Composition for preventing and treating tobacco black shank and application

Abstract

The invention relates to a composition for preventing and treating tobacco black shank and application. The composition comprises methyl jasmonate, absolute ethyl alcohol and mancozeb. In the composition disclosed by the invention, the jasmonic acid methyl ester and the mancozeb can have a relatively good synergistic effect, the jasmonic acid methyl ester can enhance lignification of cell walls, and the mancozeb can inhibit germination of pathogenic bacteria of steamed stuffed buns in the same time and further block invasion of hyphae, so that a relatively good prevention and treatment effect is achieved.

Description

Technical Field

[0001] This invention relates to the field of agricultural fungicide technology, and in particular to a composition and its application for preventing and controlling tobacco black shank disease. Background Technology

[0002] Black shank, caused by Phytophthora infestans, is a devastating soil-borne disease that continues to threaten global tobacco production. Traditional control methods rely primarily on chemical fungicides (such as metalaxyl and cymoxanil) and the breeding of resistant varieties. However, chemical control faces challenges such as increased pathogen resistance, environmental and food safety risks, and rising costs; while resistance breeding suffers from long development cycles, limited resistance resources, and loss of resistance due to pathogen mutation. Even single resistant varieties are insufficient to cope with the complex and ever-changing field environment. Therefore, exploring new, environmentally friendly, sustainable control strategies that can effectively supplement or partially replace existing methods is of great significance.

[0003] Against this backdrop, exploring compound formulations that combine traditional chemical protectants with plant-induced disease resistance strategies, particularly utilizing methyl jasmonate (MeJA) to induce plant autoimmunity, has become a highly promising research direction. Plant-induced disease resistance (IR) is characterized by its broad-spectrum, long-lasting, and eco-compatible nature, as it stimulates the plant's own defense mechanisms. Numerous studies have confirmed that various exogenous signaling molecules, such as salicylic acid (SA), jasmonic acid (JA), and its volatile derivative methyl jasmonate (MeJA), can effectively induce systemic resistance in plants such as tobacco against oomycetes (e.g., Phytophthora), fungal, bacterial, and viral diseases. MeJA, as a key defense hormone signal, plays a central role in regulating plant defense against necrotrophic pathogens (e.g., Phytophthora). Exogenous application of MeJA can activate the jasmonic acid signaling pathway in tobacco, upregulate the expression of defense genes, accumulate defense substances, and enhance disease resistance. Preliminary studies have shown that exogenous MeJA treatment can alleviate symptoms of tobacco black shank disease.

[0004] Existing research largely focuses on validating the effectiveness of single strategies (purely chemical or pure inducer) or making preliminary explorations of single MeJA concentrations, which has significant limitations. First, there is a lack of refined concentration control; systematic research on the precise quantitative relationship between MeJA treatment concentration gradients and induced disease resistance is insufficient. Second, there is a lack of stable and efficient protocols; an optimized disease resistance protocol based on scientifically determined MeJA concentration gradients, which is reproducible and highly adaptable to different growth stages of tobacco and actual field conditions, has not yet been developed. Third, the mechanisms and resource allocation remain unclear; there are knowledge gaps regarding how to maximize induced resistance efficacy through precise control of MeJA concentrations, balance growth-defense resource allocation, and the details of its mechanisms of action. Relying solely on MeJA induction may be insufficiently protective under high disease pressure, while relying solely on chemical agents faces the aforementioned risks related to resistance and the environment.

[0005] Therefore, how to develop a stable and efficient agent for the prevention and control of tobacco black shank has become an urgent technical problem to be solved. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a composition and its application for preventing and treating tobacco black shank. The combination of methyl jasmonate, anhydrous ethanol, and mancozeb significantly enhances the control and treatment efficacy against tobacco black shank.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a composition for preventing and treating tobacco black shank disease, the composition comprising methyl jasmonate, ethanol and mancozeb.

[0009] In this invention, methyl jasmonate can activate the salicylic acid pathway and upregulate the expression of defense genes, while mancozeb can inhibit the germination of pathogenic spores. The two work synergistically. Methyl jasmonate can enhance cell wall lignification and improve the defense capabilities of tobacco plants, while mancozeb can reduce the initial source of inoculum. The above-mentioned raw materials are dissolved in water to achieve the control effect against tobacco black shank disease.

[0010] Preferably, the composition comprises 100-150 μmol / L methyl jasmonate, 1-10% ethanol (volume ratio), and 1-3 g / L mancozeb. The 100-150 μmol / L concentration can be, for example, 100 μmol / L, 105 μmol / L, 110 μmol / L, 115 μmol / L, 120 μmol / L, 125 μmol / L, 130 μmol / L, 135 μmol / L, 140 μmol / L, 145 μmol / L, or 150 μmol / L. The 1-10% concentration can be, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%. The 1-3 g / L can be, for example, 1 g / L, 1.2 g / L, 1.4 g / L, 1.6 g / L, 1.8 g / L, 2 g / L, 2.2 g / L, 2.4 g / L, 2.6 g / L, 2.8 g / L, or 3 g / L, etc.

[0011] In this invention, the above-mentioned raw materials are mixed and dissolved in water. Within the concentration range mentioned above, methyl jasmonate and mancozeb can have a good synergistic effect. Methyl jasmonate can enhance cell wall lignification, while mancozeb can inhibit the germination of pathogenic fungal buds and further block mycelial invasion, thereby achieving a better control effect.

[0012] In a second aspect, the present invention provides a method for preventing and controlling tobacco black shank disease, the method comprising spraying tobacco seedlings with the composition for preventing and controlling tobacco black shank disease described in the first aspect.

[0013] Preferably, the method includes spraying tobacco seedlings with a composition for controlling tobacco black shank disease for the first time after transplanting, culturing them, and then spraying them with the same composition for controlling tobacco black shank disease for the second time, followed by culturing them again.

[0014] Preferably, the first spraying is performed 20-30 days after the tobacco seedlings are transplanted. For example, it can be 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 days after transplanting.

[0015] In this invention, spraying is performed 20-30 days after transplanting (during the seedling stage). Firstly, the tobacco plants enter a highly susceptible stage; at this time, the stem base is tender and the cortex is thin, making it easy for Phytophthora zoospores to directly invade from the stem base and roots. Secondly, the root system extends to the pathogen accumulation layer; the tobacco seedling roots grow downwards to a depth of 5-15 cm in the soil (the main accumulation area of ​​Phytophthora blackleg), significantly increasing the risk of contact with the pathogen. Thirdly, it serves as proactive defense before the rainy season; in southern tobacco-growing areas, this stage often coincides with the first rainy season (high temperature and humidity), and spraying forms a protective film to block early infection. Finally, agricultural operations minimize disturbance; before the canopy closes, the pesticide solution can be fully sprayed onto the soil at the stem base, ensuring effective control.

[0016] Preferably, the spraying volume for the first spray is 30-40 mL / plant. For example, it can be 30 mL / plant, 31 mL / plant, 32 mL / plant, 33 mL / plant, 34 mL / plant, 35 mL / plant, 36 mL / plant, 37 mL / plant, 38 mL / plant, 39 mL / plant, or 40 mL / plant, etc.

[0017] Preferably, the first spraying is applied to the base of the stem and the roots.

[0018] Preferably, the second spraying is performed 50-60 days after the tobacco seedlings are transplanted. For example, it can be 50 days, 51 days, 52 days, 53 days, 54 days, 55 days, 56 days, 57 days, 58 days, 59 days, or 60 days.

[0019] In this invention, spraying is performed 50-60 days after transplanting (from the end of vigorous growth to the budding stage). Firstly, this is a period of high incidence of physiological wounds on the plants. Topping and pruning create numerous stem wounds, allowing pathogens to invade within 24 hours (increasing the probability of infection). Secondly, the field is saturated with humidity; after the tobacco plants close the canopy, the relative humidity under the canopy exceeds 90%, and this sustained high humidity for 48 hours can induce a large release of spores. Thirdly, nutrient transfer reduces resistance; during the budding stage, nutrients are transferred to the flower buds, reducing the synthesis of disease-resistant substances (such as phenols and phytoalexins) in the roots and stem base. Finally, it blocks the secondary infection peak; latent pathogens in the soil enter their reproductive and explosive phase, and spraying directly kills the zoospores to prevent their spread.

[0020] Preferably, the spraying volume for the second spray is 40-60 mL / plant. For example, it can be 40 mL / plant, 42 mL / plant, 44 mL / plant, 46 mL / plant, 48 mL / plant, 50 mL / plant, 50 mL / plant, 52 mL / plant, 54 mL / plant, 56 mL / plant, 58 mL / plant, or 60 mL / plant, etc.

[0021] Preferably, the second spraying is applied to the base of the stem and the roots.

[0022] Preferably, the culture temperature is 20-30℃, and the light exposure time is 10-14 h. The 20-30℃ can be, for example, 20℃, 21℃, 22℃, 23℃, 24℃, 25℃, 26℃, 27℃, 28℃, 29℃, or 30℃. The 10-14 h can be, for example, 10 h, 11 h, 12 h, 13 h, or 14 h.

[0023] Thirdly, the present invention provides the application of the composition for preventing and treating tobacco black shank according to the first aspect or the method for preventing and treating tobacco black shank according to the second aspect in the prevention and treatment of tobacco black shank.

[0024] Compared with the prior art, the present invention has at least the following beneficial effects:

[0025] In this invention, a combination of methyl jasmonate and mancozeb is used. Methyl jasmonate can activate the salicylic acid pathway and upregulate the expression of defense genes, while mancozeb can inhibit the germination of pathogenic spores. The two work synergistically. Methyl jasmonate can enhance cell wall lignification and improve the defense ability of tobacco plants, while mancozeb can reduce the initial source of inoculum, thereby achieving the effect of preventing and controlling tobacco black shank disease. Attached Figure Description

[0026] Figure 1 This is a picture of mycelium in a culture dish for the control group.

[0027] Figure 2 This is a picture of mycelium in a petri dish for Example 1.

[0028] Figure 3 This is an anatomical diagram of the plant used in Example 1.

[0029] Figure 4 This is an anatomical diagram of the plant used in Example 2.

[0030] Figure 5 This is an anatomical diagram of the plant used in Example 3.

[0031] Figure 6 This is an anatomical diagram of the plant used in Example 4.

[0032] Figure 7 This is an anatomical diagram of the plant used in Example 5.

[0033] Figure 8 This is an anatomical diagram of the plant used in Example 6.

[0034] Figure 9 This is an anatomical diagram of the plant used in Example 7.

[0035] Figure 10 This is an anatomical diagram of the plant used in Example 8.

[0036] Figure 11 This is an anatomical diagram of the plant used in Example 9.

[0037] Figure 12 For comparison, the plant anatomy diagram of Application Example 1 is shown.

[0038] Figure 13 For comparison, the plant anatomy diagram of Application Example 2 is shown.

[0039] Figure 14 For comparison, the plant anatomy diagram of Application Example 3 is shown.

[0040] Figure 15 For comparison, the plant anatomy diagram of Application Example 4 is shown.

[0041] Figure 16 For comparison, the plant anatomy diagram of Application Example 5 is shown.

[0042] Figure 17 For comparison, the plant anatomy diagram of Application Example 6 is shown.

[0043] Figure 18 For comparison, the plant anatomy diagram of Application Example 7 is shown.

[0044] Figure 19 This is an anatomical diagram of the control group plants. Detailed Implementation

[0045] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0046] Example 1

[0047] This embodiment provides a composition for preventing and treating tobacco black shank disease.

[0048] The composition consists of 120 μmol / L methyl jasmonate, 5% anhydrous ethanol, and 2 g / L mancozeb.

[0049] Example 2

[0050] This embodiment provides a composition for preventing and treating tobacco black shank disease.

[0051] The composition consists of 100 μmol / L methyl jasmonate, 1% anhydrous ethanol, and 3 g / L mancozeb.

[0052] Example 3

[0053] This embodiment provides a composition for preventing and treating tobacco black shank disease.

[0054] The composition consists of 150 μmol / L methyl jasmonate, 10% anhydrous ethanol, and 1 g / L mancozeb.

[0055] Example 4

[0056] This embodiment provides a composition for preventing and treating tobacco black shank disease. The only difference between this composition and that of Example 1 is that the composition consists of 50 μmol / L methyl jasmonate, 15% anhydrous ethanol, and 5 g / L mancozeb.

[0057] Example 5

[0058] This embodiment provides a composition for preventing and treating tobacco black shank disease. The only difference between this composition and Example 1 is that the composition consists of 200 μmol / L methyl jasmonate, 10% anhydrous ethanol, and 0.5 g / L mancozeb.

[0059] Comparative Example 1

[0060] This embodiment provides a composition for preventing and treating tobacco black shank disease. The only difference between this composition and Example 1 is that methyl jasmonate is not added; otherwise, they are the same as in Example 1.

[0061] Comparative Example 2

[0062] This embodiment provides a composition for preventing and treating tobacco black shank disease. The only difference between this composition and Example 1 is that mancozeb is not added; otherwise, they are the same as in Example 1.

[0063] Comparative Example 3

[0064] This embodiment provides a composition for preventing and treating tobacco black shank disease. The only difference between this composition and Example 1 is that potassium sulfite is used instead of mancozeb. Otherwise, the composition is the same as that in Example 1.

[0065] Comparative Example 4

[0066] This embodiment provides a composition for preventing and treating tobacco black shank disease. The only difference between this composition and Example 1 is that β-aminobutyric acid is used instead of mancozeb, while the rest is the same as in Example 1.

[0067] Comparative Example 5

[0068] This embodiment provides a composition for preventing and treating tobacco black shank disease. The only difference between this composition and Example 1 is that anhydrous ethanol is not added; otherwise, they are the same as in Example 1.

[0069] Comparative Example 6

[0070] This embodiment provides a composition for preventing and treating tobacco black shank disease. The only difference between this composition and Example 1 is that methanol is used instead of anhydrous ethanol. Otherwise, the composition is the same as Example 1.

[0071] Application Example 1

[0072] This test case demonstrates field control of tobacco black shank disease.

[0073] The preparation method of the compositions for preventing and treating tobacco black shank in the above embodiments and comparative examples is as follows: Methyl jasmonate is dissolved in a small amount of anhydrous ethanol to obtain a methyl jasmonate stock solution. Anhydrous ethanol, mancozeb suspension, and the methyl jasmonate stock solution are added to a volumetric flask, followed by distilled water. The volumetric flask is placed in a magnetic stirrer and stirred thoroughly for 15 minutes. Stirring is then stopped, and distilled water is added to bring the volume to a final concentration until all components reach the specified concentration.

[0074] Twenty tobacco seedlings were transplanted. On the 25th day after transplanting, the composition for controlling tobacco black shank prepared in Example 1 was sprayed on the base of the stems and roots at a rate of 35 mL per seedling. Immediately after spraying, the plants were covered with transparent plastic bags to maintain 90% humidity for 24 hours, simulating an environment conducive to disease development. The seedlings were then cultured at 25°C under 12 hours of light.

[0075] Seven days after the first spraying, a 2 mm deep incision was made at the base of the stem using a sterile scalpel. 5 g of *Phytophthora tobaccois* mycelial blocks / plant were inoculated and wrapped with sterile, moist cotton to retain moisture. The mixture was then incubated at 25°C under 12 hours of light.

[0076] On the 55th day after transplanting tobacco seedlings, the composition for controlling tobacco black shank prepared in Example 1 was sprayed onto the leaves at a rate of 50 mL per plant. Immediately after spraying, the plants were covered with transparent plastic bags to maintain 90% humidity for 24 hours, simulating an environment conducive to disease development. The seedlings were then cultured at 25°C under 12 hours of light.

[0077] Application Example 2

[0078] This test case demonstrates field control of tobacco black shank disease.

[0079] Twenty tobacco seedlings were transplanted. On the 20th day after transplanting, the composition for controlling tobacco black shank disease prepared in Example 2 was sprayed onto the base of the stems and roots at a rate of 30 mL per seedling. Immediately after spraying, the plants were covered with transparent plastic bags to maintain 90% humidity for 24 hours, simulating an environment conducive to disease development. The seedlings were then cultured at 20°C under 14 hours of light.

[0080] Seven days after the first spraying, a 2 mm deep incision was made at the base of the stem using a sterile scalpel. 5 g of *Phytophthora tobaccois* mycelial blocks / plant were inoculated and wrapped with sterile, moist cotton to retain moisture. The mixture was then incubated at 20°C under 14 hours of light.

[0081] Sixty days after transplanting tobacco seedlings, the composition for controlling tobacco black shank prepared in Example 1 was sprayed onto the leaves at a rate of 60 mL per plant. Immediately after spraying, the plants were covered with transparent plastic bags to maintain 90% humidity for 24 hours, simulating an environment conducive to disease development. The seedlings were then cultured at 20°C under 14 hours of light.

[0082] Application Example 3

[0083] This test case demonstrates field control of tobacco black shank disease.

[0084] Twenty tobacco seedlings were transplanted. On the 30th day after transplanting, the composition for controlling tobacco black shank disease prepared in Example 3 was sprayed onto the base of the stems and roots at a rate of 40 mL per seedling. Immediately after spraying, the plants were covered with transparent plastic bags to maintain 90% humidity for 24 hours, simulating an environment conducive to disease development. The seedlings were then cultured at 30°C under 10 hours of light.

[0085] Seven days after the first spraying, a 2 mm deep incision was made at the base of the stem using a sterile scalpel. 5 g of *Phytophthora tobaccois* mycelial blocks / plant were inoculated and wrapped with sterile, moist cotton to retain moisture. The mixture was then incubated at 30°C under 10 hours of light.

[0086] On the 50th day after transplanting tobacco seedlings, the composition for controlling tobacco black shank prepared in Example 1 was sprayed onto the leaves at a rate of 40 mL per plant. Immediately after spraying, the plants were covered with transparent plastic bags to maintain 90% humidity for 24 hours, simulating an environment conducive to disease development. The seedlings were then incubated at 30°C under 10 hours of light.

[0087] Application Example 4-5

[0088] This application example is used for field control of tobacco black shank disease. The only difference between this example and application example 1 is that the composition used for controlling tobacco black shank disease was prepared in Examples 4-5, while the rest is the same as application example 1.

[0089] Application Example 6

[0090] This application example is used for field control of tobacco black shank disease. The only difference between this example and application example 1 is that the first spraying amount is 20 mL / plant and the second spraying amount is 30 mL / plant. All other aspects are the same as application example 1.

[0091] Application Example 7

[0092] This application example is used for field control of tobacco black shank disease. The only difference between this example and application example 1 is that the first spraying amount is 80 mL / plant and the second spraying amount is 100 mL / plant. All other aspects are the same as application example 1.

[0093] Application Example 8

[0094] This application example is for field control of tobacco black shank disease. The only difference between this example and application example 1 is that the first spraying was carried out on the 15th day after the tobacco seedlings were transplanted, and the second spraying was carried out on the 65th day after the tobacco seedlings were transplanted.

[0095] Application Example 9

[0096] This application example is used for field control of tobacco black shank disease. The only difference between this example and application example 1 is that the first spraying was carried out on the 35th day after the tobacco seedlings were transplanted, and the second spraying was carried out on the 45th day after the tobacco seedlings were transplanted.

[0097] Comparative Application Examples 1-6

[0098] This comparative application example is used for field control of tobacco black shank. The only difference between this example and application example 1 is that the composition used for controlling tobacco black shank was prepared in comparative examples 1-6, while the rest is the same as application example 1.

[0099] Comparative Application Example 7

[0100] This comparative application example is used for field control of tobacco black shank disease. The only difference between this example and application example 1 is that a second spraying is not performed; otherwise, they are the same as application example 1.

[0101] Test Example 1

[0102] This test case investigates the antibacterial effect of a composition for preventing and treating tobacco black shank.

[0103] Phytophthora nicotianae was inoculated into the center of selective agar (SRA) medium. Using a streak plating apparatus, straight lines 2 mm wide and 30 mm long were drawn on the surface of the medium (10 cm in diameter) for the compositions prepared in the above examples and comparative examples to control tobacco black shank, with the ends of the lines 15 mm from the edge of the petri dish. Each group was repeated three times, and the medium was incubated at 25°C. The above procedure was repeated using sterile water as a control group.

[0104] After 5 days of incubation, when the colony area of ​​the control group expanded to 2 / 3 of the petri dish, the colony diameter was measured using the cross-sectional method, and the inhibition rate of the above composition was calculated. The inhibition rate was calculated using the formula: I = (C − T) / C × 100, where C is the average colony diameter of the control group (mm), T is the average colony diameter of the treatment group (mm), and I is the inhibition rate (%). Specific test results are shown in Table 1.

[0105] Table 1

[0106]

[0107] The results show that:

[0108] (1) By comparing Examples 1-3 with Examples 4-5 and Comparative Examples 1-6, such as Figure 1 and Figure 2 As shown in the figure, by comparing Example 1 with the control group, it can be seen that the composition of the present invention can significantly inhibit the growth of Phytophthora tobaccoii.

[0109] (2) It can be seen from the comparison between Example 1 and Examples 4-5 that outside the concentration range of the present invention, the prevention and control effect will be weakened.

[0110] (3) It can be seen from the comparison between Example 1 and Comparative Examples 1-2 that the composition of the present invention has a synergistic effect.

[0111] (4) By comparing Example 1 with Comparative Examples 3-4, it can be seen that the control effect of using other antibacterial agents in combination with methyl jasmonate is not as good as that of mancozeb.

[0112] (5) It can be seen from the comparison between Example 1 and Comparative Examples 5-6 that using different solvents or not using solvents will lead to a weakening of the prevention and control effect.

[0113] Test Example 2

[0114] This test case was used to evaluate the field efficacy of the control.

[0115] Seven days after the final spraying in the above application examples and control examples, plant height, stem circumference, and maximum leaf width were measured. Representative plants from the field were selected for basal dissection to observe black shank infection. The number of infected plants was counted, and the control effect was calculated using the following formula: Control effect (%) = (1 − Incidence rate of control group) / Incidence rate of treatment group × 100. The results of the above examples are shown in Table 2.

[0116] Table 2

[0117]

[0118] The experimental results show that:

[0119] (1) By comparing application example 1 with application examples 2-3, such as Figure 3 , Figure 4 and Figure 5 As shown, it can be seen that the composition of the present invention can significantly inhibit the incidence of Phytophthora tobaccoii.

[0120] (2) By comparing Application Example 1 with Application Examples 4-5, it can be seen that, as Figure 6 and Figure 7 As shown, outside the concentration range of this invention, the prevention and control effect will be weakened.

[0121] (3) By comparing Application Example 1 with Application Examples 6-7, it can be seen that, as Figure 8 and Figure 9 As shown, the spraying amount is outside the scope of this invention. Too low a spraying amount will lead to a decrease in the control effect, while too high a spraying amount will affect the plant and reduce the inhibitory effect on the disease.

[0122] (4) By comparing Application Example 1 with Application Examples 8-9, it can be seen that, as Figure 10 and Figure 11 As shown, spraying outside the time specified in this invention will cause the plant to miss the optimal growth stage for spraying, thereby reducing the absorption of the drug's efficacy.

[0123] (5) By comparing Application Example 1 with Comparative Application Example 1-2, it can be seen that, as Figure 12 and Figure 13 As shown, the composition of the present invention has a synergistic effect.

[0124] (6) By comparing Application Example 1 with Comparative Application Examples 3-4, it can be seen that, as Figure 14 and Figure 15 As shown, the combination of other antibacterial agents with methyl jasmonate is not as effective as mancozeb.

[0125] (7) As can be seen from the comparison between Example 1 and Comparative Application Examples 5-6, as Figure 16 and Figure 17 As shown, using different solvents or not using solvents will reduce the effectiveness of prevention and control.

[0126] (8) As can be seen from the comparison between Example 1 and Comparative Application Example 7, as Figure 18 As shown, the lack of secondary spraying leads to a decrease in the amount of sprayed material, which greatly reduces the effectiveness of the spraying.

[0127] (9) As can be seen from the comparison between Example 1 and the control group, as Figure 19 As shown, the prevention and control method of the present invention can effectively prevent Phytophthora from infecting tobacco and reduce damage to the plants.

[0128] In the composition of this invention, methyl jasmonate and mancozeb exhibit a good synergistic effect. Methyl jasmonate enhances cell wall lignification, while mancozeb inhibits the germination of pathogenic spores, further blocking mycelial invasion, thereby achieving a better control effect. The applicant declares that the above description is merely a specific embodiment of this invention, but the scope of protection of this invention is not limited thereto. Those skilled in the art should understand that any variations or substitutions easily conceived by those skilled in the art within the technical scope disclosed in this invention fall within the scope of protection and disclosure of this invention.

Claims

1. A composition for preventing and treating tobacco black shank disease, characterized in that, The composition contains methyl jasmonate, ethanol, and mancozeb.

2. A composition for preventing and treating tobacco black shank disease, characterized in that, The composition comprises 100-150 μmol / L methyl jasmonate, 1-10% ethanol and 1-3 g / L mancozeb.

3. A method for preventing and controlling tobacco black shank disease, characterized in that, The method includes spraying tobacco seedlings with the composition for controlling tobacco black shank as described in claim 1 or 2.

4. The method for preventing and controlling tobacco black shank disease according to claim 3, characterized in that, The method includes first spraying tobacco seedlings with a composition for controlling tobacco black shank disease after transplanting, followed by cultivation, and then spraying the tobacco seedlings with the same composition a second time, followed by cultivation.

5. The method for preventing and controlling tobacco black shank disease according to claim 4, characterized in that, The first spraying should be done 20-30 days after the tobacco seedlings are transplanted.

6. The method for preventing and controlling tobacco black shank according to claim 4 or 5, characterized in that, The amount of the first spray is 30-40 mL per plant; Preferably, the first spraying is applied to the base of the stem and the roots.

7. The method for preventing and controlling tobacco black shank disease according to claims 4-6, characterized in that, The second spraying should be done 50-60 days after the tobacco seedlings are transplanted.

8. The method for preventing and controlling tobacco black shank disease according to claims 4-7, characterized in that, The amount of the second spray is 40-60 mL per plant; Preferably, the second spraying is applied to the base of the stem and the roots.

9. The method for preventing and controlling tobacco black shank disease according to claims 4-8, characterized in that, The culture temperature is 20-30℃, and the light exposure time is 10-14 h.

10. The use of the composition for preventing and treating tobacco black shank according to claim 1 or 2, or the method for preventing and treating tobacco black shank according to any one of claims 3-9, in the prevention and treatment of tobacco black shank.

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