Application of thymol in prevention and treatment of litchi downy mildew

Abstract

This invention provides the natural phenolic compound thymol in inhibiting Phytophthora downy mildew (Phytophthora indicum). Peronophythora litchii This invention also provides the application of thymol in the control of litchi downy mildew. In vitro antibacterial experiments and control tests confirmed that thymol has significant inhibitory activity against litchi downy mildew and can effectively reduce the incidence of litchi downy mildew. This invention is the first to propose using thymol as an active ingredient to prepare a biological pesticide or plant-derived antifungal agent for the control of litchi downy mildew. It features high efficiency, low toxicity, and environmental friendliness, and can replace traditional chemical fungicides, reducing pesticide residues and pathogen resistance problems.

Description

Technical Field

[0001] This invention belongs to the field of modern agricultural technology, specifically relating to the application of thymol in the prevention and control of downy mildew in litchi. Background Technology

[0002] Lychees are renowned both domestically and internationally for their vibrant color, fragrant aroma, and sweet taste, and their fresh fruit and processed products have become a vital pillar of the southern economy. However, lychee downy blight, the most significant disease affecting lychee production, causes severe industry losses by infecting lychee fruits before and after harvest, leading to rot.

[0003] Lychee downy mildew is caused by the obligate parasitic oomycete Phytophthora (Lychee downy mildew). Peronophythora litchii This is a systemic disease caused by *Phytophthora lychee*. *Phytophthora lychee* can infect branches, clusters, and fruits in a latent state before harvest, and can also infect post-harvest fruits through mechanical wounds, gradually growing as the fruit is stored. *Phytophthora lychee* can spread widely by continuously inoculating healthy litchi fruits, seriously threatening the post-harvest litchi industry. *Phytophthora lychee* (… P. litchii ) belongs to the kingdom Chromista, phylum Oomycota, class Oomycetes, order Peronosporales, family Peronophythoraceae, genus Phytophthora. Peronophythora This pathogenic oomycete differs significantly from fungi such as anthracnose fungi and Fusarium. Its life cycle includes both asexual and sexual stages: asexual reproduction produces sporangiophores and sporangia; the sporangiophores are highly differentiated, varying in length and resembling tree branches, exhibiting a multi-level determinate growth pattern; sexual reproduction produces oospores. *Phytophthora downyensis* primarily overwinters as oospores or mycelium on infected leaves and fruits, becoming the initial source of infection for the following year. The fungus produces sporangia, which are dispersed by wind and rain. Upon contact with water, they can germinate directly to form germ tubes, or first release zoospores which then develop into germ tubes, subsequently infecting leaves and fruits, leading to disease. Infected leaves and fruits will then produce sporangia again, triggering subsequent infections, thus completing its infection cycle. The systemic harm caused by this pathogen stems from its unique oomycete biological characteristics: taxonomically, it belongs to the phylum Oomycota, which is an evolutionary gap from the kingdom Fungi. Its cell wall has a core skeleton of β-glucan and cellulose (fungi rely on chitin), and its diploid chromosome set encodes unique infection effect factors. During development, it relies on biflagellated zoospores for waterborne transmission (fungi are transmitted airborne through non-flagellated conidia), and its sterol metabolism synthesizes stigmasterol (fungi synthesize ergosterol). These multidimensional differences lead to the general ineffectiveness of fungal pathogen control agents against Phytophthora litchii.

[0004] Current chemical control methods pose risks of pesticide residues and resistance, necessitating the development of natural solutions. Thymol (2-isopropyl-5-methylphenol), also known as thymol, is a natural monoterpene phenol primarily found in the essential oils of thyme, oregano, and orange peel. Thymol has been classified as a food additive by the U.S. Food and Drug Administration (FDA) because it is considered a Generally Recognized As Safe (GRAS) substance.

[0005] Although current technology shows that thymol has good broad-spectrum antibacterial activity against a variety of plant pathogenic fungi, such as Rhizopus creepingus, Penicillium italicum, Colletotrichum gloeosporioides, Geotrichum candida, Rhizoctonia solani, Rhizoctonia solani, and Fusarium oxysporum, Phytophthora lichrysogenum (Lychee downy mildew) Peronophythora litchii Belonging to the oomycete family, not the fungus family, *Phytophthora litchi* possesses significant unique pathogenic characteristics, posing unique challenges to its control and making the effectiveness of thymol not readily apparent or easily extrapolated. Thymol inhibits the pathogen by disrupting cell membranes, inducing lipid peroxidation, and interfering with ergosterol synthesis. However, the unique membrane lipid composition of *Phytophthora litchi* (such as a high proportion of oleic and linoleic acids) makes it more sensitive to membrane damage effects. During infection, this fungus induces the host to produce large amounts of reactive oxygen species (ROS). Thymol, by scavenging ROS and inhibiting membrane lipid peroxidation, can simultaneously inhibit pathogen growth and reduce oxidative damage to the host. This dual mechanism of action has not been confirmed in other plant-pathogen interaction systems. Therefore, thymol may have the potential to be developed into a novel phytochemical for controlling *Phytophthora litchi*. Summary of the Invention

[0006] The first aspect of the present invention is to provide the use of thymol in the preparation of products that inhibit the activity of Phytophthora litchii.

[0007] The second objective of this invention is to provide the application of thymol in the preparation of products for the prevention and control of downy mildew of litchi.

[0008] The third objective of this invention is to provide a method for preventing and controlling downy mildew in litchi.

[0009] To achieve the above-mentioned objectives of this invention, the technical solution adopted by this invention is as follows:

[0010] A first aspect of the present invention provides the use of thymol in the preparation of a product that inhibits the activity of Phytophthora licoricei, wherein the chemical formula of thymol is C 10 H 14 O, the structural formula is shown in equation (Ⅰ):

[0011] Equation (Ⅰ).

[0012] In some embodiments of the application, the inhibiting the activity of P. litchicola includes any one or more of:

[0013] (1) inhibiting hyphal growth of P. litchicola;

[0014] (2) inhibiting sporangium production of P. litchicola;

[0015] (3) inhibiting zoospore release of P. litchicola;

[0016] (4) inhibiting oospore production of P. litchicola;

[0017] (5) disrupting cell membrane structure of P. litchicola;

[0018] (6) inducing reactive oxygen species production and release of P. litchicola.

[0019] In a second aspect of the application, there is provided a use of thymol in the preparation of a product for preventing and treating P. litchicola disease.

[0020] In some embodiments of the application, the P. litchicola disease is a disease caused by infection of P. litchicola, mainly harming near-mature and mature fruits, sometimes also harming young fruits, flower spikes and leaves. The surface of the diseased leaves, flowers and fruits grows white mold-like substances, and the flower spikes and fruits become brown and rotten.

[0021] In relation to the first and second aspects of the application:

[0022] In some embodiments of the application, the prevention and treatment include prophylaxis and therapy.

[0023] In some embodiments of the application, the thymol includes thymol or a pharmaceutically acceptable salt form thereof.

[0024] In some embodiments of the application, the pharmaceutically acceptable salt includes an acid addition salt, a base addition salt.

[0025] In some embodiments of the application, "pharmaceutically acceptable acid addition salt" refers to salts of the free base which retain the biological effectiveness and properties of the free base and which are not biologically or otherwise undesirable, formed with inorganic acids such as, but not limited to, hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid and the like, and organic acids such as, but not limited to, acetic acid, adipic acid, alginic acid, ascorbic acid, aspartic acid, benzenesulfonic acid, benzoic acid, camphoric acid, camphor 10 sulfonic acid, capric acid, caproic acid, caprylic acid, carbonic acid, cinnamic acid, citric acid, cyclamic acid, dodecyl sulfuric acid, ethane 1, 2 disulfonic acid, ethanesulfonic acid, 2 hydroxyethanesulfonic acid, fumaric acid, galactaric acid, gentisic acid, glucoheptonic acid, gluconic acid, glucuronic acid, glutamic acid, glutaric acid, 2 oxoglutaric acid, glycerophosphoric acid, glycolic acid, hippuric acid, isobutyric acid, lactic acid, lactobionic acid, lauric acid, maleic acid, malic acid, malonic acid, mandelic acid, methanesulfonic acid and the like.

[0026] In some embodiments of the application, "pharmaceutically acceptable base addition salt" refers to a salt of the free acid which retains the biological effectiveness and properties of the free acid and which is not biologically or otherwise undesirable. These salts are prepared from inorganic bases or from organic bases. Salts derived from inorganic bases include, but are not limited to, sodium salts, potassium salts, lithium salts, ammonium salts, calcium salts, magnesium salts, iron salts, zinc salts, copper salts, manganese salts, aluminum salts and the like. Preferred inorganic salts are the ammonium, sodium, potassium, calcium, and magnesium salts. Salts derived from organic bases include, but are not limited to, salts of primary, secondary, and tertiary amines, substituted amines including naturally occurring substituted amines, cyclic amines and basic ion exchange resins, such as ammonia, isopropylamine, trimethylamine, diethylamine, triethylamine, tripropylamine, diethanolamine, ethanolamine, dicyclohexylamine, lysine, arginine, histidine, caffeine, ethylenediamine, glucosamine, methylglucosamine, theobromine, triethanolamine, tromethamine, purines, piperazine, piperidine, N-ethylpiperidine, polyamine resins and the like. Especially preferred organic bases are isopropylamine, diethylamine, ethanolamine, trimethylamine, dicyclohexylamine, choline, and caffeine.

[0027] In some embodiments of the application, the product comprises a pesticide.

[0028] In some embodiments of the application, the pesticide comprises a pharmaceutically acceptable excipient.

[0029] In some embodiments of the application, the pharmaceutically acceptable excipient comprises at least one of a solvent, a propellant, a solubilizer, a co-solvent, an emulsifier, a colorant, a binder, a disintegrant, a filler, a lubricant, a wetting agent, an osmotic pressure regulator, a stabilizer, a glidant, a preservative, a suspending agent, a fragrance, an anti-caking agent, a penetration enhancer, a pH adjuster, a buffer, a plasticizer, a surfactant, a foaming agent, an antifoaming agent, a thickening agent, a clathrate agent, a humectant, an absorbent, a diluent, a flocculating and deflocculating agent, a filter aid.

[0030] In some embodiments of the present application, the above-mentioned pharmaceutically acceptable excipients are generally recognized for this purpose and as inactive ingredients of a medicament. A compilation of pharmaceutically acceptable excipients can be found in the Handbook of Pharmaceutical Excipients, 2nd Edition, Edited by A. Wade and P. J. Weller; published by American Pharmaceutical Association, Washington and The Pharmaceutical Press, London, 1994; the Pharmacopoeia of the People's Republic of China - Pharmaceutical Excipients; and the like.

[0031] In some embodiments of the present application, the dosage form of the pesticide includes one of a solid preparation, a liquid preparation, and a volatile preparation.

[0032] In some embodiments of the present application, the dosage form of the pesticide can be found in the National Standard of Pesticide Dosage Form Names and Codes GB / T 19378-2017 and the like.

[0033] In some embodiments of the present application, the usage concentration of the thymol is 1-500 μg / mL.

[0034] In some embodiments of the present application, for inhibiting the mycelium growth of Peronophythora litchii, the usage concentration of the thymol is 50-150 μg / mL.

[0035] In some embodiments of the present application, for inhibiting the sporangium production of Peronophythora litchii, the usage concentration of the thymol is 40-70 μg / mL.

[0036] In some embodiments of the present application, for inhibiting the zoospore release of Peronophythora litchii, the usage concentration of the thymol is 40-160 μg / mL.

[0037] In some embodiments of the present application, for inhibiting the oospore production of Peronophythora litchii, the usage concentration of the thymol is 2-15 μg / mL.

[0038] In some embodiments of the present application, for destroying the cell membrane structure of Peronophythora litchii, the usage concentration of the thymol is 40-150 μg / mL.

[0039] In some embodiments of the present application, for inducing the reactive oxygen species production and release of Peronophythora litchii, the usage concentration of the thymol is 40-100 μg / mL.

[0040] In a third aspect of the present application, a method for preventing and treating litchi downy mildew is provided, comprising the following steps:

[0041] The litchi is treated with thymol.

[0042] In some embodiments of the present application, the prevention and treatment include prophylaxis and therapy.

[0043] In some embodiments of the present application, the prevention and treatment include prevention and treatment of litchi growth and after harvest.

[0044] In some embodiments of the present application, the thymol is in the form of an aqueous solution, and the fruit is soaked for 1-10 minutes.

[0045] In some embodiments of the present application, when used for prophylaxis, the concentration of the thymol in the aqueous solution is 100-500 mg / kg (100-500 mg / L).

[0046] In some embodiments of the present application, when used for therapy, the concentration of the thymol in the aqueous solution is 200-500 mg / kg (200-500 mg / L).

[0047] The present application has the following beneficial effects:

[0048] The present application provides a natural phenolic compound, thymol, for inhibiting litchi downy mildew fungus (Peronophythora litchii Chen et al.) and also provides an application of thymol in preventing and treating litchi downy mildew. Peronophythora litchii Through in-vitro bacteriostatic experiments and prevention and control experiments, it is confirmed that thymol has significant inhibitory activity on litchi downy mildew fungus and can effectively reduce the incidence of litchi downy mildew. The present application first proposes to use thymol as an active ingredient for preparing a biological pesticide or a plant-derived bacteriostatic agent for preventing and treating litchi downy mildew, which has the characteristics of high efficiency, low toxicity and environmental friendliness, can replace traditional chemical fungicides, and can reduce pesticide residues and pathogenic bacteria resistance problems. BRIEF DESCRIPTION OF DRAWINGS

[0049] The present application will be further described below in combination with the drawings and examples, in which:

[0050] Figure 1 Inhibition of mycelial growth of litchi downy mildew by different concentrations of thymol, in which A is the phenotypic result and B is the statistical result.

[0051] Figure 2 Inhibition of sporangium production of litchi downy mildew by different concentrations of thymol, in which A is the phenotypic result and B is the statistical result.

[0052] Figure 3Inhibition of zoospore release of P. litchicola by thymol at different concentrations. A: phenotype results; B: statistical results.

[0053] Figure 4 Inhibition of oospore production of P. litchicola by thymol at different concentrations.

[0054] Figure 5 Changes in the electrical conductivity of P. litchicola mycelium after treatment with thymol.

[0055] Figure 6 SYTOX Green staining test of P. litchicola mycelium after treatment with thymol.

[0056] Figure 7 Effect of thymol on the production of reactive oxygen species in P. litchicola mycelium.

[0057] Figure 8 Preventive effect of thymol on P. litchicola disease of postharvest litchi fruit. DETAILED DESCRIPTION

[0058] The concept and technical effects of the present application will be described below in conjunction with examples for a clear and complete understanding of the purpose, features and effects of the present application. Obviously, the described examples are only a part of the examples of the present application, but not all examples. Based on the examples of the present application, other examples obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0059] The materials, reagents, etc. used in the following examples can be obtained from commercial channels unless otherwise specified.

[0060] Test pathogen: The P. litchicola used in the present application is the wild type reference strain SHS3, which is a strain preserved by the present experiment.

[0061] Main reagents: Thymol was purchased from Hainan Qingfeng Biological Technology Co., Ltd. with a purity of > 98%. The pure compound thymol was dissolved in anhydrous ethanol to prepare a 5 x 10 4 pg / mL stock solution for use.

[0062] 10% V8 medium was used to culture P. litchicola. Note: 10% V8 medium is composed of 100 mL V8 vegetable juice, 900 mL H2O, and 20 g agar, pH = 7.2.

[0063] Example 1: Activity test of thymol on P. litchicola mycelial growth

[0064] Specific procedures: The inhibitory effect of different concentrations of thymol on the mycelial growth of the pathogen was determined using the mycelial growth rate method. After culturing *Phytophthora lichei* on V8 medium for 5 days, mycelial cakes were collected using a 5 mm diameter punch and inoculated onto V8 medium plates containing thymol at final concentrations of 30, 40, 60, 90, and 130 μg / mL. An anhydrous ethanol control group was included in each experiment, and three parallel treatments were set up. After 5 days of culture, the colony diameter after thymol treatment was measured using the cross-multiplication method, and the inhibition rate was calculated. Each experiment was repeated three times. The virulence regression equation and the median inhibitory concentration (EC50) were then calculated using SPSS software.

[0065] See results Figure 1 Phytophthora lichei mycelia continued to grow throughout the culture period, but thymol effectively inhibited their growth. After treatment with thymol at concentrations of 30, 40, 60, 90, and 130 μg / mL for 5 days, the colony diameter of Phytophthora lichei decreased by 10.2%, 21.26%, 55.51%, 92.79%, and 97.76%, respectively. The half-maximum effective concentration (EC50) of thymol for the growth of Phytophthora lichei mycelia was 54.10 μg / mL.

[0066] Example 2: Activity test of thymol in inhibiting sporangium production of Phytophthora licoriceis

[0067] Specific procedures: *Phytophthora lichee* mycelium cakes (5 mm in diameter) were inoculated onto V8 agar plates containing thymol at final concentrations of 0, 40, 50, 60, and 70 μg / mL. A solvent control and a blank control group were included, and three parallel treatments were established. After 5 days of incubation, 5 mL of deionized water was added to the colonies, and the mixture was filtered to obtain a total sporangium suspension. 10 μL of the sporangium suspension was dropped onto a hemocytometer and observed under a microscope. The number of sporangia was counted using the hemocytometer. Each sample was counted six times, with three parallel treatments and each experiment repeated three times. The virulence regression equation and the median inhibitory concentration (EC50) were then determined using SPSS software.

[0068] See results Figure 2 The number of sporangia in the blank control group was 63.70 × 10⁻⁶. 5 The sporangium yield was 47.78, 32.78, 21.85, 13.15, and 6.11 × 10⁶ sporangia / mL after treatment with 30, 40, 50, 60, and 70 μg / mL thymol, respectively. 5 The concentration of thymol at 1 / mL indicates that thymol inhibits the production of sporangia of Phytophthora litchii. The half-maximum effective concentration (EC50) of thymol for the production of sporangia of Phytophthora litchii is 40.77 μg / mL.

[0069] Example 3 Activity test of thymol on zoospore release of Peronophythora litchii

[0070] Specific operation: After each test strain was cultured on V8 solid medium for 5 days, 3 mL of sterile water was added to the colony, which was gently blown and then the spore suspension was taken into a 2 mL centrifuge tube. Thymol was added to the centrifuge tube to make the final concentration of thymol 30, 40, 60, 80, and 160 μg / mL. After 0.5 h of low-temperature treatment at 12°C, the centrifuge tube was placed at room temperature for 10 min. The zoospores of each strain were observed under a microscope and the inhibition rate was calculated. The toxicity regression equation and the median inhibitory concentration (EC50) were calculated by using SPSS software.

[0071] The results are shown in Table 1. Figure 3 The inhibition effect of thymol on the release of zoospores of Peronophythora litchii was significantly higher than that of the control group. The inhibition rates of thymol at concentrations of 30, 40, 60, 80, and 160 μg / mL on the release of zoospores of Peronophythora litchii were 38.05%, 65.3%, 75.84%, 89.20, and 96.79%, respectively. The half maximal effective concentration (EC50) of thymol on the release of zoospores of Peronophythora litchii was 43.68 μg / mL.

[0072] Example 4 Activity test of thymol on oospore production of Peronophythora litchii

[0073] Specific operation: Peronophythora litchii cakes (5 mm in diameter) were inoculated on V8 medium plates containing thymol at a final concentration of 2.5, 5, 7.5, 10, and 15 μg / mL. After 10 days of culture at 25°C in the dark, the mycelium and sporangia on the surface of the culture medium were scraped off. A puncher was used to take 5 mm-diameter mycelium blocks around the original inoculation mycelium block, which was pressed into a sheet. The number of oospores of each strain was counted. Three mycelium blocks were taken from each plate, 10 fields of view containing oospores were observed for each mycelium block, and each test was repeated three times. The inhibition rate was calculated. The toxicity regression equation and the median inhibitory concentration (EC50) were calculated by using SPSS software.

[0074] The results are shown in Table 2. Figure 4 Thymol showed very strong antibacterial activity on the production of oospores of Peronophythora litchii. In comparison, the sensitivity of oospore production was significantly enhanced (EC50= 2.76 μg / mL).

[0075] Example 5 Effect of thymol on the permeability of the cell membrane of Peronophythora litchii

[0076] Procedure: Membrane permeability of P. litchicola was measured using conductivity method. Mycelium was packed in V8 liquid medium on a rotary shaker (25 °C, 120 rpm) for 48 h. Then the mycelium was washed 3 times with sterile distilled water, drained using a Buchner funnel, and exposed to different concentrations (0, 30, 40, 60, 90, 130 pg / mL) of thymol solution, with sterile distilled water as control. Conductivity was measured at 0, 10, 20, 30, 40, 60, 80, 100, 120, 140, 160, and 180 min using a conductivity meter. Finally, the mycelium was boiled for 20 min, and the final conductivity was measured to calculate the relative conductivity. Each experiment was repeated 3 times.

[0077] Results are shown in Figure 5 , the relative conductivity of P. litchicola mycelium increased with the increase of thymol treatment time, and was in a rising trend in the later period. With the increase of thymol concentration, the relative conductivity value was also higher and higher. It showed that thymol destroyed the cell membrane of P. litchicola mycelium.

[0078] Example 6 - Effect of thymol on cell membrane integrity of P. litchicola

[0079] Procedure: Membrane integrity of P. litchicola was evaluated using SYTOX Green staining. P. litchicola sporangia suspension (1 x 10 5 sporangia / mL) was collected from V8, and the sporangia suspension was treated with 50 and 80 pg / mL thymol at 25 °C for 6 h, with a blank control. Then, the sporangia suspension was stained with 0.2 pM SYTOX Green at 25 °C for 30 min in the dark, and observed under a fluorescence microscope after washing 3 times with phosphate buffered saline (PBS).

[0080] Results are shown in Figure 6 In the control, no fluorescence was observed for the sporangia, while strong fluorescence was observed for the sporangia treated with 80 pg / mL thymol. This proved that the membrane integrity was destroyed. In addition, when the sporangia were treated with a lower concentration of 50 pg / mL, its fluorescence was observed to be weaker compared to that treated with 80 pg / mL. Therefore, these data also indicated that the changes in the plasma membrane caused by thymol were concentration-dependent.

[0081] Example 7 - Effect of thymol on reactive oxygen species production of P. litchicola

[0082] Specific operation: The accumulation of intracellular reactive oxygen species (ROS) was evaluated by observing spores stained with 2',7'-dichlorofluorescin diacetate (DCFH-DA). DCFH-DA was used as a ROS fluorescent probe because it emits green fluorescence in the presence of ROS. The sporangia suspension of P. litchicola was adjusted to 1 × 10 4 sporangia mL -1 and treated with 50 μg / mL, 80 μg / mL or sterile water (control) for 6 h. Then, all sporangia were collected, washed with phosphate buffered saline (PBS) and then incubated in PBS containing 10 μmol L -1 DCFH-DA at 25 °C for 20 min, and observed using a fluorescence microscope.

[0083] The results are shown in Figure 7 , and quantitative determination showed that the fluorescence intensity of the thymol-treated sporangia was 1.32 and 1.95 times that of the control, respectively, indicating that thymol treatment induced the accumulation and release of intracellular ROS in a dose-dependent manner.

[0084] Example 8. Experiment on the efficacy of thymol against postharvest P. litchicola disease of litchi fruit

[0085] Test material: The litchi variety "Feixiaoshuo" was purchased from the market. Healthy fruits of uniform size, shape and maturity were selected, disinfected with 75% alcohol for 30 s, and washed with sterile water three times.

[0086] Specific operation: To determine the protective activity, litchi fruits were soaked in thymol solution (100, 200, 400 mg·kg-1) for 5 min, air-dried, and incubated at 25 °C in the dark. After 24 h, the fruits were inoculated with mycelial plugs. The fruits were then incubated at 25 °C under humid conditions for 72 h. To determine the therapeutic activity, the fruits were inoculated and incubated at 25 °C for 24 h, then soaked in thymol solution (100, 200, 400 mg·kg -1 ) for 5 min, air-dried, and further incubated for 48 h. The inhibition rate was calculated according to the formula, and t-test was used for significance analysis. Each experiment was repeated three times. Inhibition rate (%) = (disease spot size of control fruit - disease spot size of treated fruit) / disease spot size of control fruit × 100.

[0087] The results are shown in Figure 8 , and the experimental results showed that thymol exhibited excellent control effect on P. litchicola of litchi, and the protective effect of thymol was better than the therapeutic effect. The protective efficacy of thymol at 100, 200 and 400 mg·kg -1 was 48.14%, 83.51% and 96.35%, respectively, while the therapeutic efficacy of thymol at 100, 200 and 400 mg·kg-1 The therapeutic efficacy of the treatment was 2.67%, 41.67% and 83.33%, respectively.

[0088] The above detailed description of the embodiments of the present application is made in conjunction with the accompanying drawings, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application. Furthermore, the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

Claims

1. Use of thymol in the preparation of a product for preventing or treating Peronophythora litchii; The prevention or treatment of Peronophythora litchii includes any one or more of the following: (1) inhibiting the production of sporangia of Peronophythora litchii; (2) inhibiting the release of zoospores of Peronophythora litchii; (3) inhibiting the production of oospores of Peronophythora litchii; (4) destroying the cell membrane structure of Peronophythora litchii; (5) inducing the production and release of reactive oxygen species of Peronophythora litchii.

2. The use according to claim 1, wherein: The thymol includes thymol or a pharmaceutically acceptable salt form thereof.

3. The use according to claim 1, wherein: The product includes a pesticide.

4. The use according to claim 3, wherein: The pesticide includes a pharmaceutically acceptable excipient.

5. The use according to claim 4, wherein: The pharmaceutically acceptable excipient includes at least one of a coloring agent, a binding agent, a disintegrating agent, a lubricating agent, an osmotic pressure adjusting agent, a stabilizing agent, a preservative, a suspending agent, an aromatic agent, an anti-adhesion agent, a penetration enhancer, a pH adjusting agent, a buffer, a plasticizer, a surfactant, a foaming agent, an antifoaming agent, a thickening agent, a clathrate agent, a humectant, an absorbent, a diluent, a flocculating agent and a deflocculating agent, a filter aid.

6. The use according to claim 5, wherein: The dosage form of the pesticide includes one of a solid preparation, a liquid preparation, and a volatile preparation.

7. The use according to claim 1, wherein: The concentration of the thymol used is 1-500 μg / mL.

8. A method for preventing or treating Peronophythora litchii, comprising the steps of: treating litchi with thymol; The prevention or treatment of Peronophythora litchii includes any one or more of the following: (1) inhibiting the production of sporangia of Peronophythora litchii; (2) inhibiting the release of zoospores of Peronophythora litchii; (3) inhibiting the production of oospores of Peronophythora litchii; (4) destroying the cell membrane structure of Peronophythora litchii; (5) inducing the production and release of reactive oxygen species of Peronophythora litchii.

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