Application of linalool in prevention and treatment of plant rust disease

Abstract

The invention discloses application of linalool in prevention and treatment of plant rust, and belongs to the technical field of biological prevention and treatment. The linalool is used for preventing and treating the rust disease, and particularly has a good effect on preventing and treating the rust disease of pepper, fatsia japonica, willow, rosa banksiae and ryegrass. According to the linalool microcapsule suspending agent, linalool serves as a parent drug, the optimal formula of the linalool microcapsule suspending agent is obtained through formula screening, the linalool microcapsule suspending agent is prepared through an interfacial polymerization method, the capsule shape is regular, the appearance is smooth, the particle size is moderate, the requirement for the particle size of pesticide microcapsules is met, and through potting and field trials, the effect is good. The linalool micro-capsule suspending agent is proved to have a relatively strong inhibition effect on germination of sphingella zanthoxyli uredospore bud tubes, and a relatively good prevention and treatment effect can be achieved by preventing rust diseases in advance before the rust diseases occur.

Description

Technical Field

[0001] The invention relates to the technical field of biological control, and in particular to application of linalool in preventing and controlling plant rust. Background Art

[0002] Rust is a type of disease caused by fungal parasites, which has a series of damages to the leaves, stems and fruits of plants. Rust is a disease that can be circulated multiple times, and its transmission pathway is wide, which allows rust to form a large-scale infection in a short period of time. There are certain differences in the symptoms manifested by infection with different pathogens, but the main symptom of rust is the appearance of yellow powder or rust on the back of the infected plant leaves. When rust occurs on a large scale between plants, the plants are severely damaged and the yield of the plants is greatly reduced. For example, pepper rust is a leaf disease that is common in pepper cultivation areas. Pepper rust mainly harms the leaves and can cause a large number of pepper leaves to fall off, resulting in the pepper tree sprouting new leaves again. This not only affects the nutrient accumulation of the pepper tree in the current year and the pepper yield and quality in the following year, but more importantly, it poses a great threat to the life of the pepper tree. In the early stage of the disease, water-soaked chlorotic spots appear on the front of the leaves, and there are light yellow dots in the center of the chlorotic spots on the back of the leaves. The spots continue to expand and form orange-yellow blister-like summer spores. After these blisters burst, orange-yellow powdery summer spores are released. There are more summer spores on the back of the leaves. In severe cases, some are arranged in a ring shape. The new leaves that grow can still be infected. The affected leaves turn yellow in the later stage of growth and are easy to fall off, which has a serious impact on the growth of the plant. In severe cases, the diseased leaf rate can reach more than 90%.

[0003] Linalool, as a monoterpene substance, is widely present in many plant essential oils. It is widely used in the medical field because of its significant pharmacological activity in anti-anxiety, anti-inflammatory, antioxidant, and anti-tumor aspects. In the field of crop production, Wang Qifang et al.'s research showed that linalool has a significant inhibitory effect on the growth of Botrytis cinerea and has a good control effect on tomato gray mold. Li Yuansong et al.'s research believes that linalool can play an antibacterial role by destroying the cell structure of Pseudomonas fragariae and inhibiting its respiratory metabolism, and is expected to be used as a natural preservative for food preservation. Zhou Lirong et al.'s research found that linalool inhibits the growth of mycelium and spore germination of ginger wilt fungus Fusarium oxysporum and destroys its cell structure, thereby affecting its normal physiological function, which can provide new ideas for the prevention and control of ginger wilt. However, there is no report on the use of linalool for rust prevention and control in the prior art. Summary of the invention

[0004] In order to solve the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide an application of linalool in preventing and treating plant rust. The present invention prepares linalool into a microcapsule suspension, which can effectively prevent and treat a variety of plant rusts.

[0005] The technical solution of the present invention to solve the above technical problems is as follows: providing an application of linalool in preventing and controlling plant rust diseases.

[0006] Further, the plants are Zanthoxylum bungeanum, Fatsia japonica, Salix babylonica, Rosa banksiae, Lolium perenne.

[0007] Further, the rust disease of Zanthoxylum bungeanum is caused by Coleosporium zanthoxyli, the rust disease of Fatsia japonica is caused by Coleosporium sp., the rust disease of Salix babylonica is caused by Melampsora coleosporioides Diet., the rust disease of Rosa banksiae is caused by Phragmidium sichuanensis, and the rust disease of Lolium perenne is caused by Puccinia rubigovera (DC.) Winl.

[0008] An application of a biological agent in preventing and controlling plant rust diseases, the biological agent includes linalool.

[0009] Further, the above biological agent is a linalool microcapsule suspension.

[0010] Further, the above linalool microcapsule suspension includes the following components in parts by weight: 1 part of linalool, 1 - 1.5 parts of emulsifier, 1 - 3 parts of capsule skin material, 1.5 - 3 parts of dispersant, 1 - 3 parts of initiator.

[0011] Further, the above linalool microcapsule suspension includes the following components in parts by weight: 1 part of linalool, 1.5 parts of emulsifier, 2 parts of capsule skin material, 2.5 parts of dispersant, 2 parts of initiator.

[0012] Further, the emulsifier is Tween 20.

[0013] Further, the capsule skin material is isophorone diisocyanate (IPDI).

[0014] Further, the dispersant is sodium dodecylbenzenesulfonate.

[0015] Further, the initiator is triethanolamine.

[0016] Further, it also includes a solvent, the solvent is absolute ethanol, and the mass ratio of linalool to absolute ethanol is 1:1 - 4; preferably, the mass ratio of linalool to absolute ethanol is 1:3.

[0017] Further, the above linalool microcapsule suspension is prepared by the following method:

[0018] Dissolve linalool, add the emulsifier and the capsule skin material and mix evenly to obtain an oil phase;

[0019] Shear water and the dispersant at a rate of 8000 - 12000 rpm for 2 - 4 min to obtain an aqueous phase;

[0020] Mix the aqueous phase and the oil phase and shear at a rate of 8000 - 12000 rpm for 2 - 4 min to obtain the linalool microcapsule suspension.

[0021] Further, shear water and the dispersant at a rate of 10000 rpm for 3 min to obtain the aqueous phase.

[0022] Further, mix the aqueous phase and the oil phase and shear at a rate of 10000 rpm for 3 min.

[0023] The present invention has the following beneficial effects:

[0024] The present invention uses linalool for the control of rust diseases, especially has good effects on the control of rust diseases of Zanthoxylum bungeanum, Fatsia japonica, Salix babylonica, Rosa banksiae, and Lolium perenne. The present invention uses linalool as the mother drug, obtains the optimal formula of the linalool microcapsule suspension through formula screening, and prepares the linalool microcapsule suspension through the interfacial polymerization method. Its capsule shape is relatively regular, the appearance is smooth, the particle size is moderate, meeting the particle size requirements of pesticide microcapsules. Through pot and field experiments, it is proved that the linalool microcapsule suspension has a strong inhibitory effect on the germination of the uredospore germ tubes of Coleosporium zanthoxyli, and can play a good control effect by preventing in advance before the rust disease occurs. Description of the Drawings

[0025] Figure 1 It is the electron microscope image during the screening process of capsule skin types; among them, Figure a is 4,4'-methylenebis(phenyl isocyanate), Figure b is toluene - 2,4 - diisocyanate, and Figure c is isophorone diisocyanate.

[0026] Figure 2 It is the electron microscope image during the screening process of the mixing and shearing time of the oil and aqueous phases; among them, Figure a is the shearing time of 1 min, Figure b is the shearing time of 2 min, Figure c is the shearing time of 3 min, and Figure d is the shearing time of 4 min.

[0027] Figure 3 It is the electron microscope image during the screening process of dispersant types; among them, Figure a is sodium dodecylbenzenesulfonate, Figure b is sodium lignosulfonate, and Figure c is polyvinyl alcohol.

[0028] Figure 4 It is the electron microscope image during the screening process of the shearing time of the aqueous phase; among them, Figure a is the shearing time of 1 min, Figure b is the shearing time of 2 min, Figure c is the shearing time of 3 min, and Figure d is the shearing time of 4 min.

[0029] Figure 5 It is the electron microscope image during the screening process of initiator types; among them, Figure a is triethanolamine, Figure b is 1,4 - butanediol, Figure c is diethylenetriamine, and Figure d is 1,6 - hexanediamine.

[0030] Figure 6 Electron microscope image of linalool microcapsule suspending agent prepared with the optimal formula.

[0031] Figure 7 Microscope images after dropping different medicaments on water agar plates; among them, Figure a is the image after dropping epoxiconazole suspending agent, and Figure b is the image after dropping linalool microcapsule suspending agent.

[0032] Figure 8 Microscope images of rust fungi on Fatsia japonica, willow, Banksia rosea, and Lolium perenne after dropping linalool microcapsule suspending agent; among them, Figure a is Fatsia japonica, Figure b is willow, Figure c is Banksia rosea, Figure d is Lolium perenne, Figure e is the germination situation of rust fungi on Fatsia japonica after dropping linalool microcapsule suspending agent, Figure f is the germination situation of rust fungi on willow after dropping linalool microcapsule suspending agent, Figure g is the germination situation of rust fungi on Banksia rosea after dropping linalool microcapsule suspending agent, Figure h is the germination situation of rust fungi on Lolium perenne after dropping linalool microcapsule suspending agent, Figure i is the germination situation of rust fungi on Fatsia japonica, Figure j is the germination situation of rust fungi on willow, Figure k is the germination situation of rust fungi on Banksia rosea, and Figure l is the germination situation of rust fungi on Lolium perenne.

[0033] Figure 9 Incidence results of different treatment groups in pot experiments and field experiments; among them, Figure a is spraying medicament in advance when not diseased after inoculation in pot experiments, Figure b is spraying medicament when diseased after inoculation in pot experiments, and Figure c is spraying medicament in advance when not diseased in field experiments; 1 - 3 are the investigation times in pot experiments, and 1 - 8 are the investigation times in field experiments.

[0034] Figure 10 Disease index and control effect of different treatment groups in pot experiments and field experiments; among them, Figure a is spraying medicament in advance when not diseased after inoculation in pot experiments, Figure b is spraying medicament when diseased after inoculation in pot experiments, and Figure c is spraying medicament in advance when not diseased in field experiments; 1 - 3 are the investigation times in pot experiments, and 1 - 8 are the investigation times in field experiments.

[0035] Figure 11 Leaf control effect diagrams of pot experiments and field experiments; among them, Figure a is the control leaf in pot experiments, Figure b is the treated leaf in pot experiments, Figure c is the control leaf in field experiments, and Figure d is the treated leaf in field experiments. Specific implementation manners

[0036] The test strains, test medicaments, auxiliaries, and capsule skin materials used in the present invention are as follows:

[0037] 1. Test strains

[0038] Coleosporium zanthoxyli (accession number: NL4: MN608178.1, ITS: MN611081.1) is stored in the Forest Pathology Laboratory of Sichuan Agricultural University.

[0039] 2. Test agents

[0040] Linalool (98%) was purchased from Chengdu Macklin Biochemical Technology Co., Ltd.; flutriafol suspension and pyraclostrobin emulsifiable concentrate were purchased from Xuzhou Sunshine Agricultural Resources Business Department; diniconazole wettable powder and tebuconazole suspension were purchased from Chengdu Yehe Agricultural Resources Co., Ltd.

[0041] 3. Auxiliaries and capsule skin materials

[0042] Emulsifier OP8, emulsifier OP10, castor oil polyoxyethylene ether EL-40, fatty alcohol polyoxyethylene ether AEO-9, octylphenol polyoxyethylene ether phosphate OP-10P were purchased from Qingdao Yousuo Chemical Technology Co., Ltd.; Tween 20, Tween 80, and absolute ethanol were purchased from Chengdu Haobo You Co., Ltd.; fatty alcohol polyoxyethylene ether AEO3, sodium lignosulfonate, sodium dodecylbenzenesulfonate, polyvinyl alcohol, triethanolamine, diethylenetriamine, 1,6-hexanediamine, 1,4-butanediol, isophorone diisocyanate (IPDI), 4,4'-methylenebis(phenyl isocyanate) (MDI), toluene-2,4-diisocyanate (TDI) were purchased from Chengdu Macklin Biochemical Technology Co., Ltd.

[0043] The following examples are only used to explain the present invention and are not intended to limit the scope of the present invention. For those not specified in the examples, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0044] Example 1: Preparation of linalool microcapsule suspension

[0045] I. Formula screening and preparation

[0046] 1. Screening of solvents

[0047] Weigh 1 g of linalool (technical material), and add solvents to the technical material in different proportions. The evaluation index is whether the solution is clear and transparent after dissolution.

[0048] 2. Screening of emulsifiers

[0049] Dissolve the technical material according to the mass ratio of solvent to technical material of 3:1, add emulsifiers in different proportions, stir evenly, and screen the types and dosages of emulsifiers with the water entry state of the emulsion, 24-hour stability, and thermal storage stability as the evaluation indexes.

[0050] 3. Screening of capsule skin materials

[0051] (1) Screening of the type and dosage of the capsule skin

[0052] Weigh 1 g of the mother drug, dissolve the mother drug with 3 g of solvent, add 1.5 g of emulsifier, and add the capsule skin material to the aqueous phase in different proportions. The dosage of the dispersant is 2.5 g, and the dosage of the initiator is 2 g. Taking the capsule formation state, encapsulation efficiency, and particle size of the microcapsules as evaluation indexes, screen the type and dosage of the capsule skin material.

[0053] (2) Screening of the mixing and shearing time of the oil phase and aqueous phase

[0054] The oil phase consists of the original drug, capsule skin, solvent, and emulsifier, and the aqueous phase consists of water and dispersant. Shear the aqueous phase at a rate of 10000 rpm for 3 min. After the shearing of the aqueous phase is completed, slowly add the pre-mixed oil phase, and conduct microscopic examination every 1 min. Taking the forming state and dispersibility of the microcapsules as evaluation indexes, screen the shearing time.

[0055] 4. Screening of the dispersant

[0056] (1) Screening of the type and dosage of the dispersant

[0057] Weigh 1 g of the mother drug, dissolve the mother drug with 3 g of solvent, add 1.5 g of emulsifier, and then add 2 g of capsule skin material as the oil phase. The dosage of the initiator is 2 g, and the dispersant is dissolved in water in different proportions. Taking the capsule formation state, encapsulation efficiency, and particle size of the microcapsules as evaluation indexes, screen the type and dosage of the dispersant.

[0058] (2) Screening of the shearing time of the dispersant

[0059] Weigh 2.5 g of the dispersant and add it to water. After shearing at a rate of 10000 rpm for 1 min, 2 min, 3 min, and 4 min respectively, observe the morphology under the microscope. Taking the size and dispersibility of the droplets after shearing as the evaluation index for the appropriate shearing time of the dispersant.

[0060] 5. Screening of the initiator

[0061] Weigh 1 g of the mother drug, dissolve the mother drug with 3 g of solvent, add 1.5 g of emulsifier, and then add 2 g of capsule skin material as the oil phase. The dispersant is 2.5 g, which is added to water as the aqueous phase. The initiator is added to the oil-water mixture in different dosages. Taking the capsule formation state, encapsulation efficiency, and particle size of the microcapsules as evaluation indexes, screen the type and dosage of the initiator.

[0062] II. Characterize the linalool microcapsule suspension prepared above as follows:

[0063] 1. Morphology characterization

[0064] Use a differential interference microscope system to observe the appearance morphology of the microcapsules. After diluting the sample to be tested with an appropriate amount of distilled water, observe the microencapsulation status of the microcapsules and capture images under the differential interference microscope system.

[0065] 2. Particle size determination

[0066] Take a small amount of the microcapsule suspension on a glass slide, dilute it by a certain multiple with deionized water, observe the morphological characteristics of the microcapsules under the differential interference microscope system respectively, take pictures with relevant software, measure the particle size of the microcapsules with corresponding software on the computer, count no less than 200, and calculate their average particle size.

[0067] 3. Encapsulation efficiency determination

[0068] Accurately weigh 0.3 g of the sample, quantitatively transfer it to a 50 mL volumetric flask, then add about 50 mL of methanol solution. Place the volumetric flask on an ultrasonic crusher and crush it for 30 min, then take it out. After shaking well, take out a certain amount of the liquid, centrifuge it at a speed of 12000 r / min for 1 min. Pipette a certain amount of the supernatant, dilute it by a certain multiple, and measure its absorbance at a wavelength of 205 nm with a UV-visible spectrophotometer; then measure the absorbances of 10 different known concentrations of linalool methanol solutions at a wavelength of 205 nm respectively, make a standard curve of concentration and absorbance, obtain the relationship equation between absorbance and concentration, and then measure the absorbance of the test solution at 205 nm. According to the standard curve, the concentration of the test solution can be calculated.

[0069] 4. Microcapsule suspension rate determination

[0070] Determine according to the method for determining the suspension rate of pesticides in GB / T 14825-2023.

[0071] 5. pH determination

[0072] Determine according to the method for determining the pH of pesticides in GB / T 1601-2023.

[0073] 6. Thermal storage stability determination

[0074] Determine according to the method for determining the thermal storage stability of pesticides. The specific process is as follows: Take 50 mL of the prepared microcapsule suspension agent and place it in a bottle, then seal it. Place it in an oven at (54 ± 2) °C and keep it at a constant temperature for 14 d. Take it out and cool it to room temperature, and observe the morphological changes of the microcapsules after storage with a microscope.

[0075] 7. Cold storage stability determination

[0076] It is measured according to the method for determining the cold storage stability of pesticides. The specific process is as follows: Take 50 mL of the prepared microcapsule suspension and place it in a bottle, then seal it. Place it in a refrigerator at 4°C for 7 days, take it out and observe the morphological changes of the microcapsules after storage with a microscope.

[0077] 8. Determination of dispersibility

[0078] Use a pipette to suck 0.5 mL of the microcapsule suspension and transfer it into a graduated cylinder containing 99.5 mL of water. Carefully observe the dispersion state of the suspension in water, and record whether there is particle sedimentation after a certain period of time. The dispersion of the suspension in water is divided into the following three levels:

[0079] Excellent: The suspension is in a cloud-like state and can be automatically dispersed, and there are no visible particles settling.

[0080] Good: The suspension is slowly and automatically dispersed, but there are particles settling, and the particles can be redispersed after gentle shaking.

[0081] Poor: The suspension cannot be dispersed after entering the water, showing flocculent or granular sedimentation, and needs to be shaken violently to be redispersed, but the dispersion is not complete.

[0082] III. Results and analysis

[0083] 1. Screening of solvents

[0084] The solvent used is anhydrous ethanol. After testing, when the technical material is added to anhydrous ethanol, the solubility is good, and the dissolution will not affect the final result of the experiment. Therefore, anhydrous ethanol is selected as the solvent for the technical material. When the amount of anhydrous ethanol added is 3 g, the dissolution effect is excellent. Therefore, the mass ratio of the technical material to the solvent is determined to be 1:3. The specific screening process is shown in Table 1:

[0085] Table 1 Solvent screening of linalool microcapsule suspension

[0086] Dosage of absolute ethanol (g) Dissolution effect 1 Poor 2 Good 3 Excellent 4 Excellent

[0087] 2. Screening of emulsifiers

[0088] The emulsifiers selected in the screening process of the present invention are Tween 20, Tween 80, castor oil polyoxyethylene ether EL-20, fatty alcohol polyoxyethylene ether AEO3, fatty alcohol polyoxyethylene ether AEO9, OP-4, OP-8, OP-10P. Among them, the emulsification effect of Tween 20 is the best. It is in a cloud-like state when entering the water, and there is no floating oil after shaking well. The appearance does not change after the heat storage stability experiment; the emulsification effect of Tween 80 is the second best. It is in a fog-like state when entering the water, but there is some layering; the emulsification effects of OP-4 and OP-8 are poor. Their emulsions are not in a cloud-like state when entering the water, and the floating oil is very serious. Therefore, Tween 20 with excellent primary emulsification state is selected to prepare microcapsules. The specific screening process is shown in Table 2:

[0089] Table 2 Screening of Emulsifier Types for Linalool Microcapsule Suspension

[0090] Type of emulsifier Emulsification effect Stability in 24h Judgment result Tween 20 Excellent Normal √ Tween 80 Good Normal × Castor oil polyoxyethylene ether EL-20 Poor Oil floating × Fatty alcohol polyoxyethylene ether AEO3 Poor Oil floating × Fatty alcohol polyoxyethylene ether AEO9 Poor Oil floating × OP-4 Poor Serious oil floating × OP-8 Poor Serious oil floating × OP-10P Poor Oil floating ×

[0091] The present invention also screened the dosage of Tween 20 emulsifier, and the results are shown in Table 3. It can be seen from Table 3 that when the dosage of emulsifier Tween 20 is 1% and 1.5%, the emulsion shows a cloudy state when it enters the water, and the emulsification effect is excellent. However, when the dosage is 2%, floating oil and stratification occur 24 hours after entering the water. Therefore, the dosage of the emulsifier is determined to be 1.5%, and there is no floating oil on the top after standing for 24 hours. The results of the thermal storage stability experiment show that the emulsion does not separate oil or stratify, and can meet the requirements of emulsifier stability.

[0092] Table 3 Screening of Emulsifier Dosage for Linalool Microcapsule Suspension

[0093]

[0094]

[0095] 3. Screening of Capsule Wall Materials

[0096] (1) Screening of Capsule Wall Types and Dosages

[0097] The capsule wall materials selected during the screening process of the present invention are isophorone diisocyanate (IPDI), 4,4'-methylenebis(phenyl isocyanate) (MDI), and toluene-2,4-diisocyanate (TDI). The capsule formation situation is shown in Figure 1 . From Figure 1 it can be seen that when isophorone diisocyanate (IPDI) is used as the capsule wall material for capsule formation, the microcapsules have regular capsule shapes and are spherical. When 4,4'-methylenebis(phenyl isocyanate) (MDI) and toluene-2,4-diisocyanate (TDI) are used for capsule formation, the capsule formation shapes are irregular, and the capsule formation property is poor or even unable to form capsules. Therefore, isophorone diisocyanate (IPDI) is selected as the capsule wall material for linalool microcapsule suspension. The screening results of the dosage of isophorone diisocyanate (IPDI) are shown in Table 4.

[0098] Table 4 Screening of Dosage of Capsule Wall Materials for Linalool Microcapsule Suspension

[0099] Dosage of IPDI / g Average particle size / μm Entrapment efficiency / % 1 4.202 71.9 2 3.687 90.16 3 4.458 93.5

[0100] As can be seen from Table 4, when the dosage of IPDI increased from 1 g to 2 g, the particle size decreased from 4.202 μm to 3.687 μm, and the encapsulation efficiency increased from 71.9% to 90.16%. When the dosage of IPDI increased from 2 g to 3 g, the particle size increased from 3.687 μm to 4.458 μm, and the encapsulation efficiency increased from 90.16% to 93.5%. Therefore, considering the particle size distribution and encapsulation efficiency, 2 g of IPDI was finally selected as the dosage of the capsule wall material for the linalool microcapsule suspension.

[0101] (2) Screening of the mixing and shearing time of the oil phase and water phase

[0102] The length of the shearing time will directly affect the particle size, capsule formation status and encapsulation efficiency of the microcapsules. Therefore, in this invention, the mixing and shearing time of the oil phase and water phase in the preparation of the microcapsules was screened. Shearing was carried out at a rate of 10,000 rpm, and microscopic examination was carried out every 1 min under the microscope. The results are as Figure 2 shown. When shearing for 1 min, no capsule was formed. When shearing for 2 min, partial capsule formation occurred. When shearing for 3 min, the capsule formation was complete and dispersed. Therefore, the mixing and shearing time of the oil phase and water phase was determined to be 3 min.

[0103] 4. Screening of the dispersant

[0104] (1) Screening of the type and dosage of the dispersant

[0105] The dispersants selected in the screening process of this invention were sodium dodecylbenzenesulfonate, sodium lignosulfonate and polyvinyl alcohol. The droplet conditions formed by them are shown in Figure 3 . From Figure 3 it can be seen that when sodium dodecylbenzenesulfonate was selected as the dispersant of the microcapsules, the droplet sizes after shearing were consistent and the distribution was uniform. When sodium lignosulfonate was selected as the dispersant, no droplets were formed. When polyvinyl alcohol was used as the dispersant, only a small amount of droplets were formed and the droplet sizes were uneven. Therefore, sodium dodecylbenzenesulfonate was selected as the dispersant of the microcapsule suspension.

[0106] This invention also screened the dosage of sodium dodecylbenzenesulfonate. The screening situation is shown in Table 5. As can be seen from Table 5, when the dosage of sodium dodecylbenzenesulfonate increased from 2 g to 2.5 g, the particle size decreased from 7.437 μm to 5.270 μm, and the encapsulation efficiency increased from 57.65% to 92.44%. When the dosage of sodium dodecylbenzenesulfonate was 2.5 g, the particle size was 5.270 μm and the encapsulation efficiency was 92.44%. Therefore, the dosage of sodium dodecylbenzenesulfonate was determined to be 2.5 g.

[0107] Table 5 Screening of the dosage of sodium dodecylbenzenesulfonate for the linalool microcapsule suspension

[0108] Dosage / g Average particle size / μm Entrapment efficiency / % 1.5 9.539 43.97 2 7.437 57.65 2.5 5.270 92.44 3 4.412 58.28

[0109] (2) Screening of Aqueous Phase Shearing Time

[0110] In the present invention, the shearing time of the aqueous phase in the preparation of microcapsules was screened. Shearing was carried out at a rate of 10,000 rpm, and microscopic examination was performed every 1 minute under a microscope. As Figure 4 shown, as the shearing time increased, the droplets became more dispersed and uniform. After shearing for 3 minutes, the droplets were uniform and dispersed. However, after shearing for 4 minutes, the droplets tended to increase in size. Therefore, 3 minutes was finally selected as the shearing time for the aqueous phase.

[0111] 5. Screening of Initiators

[0112] The initiators selected during the screening process of the present invention were triethanolamine, 1,4-butanediol, diethylenetriamine, and 1,6-hexanediamine. The agglomeration situation during the encapsulation process is shown in Figure 5 shown. As can be seen from Figure 5 , when triethanolamine was selected as the encapsulation initiator, the microcapsules had good encapsulation properties, uniform distribution, and no agglomeration phenomenon; while when 1,4-butanediol was selected as the initiator, there was an agglomeration phenomenon; when diethylenetriamine and 1,6-hexanediamine were selected as the initiators, the microcapsules had different sizes and an agglomeration phenomenon. Therefore, triethanolamine was selected as the initiator for the microcapsule suspending agent.

[0113] In addition, the dosage of triethanolamine was also screened, and the results are shown in Table 6. As can be seen from Table 6, when the dosage of triethanolamine increased from 1 g to 2 g, the particle size decreased from 7.917 μm to 4.539 μm, and the encapsulation efficiency increased from 68.9% to 88.2%. When the dosage of triethanolamine increased from 2 g to 3 g, the particle size increased from 4.539 μm to 8.923 μm, and the encapsulation efficiency decreased from 88.2% to 78%. It can be seen from this that when the dosage of triethanolamine was 2 g, the particle size was small and the encapsulation efficiency was high. Therefore, the dosage of triethanolamine was determined to be 2 g.

[0114] Table 6 Screening of Triethanolamine Dosage for Linalool Microcapsule Suspending Agent

[0115] Dosage / g Average particle size / μm Entrapment efficiency / % 1 7.917 68.9 2 4.539 88.2 3 8.923 78

[0116] 6. Optimal Formula of Linalool Microcapsule Suspending Agent

[0117] By screening the types and dosages of solvents, emulsifiers, capsule wall materials, dispersants, and initiators, the optimal formula of the linalool microcapsule suspending agent was determined: 1% of the active ingredient, 3% of anhydrous ethanol as the solvent, 1.5% of Tween 20 as the emulsifier, 2% of isophorone diisocyanate (IPDI) as the capsule wall material, 2.5% of sodium dodecylbenzenesulfonate as the dispersant, 2% of triethanolamine as the initiator, and water was added to make up to 100%; the above percentages are mass percentages.

[0118] 7. Results of Microcapsule Morphology Determination

[0119] The linalool microcapsule suspending agent prepared with the optimal formula shows its capsule-forming state under the microscope as shown in Figure 6 . As can be seen from Figure 6 , the microcapsules have regular capsule shapes, are spherical, have smooth exteriors, relatively uniform sizes, and good dispersibility.

[0120] 8. Results of microcapsule particle size measurement

[0121] Through the measurement of the microcapsule particle size, its particle size distribution shows a normal distribution, the particle size is qualified, and the particle size distribution is relatively concentrated. The prepared microcapsules meet the particle size requirements of pesticide microcapsules.

[0122] 9. Results of microcapsule encapsulation efficiency measurement

[0123] The encapsulation efficiency of the linalool microcapsule suspending agent was measured, and the encapsulation efficiency measured three times was all above 90%. The experimental results show that the interfacial polymerization method for preparing microcapsules has a good encapsulation efficiency.

[0124] 10. Results of microcapsule suspension rate measurement

[0125] The suspension rate of the linalool microcapsule suspending agent was measured, and the suspension rates measured three times were all above 70%. The average value was 75.61%, higher than 70%, meeting the suspension rate requirements of pesticide microcapsule suspending agents.

[0126] 11. Results of pH value measurement

[0127] The pH value measurement results for three times were 7.00, 7.05, and 6.96 respectively, with an average value of 7.00, being neutral and meeting the requirements.

[0128] 12. Results of thermal storage stability measurement

[0129] After 14 days of thermal storage, the appearance of the linalool microcapsule suspending agent did not change significantly, meeting the standards of microcapsule suspending agents.

[0130] 13. Results of cold storage stability measurement

[0131] The experimental results of cold storage stability show that: the appearance of the linalool microcapsule suspending agent did not change significantly, meeting the requirements of microcapsule suspending agents.

[0132] 14. Results of dispersibility measurement

[0133] The dispersibility measurement results show that: the linalool microcapsule suspending agent has good dispersibility, shows a cloud-like state when entering water, and has no obvious precipitation and sinking.

[0134] Example 2: Bacteriostatic effect of linalool microcapsule suspending agent on uredospores of Coleosporium zanthoxyli

[0135] Preparation of urediniospore suspension of Coleosporium zanthoxyli: Put the newly collected urediniospore powder into a 1.5 mL centrifuge tube, add an appropriate amount of sterile water, shake well to make a spore suspension, then count under a microscope and adjust the spore concentration to about 2x10 4 per mL.

[0136] Preparation of water agar plate for spore germination: Pour the prepared 1.3% water agar into a disposable petri dish to make a water agar plate with a thickness of about 1 - 2 mm, cover the dish lid and set aside.

[0137] Determination of antibacterial effect: Prepare aqueous solutions of linalool microcapsule suspension, difenoconazole suspension, pyraclostrobin emulsifiable concentrate, tebuconazole suspension, and diniconazole wettable powder with mass concentrations of 0.04, 0.08, 0.12, 0.16, and 0.2 g / L respectively. Use sterile water as a control. Pipette 10 μL of the spore suspension and drop it on the water agar plate, then drop 20 μL of aqueous solutions with different drug concentrations directly above it. After 24 h, count the number of germinated spores under a microscope and calculate the antibacterial rate. The microscope images of the water agar plate after dropping different drugs are shown in Figure 7 , and the antibacterial results are shown in Table 7.

[0138]

[0139] Table 7 Inhibitory effects of different drugs on the germ tube germination of Coleosporium zanthoxyli

[0140]

[0141]

[0142] As can be seen from Table 7, when the mass concentrations of linalool microcapsule suspension are 0.02, 0.08, 0.12, 0.16, and 0.2 g / L, the antibacterial rates against the urediniospore germ tubes of Coleosporium zanthoxyli are 0%, 23.7%, 87.4%, 93%, and 100% respectively. As the mass concentration of the drug increases, the antibacterial rate of the urediniospore germ tubes of Coleosporium zanthoxyli also gradually increases. The results show that the antibacterial activity of linalool microcapsule suspension is positively correlated with its effective mass concentration; linalool microcapsule suspension has a better inhibitory effect on the urediniospores of Coleosporium zanthoxyli, and its antibacterial rate is better than other drugs for controlling rust fungi on the market. In addition, from Figure 7 it can be seen that after dropping linalool microcapsule suspension on the water agar plate, the urediniospores of Coleosporium zanthoxyli change from the original orange - yellow to gray, while when dropping other drugs, the spore color does not change and remains orange - yellow all the time.

[0143] Example 3: Inhibition of linalool microcapsule suspension on rust fungi of Fatsia japonica, Salix babylonica, Rosa banksiae, and Lolium perenne

[0144] Fresh rust spore powder was collected from Fatsia japonica, Salix babylonica, Rosa banksiae, and Lolium perenne respectively (the rust spore powder of Fatsia japonica is Coleosporium sp., the rust spore powder of Salix babylonica is Melampsora coleosporioides Diet., the rust spore powder of Rosa banksiae is Phragmidium sichuanensis, and the rust spore powder of Lolium perenne is Pucciniarubigovera (DC.) Winl), and a spore suspension was prepared. The preparation method and statistical method were the same as those in Example 2.

[0145] The prepared linalool microcapsule suspension was diluted to 0.2 g / L, and then an antibacterial experiment was carried out on the above spore suspension. The specific process was the same as that in Example 2.

[0146] Microscopic images of the rust fungi on Fatsia japonica, Salix babylonica, Rosa banksiae, and Lolium perenne after dropping the linalool microcapsule suspension are shown in Figure 8 ; The inhibition results of the linalool microcapsule suspension on the rust fungi on Fatsia japonica, Salix babylonica, Rosa banksiae, and Lolium perenne are shown in Table 8.

[0147] Table 8 Inhibition results of linalool microcapsule suspension on rust fungi of other plants

[0148]

[0149] From Figure 8 and Table 8, it can be seen that the linalool microcapsule suspension also has a good antibacterial effect on the rust fungi on Fatsia japonica, Salix babylonica, Rosa banksiae, and Lolium perenne.

[0150] Example 4: Pot and field trials of linalool microcapsule suspension for controlling Zanthoxylum bungeanum rust

[0151] (1) Pot experiment: It was carried out in a greenhouse with a temperature of 15 - 25 °C and a relative humidity of 70 - 80%. 30 two-year-old fresh and healthy Zanthoxylum armatum plants with basically the same growth vigor were selected from the greenhouse for artificial inoculation. The treatments were as follows:

[0152] Artificial inoculation: Fresh uredospores of Zanthoxylum bungeanum sheath rust were collected, and the surface of the inoculated leaves was smeared with an aqueous solution containing 2‰ Tween 20 to make the Tween water evenly distributed on the leaf surface, and a spore suspension was prepared. The prepared spore suspension was used to treat the leaves of Zanthoxylum armatum by smearing method, and the front and back of the leaves were evenly sprayed with water to form a water mist without dripping water droplets. After spraying, it was moisturized with a transparent plastic bag. At the same time, sterile water was inoculated as a control. All the Zanthoxylum bungeanum plants after inoculation were moisturized at 18 °C in the dark with 100% humidity for 48 h, and then transferred to suitable conditions for cultivation.

[0153] The medicament was sprayed 3 days after artificial inoculation and also after uredinia appeared on the leaves; four concentration gradients were set, namely 0.2, 0.4, 0.6, and 0.8 g / L dilution solutions, with sterile water as the blank control. There were a total of 5 treatments, with 3 replicates. The medicament was evenly sprayed on both the front and back sides of the leaves. The medicine was applied once every about 14 days. 7 days after each application of the medicine, the disease incidence, disease index, and control effect were observed with reference to Table 9 and calculated.

[0154] Field experiment: Conducted in the Chinese prickly ash nursery. When no symptoms of rust disease had yet appeared on the Chinese prickly ash leaves, the medicine was sprayed in advance for prevention and control. The concentration of the medicine in the field experiment was set at 4 concentration gradients with reference to the control effect after the pot experiment, namely 0.2, 0.4, 0.6, and 0.8 g / L dilution solutions, and at the same time, a water control was set. A total of 5 treatments were set, and each treatment was divided into one plot, for a total of five plots. After the suspension was diluted to the required concentration, it was evenly sprayed on both the front and back sides of the leaves. The medicine was applied once every 14 days. 7 days after the application of the medicine, the disease incidence was observed, and the disease incidence, disease index, and control effect were calculated.

[0155] Investigation method: For each plant in each treatment, one secondary branch was selected from the four directions of southeast, northwest, and the prevention and control effect was investigated with reference to the grading standard of the severity of Chinese prickly ash rust disease in Table 9, and the disease incidence and disease index were calculated. 7 days after spraying the medicine, the disease incidence and disease index of Chinese prickly ash rust were investigated and recorded at fixed points and fixed plants.

[0156]

[0157] Control effect (%) = (control disease index - treatment disease index) / control disease index × 100

[0158] Table 9 Grading standard for the severity of Chinese prickly ash rust disease

[0159]

[0160]

[0161] The disease incidence results of different treatment groups in the pot experiment and field experiment are shown in Figure 9 ; the disease index and control effect are shown in Figure 10 ; the leaf control effect diagrams of the pot experiment and field experiment are shown in Figure 11 .

[0162] In the pot control experiment, by Figure 9It can be seen that before the rust disease occurs, spraying pesticides in advance for prevention, the incidence rate of the control group reaches more than 80%, which is significantly higher than that of other treatment groups. When spraying pesticides for control after the rust disease appears, the incidence rate of the control group reaches more than 88%, and the incidence rate of the 0.2g / L treatment group is similar to that of the control. The incidence rate of the 0.8g / L treatment group is 37.04%. The results show that after the rust disease occurs, pesticides with relatively low concentrations have very limited control effects on Zanthoxylum bungeanum rust disease.

[0163] In the potted plant control experiment, it can be seen from Figure 10 that the control effect of spraying pesticides in advance before the rust disease appears is significantly higher than that of spraying pesticides when the rust disease appears, and the inhibitory ability of linalool microcapsule suspension on pathogenic bacteria shows an upward trend with the increase of concentration. The 0.8g / L linalool microcapsule suspension is the most effective in controlling Zanthoxylum bungeanum rust disease. When spraying pesticides in advance for control before the rust disease appears after inoculation, the disease indices of the 0.8g / L and 0.6g / L concentrations are relatively low, and the control effect reaches more than 90% in the early stage, but the control effect shows a downward trend over time; this may be because in the middle and late stages of the occurrence of the rust disease, the control effect of pesticides is limited, so it shows a downward trend. When inoculating pathogenic bacteria and then applying linalool microcapsule suspension treatment when the rust disease begins to appear, its control effect is significantly reduced. It can be seen from Figure 10 that after applying suspension agents with different concentrations, the overall control effect shows a downward trend, indicating that when the rust disease is in the middle stage of onset, the control difficulty is large and the control effect is limited.

[0164] In the field control experiment, it can be seen from Figure 9 and Figure 10 that the inhibitory ability of linalool microcapsule suspension on pathogenic bacteria generally shows an upward trend with the increase of concentration. Treating in advance with linalool microcapsule suspension before the disease occurs can effectively reduce the disease index and improve the control effect. When applying microcapsule suspensions with different concentrations in advance before the disease occurs, the incidence rates and disease indices of all treatment groups are significantly lower than those of the control. The study found that after continuously applying suspension agents with different concentrations, over time, when the disease index and incidence rate of the control are relatively large, the control effect of the suspension agent on Zanthoxylum bungeanum rust disease shows a downward trend, indicating that when the rust disease is in the middle and late stages of onset, the control difficulty is large and the control effect is limited. In addition, the flutriafol suspension purchased on the market is used for the control of rust disease in the field, and its incidence rate and disease index are higher than those of the linalool microcapsule suspension treatment group, and its control effect is lower than that of the microcapsule suspension treatment group. In summary, the lower the concentration of linalool microcapsule suspension, the lower the relative control effect. In the field environment, spraying microcapsule suspension in advance before the rust disease occurs can play a better preventive role.

[0165] It can be seen from Figure 11It can be seen that from the apparent results of the leaves, the linalool microcapsule suspension has a good control effect on the rust of Zanthoxylum bungeanum.

[0166] To sum up, through single-factor screening tests, the present invention screened the types and dosages of solvents, emulsifiers, capsule wall materials, dispersants, and initiators, and finally determined that the mass fractions of the components of the linalool microcapsule suspension were 1% of the technical material, 3% of absolute ethanol, 1.5% of Tween 20, 2% of isophorone diisocyanate (IPDI), 2.5% of sodium dodecylbenzenesulfonate, 2% of triethanolamine, and the balance was made up to 100% with water. The linalool microcapsule suspension was prepared by the interfacial polymerization method. Its appearance was regular spherical, with a smooth surface, the average particle size was between 3 and 10 μm, and the encapsulation rate was over 90%. The quality inspection results showed that its content of the active ingredient, microcapsule suspension rate, pH value, thermal storage stability, and cold storage stability all met the relevant requirements of the pesticide microcapsule suspension.

[0167] In addition, the present invention used the water-agar plate germination method to determine the bacteriostatic rate of the linalool microcapsule suspension and the commonly used rust-control agents on the market against the urediniospores germination of Coleosporium zanthoxyli, and also conducted plate bacteriostatic tests on the rust fungi collected from different plants. At the same time, the pot and field control effects of the rust of Zanthoxylum bungeanum were determined using the prepared microcapsule suspension. It was found that the microcapsule suspension prepared by this method had a high encapsulation rate and had a good control effect on the rust of various plants.

[0168] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. Application of linalool in preventing and controlling plant rust diseases.

2. The application according to claim 1, wherein The plants are Zanthoxylum bungeanum, Fatsia japonica, Salix babylonica, Rosa banksiae, Lolium perenne.

3. The application according to claim 2, wherein The rust disease of Zanthoxylum bungeanum is caused by Coleosporium zanthoxyli, the rust disease of Fatsia japonica is caused by Coleosporium sp., the rust disease of Salix babylonica is caused by Melampsora coleosporioides Diet., the rust disease of Rosa banksiae is caused by Phragmidium sichuanensis, and the rust disease of Lolium perenne is caused by Puccinia rubigovera (DC.) Winl.

4. Use of a biological agent in controlling plant rust, characterized in that, The biological agent includes linalool.

5. The application according to claim 4, wherein The biological agent is a linalool microcapsule suspension.

6. The application according to claim 5, wherein The linalool microcapsule suspension includes the following components in parts by weight: 1 part of linalool, 1 - 1.5 parts of emulsifier, 1 - 3 parts of capsule wall material, 1.5 - 3 parts of dispersant, 1 - 3 parts of initiator.

7. The application according to claim 6, wherein The linalool microcapsule suspension includes the following components in parts by weight: 1 part of linalool, 1.5 parts of emulsifier, 2 parts of capsule wall material, 2.5 parts of dispersant, 2 parts of initiator.

8. The application according to claim 6 or 7, characterized in that, The emulsifier is Tween 20, the capsule wall material is isophorone diisocyanate, the dispersant is sodium dodecyl benzene sulfonate, and the initiator is triethanolamine.

9. The application according to claim 8, characterized in that, The linalool microcapsule suspension further includes a solvent, the solvent is absolute ethanol, and the mass ratio of linalool to absolute ethanol is 1:1 - 4.

10. The application according to claim 8, wherein, The linalool microcapsule suspension is prepared by the following method: Dissolve linalool, add the emulsifier and the capsule wall material and mix evenly to obtain an oil phase; Shear water and the dispersant at a rate of 8000 - 12000 rpm for 2 - 4 min to obtain an aqueous phase; Mix the aqueous phase and the oil phase, and shear at a rate of 8000 - 12000 rpm for 2 - 4 min to prepare the linalool microcapsule suspension.

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