Application of artemisia apiacea residue extract in prevention and treatment of tobacco bacterial wilt

Abstract

The invention belongs to the technical field of plant disease prevention and treatment, and relates to application of an artemisia apiacea residue extract in prevention and treatment of tobacco bacterial wilt. The invention provides application of an artemisia apiacea residue extract in prevention and treatment of tobacco bacterial wilt. The artemisia apiacea residue extract is obtained by extracting an artemisia apiacea residue raw material with an organic solvent. The organic solvent is a mixed solution of ethyl acetate and petroleum ether; the artemisia apiacea residue raw material is waste residue obtained by extracting artemisinin from artemisia apiacea. After the artemisia apiacea residue extract is prepared into the 4% artemisia apiacea residue extract microemulsion, the prevention and control effects of 1400-fold liquid and 800-fold liquid of the 4% artemisia apiacea residue extract microemulsion on tobacco bacterial wilt reach 60% or above, and the prevention and control effects of the 1400-fold liquid and the 800-fold liquid of the 4% artemisia apiacea residue extract microemulsion are superior to those of a conventional medicament of 20%

Description

Technical Field

[0001] The invention belongs to the technical field of plant disease prevention and control, and relates to application of an Artemisia annua residue extract in preventing and controlling tobacco bacterial wilt. Background Art

[0002] Artemisia annua L., a traditional Chinese medicine, is the dried, above-ground part of the Asteraceae plant. The Shennong Bencao Jing (Shen Nong's Classic of Materia Medica) records that it has the effects of relieving summer heat, reducing fever, and treating malaria. Studies have shown that Artemisia annua L. contains terpenes, flavonoids, coumarins, and volatile oils, making it the primary source plant for artemisinin extraction. Existing artemisinin extraction processes produce a large amount of residue when extracting high-purity artemisinin from Artemisia annua L. This residue is often used as a feed additive or disposed of as waste, resulting in significant resource waste and environmental pollution. Summary of the Invention

[0003] Based on this, the technical problem to be solved by the present invention is to provide an Artemisia annua residue extract prepared using the Artemisia annua residue remaining after extracting artemisinin for use in preventing and controlling tobacco bacterial wilt. After the Artemisia annua residue extract is made into a 4% Artemisia annua residue extract microemulsion, its 1400-fold and 800-fold solutions have a prevention and control effect of more than 60% on tobacco bacterial wilt, which is better than the conventional agent 20% thiophanate-methyl suspension 500-fold solution.

[0004] In one aspect, the present invention relates to the use of an extract of Artemisia annua residue in preventing and treating tobacco bacterial wilt, wherein the extract of Artemisia annua residue is obtained by extracting Artemisia annua residue raw material with an organic solvent;

[0005] The organic solvent is a mixture of ethyl acetate and petroleum ether;

[0006] The Artemisia annua residue raw material is the waste residue from extracting artemisinin from Artemisia annua.

[0007] Furthermore, in the application of the Artemisia annua residue extract provided by the present invention in preventing and treating tobacco bacterial wilt, the proportion of ethyl acetate in the organic solvent is 80-100% by mass.

[0008] Furthermore, in the application of the Artemisia annua residue extract provided by the present invention in preventing and treating tobacco bacterial wilt, the solid-liquid ratio of the Artemisia annua residue raw material to the organic solvent is 1:6 to 1:10, calculated in g:mL.

[0009] Furthermore, in the application of the Artemisia annua residue extract provided by the present invention in preventing and treating tobacco bacterial wilt, the extraction time is 60 to 80 minutes.

[0010] Furthermore, in the application of the Artemisia annua residue extract provided by the present invention in preventing and treating tobacco bacterial wilt, the Artemisia annua residue raw material is extracted with the organic solvent and then concentrated with a macroporous adsorption resin.

[0011] Furthermore, in the application of the Artemisia annua residue extract provided by the present invention in preventing and treating tobacco bacterial wilt, the macroporous adsorption resin is an NKA-2 type macroporous adsorption resin.

[0012] Furthermore, in the application of the Artemisia annua residue extract provided by the present invention in preventing and treating tobacco bacterial wilt, the Artemisia annua residue extract mainly comprises, by mass percentage, 5% scopoletin, 3% artemisinic acid, 3% isofraxidin, 3% syringetin and 2% deoxyartemisinin.

[0013] Furthermore, in the application of the Artemisia annua residue extract provided by the present invention in preventing and treating tobacco bacterial wilt, the Artemisia annua residue extract is prepared into a microemulsion and then applied.

[0014] Furthermore, in the application of the Artemisia annua residue extract provided by the present invention in preventing and treating tobacco bacterial wilt, the microemulsion is composed of 1-10% of the Artemisia annua residue extract, 20-30% of a solvent, 15-20% of an emulsifier, 1-10% of an anionic surfactant, and the remainder water, calculated by mass percentage.

[0015] Furthermore, in the application of the Artemisia annua residue extract provided by the present invention in preventing and treating tobacco bacterial wilt, the ratio of acetone, ethyl acetate and ethanol in the solvent is 2-3:1-3:1-3 by mass ratio;

[0016] The emulsifier is EL-20;

[0017] The anionic surfactant is 500# (calcium dodecylbenzenesulfonate).

[0018] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages:

[0019] The present invention develops a technical solution for the efficient prevention and treatment of tobacco bacterial wilt by utilizing the waste residues from artemisinin production. Although the scopoletin content in the extract of Artemisia annua residue is only 5%, it forms a multi-component synergistic system with components such as artemisinic acid (3%), isoflurane (3%), syringetin (3%) and deoxyartemisinin (2%), breaking through the limitations of traditional reliance on a single active ingredient. Field trials have shown that the 4% Artemisia annua residue microemulsion prepared by the optimized process (ethyl acetate ratio 82%, solid-liquid ratio 1:8, extraction time 77 minutes) has a prevention and control effect of more than 60% on tobacco bacterial wilt after dilution to 1400 times and 800 times, which is significantly better than the conventional agent thiophanate-methyl (prevention effect 30.78% to 52.26%). In addition, this technology realizes the resource utilization of waste, reduces environmental pollution, and the preparation has no adverse effects on tobacco growth (safety factor of 4), combining environmental protection, economy and safety, and provides an innovative solution for green agriculture. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 This is a line graph showing the effect of ethyl acetate ratio on the extraction rate of scopoletin.

[0022] Figure 2 This is a line graph showing the effect of the material-liquid ratio on the extraction rate of scopoletin.

[0023] Figure 3 This is a line graph showing the effect of extraction time on the extraction rate of scopoletin.

[0024] Figure 4 is the response surface plot of the interaction effect. DETAILED DESCRIPTION

[0025] The technical solutions of the present invention are described below with reference to the following examples. However, the present invention is not limited to the following examples. The experimental and detection methods described in each example are conventional methods unless otherwise specified. The reagents and materials described are commercially available unless otherwise specified. The percentages in the following examples are percentages by mass unless otherwise specified. The ratios in the following examples are ratios by mass unless otherwise specified.

[0026] In the following examples, the raw material of Artemisia annua residue is the waste residue of extracting artemisinin from Artemisia annua, which is obtained by evaporating and drying the solvent.

[0027] Scopoletin standard (98%) was purchased from Nanjing Herbal Source Biotechnology Co., Ltd.; ethyl acetate (99.7%), anhydrous ethanol and acetone (99.7%) were purchased from Shanghai Yien Chemical Technology Co., Ltd.; EL-20, 500# and petroleum ether (99.8%) were purchased from Chongqing Jiyuan Chemical Co., Ltd.

[0028] Example 1

[0029] This example provides the preparation and purification process of the Artemisia annua residue extract.

[0030] Accurately weigh 10.0 g of Artemisia annua residue, place it in a 250 mL volumetric flask, add the corresponding volume of a mixture of ethyl acetate and petroleum ether, weigh the total weight, and perform heating reflux extraction under different conditions. The temperature is controlled at 60°C. Filter while hot to obtain the filtrate, make up for the weight loss, accurately transfer 5 mL of the filtrate to a penicillin bottle, evaporate the solvent to dryness, and then dilute the volume to 5 mL with methanol. Pass it through a 0.22 μm filter membrane and perform liquid phase detection. Substitute the obtained peak area into the regression equation to obtain the sample solution concentration. After conversion, the extraction rate of scopoletin in the sample can be calculated.

[0031] Taking the extraction rate of scopoletin as an indicator, the effects of different ethyl acetate ratios, different solid-liquid ratios, and different extraction times on the extraction rate of scopoletin were explored. The single factor level settings are shown in Table 1. The three variable factors initially set for exploration were 50% ethyl acetate, a solid-liquid ratio of 1:10, and an extraction time of 60 min. The sample weight of each sample was 10.0 g.

[0032] Table 1 Single factor test

[0033]

[0034] Taking the ratio of ethyl acetate and petroleum ether as a variable, the effects of 10% ethyl acetate, 20% ethyl acetate, 50% ethyl acetate, 80% ethyl acetate and 100% ethyl acetate on the extraction rate of scopoletin were compared when the solid-liquid ratio was 1:10 and the extraction time was fixed at 60 min.

[0035] Taking the solid-liquid ratio as a variable, the effects of solid-liquid ratios of 1:6, 1:8, 1:10, 1:12, and 1:14 on the extraction rate of scopoletin were compared when the ethyl acetate ratio was 50% and the extraction time was fixed at 60 min.

[0036] Taking the extraction temperature as a variable, the effects of extraction time of 40min, 50min, 60min, 70min and 80min on the extraction rate of scopoletin were compared when the proportion of ethyl acetate was 50% and the solid-liquid ratio was fixed at 1:10.

[0037] Based on the optimal values of each factor screened out by the single-factor experiment, a three-factor three-level Box-Behnken experiment was designed for the ethyl acetate ratio (A), solid-liquid ratio (B) and extraction time (C) using Design Expert 13 software (as shown in Table 2). The extraction rate of scopoletin (Y) was used as the response index to determine the optimal process conditions for scopoletin extraction.

[0038] Table 2 Response surface test factors and levels

[0039]

[0040] Depend on Figure 1 It can be seen that as the proportion of ethyl acetate increases, the extraction rate of scopoletin increases continuously, reaching a peak at 80% ethyl acetate. This is because as the ethyl acetate concentration increases, the solubility of scopoletin in the sample is better. However, when the proportion continues to increase to 100% ethyl acetate, the extraction rate of scopoletin shows a downward trend. This may be because as the ethyl acetate concentration increases, more fat-soluble substances are extracted, affecting the extraction of scopoletin and reducing the extraction rate of scopoletin. Therefore, 80% ethyl acetate was selected as the optimal extraction solvent, and the extraction rate at this time was 0.096%. Therefore, 50% ethyl acetate, 80% ethyl acetate, and 100% ethyl acetate were selected as factors for the design of the response surface experiment.

[0041] Depend on Figure 2 It can be seen that when the solid-liquid ratio increases from 1:6 to 1:8, the most scopoletin is extracted and the extraction effect is the best. Then, as the solid-liquid ratio continues to increase, the extraction rate shows a downward trend. When the solvent dosage reaches a certain value, scopoletin has been completely extracted. Continuing to increase the solvent dosage will not only cause the concentration of scopoletin per unit extract to decrease, but also cause waste of resources. Therefore, solid-liquid ratios of 1:6, 1:8, and 1:10 are selected as factors for designing the response surface experiment.

[0042] Depend on Figure 3 It can be seen that the extraction rate of scopoletin increases with the increase of extraction time, reaching a maximum of 0.092% at 70 minutes. However, when the extraction time continues to increase, the extraction rate of scopoletin decreases. Therefore, 70 minutes was selected as the optimal extraction time, and 60 minutes, 70 minutes, and 80 minutes were selected as factors for the response surface design experiment.

[0043] The response surface design results are shown in Table 3. Design Expert 13 software was used to fit the effects of the independent variables ethyl acetate ratio (A), solid-liquid ratio (B), and extraction time (C) on the scopoletin extraction rate (Y), and the resulting multiple regression equation was as follows:

[0044] Y=0.0923-0.0001A-0.0003B+0.0016C-0.0077AB+0.0070AC+0.0072BC-0.0079A 2 -0.0127B 2 -0.0029C 2

[0045] Table 3 Response surface experimental design and results

[0046]

[0047] As shown in Table 4, the P value of the regression model is 0.0123 (P < 0.05), so the model is significant. The P value of the lack-of-fit term is 0.9471 (P > 0.05), and the lack-of-fit term is not significant. It can be seen that the model has high credibility and good fit, and can better predict the optimal extraction process. 2 、B 2 The interaction terms AB, AC, and BC had significant effects on the extraction of scopoletin (P < 0.05), and the first-order terms A, B, C and the second-order term C 2 The extraction effect on scopoletin was not significant (P>0.05).The influence of each factor was in the following order: C (extraction time)>B (material-liquid ratio)>A (ethyl acetate ratio).

[0048] Table 4 Analysis of variance

[0049]

[0050]

[0051] Depend on Figure 4 As can be seen, the surface plots for each interaction response all open downward and have their highest points. The center of the minimum ellipse in the contour plot lies within the range of the experimental factor conditions, indicating that the scopoletin extraction rate reaches its maximum value within the range set by each factor. The response surfaces for each factor interaction show that the AB response surface (ethyl acetate ratio and solid-liquid ratio) has the steepest slope, indicating that the interaction between ethyl acetate ratio and solid-liquid ratio has the most significant effect on the scopoletin extraction rate. The scopoletin extraction rate peaks around 80% ethyl acetate and around a solid-liquid ratio of 1:8. The BC response surface (solid-liquid ratio and extraction time) has a lower steepness than the AB response surface, indicating that the interaction between solid-liquid ratio and extraction time has the second greatest impact on the scopoletin extraction rate. The scopoletin extraction rate peaks between a solid-liquid ratio of 1:8 and an extraction time of 70-80 minutes. Through response surface analysis, it can be concluded that the significance of the interaction effects of various factors on the extraction rate of scopoletin is AB>BC>AC, and the results of surface analysis are consistent with the results of significance analysis of the regression model.

[0052] The regression equation model was fitted and analyzed using Design Expert 13 software, and the optimal process conditions for scopoletin extraction were obtained as follows: 81.525% ethyl acetate ratio, 1:8.247 solid-liquid ratio, and 77.464 min extraction time. Considering the feasibility of actual operation, the ethyl acetate ratio was adjusted to 82% and the solid-liquid ratio was adjusted to 1:8 (g·mL -1 ), the extraction time was adjusted to 77 min, and the test was repeated three times for verification. The test results showed that the extraction rate of scopoletin was (0.091±0.0021)%, which was consistent with the expectation.

[0053] As shown in Table 5, by evaluating the static adsorption capacity of 12 different types of macroporous adsorption resins, NKA-2 macroporous adsorption resin was screened out to have the strongest adsorption capacity for scopoletin, which was 92.3%. Subsequently, NKA-2 macroporous resin was used to study the purification process of scopoletin. The purity of scopoletin was increased from 1% to 5% by enrichment with macroporous adsorption resin, and an Artemisia annua residue extract containing 5% scopoletin was obtained.

[0054] Table 5 Static adsorption capacity of scopoletin by different types of macroporous adsorption resins

[0055] model <![CDATA[Adsorption capacity (mg·g -1 )]]> Adsorption rate / % Desorption rate / % D4006 0.864 46.75 81.44 HPD100 0.942 50.93 87.89 HPD600 1.393 75.34 84.43 X-5 1.241 67.10 77.62 S-8 0.753 40.74 91.37 D4020 1.124 60.28 80.94 D001 0.619 33.51 59.39 D101 1.254 67.82 82.07 NKA-2 1.706 92.30 67.52 NKA-9 1.214 65.64 80.48 AB-8 1.254 67.85 78.24 ADS-7 1.106 59.81 80.63

[0056] Table 6 Main components of Artemisia annua residue extract

[0057]

[0058]

[0059] As described above, the Artemisia annua residue extract was prepared in this embodiment. The Artemisia annua residue extract mainly includes 5% scopoletin, 3% artemisinic acid, 3% isofraquinone, 3% syringetin and 2% deoxyartemisinin.

[0060] Example 2

[0061] This example provides the preparation of Artemisia annua residue microemulsion.

[0062] The solubility of Artemisia annua residue extract in different solvents was determined. It can be seen that the solubility of Artemisia annua residue extract in acetone is the best, and the solubility in ethyl acetate, N,N-dimethylformamide and ethanol is relatively large. The solubility and cold storage stability in other solvents are poor.

[0063] Taking cost factors into consideration and in order to reduce the use of restrictive organic solvents, acetone, ethyl acetate and ethanol were selected in combination, and 42 solvent combinations were screened.

[0064] According to the results in Table 7, taking into account factors such as solubility, cost, and toxicity, the solvent combination of acetone:ethyl acetate:ethanol was finally selected at 3:1:1 (total solvent amount was 25%) for the next step of emulsifier screening.

[0065] Table 7 Solvent combinations with good solubility for Artemisia annua residue extracts

[0066]

[0067]

[0068]

[0069] Non-ionic surfactants were screened under the above-mentioned solvent ratio. From the appearance of the preparation, cold storage stability, hot storage stability, and dilution stability, it can be seen from Table 8 that EL-20 meets the relevant requirements. Therefore, EL-20 was selected as the emulsifier for the microemulsion of Artemisia annua residue extract.

[0070] Table 8 Emulsifier screening results

[0071]

[0072] The selected emulsifier, EL-20, was set at six concentration gradients. After adding the emulsifier to the aforementioned solvent formulation, the concentration was topped up to 100% with deionized water. Table 9 shows that increasing emulsifier content gradually improved the microemulsion's appearance, low-temperature stability, thermal storage stability, and dilution stability. At 15% EL-20, the formulation essentially met the relevant standards. Considering factors such as cost and environmental impact, the final EL-20 concentration in the Artemisia annua residue extract microemulsion was 15%.

[0073] Table 9 Emulsifier content determination results

[0074]

[0075]

[0076] Based on the above series of test results, the formula composition of the Artemisia annua residue extract microemulsion was finally determined, as shown in Table 10 below.

[0077] Table 10 Microemulsion formulation composition

[0078] Components content(%) Artemisia annua residue extract 4 acetone 15.0 Ethyl acetate 5.0 ethanol 5.0 EL-20 15.0 500# 5.0 water Fill in

[0079] Example 3

[0080] This example provides the effect of Artemisia annua residue microemulsion on tobacco safety.

[0081] Experimental design and investigation: Each tobacco variety safety test was conducted with four treatments, namely 800-fold, 1400-fold, and 2000-fold dilutions of Artemisia annua residue extract microemulsions and a water control. Each plot was approximately 18 m2. 2 Application Method: The experiment involved two applications, one at the three-leaf, one-heart stage after transplanting, and another application every 7-10 days. Each spray volume per plot was 1.36L. Survey Method: The height of each treated tobacco plant was surveyed before the first application and 21 days after the last application. Starting from the first application, daily visual inspections were conducted to assess whether the tobacco had any signs of damage, such as discoloration, necrosis, wilting, or deformity.

[0082] Result statistics: The safety of Artemisia annua residue extract microemulsion to tobacco is described according to the following formula.

[0083]

[0084]

[0085] The results of the investigation on the direct effects of the test microemulsion of Artemisia annua residue extract on the growth of three tobacco varieties are shown in Table 11. Within 21 days after treatment with 800-fold, 1400-fold and 2000-fold dilutions of Artemisia annua residue extract microemulsion, the leaves of the three tobacco varieties did not show symptoms of phytotoxicity such as discoloration, necrosis, deformity and wilting.

[0086] The effects of the test agent, Artemisia annua residue extract microemulsion, on tobacco growth and development are shown in Table 12. As shown in Table 12, after treatment with 800-fold, 1400-fold, and 2000-fold dilutions of Artemisia annua residue extract microemulsion, there was no significant difference in plant height compared to the water control for the three tobacco varieties, and the growth rate inhibition rates were all less than 10%, indicating that the test agent is safe for tobacco growth.

[0087] In conclusion, the treatment with microemulsion of Artemisia annua residue extract had no adverse effects on the growth of the three tobacco varieties, with a safety factor of 4.

[0088] Table 11 Effect of Artemisia annua residue extract microemulsion on tobacco safety

[0089]

[0090]

[0091] Table 12 Effects of Artemisia annua residue extract microemulsion on tobacco growth

[0092]

[0093] Example 4

[0094] This example provides the field control effect of Artemisia annua residue microemulsion on tobacco bacterial wilt.

[0095] Preparation of microemulsions of Artemisia annua residue extracts and field efficacy trials were conducted in Zunyi, Guizhou, Weng'an, Guizhou, Qianjiang and Pengshui, Chongqing, and Yibin, Sichuan.

[0096] Experimental treatment: There are 4 treatments in total, namely 2000 times, 1400 times, 800 times of microemulsion of Artemisia annua residue, and 500 times of 20% thiophanate-methyl suspension concentrate. Each treatment is repeated 3 times. The area of each plot is about 30m 2 .

[0097] Application method: The experiment applied pesticides twice, once during the clustering stage and once during the vigorous growth stage after tobacco transplanting, and the spraying liquid volume per plot was 2.25L each time.

[0098] Survey method: Surveys were conducted in the early stages of tobacco bacterial wilt according to GB / 23222-2008 "Grading and Survey Methods for Tobacco Pests and Diseases". The grading standards are as follows:

[0099] Level 0: The whole plant is disease-free;

[0100] Level 1: Occasional chlorotic spots on the stem, or less than 1 / 2 of the leaves on the diseased side wilt;

[0101] Level 3: There are black streaks on the stem, but not exceeding 1 / 2 of the stem height, or 1 / 2 to 2 / 3 of the leaves on the diseased side are withered;

[0102] Level 5: Black streaks on the stem exceed 1 / 2 of the stem height but do not reach the top of the stem, or more than 2 / 3 of the leaves on the diseased side wilt;

[0103] Level 7: Black streaks on the stem reach the top of the stem, or all leaves of the diseased plant wilt;

[0104] Level 9: The diseased plants are basically dead.

[0105] The disease index and prevention efficacy were calculated according to the following formula.

[0106]

[0107] Table 13 Control effect of Artemisia annua residue extract microemulsion on tobacco bacterial wilt

[0108]

[0109]

[0110] As shown in Table 13, the control effect of 1400-fold and 800-fold dilutions of the microemulsion of Artemisia annua residue extract on tobacco bacterial wilt reached more than 60%, which was better than the control agent 500-fold dilution of 20% thiophanate-methyl suspension.

[0111] The embodiments described above are only some of the embodiments of the present invention, rather than all of them. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention as claimed, but merely represents the preferred embodiments of the present invention. All other embodiments obtained without creative effort and through deduction and substitution by a person of ordinary skill in the art based on the concept of the present invention are within the scope of protection of the present invention.

Claims

1. The application of Artemisia annua residue extract in preventing and treating tobacco bacterial wilt, characterized in that: The Artemisia annua residue extract is obtained by extracting the Artemisia annua residue raw material with an organic solvent; The organic solvent is a mixture of ethyl acetate and petroleum ether; The Artemisia annua residue raw material is the waste residue from extracting artemisinin from Artemisia annua.

2. The use of the Artemisia annua residue extract in preventing and treating tobacco bacterial wilt according to claim 1, characterized in that: In terms of mass percentage, the proportion of ethyl acetate in the organic solvent is 80-100%.

3. The use of the Artemisia annua residue extract in preventing and treating tobacco bacterial wilt according to claim 1, characterized in that: In terms of g:mL, the solid-liquid ratio of the Artemisia annua residue raw material and the organic solvent is 1:6 to 1:

10.

4. The use of the Artemisia annua residue extract in preventing and treating tobacco bacterial wilt according to claim 1, characterized in that: The extraction time is 60 to 80 minutes.

5. The use of the Artemisia annua residue extract in preventing and treating tobacco bacterial wilt according to claim 1, characterized in that: The Artemisia annua residue raw material is extracted with the organic solvent and then concentrated with a macroporous adsorption resin.

6. The use of the Artemisia annua residue extract in preventing and treating tobacco bacterial wilt according to claim 5, characterized in that: The macroporous adsorption resin is NKA-2 type macroporous adsorption resin.

7. The use of the Artemisia annua residue extract in preventing and treating tobacco bacterial wilt according to claim 6, characterized in that: Calculated by mass percentage, the extract of the Artemisia annua residue mainly includes 5% scopoletin, 3% artemisinic acid, 3% isofraquinone, 3% syringetin and 2% deoxyartemisinin.

8. The use of the Artemisia annua residue extract in preventing and treating tobacco bacterial wilt according to claim 1, characterized in that: The extract of the Artemisia annua residue is prepared into a microemulsion and then administered.

9. The use of the Artemisia annua residue extract in preventing and treating tobacco bacterial wilt according to claim 8, characterized in that: Calculated by mass percentage, the microemulsion consists of 1-10% of the Artemisia annua residue extract, 20-30% of a solvent, 15-20% of an emulsifier, 1-10% of anionic surfactant and the balance of water.

10. The use of the Artemisia annua residue extract in preventing and treating tobacco bacterial wilt according to claim 9, characterized in that: In terms of mass ratio, the ratio of acetone, ethyl acetate and ethanol in the solvent is 2-3:1-3:1-3; The emulsifier is EL-20; The anionic surfactant is 500#.

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