Effervescent tablet for preventing and treating rice sheath blight disease and preparation method thereof

Abstract

The invention discloses an effervescent tablet for preventing and treating rice sheath blight disease and a preparation method thereof, and the effervescent tablet comprises the following components in parts by mass: 18-30 parts of an active component, 15-20 parts of an acid source, 18-23 parts of an alkali source, 12-18 parts of water-soluble starch, 12-18 parts of a diluent, 1-5 parts of an adhesive and 0.5-10 parts of an auxiliary agent, wherein the active component is composed of thifluzamide and pydiflumetofen in a mass ratio of (8: 1)-(2: 1). According to the novel pesticide disclosed by the invention, the thifluzamide and the pydiflumetofen are compounded to achieve a remarkable synergistic effect on prevention and treatment of the rice sheath blight disease, and an unexpected effect is achieved on the indoor toxicity coefficient and the field pesticide effect of the rice sheath blight disease.

Description

Technical Field

[0001] The invention belongs to the technical field of rice sheath blight prevention and treatment, and particularly relates to an effervescent tablet for preventing and treating rice sheath blight and a preparation method thereof. Background Art

[0002] Rice sheath blight is one of the three major diseases of rice in my country. It can continue to occur from the rice seedling stage to the growth stage, causing serious impact on rice yield and quality. Therefore, the prevention and control of rice sheath blight has always attracted much attention. At present, chemical control still occupies a major position in the prevention and control of rice sheath blight, among which suspension concentrate and aqueous solution are the main pesticide formulations, mostly spraying. Thifluzamide is a fungicide with both preventive and therapeutic effects. It is widely used in the prevention and control of rice sheath blight caused by Rhizoctonia solani. It is usually used as a single agent or a mixed suspension preparation of thifluzamide, ...

[0003] However, in order to comply with the pesticide industry's policy of reducing the use of pesticides, reduce the amount of pesticides used, improve the prevention and control effects of pesticides, and delay pesticide resistance, the efficacy test evaluation and prevention and control effects of conventional pesticide formulations still need to be improved and enhanced. In addition, traditional aqueous or suspended formulations are prone to drift and splashing during use, resulting in low pesticide utilization. Summary of the invention

[0004] Purpose of the invention: In order to solve the technical problems existing in the prior art, the present invention provides an effervescent tablet for preventing and controlling rice sheath blight and a preparation method thereof. The novel pesticide of the present invention significantly enhances the prevention and control of rice sheath blight through the combination of thiophanate-methyl and fluazifop-dioxin, and achieves unexpected effects on the indoor toxicity coefficient and field efficacy of rice sheath blight.

[0005] Technical solution: To achieve the above-mentioned invention object, the present invention adopts the following technical solution: an effervescent tablet for preventing and controlling rice sheath blight, comprising the following components in parts by mass: 18-30 parts of active ingredients, 15-20 parts of acid sources, 18-23 parts of alkali sources, 12-18 parts of water-soluble starch, 12-18 parts of diluents, 1-5 parts of adhesives and 0.5-10 parts of auxiliary agents, wherein: the active ingredient is composed of thiophanate-methyl and fluazifop-dioxin in a mass ratio of 8:1 to 4:1.

[0006] Preferably, the acid source is citric acid or malic acid; and the alkali source is sodium bicarbonate.

[0007] Preferably, the diluent is diatomaceous earth.

[0008] Preferably, the adhesive is sodium hydroxymethyl cellulose.

[0009] Preferably, the auxiliary agent includes 0.1-1.0 parts of lubricant magnesium stearate, 2-6 parts of dispersant sodium lauryl sulfate and 0.5-2 parts of flow aid white carbon black.

[0010] Preferably, the mass ratio of thiophanate-methyl to fluazifop-dioxin in the active ingredient is 4:1.

[0011] Preferably, the mass parts of the components are as follows: 20 parts of thiophanate-methyl, 5 parts of fluopicolide, 17 parts of citric acid, 21 parts of sodium bicarbonate, 15 parts of water-soluble starch, 15 parts of diatomaceous earth, 2.5 parts of sodium hydroxymethylcellulose, 0.5 parts of magnesium stearate, 3 parts of sodium lauryl sulfate and 1 part of white carbon black.

[0012] The present invention also provides a method for preparing an effervescent tablet for preventing and treating rice sheath blight, comprising the following steps:

[0013] S1, grinding the thiophanate-methyl technical, fluopicolide technical, water-soluble starch, diluent, adhesive and other additives according to the mass ratio, passing through a 200-mesh sieve, and setting aside;

[0014] S2, dividing the material after grinding and sieving in step S1 into two groups, stirring and mixing them with the acid source and the alkali source in different areas respectively, and then filling them into molds for tableting after weighing to obtain thiophanate-flunix effervescent tablets.

[0015] Beneficial effects: Compared with the prior art, the present invention compounds thiophanate-methyl and fluopicolide and prepares an effervescent tablet. Experiments show that the indoor toxicity coefficient and field efficacy of rice sheath blight can achieve unexpected results, and significantly enhance the prevention and treatment of rice sheath blight. The activity of the compounded thiophanate-methyl and fluopicolide is significantly higher than that of thiophanate-methyl and fluopicolide alone, and compared with conventional single-dose or compound preparations, the prevention effect is significantly different, thereby achieving reduced application of pesticides.

[0016] In addition, the present invention adopts an effervescent tablet form, which can be directly put into a paddy field without dilution with water during use, and the carbon dioxide generated during the disintegration process promotes the diffusion of the effective ingredient. Due to the high solubility of the effervescent tablet in water, it can be quickly and evenly dispersed in water, and then form a protective layer around the root system of the crop, which can effectively improve the utilization rate and control effect of the agent. In addition, compared with traditional pesticide formulations such as powders and suspensions, effervescent tablets reduce dust pollution, improve the stability and dispersibility of pesticides, and can effectively reduce the impact of the agent on the environment and the applicator. DETAILED DESCRIPTION

[0017] The present invention is further explained below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0018] The effervescent tablet for preventing and controlling rice sheath blight of the present invention mainly comprises 25% thiophanate-methyl and fluopicolide (mass ratio is 4:1) as effective active compound ingredients, selects an acid source and an alkali source in a suitable ratio, and is assisted by other auxiliary agents.

[0019] The following content is that the present invention will study the effective ratio of thiophanate-methyl and fluopicolide through the screening test of active ingredients; further screen out the formula composition with thiophanate-methyl and fluopicolide as active ingredients through experiments, and then evaluate its control effect on rice sheath blight through field efficacy tests. The following is a detailed description through specific cases:

[0020] 1. Screening of the ratio of active ingredients in 25% thiophanate-flutrifloxystrobin effervescent tablets

[0021] Thifluzamide technical and fluopicolide technical were prepared into 10 μg / mL mother solutions respectively and placed in a 4℃ refrigerator for later use. After the mother solutions were dissolved with an appropriate amount of sterile water, the inhibition rate of the mixture was determined by the growth rate inhibition method based on the single-dose indoor antibacterial activity test, and the mass ratio of thifuramide to fluopicolide mother solution was 8:1, 4:1, 1:1, 4:1, and 1:8.

[0022] On the basis of the initial screening, the mother solutions of thiophanate-methyl, fluopicolide and five mixed combinations were set at five gradient mass concentrations. The mycelium growth rate method was used, and PDA medium was used. On the basis of the preliminary test, the test agent was diluted to a mother solution of appropriate concentration with sterile water, and evenly mixed with the sterilized PDA medium to prepare a drug-containing medium with an isotropic gradient of drug concentration. 10-12 mL was poured into a 9 cm diameter culture dish for cooling. The rice sheath blight bacteria selected after activation were taken out and placed in a clean workbench. A 6 mm diameter puncher (dipping alcohol, burning on a flame and cooling) was used to punch several bacterial discs at 1 / 3 of the outer edge of the colony. The bacterial discs were picked up with an inoculation needle to the middle position of the drug-containing medium plate, with the mycelium facing down, one bacterial disc per plate, sealed well, and marked, and the culture dish was placed upside down. The culture dish without the drug was set as the blank control group. Each group was treated 3 times. After the inoculation, all the culture dishes were placed in a 28℃ constant temperature box for culture. After 24 hours of inoculation, the growth was observed every day until the control group grew all over the culture dish. The colony diameter of each treatment was measured by the cross method, and the average of the two diameters was taken as the diameter of the colony. The inhibition rate of different agents on rice sheath blight was calculated based on the measured data. For the convenience of calculation, the concentration of the agent needs to be converted into a logarithm, and the growth inhibition rate is converted into a probability value. Finally, Excel and SPSS software were used to perform data analysis between the logarithm of the agent concentration and the probability value, so as to calculate the linear regression equation Y=aX+b, and then the EC 50 The formula for mycelial growth inhibition rate is as follows and the results are shown in Table 1.

[0023] Inhibition rate = (colony diameter of control group - colony diameter of treatment group) ( / colony diameter of control group - diameter of bacterial plate) × 100%

[0024] Table 1 Indoor toxicity test of each agent against rice sheath blight pathogen (24 hours)

[0025] As can be seen from Table 1, the inhibitory concentrations of thiophanate-methyl, pentocyclanil, and the mixtures of thiophanate-methyl and pentocyclanil in different ratios on tomato gray mold were EC 50 The values ​​were 0.14, 0.12, 0.59, 0.10, 0.09, 0.15, 0.14, 0.25, 0.34, and 0.42 μg / mL in the order (12:1, 8:1, 4:1, 2:1, 1:1, 1:4, 1:8, and 1:12), respectively.

[0026] According to the Sun Yunpei co-toxicity coefficient method (CTC), a co-toxicity coefficient CTC value less than 80 indicates antagonism, a CTC value greater than 120 indicates synergistic effect, and a co-toxicity coefficient CTC value between 80 and 120 indicates additive effect. The co-toxicity coefficients of thiophanate-methyl and fluopicolide in various ratios (12:1, 8:1, 4:1, 2:1, 1:1, 1:4, 1:8 and 1:12) are 91.24, 130.12, 153.35, 112.59, 139.53, 132.96, 120.11 and 109.67 respectively.

[0027] The test results show that after pydiflumetofen and thiophanate-methyl are effectively mixed in ratios (8:1, 4:1, 1:1, 1:4 and 1:8), their co-toxicity coefficients CTC values ​​are all greater than 120, which has a significant synergistic effect, and the synergistic effect is most obvious when the mass ratio is 4:1. Pydiflumetofen is usually used to prevent and control wheat fusarium head blight, rapeseed sclerotinia, lawn dollar spot, rice false smut, and peanut leaf spot, and does not have relevant activity and effectiveness in preventing and controlling rice sheath blight, as shown by the indoor toxicity test results of the above-mentioned single-dose thiophanate-methyl against rice sheath blight. The preparation of the present invention, which combines thiophanate-methyl and thiophanate-methyl as active ingredients, produces an unexpected prevention effect on rice sheath blight that is different from that of thiophanate-methyl suspension, and has obvious advantages. It can also be seen from Table 1 that when the ratio of thiophanate-methyl to fluopicolide ranges from 8:1 to 4:1, it has an inhibitory effect on tomato gray mold, but as the amount of fluopicolide continues to increase, the inhibitory effect on tomato gray mold decreases.

[0028] 2. Screening of disintegrant types and proportions in 25% thiophanate-flutrifloxystrobin effervescent tablets

[0029] In this study, 25% thiophanate-methyl fluopicolide effervescent tablets were prepared by direct tablet compression. Specifically, thiophanate-methyl technical, fluopicolide technical, excipients and fillers were ground in a mortar and passed through a 200-mesh sieve. In order to avoid premature reaction of the acid and alkali sources, they were mixed in proportion and stirred evenly. Without granulation, they were weighed and filled into the mold, and directly compressed into thiophanate-methyl effervescent tablets by an eccentric wheel tablet press. A series of preliminary experiments were conducted to investigate the effects of different acid and alkali source ratios, excipient types and concentrations on the disintegration properties of effervescent tablets to determine the final material combination.

[0030] Preliminary experiments have preliminarily determined that the active ingredients of the effervescent tablets, thiophanate-methyl and fluopicolide, account for 25% of the total mass of the effervescent tablets (of which thiophanate-methyl accounts for 20% of the total mass of the effervescent tablets and fluopicolide accounts for 5% of the total mass of the effervescent tablets), and other ingredients are 2.5% sodium carboxymethyl cellulose, 0.5% magnesium stearate, 3% sodium dodecyl sulfate, and 1% white carbon. The disintegration performance of effervescent tablets depends on the optimal combination of acid and alkali sources, which is the basis of the disintegration of effervescent tablets. The disintegrant of the effervescent tablet is mainly composed of two parts: acid source and alkali source. When the effervescent tablet is put into the paddy field water, the ions formed by the dissolution of the acid and alkali react rapidly to produce a large amount of CO2 gas, which accelerates the disintegration and diffusion of the effervescent tablet in the water

[12] . If the amount of acid and alkali source added is insufficient, the gas will not be generated sufficiently, so that the effervescent tablet cannot be quickly and completely disintegrated; if the amount added is too much, the effervescent tablet will absorb too much water, which will not only affect the disintegration performance of the effervescent tablet, but also shorten the storage stability of the effervescent tablet. Therefore, the precise ratio of acid and alkali sources is crucial to the preparation of effervescent tablets. For this reason, this study screened the types and proportions of acid and alkali sources when the total amount of acid and alkali was 38%.

[0031] The results showed that the disintegration time of the formula with citric acid as the acid source was shorter than that of the formula with malic acid as the acid source. As the ratio of citric acid to sodium bicarbonate decreased, the disintegration time of 25% thiofluanid·fluazide effervescent tablets decreased first and then increased. The disintegration time was the shortest at 156.20 seconds when the acid-base ratio was 17:21. Based on the above results, citric acid was selected as the acid source in this study, and the disintegration effect was best when the mass ratio of citric acid to sodium bicarbonate was 17:21 (Table 2).

[0032] Table 2 Screening of disintegrants for 25% thiophanate-methyl·fluazide effervescent tablets

[0033] Note: The results are mean ± standard deviation, repeated 5 times

[0034] III. Performance analysis results of 25% thiophanate-flutrifonate effervescent tablets

[0035] 3.1 Disintegration time, CO2 release and pH value

[0036] Put the compressed 25% thiophanate-methyl fluopicolide effervescent tablets into a beaker filled with water, and start timing from the moment the tablet touches the water surface until the tablet is completely disintegrated and dispersed in the beaker (no obvious undissolved tablet residue, the liquid surface is calm and no gas is generated, which is considered complete disintegration). After the effervescent tablet is completely dissolved, use a pH meter to measure the pH value of the solution. Immerse the calibrated pH meter electrode in the solution, ensuring that the electrode is completely immersed and does not touch the bottom or side of the container. After 1 minute, the electrode and sample reach equilibrium, and then read and record the pH value.

[0037] The weight loss method was used to determine the mass of CO2 released by the effervescent tablets. Specifically, the beaker was filled with water and weighed and recorded, and the prepared thiothiazide effervescent tablets were placed in the beaker. After the reaction was complete and no carbon dioxide gas was produced, the weight was weighed and recorded again. According to the law of conservation of mass, the difference in mass before and after is the weight of carbon dioxide released, and the calculation formula is as follows: Vrelease = (m0+m 泡 -m1)×1.98,

[0038] Where: m0 is the total mass of the beaker and water before the effervescent tablet is put into the beaker; m 泡 is the mass of the effervescent tablet; m1 is the total mass of the beaker and water after the reaction is completed.

[0039] Based on the above formulation, the disintegration time of 25% thiophanate-flutrifloxystrobin effervescent tablets was 155 seconds, the CO2 release was 0.0622 g, and the pH value was 6.21 (Table 3).

[0040] Table 3 Disintegration time, CO2 release and pH value of 25% thiothiazide effervescent tablets

[0041] Note: The results are mean ± standard deviation, repeated 5 times

[0042] 3.2 Hygroscopicity

[0043] Since the acid-base disintegrant in the effervescent tablet is sensitive to moisture, the hygroscopicity of the effervescent tablet determines its shelf life. Therefore, this study conducted a 14-day hygroscopic test on the effervescent tablet. The prepared effervescent tablet was placed in a constant temperature incubator for moisture absorption test, and the weight of the effervescent tablet was weighed and recorded on days 1, 2, 3, 5, 7, 10, and 14. The results showed that the weight of the prepared effervescent tablet was 0.5064 g, and its weight rose rapidly after 1 day to 0.5671 g, and then reached moisture absorption saturation (Table 4).

[0044] Table 4 Hygroscopicity of 25% thiophanate-flunisal effervescent tablets

[0045] Note: The results are the mean ± standard deviation of 5 replicates.

[0046] 3.3 Hot storage stability

[0047] The prepared 25% thiophanate-flutrifonate effervescent tablets containing 0.05 g were placed in a water bath at 54±2°C for heat storage for 14 days. The effervescent tablets were then dissolved in 500 mL of methanol, and the thiophanate-flutrifonate content in the effervescent tablets before and after heat storage was determined by high performance liquid chromatography.

[0048] The instrumental detection conditions of thiofuranamide by high performance liquid chromatography are C 18 The chromatographic column was (250 mm×4.6 mm, 5 μm), the column temperature was 25°C, the detection wavelength was 220 nm, the mobile phase ratio was acetonitrile / water (volume ratio was 60:40), the flow rate was 1 mL / min, and the injection volume was 10 μL. The instrumental detection conditions of HPLC for fluopicolide were C 18 The chromatographic column was (250 mm×4.6 mm, 5 μm), the column temperature was 25°C; the detection wavelength was 230 nm; the mobile phase ratio was acetonitrile / water (volume ratio was 65:35), the flow rate was 1 mL / min; and the injection volume was 10 μL.

[0049] The changes in the content of active ingredients in 25% thiophanate-methyl·flutriazole effervescent tablets before and after heat storage were analyzed by high performance liquid chromatography to evaluate the heat storage stability. The study showed that the content of thiophanate-methyl in the effervescent tablets before heat storage was 20.18%, and the content of active ingredients in the sample after 14 days of heat storage was 20.01%; the content of flutriazole in the effervescent tablets before heat storage was 5.04%, and the content of flutriazole in the sample after 14 days of heat storage was 4.99%. The results showed that there was no significant difference in the content of active ingredients in 25% thiophanate-methyl·flutriazole effervescent tablets before and after heat storage, indicating that the effervescent tablets have ideal heat stability.

[0050] 3.4 Control effect of 25% thiophanate-flufenacil effervescent tablets on rice sheath blight

[0051] The field experiment was carried out in the experimental field of Yangzhou University. The test plots had good drainage and uniform soil fertility. The test plots were divided into 20 plots with an area of ​​2.4 m 2 The plots were divided into five plots, of which 25% thiophanate-methyl·flutriazole effervescent tablets were used to control rice sheath blight. A blank treatment group (water spray treatment group) and a control agent treatment group (240 g / L thiophanate-methyl suspension, 240 g / L flutriazole suspension) were set up. Nanjing 46 was disinfected, soaked, and germinated under laboratory conditions to cultivate strong rice seedlings. When the rice seedlings grew to three leaves and one heart, 3-5 plants were transplanted into the field per hole.

[0052] Before the tillering stage of rice, a toothpick covered with mycelium of rice sheath blight on potato dextrose broth (PDB) medium was inserted into the inverted three-leaf sheath of rice plants to make full contact. On the 14th day after inoculation, the number of rice lesions in the field was randomly surveyed and the pesticide treatment was carried out. According to the active ingredient content of thiophanate-methyl effervescent tablets, the prepared 25% thiophanate-methyl fluopicolide effervescent tablets (0.5 g) were directly put into the paddy field water to make it evenly disintegrate; the blank control group was only sprayed with clean water, and the application dosage of 240 g / L thiophanate-methyl suspension was 20 g / mu and the application dosage of 240 g / L fluopicolide suspension was 50 ml / mu. After 7 and 14 days of application, the five-point sampling method was used to sample each plot, and 10 plants were surveyed at each sampling point, and the number of lesions was recorded. The control effect was calculated according to the following formula.

[0053] Disease index = Σ (number of diseased leaves at each level × representative value of that level) / (total number of leaves surveyed × highest representative value) × 100

[0054] Grading standards for rice sheath blight diseased leaves:

[0055] Level 0: no lesions;

[0056] Level 1: 1-5 leaf spots, less than 1 cm in length;

[0057] Level 2: There are 6-10 lesions on the leaves, some of which are longer than 1 cm;

[0058] Level 3: There are 11-25 lesions on the leaves, some of which are connected, and the area of ​​lesions accounts for 10-25% of the leaf area;

[0059] Level 4: There are more than 26 lesions on the leaves, the lesions are connected into pieces, and the area of ​​lesions accounts for 26-50% of the leaf area;

[0060] Level 5: The spots are connected into pieces, and the area of ​​the spots occupies more than 50% of the leaf area.

[0061] Preventive and therapeutic effect (%) = (1-(pre-drug control disease index × post-drug treatment disease index) / (post-drug control disease index × pre-drug treatment disease index)) × 100

[0062] Table 5 The efficacy of 25% thiophanate-flutrifloxystrobin effervescent tablets against rice sheath blight

[0063] The control effects of 25% thiophanate-methyl·flutriazole effervescent tablets on rice sheath blight were 87.46% and 93.71% at 7 and 14 days after treatment, respectively, and the control effect was higher than that of the control agent treatment group (Table 5). The above efficacy results show that the 25% thiophanate-methyl·flutriazole effervescent tablets prepared in this study have a good control effect on rice sheath blight.

[0064] In production, effervescent tablets are a new type of pesticide dosage form, which has the characteristics of rapid disintegration and easy use, and can greatly improve the utilization rate and control effect of pesticides. Studies have shown that 30% mefenacet effervescent has excellent control effect on barnyard grass in rice fields with straw obstacles. In addition, effervescent tablets can also reduce the use and cost of pesticides, reduce environmental pollution, and meet the needs of green and sustainable agricultural development.

[0065] The most preferred 25% thiophanate-methyl·flutriazole effervescent tablet prepared by the present invention comprises 20% thiophanate-methyl and 5% flutriazole as active ingredients, 17% citric acid as an acid source, 21% sodium bicarbonate as an alkali source, 15% water-soluble starch, 15% diatomaceous earth as a diluent, 2.5% sodium carboxymethyl cellulose as a binder, 0.5% magnesium stearate as a lubricant, 3% sodium lauryl sulfate as a dispersant, and 1% white carbon black as a flow aid. The prepared 25% thiophanate-methyl·flutriazole effervescent tablet has a good prevention and control effect on rice sheath blight.

[0066] The above descriptions are only some embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An effervescent tablet for preventing and treating rice sheath blight, characterized in that: The invention comprises the following components in parts by weight: 18-30 parts of active ingredients, 15-20 parts of acid sources, 18-23 parts of alkali sources, 12-18 parts of water-soluble starch, 12-18 parts of diluents, 1-5 parts of adhesives and 0.5-10 parts of auxiliary agents, wherein the active ingredients are composed of thiophanate-methyl and fluopicolide in a mass ratio of 8:1 to 4:

1.

2. The effervescent tablet for preventing and controlling rice sheath blight according to claim 1, characterized in that: The acid source is citric acid or malic acid; the alkali source is sodium bicarbonate.

3. The effervescent tablet for preventing and controlling rice sheath blight according to claim 1, characterized in that: The diluent is diatomaceous earth.

4. The effervescent tablet for preventing and controlling rice sheath blight according to claim 1, characterized in that: The adhesive is sodium hydroxymethylcellulose.

5. The effervescent tablet for preventing and controlling rice sheath blight according to claim 1, characterized in that: The auxiliary agent includes 0.1-1.0 parts of lubricant magnesium stearate, 2-6 parts of dispersant sodium lauryl sulfate and 0.5-2 parts of flow aid white carbon black.

6. The effervescent tablet for preventing and controlling rice sheath blight according to claim 1, characterized in that: The mass ratio of thiophanate-methyl to pentothiazolinone in the active ingredients is 4:

1.

7. The effervescent tablet for preventing and controlling rice sheath blight according to claim 1, characterized in that: The mass parts of the components are as follows: 20 parts of thiophanate-methyl, 5 parts of fluopicolide, 17 parts of citric acid, 21 parts of sodium bicarbonate, 15 parts of water-soluble starch, 15 parts of diatomaceous earth, 2.5 parts of sodium hydroxymethylcellulose, 0.5 parts of magnesium stearate, 3 parts of sodium lauryl sulfate and 1 part of white carbon black.

8. A method for preparing the effervescent tablet for preventing and controlling rice sheath blight according to any one of claims 1 to 7, characterized in that The following steps are involved: S1, grinding thiophanate-methyl technical, fluopicolide technical, water-soluble starch, diluent, adhesive and other additives respectively according to the mass ratio, passing through a 200-mesh sieve, and setting aside; S2, dividing the material after grinding and sieving in step S1 into two groups, stirring and mixing them with the acid source and the alkali source in different areas respectively, and then filling them into molds for tableting after weighing to obtain thiophanate-flunix effervescent tablets.

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