. Plant-derived fungicides, such as various extracts rich in flavonoids, have attracted much attention due to their good environmental compatibility. However, these natural active molecules have encountered insurmountable technical bottlenecks in their transition from laboratory to field applications: their inherent low water solubility and instability in complex field environments result in extremely low bioavailability, making it difficult for the active ingredients to reach concentrations sufficient to inhibit pathogens at their target sites. Consequently, the theoretically expected antibacterial activity cannot be translated into stable field control effects. On the other hand, nano-antibacterial materials, such as nano-copper, offer a new approach to disrupting pathogen cell structures due to their unique physicochemical properties and small size effect. However, applying nanotechnology to field fungicides also faces severe challenges: the high surface energy of nanoparticles makes them prone to aggregation, leading to loss of activity; conventionally prepared nano-copper particles are chemically unstable in the environment, and the dynamics of their released copper ions are uncontrollable, potentially having negative impacts on crops and soil micro-ecosystems; furthermore, complex synthesis processes and high production costs also hinder their large-scale agricultural application.

[0004] Therefore, the current technological landscape presents a clear divide: on one hand, there are traditional chemical agents facing bottlenecks such as resistance and phytotoxicity; on the other hand, there are promising new technologies based on bio-based and nanomaterials, but their practical application is limited by their own physicochemical properties. The existing technological system has not yet provided a comprehensive solution that can simultaneously overcome these shortcomings. Technological evolution urgently requires a completely new design philosophy that not only maintains high-efficiency bactericidal activity but also inherently avoids the risk of resistance and fundamentally solves core problems such as the low efficiency of natural ingredients and the poor stability and uncontrollable environmental behavior of nanomaterials. Therefore, there is an urgent need to develop a novel fungicide formulation that integrates the rapid action of chemicals, the safety of biomaterials, and the high efficiency of nanotechnology to form a stable composite system. This would effectively solve systemic problems that cannot be addressed by a single technological approach, opening a new technological path for the green control of crop diseases. Summary of the Invention

[0005] This invention provides a compound bactericide and its application to solve the systemic problem of balancing high efficiency and environmental safety, which cannot be solved by a single technical approach.

[0006] In a first aspect, the present invention provides a composite bactericide, which, by mass percentage, comprises the following components: 20-40% alkylamidine, 1-5% nano-copper solution with a concentration of 1000 ppm, 3-9% milk thistle extract, 4-8% tartaric acid, and the balance being sterile deionized water with a pH of 4.5-5.5; wherein the nano-copper in the nano-copper solution has a particle size of 50-100 nm.

[0007] As one configuration, the compound bactericide consists of the following components: 40% propanemidine, 9% milk thistle extract, 5% 1000ppm nano copper solution, 8% tartaric acid, and the balance being sterile deionized water with a pH of 4.5-5.5.

[0008] As one configuration, the compound bactericide consists of the following components: 30% propanemidine, 7.5% milk thistle extract, 5% 1000ppm nano copper solution, 8% tartaric acid, and the balance being sterile deionized water with a pH of 4.5-5.5.

[0009] As one configuration, the compound bactericide consists of the following components: 20% propanemidine, 6% milk thistle extract, 5% 1000ppm nano copper solution, 4% tartaric acid, and the balance being sterile deionized water with a pH of 4.5-5.5.

[0010] As one configuration, the composite bactericide consists of the following components: 40% propanemidine, 6% milk thistle extract, 5% 1000ppm nano copper solution, 7% tartaric acid, and the balance being sterile deionized water with a pH of 4.5-5.5; the nano copper has a particle size of 50-100nm.

[0011] As one configuration, the composite bactericide consists of the following components: 20% propanemidine, 9% milk thistle extract, 5% 1000ppm nano copper solution, 4% tartaric acid, and the balance being sterile deionized water with a pH of 4.5-5.5; the nano copper has a particle size of 50-100nm.

[0012] Secondly, the present invention provides an application of the above-mentioned compound fungicide for the prevention and control of at least one of crop gray mold, anthracnose, large leaf spot, and apple rot.

[0013] Furthermore, the application method is foliar spraying, with a dilution ratio of 100-400 times.

[0014] Furthermore, it is applicable to use throughout the entire growth period of crops.

[0015] Furthermore, the crop is at least one of strawberry, grape, tomato, and apple.

[0016] The technical solution of this invention has the following advantages: (1) A three-in-one multi-layered protection mechanism has been formed, with a long-lasting effect. This fungicide constructs a unique comprehensive protection system: propanemidine provides direct and powerful killing action; nano-copper forms a stable physicochemical protective film on the crop surface, providing a long-lasting barrier protection effect; and milk thistle extract can activate the crop's own immune system, inducing systemic resistance. This triple mechanism of action of "direct killing + physical protection + active immunization" makes the product not only fast-acting but also provides long-lasting protection, effectively extending the duration of efficacy.

[0017] (2) Innovative application of low-concentration nanotechnology, taking into account both high efficiency and environmental safety. Nanomaterials possess inherent advantages such as large specific surface area and high surface energy. This solution employs a low-concentration nano-copper solution of 1000 ppm, a highly ingenious approach. This concentration fully leverages the advantages of nanomaterials' large specific surface area and high surface energy, allowing nano-copper to exhibit excellent adhesion and bioactivity, ensuring the desired bactericidal / plant protection effects without relying on high concentrations to enhance efficacy. It also significantly avoids the problems associated with high-concentration nanoparticles, such as agglomeration, poor stability, and potential environmental risks. Specifically, high-concentration nanoparticles are more prone to collision and aggregation, leading to a significant decrease in efficacy; decreased stability can cause stratification and precipitation during storage and use; and excessive release of copper poses potential environmental risks to soil, crops, and water bodies. Simultaneously, the low concentration means more controllable product costs and a smaller environmental impact, successfully resolving the contradictions between "high efficiency and safety" and "effectiveness and cost" often faced when transitioning nanopesticides from the laboratory to industrialization; resulting in lower cost and better safety.

[0018] (3) It has excellent resistance management function and effectively delays the development of drug resistance in pathogens. Because this composition integrates multiple mechanisms, including chemical killing, physical barriers, and induced immunity, it forms a multi-target synergistic attack on pathogens. Pathogens are unlikely to resist all mechanisms of action simultaneously through a single mutation, which greatly delays the emergence and development of drug resistance. Therefore, this product is not only a highly effective bactericide but also a strategic resistance management tool, significantly extending its market lifespan.

[0019] (4) It has good environmental compatibility and meets the requirements of green agriculture and agricultural product safety. The milk thistle extract in the formula is derived from natural plants, tartaric acid is a recognized safe food additive, and nano-copper can exert high efficiency even at low dosages. The entire system aims to reduce the overall amount of pesticides used by improving efficiency, thereby reducing the impact on non-target organisms and the ecological environment, contributing to the production of safer agricultural products, and fully aligning with global requirements for pesticide reduction and green sustainable development.

[0020] (5) Safety is more plant-friendly In the formulation of this invention, the optimization of the acidic environment makes the fungicide more friendly to the plant leaf surface and root environment, especially for highly sensitive crops, such as fruits and vegetables. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a diagram showing localized damage to the hyphae of *Botrytis cinerea* after treatment in Example 1. Figure 2 This is an electron micrograph of Botrytis cinerea hyphae after treatment in Example 3. Detailed Implementation

[0023] The following embodiments are provided to better understand the present invention, but the following embodiments do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0024] Unless otherwise specified, all experimental steps or conditions in the examples were performed according to conventional experimental procedures and conditions in the art. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0025] The sources of the materials and reagents used in this application are as follows: Propanamidine: Yangling Pesticide Chemical, CAS: 104-32-5; Tartaric acid: Xilong Scientific Chemical Industry, CAS: 87-69-4; Milk thistle extract: Purchased from Liaoning Fengrui Tiancheng Biotechnology Co., Ltd., it is a powder mixture extracted from dried milk thistle fruit. The mass percentage of silybin in this milk thistle extract is 50%-60%. Nano-copper solution: 5 g of a mixture of copper powder and copper oxide (supplied by Guangzhou Logos Biotechnology Co., Ltd.) was mixed with a 1.25 g / L aqueous solution of ethylenediaminetetraacetic acid. The reaction temperature was controlled at 50 ℃, and the stirring speed was kept constant at 200 rpm for 48 h. After the reaction was completed, stirring was stopped, and the mixture was allowed to stand at room temperature for 24 h to separate into layers, finally obtaining a metal ion complex solution containing divalent copper ions. This metal ion complex solution containing divalent copper ions is the nano-copper solution. The mass concentration of divalent copper ions in the obtained nano-copper solution is 3000 ppm, and the particle size of the nano-copper is 50-100 nm, which is the Dv50 particle size. The nano-copper solution with a mass concentration of 3000 ppm divalent copper ions was then diluted with water to prepare a 1000 ppm nano-copper solution. It should be noted that the 1-5% nano-copper solution with a concentration of 1000ppm in this invention can be replaced by a nano-copper solution with a concentration of 2000ppm at 0.5-2.5%, as long as the mass content of nano-copper in the composite bactericide is within this specific range.

[0026] Example 1 The preparation process of the compound bactericide includes: The components, by mass percentage, are: 40% propanemidine, 9% milk thistle extract, 5% 1000ppm nano copper solution, 8% tartaric acid, with the remainder being water as a solvent. After mixing the above components evenly and shaking at room temperature, the reaction is carried out for 35 minutes to obtain the composite preparation.

[0027] Example 2 The preparation process of the compound bactericide includes: The components, by mass percentage, are: 30% propanemidine, 7.5% milk thistle extract, 5% 1000ppm nano copper solution, 8% tartaric acid, with the remainder being water as a solvent. After mixing the above components evenly and shaking at room temperature, the reaction is carried out for 35 minutes to obtain the composite preparation.

[0028] Example 3 The preparation process of the compound bactericide includes: The components, by mass percentage, are: 20% propanemidine, 6% milk thistle extract, 5% 1000ppm nano copper solution, 4% tartaric acid, with the remainder being water as a solvent. After mixing the above components evenly and shaking at room temperature, the reaction is carried out for 35 minutes to obtain the composite preparation.

[0029] Example 4 The preparation process of the compound bactericide includes: The components, by mass percentage, are: 40% propanemidine, 6% milk thistle extract, 5% 1000ppm nano copper solution, 7% tartaric acid, and the remainder is water as a solvent. After mixing the above components evenly and shaking at room temperature, the reaction is carried out for 35 minutes to obtain the composite preparation.

[0030] Example 5 The process of preparing a compound bactericide includes: The components, by mass percentage, are: 20% propanemidine, 9% milk thistle extract, 5% 1000ppm nano copper solution, 4% tartaric acid, and the remainder is water as a solvent. After mixing the above components evenly and shaking at room temperature, the reaction is carried out for 35 minutes to obtain the composite preparation.

[0031] Comparative Example 1 The preparation process of the compound bactericide includes: The components, by mass percentage, are: 40% propanemidine, 5% 1000ppm nano copper solution, 9% milk thistle extract, and the remainder is water as a solvent. After mixing the above components evenly and shaking at room temperature, the reaction is carried out for 35 minutes to obtain the composite preparation.

[0032] Comparative Example 2 The preparation process of the compound bactericide includes: The components, by mass percentage, are: 40% propanemidine, 9% milk thistle extract, 5% tartaric acid, with the remainder being water as a solvent. After mixing the above components evenly and shaking at room temperature, the reaction is carried out for 35 minutes to obtain the composite preparation.

[0033] Comparative Example 3 The preparation process of the compound bactericide includes: The components, by mass percentage, are: 40% propanemidine, 5% 1000ppm nano copper solution, 5% tartaric acid, and the remainder is water as a solvent. After mixing the above components evenly and shaking at room temperature, the reaction is carried out for 35 minutes to obtain the composite preparation.

[0034] Comparative Example 4 The preparation process of the compound bactericide includes: The components, by mass percentage, are: 6% milk thistle extract, 5% 1000ppm nano copper solution, 3% tartaric acid, and the remainder is water as a solvent. After mixing the above components evenly and shaking at room temperature, the reaction is carried out for 35 minutes to obtain the composite preparation.

[0035] Experimental Example 1 This experimental example aims to verify the antibacterial effects of Examples 1-5 and Comparative Examples 1-4 above.

[0036] 1. Experimental pathogen: Botrytis cinerea ( Botrytis cinerea ), Colletotrichum ( Colletotrichum lagenarium ), large spot disease bulging umbelliferous worms ( Exsero turcicum ), Apple shell cystis ( Valsa mali Migable et Yamada) .

[0037] 2. Experimental Methods: (1) Dilution and preparation of medicines The compound bacterial agents prepared in Examples 1-5 and Comparative Examples 1-4 were successively diluted with sterile deionized water to 100 times, 200 times, and 400 times (e.g., the corresponding original drug concentrations after dilution in Example 1 were 5700.5 mg / L, 2850.25 mg / L, and 1425.13 mg / L, respectively). The diluted solutions were then filtered through a 0.22 μm sterile filter membrane to obtain the sterilized compound bacterial agent.

[0038] (2) Determination of antibacterial spectrum Add the sterilized compound microbial agent at a dosage of 5% to sterilized PDA medium cooled to approximately 50°C, mix thoroughly, and then pour into plates. After the plates have completely solidified, inoculate the center of each plate with a 5 mm diameter mycelium of *Botrytis cinerea*, *Colletotrichum spp.*, *Helicobacter pylori*, and *Carya caryopsis*. Incubate the inoculated plates at 25°C for 48 hours.

[0039] (2.1) Obtaining the antibacterial rate: When the control colonies have evenly covered the petri dish, the diameter of the pathogens in each treatment is measured using the cross-hatching method, and the inhibition rate is calculated using the following formula (1). , The control group consisted of PDA culture medium without compound microbial agents, i.e., pure PDA culture medium.

[0040] (2.2) Obtaining the toxicity EC50 value, theoretical EC50, and co-toxicity coefficient CTC: Data statistical analysis was performed using DPS software. Linear regression was conducted with the logarithm of the fungicide concentration as x and the corresponding mycelial growth inhibition rate as y to derive the virulence regression equation and the EC50 value of the agent's virulence against the target pathogen. The theoretical EC50 was calculated using the Sun Yunpei method based on the EC50 value of each single agent corresponding to the pathogen and the mass proportion of each component in the formulation of the examples. The co-toxicity coefficient CTC = measured EC50 / theoretical EC50 × 100. CTC > 120 was considered significantly synergistic, 80 ≤ CTC ≤ 120 was considered additive, and CTC < 80 was considered antagonistic.

[0041] (3) Storage stability, particle size and suspension rate of the formulation Undiluted stock solutions from Examples 1, 3, Comparative Example 1, and Comparative Example 4 were taken for testing.

[0042] Storage stability test: Equal volumes of each test formulation stock solution were measured and placed into sealed, transparent, heat-resistant containers, with three replicates for each group of samples; the sealed samples were placed in a constant temperature and humidity oven at 54℃ and stored in the dark for 14 days; samples were taken before heat storage and after 14 days of heat storage, and various indicators were tested in sequence: pH value, suspension rate, total retention rate of active ingredients, and particle D90 size; the appearance of the samples was observed throughout the process, and abnormal phenomena such as layering, flocculation, precipitation, and discoloration were recorded.

[0043] Particle size detection method: Take appropriate amounts of the original solution before heat storage and after heat storage at 54℃ for 14 days, respectively, and use a laser particle size analyzer to determine the particle size distribution. Record the D90 particle size values ​​of each group of samples and compare the degree of nanoparticle aggregation of each group.

[0044] Suspension rate determination method: Refer to the standard testing method for pesticide suspension formulations, conduct suspension rate tests on each group of original solutions before and after heat storage, and calculate the sample suspension rate values.

[0045] (4) Detect the retention rate of antibacterial activity after simulated rainfall Undiluted stock solutions of Examples 1, 3, Comparative Example 1, and Comparative Example 4 were used to conduct rain erosion resistance tests. Each formulation was evenly sprayed onto the leaves of the test plants, and the solution was allowed to form a film on the leaf surface naturally. Artificial rainfall was conducted using two gradients of 20 mm and 50 mm to simulate rainfall. After the rainfall, the antibacterial activity of the residual agent on the leaf surface was measured, and the retention rate of antibacterial activity for each group was calculated. The leaf adhesion and erosion resistance of different formulations were compared.

[0046] (5) Field control effect of grape gray mold Experimental plants with uniform growth and even severity of gray mold disease were selected. A randomized block design was used, with the same number of grapevines in each plot. Three replicates were set up for each plot, and isolation zones were set up between plots to eliminate experimental errors caused by pesticide drift.

[0047] The formulations of Example 1, Example 3, Comparative Example 1, and Comparative Example 4 were diluted 200 times to serve as test solutions. An equal volume of sterile deionized water was sprayed on the blank control. The entire plant was sprayed evenly, ensuring that the leaves and fruit ears were completely wetted without dripping. The application was done only once.

[0048] The incidence of grape gray mold was investigated at 7 days and 14 days after application of the pesticide. Electron micrographs of Botrytis cinerea hyphae were obtained at 14 days.

[0049] Formula for calculating efficacy: Efficacy (%) = [(Blank control disease index)] [Drug treatment disease index ÷ Blank control disease index] × 100%.

[0050] (6) Inhibition effect on the spread of apple rot lesions The test reagents were those used in Examples 1, 3, 1, and 4. Each formulation was diluted 200 times with sterile deionized water before use. Uniform, undamaged apples were selected, and inoculation wounds of the same size were prepared. Apple rot pathogens were quantitatively inoculated to construct lesions of uniform initial size. The diluted drug solution was evenly applied to the lesion area, and water treatment served as a blank control. Repeat samples were set for each group. The lesions were continuously cultured at a constant temperature for 14 days. The length of the lesions was measured at the beginning of the experiment and after 14 days of culture. The lesion expansion inhibition rate was calculated to evaluate the inhibitory ability of each formulation on the expansion of apple rot lesions.

[0051] 3. Experimental Results: 1) Results of antibacterial spectrum assay 1.1) The results of the antibacterial rate are shown in Table 1 and Table 2 below.

[0052] Table 1. Antibacterial spectrum of bactericides (antibacterial rate at a dilution ratio of 1:200)

[0053] Table 1 shows that, at a 200-fold dilution, Example 1 exhibited an inhibition rate exceeding 95% against all four tested pathogens (Botrytis cinerea, Colletotrichum spp., Helicobacter pylori, and Caryophyllus maculata), demonstrating broad-spectrum and highly effective bactericidal properties. In contrast, Comparative Examples 1 and 4 showed significantly lower inhibition rates, further confirming the synergistic effect of the composition of this invention.

[0054] Table 2. Antibacterial rate (%) at different dilution ratios

[0055] Table 2 shows that even at a high dilution of 400 times, Example 1 maintained an inhibition rate of over 84% against the four pathogens, demonstrating excellent long-lasting efficacy and potential for field application. Example 3, under the same conditions, performed slightly worse than Example 1, but was still superior to all comparative examples.

[0056] 1.2) Indoor toxicity test results The results of indoor toxicity testing are shown in Tables 3-5.

[0057] Table 3. Effects of different treatments on indoor toxicity assays of Botrytis cinerea.

[0058] As shown in Table 3, the composite fungicides of Examples 1-5 of this invention exhibited extremely high toxicity against *Botrytis cinerea*, with EC50 values ​​all below 2.5 μg / mL. Among them, Example 1 had the lowest EC50 value, only 0.72 μg / mL, significantly superior to all comparative examples. In contrast, the toxicity of Comparative Example 1 (EC50 = 5.86 μg / mL, without malic acid), Comparative Example 2 (EC50 = 3.68 μg / mL, without nano-copper), Comparative Example 3 (EC50 = 4.95 μg / mL, without extract), and Comparative Example 4 (EC50 = 14.25 μg / mL, without propanemidine) was far lower than that of the examples. This indicates that all four components are indispensable, and their synergistic effect significantly enhances the fungicidal activity.

[0059] Table 4. EC50 data (μg / mL) of different treatments against different pathogens.

[0060] As shown in Table 4, the toxicity trend of the compound fungicide in the embodiments and comparative examples of the present invention against other pathogens is basically similar to that against Botrytis cinerea, indicating that the synergistic effect of the four components significantly enhances the fungicidal activity against Botrytis cinerea, Colletotrichum spp., Helicobacter pylori, and Helicobacter pylori.

[0061] Table 5. Results of Synergistic Effect Measurement

[0062] According to the co-toxicity coefficient (CTC) analysis in Table 5, the CTC values ​​of Examples 1-5 are all greater than 120, showing a significant synergistic effect. In particular, Example 1 has a CTC value as high as 242.8, indicating that the combination of propanemidine, milk thistle extract, nano copper and malic acid produces a synergistic effect far exceeding expectations, rather than a simple additive effect.

[0063] 2) Evaluation of the physicochemical properties of the formulation The physicochemical properties of the formulation are evaluated as shown in Table 6.

[0064] Table 6. Storage stability, particle size, and suspension rate of the formulation

[0065] Table 6 shows that the formulations of this invention (Examples 1 and 3) exhibit good thermal storage stability. After storage at 54°C for 14 days, the pH value changed very little, the suspension rate was over 93%, and the retention rate of active ingredients exceeded 95%. Simultaneously, the D90 particle size remained below 100 nm, significantly smaller than the comparative examples, confirming that the addition of malic acid effectively inhibited the aggregation of nanoparticles, ensuring the long-term stability of the formulation. The continued high suspension rate and retention rate of active ingredients after high-temperature storage indicate that the organic acid system helps maintain the dispersion of the copper nanoparticles and reduces the risk of flocculation and sedimentation.

[0066] 3) Resistance to rainwater erosion The resistance to rain erosion is shown in Table 7.

[0067] Table 7. Antibacterial activity retention rate after simulated rainfall

[0068] Table 7 shows that the simulated rainfall experiments in Example 1, after experiencing 20 mm and 50 mm of simulated rainfall, maintained antibacterial activity at rates as high as 95.16% and 88.58%, respectively, which is significantly better than Comparative Example 1 (83.00% and 65.41%) and Comparative Example 4 (75.02% and 56.68%). This indicates that the quaternary system of the formulation of this invention maintains high antibacterial activity after simulated rainfall, suggesting that the composite protective film formed by nano-copper, plant extracts, and organic acids can improve leaf adhesion and erosion resistance, thus extending the duration of efficacy.

[0069] 4) Field control effect The results of the field trial for grape gray mold are shown in Table 8. Electron micrographs of *Botrytis cinerea* hyphae obtained after treatments in Examples 1 and 3 are shown below. Figure 1 and Figure 2 As shown.

[0070] Table 8 Field control efficacy of grape gray mold

[0071] Table 8 shows that the efficacy of Example 1 reached 93.2% and 89.1% at 7 and 14 days after application, respectively, which was significantly higher than that of Comparative Example 1 (72.3% and 64.2%) and Comparative Example 4 (51.8% and 43.9%). Furthermore, no phytotoxicity was observed throughout the entire test period, demonstrating that it has both high efficacy and safety.

[0072] 5) Therapeutic effect on apple rot disease The therapeutic effects on apple rot are shown in Table 9.

[0073] Table 9. Inhibition effect on the spread of apple rot lesions

[0074] Table 9 shows that Example 1 achieved an 85.4% inhibition rate on the spread of apple rot lesions, demonstrating significant efficacy. After 14 days of treatment, the lesion length increased only from 12.3 mm to 13.8 mm, while the lesion length in the control group (Comparative Example 4) rapidly expanded from 12.5 mm to 30.4 mm. This indicates that the composition of the present invention not only prevents the disease but also has excellent therapeutic and lesion control effects.

[0075] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A compound bactericide, characterized in that, The product is composed of the following components by mass percentage: 20-40% alkylamidine, 1-5% nano-copper solution with a concentration of 1000ppm, 3-9% milk thistle extract, 4-8% tartaric acid, and the balance being sterile deionized water with a pH of 4.5-5.5; the nano-copper in the nano-copper solution has a particle size of 50-100nm.

2. The compound bactericide according to claim 1, characterized in that, By mass percentage, it consists of the following components: 40% propanemidine, 9% milk thistle extract, 5% 1000ppm nano copper solution, 8% tartaric acid, and the balance being sterile deionized water with a pH of 4.5-5.

5.

3. The compound bactericide according to claim 1, characterized in that, By mass percentage, it consists of the following components: 30% propanemidine, 7.5% milk thistle extract, 5% 1000ppm nano copper solution, 8% tartaric acid, and the balance being sterile deionized water with a pH of 4.5-5.

5.

4. The compound bactericide according to claim 1, characterized in that, By mass percentage, it consists of the following components: 20% propanemidine, 6% milk thistle extract, 5% 1000ppm nano copper solution, 4% tartaric acid, and the balance being sterile deionized water with a pH of 4.5-5.

5.

5. The compound bactericide according to claim 1, characterized in that, The product is composed of the following components by mass percentage: 40% propanemidine, 6% milk thistle extract, 5% 1000ppm nano copper solution, 7% tartaric acid, and the balance being sterile deionized water with a pH of 4.5-5.5; the nano copper has a particle size of 50-100nm.

6. The compound bactericide according to claim 1, characterized in that, The product is composed of the following components by mass percentage: 20% propanemidine, 9% milk thistle extract, 5% 1000ppm nano copper solution, 4% tartaric acid, and the balance being sterile deionized water with a pH of 4.5-5.5; the nano copper has a particle size of 50-100nm.

7. The application of a compound bactericide as described in any one of claims 1-6, characterized in that, It is used to control at least one of the following diseases in crops: gray mold, anthracnose, large leaf spot, and apple rot.

8. The application according to claim 7, characterized in that, The application method is foliar spraying, with a dilution ratio of 100-400 times.

9. The application according to claim 7, characterized in that, Suitable for use throughout the entire growth period of crops.

10. The application according to claim 7, characterized in that, The crop is at least one of strawberry, grape, tomato, and apple.

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