Bactericide and application thereof

Abstract

The invention discloses a bactericide and application thereof, the bactericide comprises an active component, and the active component is one or more of spearmint oil and L-carvone. The pesticide can effectively inhibit citrus canker pathogens, takes effect quickly, is free of residues, improves the citrus quality, and has a better effect compared with basic copper sulfate. The kiwifruit canker pathogen inhibitor can effectively inhibit kiwifruit canker pathogen, takes effect quickly, is free of residues, improves the kiwifruit quality, and has a better effect compared with kasugamycin.

Description

Technical Field

[0001] The invention relates to the field of pesticides, in particular to a fungicide and application thereof. Background Art

[0002] The harm caused by plant pathogens seriously threatens the yield and quality of environmental crops. Among them, bacterial diseases such as kiwi canker, citrus canker, citrus Huanglongbing, tomato bacterial wilt, and rice white leaf blight have a particularly serious impact on the industry, not only leading to reduced production and loss of harvest, but also possibly destroying the orchard and causing no harvest. At present, the main methods for preventing and controlling bacterial diseases include inorganic copper, organic copper, antibiotics, and microbial pesticides. Copper preparations for bacterial diseases are widely used in production, including copper hydroxide, copper oxychloride, and basic copper sulfate. The active ingredients have a single target, and long-term use has caused bacteria to develop high drug resistance. In addition, the use of inorganic copper preparations at high temperatures is prone to produce pesticide damage and stimulate the occurrence of red spiders; bacterial diseases show cross-resistance to organic copper preparations such as quinoline copper and inorganic copper preparations, and the field control effect is not good; microbial pesticides such as Bacillus subtilis are extremely unstable and have poor rapidity; antibiotics such as tetramycin, kasugamycin, and zhongshengmycin have weak resistance to rain erosion and poor permeability, and are not effective in protecting crops in the continuous rainy conditions in the south, and cannot be mixed with alkaline pesticides. The existing product registration dosage forms are mainly wettable powders, emulsifiable concentrates, aqueous solutions, soluble solutions, water-dispersible granules, etc. This type of dosage form cannot transmit active ingredients to the phloem, and the permeability and resistance to rain erosion are not ideal, and the control effect on bacterial diseases is not good. Therefore, the development of fungicides with unique mechanisms of action and excellent biological activity has always been a research hotspot in the field of new pesticides, especially the exploration of plant-derived active ingredients with high antibacterial activity and the development of environmentally friendly agricultural fungicides are very promising.

[0003] Spearmint oil is also known as mint oil, spearmint oil or green mint oil. Spearmint oil can be obtained by steam distilling the whole spearmint plant. It is a light yellow to light yellow-green liquid with the sweet and slightly cool aroma of spearmint leaves. The main components are L-carvone (about 60%), limonene, dihydrocarvone, dihydrocarvol, menthone, isomenthone, pulegone, phellandrene, pinene, oleyl alcohol, 3-octanol, octanol acetate, etc. According to my country's "Standards for the Use of Food Additives" (GB 2760--2021), spearmint oil is an edible natural flavor allowed for use. It can be directly used in candies, gummies, cosmetics, and can also be used to prepare flavors. In actual production, the largest use of spearmint oil is for oral hygiene products including toothpaste, mouthwash, etc. It has the effects of expelling wind and relieving symptoms, anti-inflammatory and analgesic, antibacterial and insecticidal. Chinese invention patent CN201110032801.2 provides an application of spearmint oil in the treatment of chronic obstructive pulmonary disease, which has an improvement effect on rat chronic obstructive pulmonary disease models caused by Klebsiella pneumoniae infection and LPS, and has a reducing effect on the enhanced expression of Nrf2 protein in lung tissue of COPD models. Chinese invention patent application CN114304158A discloses a compound insecticide composition containing spinosad, its preparation method and use. The compound fungicide composition package of spearmint oil, catechins and tamarind gum can be used to prevent and control chewing mouthparts pests and rasp-sucking mouthparts pests, which has the advantage of reducing the damage of pests to crop leaves. There is no report on the application of spearmint oil in pesticide fungicides.

[0004] The chemical name of L-carvone is 1-methyl-4-isopropen-6-cyclohexene-2-one. It is the main component of spearmint oil extracted from spearmint leaves. It is also used in the food industry through chemical synthesis. It is mainly used in foods such as chewing gum, and is also used in medicine as a flavoring for poultices, mouth fresheners, and toothpaste. It is included in the "Food Additives Usage Standard" (GB 2760-2021) as a food flavor. There is a chiral center in the molecular structure of carvone, with a pair of racemic L-carvone and D-carvone, which have different stereostructures and functional performances. Pharmacological studies have shown that L-carvone has multiple pharmacological activities such as antibacterial, antifungal, antiparasitic, anti-neuraminidase, antioxidant, anti-inflammatory and anti-cancer. Its antibacterial effect is mainly related to the effect on the cell membrane and changes in ultrastructure. The research paper "Biological Activity and Control Effect of Five Terpenes and Synergistic Combinations on Green Peach Aphid" published in the Journal of Inner Mongolia Agricultural University (Natural Science Edition) reported that the repellency rate of L-carvone on green peach aphid was 49.6%, and the lethal concentration LC 50 0.56mL / L. Chenyu The dissertation "Study on the sublethal effect of a mixed solution of L-carvone and cuminol on caterpillars" reported that a mixed solution of L-carvone and cuminol has a contact killing effect on caterpillars and peach aphids. Food Industry Technology ”(2016,37(16) ) reported that L-carvone has a strong antibacterial effect on Escherichia coli and Salmonella, with a minimum inhibitory concentration of 12.5 μg / mL. Chinese invention patent application CN109329410A discloses a L-carvone fruit and vegetable bactericidal preservative. The preservative can effectively inhibit the infection of pathogens and inhibit the occurrence of post-harvest diseases of fruits and vegetables such as gray mold, anthrax, penicillium, black spot and the like. Chinese invention patent application CN115053900A discloses a bactericide for preventing and treating avocado canker. Its active ingredient is a compound of L-carvone and diniconazole, tebuconazole or triadimefon. The addition of L-carvone exhibits a synergistic effect, which can reduce the application dosage of chemical pesticides, reduce pesticide residues, and alleviate environmental pressure. In summary, there is no report on the use of L-carvone in the prevention and treatment of citrus canker and kiwi canker. In particular, the pathogenic bacteria of avocado canker belongs to the genus Ascomycota, family Ascomycetes, order Ascomycetes, and is completely different from the pathogens of citrus canker and kiwifruit canker.

[0005] Chinese invention patent CN108835110B discloses a pesticide sustained-release microsphere and a preparation method thereof. The pesticide sustained-release microsphere of the invention is composed of a core material and a wall material in a mass ratio of 1: (1 to 6), wherein the core material is the pesticide original drug, and the wall material is composed of polylactic acid (PLA) and polybutylene succinate (PBS) (mass ratio is 1:1 to 9). Summary of the invention

[0006] In view of the above technical problems, the present invention provides an agricultural fungicide and its application, which can be used to prevent and control the harm of plant bacterial pathogens, especially the prevention and control of citrus canker and kiwi canker.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: a fungicide, the fungicide comprises an active ingredient, and the active ingredient is one or more of spearmint oil and L-carvone.

[0008] The invention provides one or more plant extracts of spearmint oil and L-carvone which can inhibit the pathogens of citrus canker and kiwifruit canker. The invention controls the occurrence of citrus canker and kiwifruit canker by inhibiting the growth and reproduction of the pathogens of citrus canker and kiwifruit canker.

[0009] Compared with other purely natural plant-derived biological pesticides or chemical pesticides, the spearmint oil and L-carvone in the present application have excellent prevention and treatment effects on citrus canker and kiwi fruit canker.

[0010] In a preferred embodiment of the present invention, the fungicide further includes an auxiliary agent, and the auxiliary agent includes one or more of a surfactant, a filler, a solvent, a carrier, an emulsifier, a dispersant, a wetting agent, a foaming agent, a defoaming agent, a thickener, a penetrant, a stabilizer, an antifreeze agent, a film-forming agent, a color paste, and a flavor. The active ingredient accounts for 0.5 to 95.0% of the total mass percentage of the fungicide. Preferably, the active ingredient accounts for 1.0 to 50.0% of the total mass percentage of the fungicide. Further preferably, the active ingredient accounts for 5.0 to 25.0% of the total mass percentage of the fungicide.

[0011] According to an embodiment of the present invention, the pesticide composition may further include a stabilizer, such as a low-temperature stabilizer, a preservative, an antioxidant, a light stabilizer or other adjuvants for improving chemical and / or physical stability.

[0012] According to an embodiment of the present invention, the pesticide active ingredient can be prepared in a known manner, for example, by mixing spearmint oil, L-carvone and adjuvants.

[0013] According to an embodiment of the present invention, the active ingredient is mixed with an adjuvant to form a dosage form suitable for use in agriculture, and the dosage form can be selected from one or more of an aqueous emulsion, a microemulsion, an oil emulsion, an emulsifiable concentrate, a latex, a paste, an ointment, a dispersible liquid, a soluble solution, a soluble gel, an oil, a granule, a wettable powder, a water-dispersible granule, a suspension, a microcapsule suspension, an oil suspension, a dispersible oil suspension, and a seed treatment suspension.

[0014] The fungicide of the present invention can be used to treat plants or plant parts, or to allow the active ingredients to act on their environment, habitat or storage space, for example, by dipping, spraying, misting, drip irrigation, injection, flushing, evaporation, spreading, coating, coating (for example, application to seeds) or seed dressing.

[0015] The spearmint oil and L-carvone in the present invention are plant extracts, which are very easy to oxidize and volatilize under natural conditions. When directly applied and exposed to the air in field applications, the active ingredients will be degraded or lost, resulting in a small amount acting on the target and reduced biological activity. The active ingredients are made into microcapsule suspensions, which can encapsulate the effective ingredients, avoid volatilization and degradation caused by ultraviolet rays, improve bioavailability, and significantly improve field prevention effects. The selection of microcapsule wall materials has a great relationship with the encapsulated active ingredients, and affects whether the drug can be fully encapsulated. The ratio in this patent is the optimal ratio of spearmint oil and L-carvone to the wall material. Too high or too low ratios will result in the drug not being fully encapsulated.

[0016] In some embodiments of the present invention, the dosage form of the fungicide is a microcapsule suspension, wherein the microcapsules are composed of a core material and a wall material in a mass ratio of 1:5 to 5:1, the core material is an active ingredient, and the wall material is composed of polybutylene succinate and polyhydroxybutyrate in a mass ratio of 1:4 to 4:1. Preferably, the fungicide comprises a core material and a wall material in a mass ratio of 1:1 to 3:1, and the mass ratio of the wall material composed of polybutylene succinate and polyhydroxybutyrate is 1:1 to 1:1.5.

[0017] For the core active ingredient of the present application, the wall material prepared by using polylactic acid (PLA) and polybutylene succinate (PBS) in the invention patent with publication number CN108835110B is easy to form capsules, but the prepared microcapsules have irregular morphology, are prone to holes, have reduced encapsulation efficiency, fast drug release, and short duration. Compared with the wall material in the invention patent with publication number CN108835110B or other wall materials, the microcapsules prepared by using polyhydroxybutyrate (PHB) and polybutylene succinate (PBS) in the present application have regular spherical morphology, good capsule formation, no agglomeration, higher encapsulation efficiency and drug loading, regular morphology, and better efficacy.

[0018] The preparation method of the bactericide comprises the following steps:

[0019] (1) Preparation of the oil phase: dissolving the active ingredient, polybutylene succinate and polyhydroxybutyrate in a low-boiling point organic solvent to obtain an oil phase containing the active ingredient and the carrier;

[0020] (2) Preparation of aqueous phase: completely dissolving the emulsifying dispersant in water to obtain an aqueous phase;

[0021] (3) Preparation of microcapsules: adding the oil phase containing the active ingredient and the carrier in step (1) to the water phase in step (2), and subjecting the mixture to high-speed shearing at room temperature. After the shearing is completed, a microemulsion is obtained. The microemulsion is stirred at a set temperature until the organic solvent is completely evaporated. After centrifugation and drying, drug-loaded microcapsules are obtained.

[0022] (4) Preparation of microcapsule suspension: Determine the active ingredient loading, then measure the mass of microcapsules, wetting agent, dispersant, thickener, penetration enhancer and stabilizer according to the microcapsule suspension ratio, combine them in a container and shear and disperse them to form a preparation.

[0023] The invention also discloses an application of the bactericide in preventing and treating kiwifruit canker disease.

[0024] In a preferred embodiment of the present invention, the active ingredient of the fungicide is spearmint oil, the mass concentration of the active ingredient in the fungicide is 5 to 25 mg / L, and the EC of the active ingredient in the fungicide is 50The EC of the active ingredient in the fungicide is 6.20 mg / L. 50 It is determined by turbidimetry.

[0025] In a preferred embodiment of the present invention, the active ingredient of the fungicide is spearmint oil, and the mass concentration of the fungicide in the field is 300-800 mg / L, preferably, the mass concentration of the fungicide in the field is 500 mg / L.

[0026] The preferred field application mass concentration of the fungicide is determined by applying the fungicide to a field test.

[0027] In one embodiment of the present invention, the active ingredient of the fungicide is L-carvone, the mass concentration of the active ingredient in the fungicide is 5-40 mg / L, and the EC of the active ingredient in the fungicide is 50 The EC of the active ingredient in the fungicide is 13.73 mg / L. 50 It is determined by turbidimetry.

[0028] The mass concentration range of the active ingredients in the fungicide can significantly inhibit the growth and reproduction of kiwifruit canker pathogens.

[0029] The invention also discloses application of the bactericide in preventing and treating citrus canker.

[0030] In one embodiment of the present invention, the active ingredient of the fungicide is spearmint oil, the mass concentration of the active ingredient in the fungicide is 5 to 25 mg / L, and the EC of the active ingredient in the fungicide is 50 The EC of the active ingredient in the fungicide is 6.45 mg / L. 50 It is determined by turbidimetry.

[0031] In a preferred embodiment of the present invention, the active ingredient of the fungicide is spearmint oil, and the mass concentration of the fungicide in the field is 200-800 mg / L, preferably, the mass concentration of the fungicide in the field is 500 mg / L.

[0032] The preferred field application mass concentration of the fungicide is determined by applying the fungicide to a field test.

[0033] In a preferred embodiment of the present invention, the active ingredient of the fungicide is L-carvone, the mass concentration of the active ingredient in the fungicide is 5-40 mg / L, and the EC of the active ingredient in the fungicide is 50 The EC of the active ingredient in the fungicide is 15.02 mg / L. 50 It is determined by turbidimetry.

[0034] The mass concentration range of the active ingredients in the fungicide can significantly inhibit the growth and reproduction of citrus canker pathogens.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) The present invention can effectively inhibit citrus canker bacteria, has a rapid onset of action, leaves no residue, improves the quality of citrus, and has a better effect than basic copper sulfate.

[0037] (2) The present invention can effectively inhibit kiwifruit canker bacteria, has a rapid onset of action, leaves no residue, improves kiwifruit quality, and has a better effect than kasugamycin. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The figure is the result of measuring the indoor toxicity of spearmint oil to kiwifruit canker pathogen by turbidimetry in Example 1; as the drug concentration increases, the color of the bacterial solution gradually becomes clear, indicating that high concentrations of spearmint oil can significantly inhibit the growth and reproduction of kiwifruit canker pathogens.

[0039] Figure 2 This is a picture of the 10% spearmint oil microcapsule suspension prepared in Example 2 being used to prevent and treat kiwifruit canker. There are no obvious symptoms of canker on the plants after the application, indicating that the 10% spearmint oil microcapsule suspension has an obvious field control effect.

[0040] Figure 3 This is a comparison of the pictures after the use of 4% kasugamycin aqueous solution for the prevention and treatment of kiwifruit canker. After the use of kasugamycin, there were obvious symptoms of canker on the leaves, indicating that the ability of 4% kasugamycin aqueous solution to prevent and treat kiwifruit canker is weak.

[0041] Figure 4 This is the result of measuring the indoor toxicity of spearmint oil against citrus canker pathogen using turbidimetry in Example 3; as the drug concentration increases, the color of the bacterial solution gradually becomes clear, indicating that high concentrations of spearmint oil can significantly inhibit the growth and reproduction of citrus canker pathogens.

[0042] Figure 5 This is a picture of the 10% spearmint oil microcapsule suspension prepared in Example 4 being used to control citrus canker. There are no obvious symptoms of canker on the plants after the application, indicating that the 10% spearmint oil microcapsule suspension has a significant field control effect.

[0043] Figure 6 To compare the pictures after using 77% basic copper sulfate water dispersible granules to prevent and control citrus canker; after using 77% basic copper sulfate water dispersible granules, there are obvious symptoms of canker on the leaves, indicating that the ability of 77% basic copper sulfate water dispersible granules to prevent and control citrus canker is weak.

[0044] Figure 7 This is the result of measuring the indoor toxicity of L-carvone to kiwifruit canker pathogen using turbidimetry in Example 7; as the drug concentration increases, the color of the bacterial solution gradually becomes clear, indicating that a higher concentration of L-carvone can significantly inhibit the growth and reproduction of kiwifruit canker pathogen.

[0045] Figure 8 This is the result of measuring the indoor toxicity of L-carvone to citrus canker pathogen using turbidimetry in Example 8; as the drug concentration increases, the color of the bacterial solution gradually becomes clear, indicating that a higher concentration of L-carvone can significantly inhibit the growth and reproduction of citrus canker pathogen. DETAILED DESCRIPTION

[0046] Embodiment 1:

[0047] In vitro inhibitory activity test method of spearmint oil against kiwifruit canker pathogen Pseudomonas syringae pv.actinidiae (Psa):

[0048] Bioassay materials: A strong pathogenic physiological subspecies of the pathogen of kiwifruit canker, Actinidia xanthomonas subspecies, collected, isolated and identified by the inventors. The strain was activated on LB solid medium and cultured at 28°C for 3 days before use.

[0049] Experimental instruments and consumables: UV spectrometer, constant temperature incubator, constant temperature shaker, centrifuge tubes, and gun tips.

[0050] Bioassay steps: Preparation of culture medium: LB liquid culture medium: 10 g tryptone, 5 g yeast extract, 10 g sodium chloride, dilute to 1000 ml with distilled water, and adjust the pH to 7.4 with NaOH.

[0051] Preparation of bacterial suspension: The strain was activated on LB solid culture medium, and after inverted culture at 28°C for 3 days, a small amount of colonies was gently scraped into LB liquid culture medium with the tip of a pipette on a clean workbench, and cultured on a shaker at 28°C and 200 rpm until the colonies were completely dispersed without lumps of precipitation. Then, the kiwifruit canker bacteria was diluted with sterile water to a bacterial suspension with an absorbance of 0.1 at 600nm on a UV spectrophotometer.

[0052] The turbidimetric method was used to determine the toxicity of the drug to kiwifruit canker pathogens. The drug was set to 5 concentration gradients, each gradient was set to 100mL of LB culture medium, and then 100μL of the prepared kiwifruit canker pathogenic bacteria solution was added and placed in a constant temperature oscillator for 24 hours at 28°C and 180r / min. The LB culture medium without adding active ingredients was used as CK, and 3 replicates were made for each test group. Then, the solubility of the bacterial solution was determined at 600nm using an ultraviolet spectrometer, and the toxicity regression equation, EC were calculated using the DPS data processing system.50 Value and correlation coefficient. The growth inhibition rate was calculated according to formula 1-1:

[0053]

[0054] Table 1 Turbidimetric determination of the indoor toxicity of spearmint oil against kiwifruit canker pathogens

[0055]

[0056] Embodiment 2:

[0057] A preparation for preventing and treating kiwifruit canker. It is prepared from the following components in parts by weight: 98 parts of deionized water, 2 parts of polyvinyl alcohol, 10 parts of spearmint oil, 2 parts of polybutylene succinate (PBS), 3 parts of polyhydroxybutyrate (PHB), and 30 parts of dichloromethane. During preparation, 98g of deionized water is measured in a conical flask, 2g of polyvinyl alcohol is slowly added, and a digital magnetic stirrer is used to heat it to 60°C and stir it at a constant temperature and high speed to completely dissolve it, and it is cooled to room temperature to prepare an aqueous phase. PBS:PHB (2:3) is used as the wall material, and the active ingredient spearmint oil is used as the core material, and the core-to-wall ratio is 2:1. 2g of polybutylene succinate (PBS) and 3g of polyhydroxybutyrate (PHB) are dissolved in 30mL of dichloromethane, fully stirred on a magnetic stirrer, and then the active ingredient spearmint oil is added thereto and continued to stir and dissolve to obtain an oil phase. After pouring the oil phase into the water phase, use a T25 digital disperser to emulsify and shear at a speed of 8000r / min for 5 minutes to prepare a stable water-in-oil mixed emulsion. Stir at a speed of 600r / min on a magnetic stirrer for 6 to 7 hours until the solvent dichloromethane is completely evaporated and the microcapsules are solidified. Separate the microcapsules and determine the active ingredient loading. Measure the mass of microcapsules, wetting agents, dispersants, thickeners, penetration enhancers and stabilizers according to the ratio of microcapsule suspensions, combine them in a container, and shear and disperse them to form a preparation. When using, dilute the preparation and water at a mass ratio of 1:200, and then spray the kiwifruit plants.

[0058] The fungicide for preventing and treating kiwifruit canker disease prepared by the preparation method of Example 2 was used in a control experiment at the base according to the method of use. The results are shown in Table 2 below:

[0059] Table 2 Field investigation results of the efficacy of 10% spearmint oil microcapsule suspension against kiwifruit canker

[0060]

[0061] Embodiment 3:

[0062] In vitro inhibitory activity test method of spearmint oil against citrus canker pathogens:

[0063] Bioassay materials: Citrus canker pathogen with strong pathogenicity, Xanthomonas citri subsp. citri (Xcc) LYGJ3-5, collected, isolated and identified by the inventors. The strain was activated on LB solid medium and cultured at 28°C for 3 days before use.

[0064] Experimental instruments and consumables: UV spectrometer, constant temperature incubator, constant temperature shaker, centrifuge tubes, and gun tips.

[0065] Bioassay steps: Preparation of culture medium: LB liquid culture medium: 10 g tryptone, 5 g yeast extract, 10 g sodium chloride, dilute to 1000 ml with distilled water, and adjust the pH to 7.4 with NaOH.

[0066] Preparation of bacterial suspension: Activate the strain on LB solid culture medium, invert and culture at 28°C for 3 days, then gently scrape a small amount of colonies into LB liquid culture medium with the tip of a pipette on a clean workbench, and culture on a shaker at 28°C and 200 rpm until the colonies are completely dispersed without lumps of precipitation. Then use sterile water to dilute the citrus canker bacteria into a bacterial suspension with an absorbance of 0.1 at 600nm on a UV spectrophotometer.

[0067] The turbidimetric method was used to determine the toxicity of the drug to citrus canker bacteria. The drug was set to 5 concentration gradients, each gradient was set to 100mL of LB culture medium, and then 100μL of the prepared citrus canker bacteria solution was added and placed in a constant temperature oscillator for 24 hours at 28°C and 180r / min. The LB culture medium without adding active ingredients was used as CK, and 3 replicates were made for each test group. Then, the solubility of the bacterial solution was determined at 600nm using an ultraviolet spectrometer, and the toxicity regression equation, EC 50 Value and correlation coefficient. The growth inhibition rate is calculated according to formula 3-1:

[0068]

[0069] Table 3 Turbidimetric determination of the indoor toxicity of spearmint oil against citrus canker pathogens

[0070]

[0071]

[0072] Embodiment 4:

[0073] A preparation for preventing and treating citrus canker. It is prepared from the following components in parts by weight: 98 parts of deionized water, 2 parts of polyvinyl alcohol, 10 parts of spearmint oil, 2 parts of polybutylene succinate (PBS), 3 parts of polyhydroxybutyrate (PHB), and 30 parts of dichloromethane. During preparation, 98g of deionized water is measured in a conical flask, 2g of polyvinyl alcohol is slowly added, and a digital magnetic stirrer is used to heat it to 60°C and stir it at a constant temperature and high speed to completely dissolve it, and it is cooled to room temperature to prepare an aqueous phase. PBS:PHB (2:3) is used as the wall material, and the active ingredient spearmint oil is used as the core material, and the core-to-wall ratio is 2:1. 2g of polybutylene succinate (PBS) and 3g of polyhydroxybutyrate (PHB) are dissolved in 30mL of dichloromethane, fully stirred on a magnetic stirrer, and then the active ingredient spearmint oil is added thereto and continued to stir and dissolve to obtain an oil phase. After pouring the oil phase into the water phase, use a T25 digital disperser to emulsify and shear at a speed of 8000r / min for 5 minutes to prepare a stable water-in-oil mixed emulsion. Stir it on a magnetic stirrer at a speed of 600r / min for 6 to 7 hours until the solvent dichloromethane is completely evaporated and the microcapsules are solidified. Separate the microcapsules and determine the active ingredient loading. Measure the mass of microcapsules, wetting agents, dispersants, thickeners, penetration enhancers and stabilizers according to the ratio of microcapsule suspensions, combine them in a container and shear and disperse to form a preparation. When using, dilute the preparation and water at a mass ratio of 1:200 and spray the kiwifruit plants.

[0074] The fungicide for preventing and treating citrus canker prepared by the preparation method of Example 4 was used in a control experiment at the base according to the method of use. The results are shown in Table 4 below:

[0075] Table 4 Field investigation results of the efficacy of 10% spearmint oil microcapsule suspension against citrus canker

[0076]

[0077] Embodiment 5:

[0078] The in vitro inhibitory activity test method of L-carvone against kiwifruit canker pathogen Pseudomonas syringae pv.actinidiae (Psa):

[0079] Bioassay materials: A strong pathogenic physiological subspecies of the pathogen of kiwifruit canker, Actinidia xanthomonas subspecies, collected, isolated and identified by the inventors. The strain was activated on LB solid medium and cultured at 28°C for 3 days before use.

[0080] Experimental instruments and consumables: UV spectrometer, constant temperature incubator, constant temperature shaker, centrifuge tubes, and gun tips.

[0081] Bioassay steps: Preparation of culture medium: LB liquid culture medium: 10 g tryptone, 5 g yeast extract, 10 g sodium chloride, dilute to 1000 ml with distilled water, and adjust pH to 7.4 with NaOH.

[0082] Preparation of bacterial suspension: The strain was activated on LB solid culture medium, and after inverted culture at 28°C for 3 days, a small amount of colonies was gently scraped into LB liquid culture medium with the tip of a pipette on a clean workbench, and cultured on a shaker at 28°C and 200 rpm until the colonies were completely dispersed without lumps of precipitation. Then, the kiwifruit canker bacteria was diluted with sterile water to a bacterial suspension with an absorbance of 0.1 at 600nm on a UV spectrophotometer.

[0083] The turbidimetric method was used to determine the toxicity of the drug to kiwifruit canker pathogens. The drug was set to 5 concentration gradients, each gradient was set to 100mL LB culture medium, and then 100μL of the prepared kiwifruit canker pathogenic bacteria solution was added and placed in a constant temperature oscillator for 24 hours at 28°C and 180r / min. The LB culture medium without adding active ingredients was used as CK, and 3 replicates were made for each test group. Then, the solubility of the bacterial solution was determined at 600nm using an ultraviolet spectrometer, and the toxicity regression equation, EC were calculated using the DPS data processing system. 50 Value and correlation coefficient. The growth inhibition rate is calculated according to formula 5-1:

[0084]

[0085] Table 5 Turbidimetric determination of the indoor toxicity of L-carvone to kiwifruit canker pathogens

[0086]

[0087] Embodiment 6:

[0088] Test method for in vitro inhibitory activity of L-carvone against citrus canker pathogens:

[0089] Bioassay materials: Citrus canker pathogen with strong pathogenicity, Xanthomonas citri subsp. citri (Xcc) LYGJ3-5, collected, isolated and identified by the inventors. The strain was activated on LB solid medium and cultured at 28°C for 3 days before use.

[0090] Experimental instruments and consumables: UV spectrometer, constant temperature incubator, constant temperature shaker, centrifuge tubes, and gun tips.

[0091] Bioassay steps: Preparation of culture medium: LB liquid culture medium: 10 g tryptone, 5 g yeast extract, 10 g sodium chloride, dilute to 1000 ml with distilled water, and adjust the pH to 7.4 with NaOH.

[0092] Preparation of bacterial suspension: Activate the strain on LB solid culture medium, invert and culture at 28°C for 3 days, then gently scrape a small amount of colonies into LB liquid culture medium with the tip of a pipette on a clean workbench, and culture on a shaker at 28°C and 200 rpm until the colonies are completely dispersed without lumps of precipitation. Then use sterile water to dilute the citrus canker bacteria into a bacterial suspension with an absorbance of 0.1 at 600nm on a UV spectrophotometer.

[0093] The turbidimetric method was used to determine the toxicity of the drug to citrus canker bacteria. The drug was set to 5 concentration gradients, each gradient was set to 100mL of LB culture medium, and then 100μL of the prepared citrus canker bacteria solution was added and placed in a constant temperature oscillator for 24 hours at 28°C and 180r / min. The LB culture medium without adding active ingredients was used as CK, and 3 replicates were made for each test group. Then, the solubility of the bacterial solution was determined at 600nm using an ultraviolet spectrometer, and the toxicity regression equation, EC 50 Value and correlation coefficient. The growth inhibition rate is calculated according to formula 6-1:

[0094]

[0095] Table 6 Turbidimetric determination of the indoor toxicity of L-carvone citrus canker pathogen

[0096]

Claims

1. A fungicide, It is characterized in that The fungicide comprises active ingredients, and the active ingredients are one or more of spearmint oil and L-carvone.

2. The bactericide according to claim 1, It is characterized in that The fungicide also includes auxiliary agents, which include one or more of surfactants, fillers, solvents, carriers, emulsifiers, dispersants, foaming agents, defoamers, wetting agents, thickeners, penetrants, stabilizers, antifreeze agents, film-forming agents, color pastes, and flavors; the active ingredient accounts for 0.5 to 95.0% of the total mass percentage of the fungicide, preferably, the active ingredient accounts for 1.0 to 50.0% of the total mass percentage of the fungicide, and further preferably, the active ingredient accounts for 5.0 to 25.0% of the total mass percentage of the fungicide.

3. The bactericide according to claim 1 or 2, It is characterized in that The active ingredient is mixed with an adjuvant to form a dosage form suitable for use in agriculture, and the dosage form can be selected from one or more of an aqueous emulsion, a microemulsion, an oil emulsion, an emulsifiable concentrate, a latex, a paste, an ointment, a dispersible liquid, a soluble solution, a soluble gel, an oil, a granule, a wettable powder, a water-dispersible granule, a suspension, a microcapsule suspension, an oil suspension, a dispersible oil suspension, and a seed treatment suspension; preferably, the dosage form is a microcapsule suspension, wherein the microcapsule is composed of a core material and a wall material in a mass ratio of 1:5 to 5:1, the core material is the active ingredient, and the wall material is composed of polybutylene succinate and polyhydroxybutyrate in a mass ratio of 1:4 to 4:1; the active ingredient is wrapped in the wall material, preferably, the fungicide comprises a core material and a wall material in a mass ratio of 1:1 to 3:1, and the mass ratio of the wall material composed of polybutylene succinate and polyhydroxybutyrate is 1:1 to 1:1.

5.

4. Use of the fungicide according to any one of claims 1 to 3 in preventing and treating kiwifruit canker disease.

5. Use of the fungicide according to claim 4 in preventing and treating kiwifruit canker disease, It is characterized in that The active ingredient of the fungicide is spearmint oil, the mass concentration of the active ingredient in the fungicide is 5 to 25 mg / L, and the EC 50 It is 6.20mg / L.

6. Use of the fungicide according to claim 4 in preventing and treating kiwifruit canker disease, It is characterized in that The active ingredient of the fungicide is spearmint oil, and the mass concentration of the fungicide in the field is 300-800 mg / L. Preferably, the mass concentration of the fungicide in the field is 500 mg / L.

7. Use of the fungicide according to claim 4 in preventing and treating kiwifruit canker disease, It is characterized in that The active ingredient of the fungicide is L-carvone, the mass concentration of the active ingredient in the fungicide is 5-40 mg / L, and the EC 50 It is 13.73mg / L.

8. Use of the fungicide according to any one of claims 1 to 3 in preventing and treating citrus canker.

9. Use of the fungicide according to claim 8 in preventing and treating citrus canker, It is characterized in that The active ingredient of the fungicide is spearmint oil, the mass concentration of the active ingredient in the fungicide is 5 to 25 mg / L, and the EC 50 6.45mg / L; The active ingredient of the fungicide is spearmint oil, and the mass concentration of the fungicide in the field is 200-800 mg / L. Preferably, the mass concentration of the fungicide in the field is 500 mg / L.

10. Use of the fungicide according to claim 8 in preventing and treating citrus canker, It is characterized in that The active ingredient of the fungicide is L-carvone, the mass concentration of the active ingredient in the fungicide is 5-40 mg / L, and the EC 50 It is 15.02mg / L.

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