Pleuromutilin suspension concentrate and preparation method therefor

Abstract

A pleuromutilin suspension concentrate and a preparation method therefor. The pleuromutilin suspension concentrate comprises: 5-25 wt% of pleuromutilin, 3-12 wt% of a surfactant, 0.5-2.5 wt% of a thickening agent, 2-6 wt% of an anti-freezing agent, 0.3-0.5 wt% of an organic silicon defoaming agent, and the balance of deionized water. The pleuromutilin suspension concentrate can be used for preventing and treating various agricultural diseases such as Xanthomonas oryzae pv. oryzae, Xanthomonas oryzae pv. oryzicola and Xanthomonas axonopodis pv. citri.

Description

A pleuromutilin suspension concentrate and a preparation method thereof Technical Field

[0001] The invention belongs to the field of pesticide suspensions, and particularly relates to a pleuromutilin pesticide suspension for preventing and treating plant bacterial diseases. Background Art

[0002] Bacterial plant diseases are a second-largest category of plant diseases, second only to viruses. They are characterized by rapid onset, widespread distribution, and difficulty in control. In recent years, with changes in crop cultivation systems and climate in my country, bacterial crop diseases such as Xanthoceras oryzae (Xoo), Xanthoceras oxysporum (Xoc), Xanthoceras citri (Xac), black rot of cabbage, sclerotinia of peach, soft rot of Chinese cabbage, sclerotinia of melon, bacterial wilt of tobacco, fruit rot of watermelon, and bacterial wilt of tomato have become more prevalent. Chemical pesticides are the primary control method for bacterial plant diseases, with copper preparations being the most widely used. However, copper preparations have issues such as poor safety and the risk of copper poisoning. Currently, there is a severe lack of effective and safe chemical agents for control, resulting in significant losses to agricultural production.

[0003] Pleuromutilin suspension concentrate is a new bactericide developed independently by Guizhou University. It boasts high efficacy, low toxicity, and low risk. It exhibits excellent antibacterial activity against pathogens such as X. oryzae (Xoo), X. oryzae (Xoc), X. citri (Xac), black rot of cabbage, Peach sclerotinia, Chinese cabbage soft rot, Melon sclerotinia, Tobacco bacterial wilt, Watermelon fruit rot, Tomato bacterial wilt, Cucumber bacterial blight, Konjac bacterial blight, Grape canker, Tomato canker, Kiwi fruit canker, Apple canker, Cucumber gray mold, Pepper wilt, Sclerotinia sclerotiorum, Gibberella fusca, Potato late blight, and Blueberry root rot. At a dosage of 200 μg / mL, it demonstrates excellent control against bacterial diseases such as X. oryzae (Xoo), X. oryzae (Xoc), and Citrus canker.

[0004] Summary of the Invention

[0005] To solve the above-mentioned problems existing in the prior art, the present invention provides a 5-25% pleuromutilin aqueous suspension preparation formula, comprising the active ingredient pleuromutilin, a wetting and dispersing agent, a thickener, an antifreeze agent, a defoaming agent, and water, wherein the weight ratios of the components are 5-25wt%, 3-12wt%, 0.5-2.5wt%, 2-6wt%, and 0.3-0.5wt%, respectively, and water is used to make up to 100%. Preferably, the weight ratio of pleuromutilin is 5-25wt%, 5-20wt%, 5-10wt%, 10-20wt%, and 10-25wt%, and most preferably 10wt% and 20wt%.

[0006] The surfactants screened in this application include dispersants or wetting agents, which are compounded ionic or nonionic adjuvants, including high molecular weight amphiphilic anionic nonionic surfactant complexes, phosphates, lignin sulfonates, salts of phenolsulfonic acid or naphthalenesulfonic acid, salts of polyacrylic acid, sulfosuccinates, alkyl sulfonates, alkylaryl sulfonates, alkyl sulfates, lauryl ether sulfates, fatty alcohol sulfates, sulfonate formaldehyde condensates, and sulfated hexadecyl, heptadecanol, and stearyl alcohols, and sulfated fatty alcohol glycol ethers;

[0007] The defoamer is 0.3-0.5 wt% of polydimethylsiloxane in an organosilicon defoamer;

[0008] The antifreeze agent is an inorganic salt;

[0009] The thickener is one or both of magnesium aluminum silicate SF-40 and xanthan gum.

[0010] Preferably, the dispersant and wetting agent are composed of a polymer amphiphilic anionic nonionic surfactant complex SC29, sodium diphenylmethanesulfonate HAS040, naphthalenesulfonic acid sodium salt formaldehyde condensation product NNO and any one of sodium p-toluenesulfonate, sodium methanesulfinate or polynaphthalene formaldehyde sulfonic acid sodium salt in a weight ratio of 2:2:2:1.5; more preferably, the wetting dispersant is composed of a polymer amphiphilic anionic nonionic surfactant complex SC29, sodium diphenylmethanesulfonate HAS040, naphthalenesulfonic acid sodium salt formaldehyde condensation product NNO and sodium p-toluenesulfonate in a weight ratio of 2:2:2:1.5.

[0011] Preferably, the thickener is a mixture of 2% magnesium aluminum silicate SF-40 or 1% magnesium aluminum silicate and 0.05% xanthan gum.

[0012] The pleuromutilin suspension concentrate for preventing and controlling plant bacterial diseases comprises a dispersant, a wetting agent, an antifreeze agent, and water in the specified weight percentages, stirring and dissolving the mixture, then adding the pleuromutilin and a thickener in the specified weight percentages. The mixture is mixed uniformly under the action of a shearing machine, and then pumped into a sander for grinding. A silicone defoamer is added in the specified weight percentages. The particle size is measured every hour. When the D90 value is approximately 6.0 μm, stirring is stopped, and the mixture is filtered to obtain a 20% pleuromutilin suspension concentrate. The particle size D90 of the suspension concentrate is 5-8 μm.

[0013] Innovation of this patent: The main significance of the developed dosage form is that through extensive screening of wetting and dispersing agents, a formulation is prepared that can effectively improve the prevention effect of the original drug in pleuromutilin suspension concentrate and pleuromutilin wettable powder on plant bacterial diseases. The pleuromutilin suspension concentrate prepared by the present invention has the characteristics of good dispersibility in water and storage is beneficial to the stability of the original drug.

[0014] 1. Screening of wetting and dispersing agents

[0015] The 5-25% pleuromutilin suspension prepared by compounding a high molecular weight amphiphilic anionic nonionic surfactant complex with different types of surfactants was subjected to heat storage and the water dispersibility of the original drug and the decomposition rate of the original drug after heat storage were measured. The specific results are shown in Table 1.

[0016] Table 1 Selection of wetting and dispersing agents

[0017] As shown in Table 1, screening of different adjuvant types revealed that the addition of sulfonate adjuvants improves the stability of the technical product. A suspension concentrate of pleuromutilin formulated with a high-molecular-weight amphiphilic anionic nonionic surfactant complex SC29, sodium diphenylmethanesulfonate HAS040, naphthalenesulfonic acid sodium salt formaldehyde condensate NNO, and sodium p-toluenesulfonate, sodium methanesulfinate, or sodium polynaphthalene formaldehyde sulfonate exhibits excellent dispersibility, with the technical product decomposition rate after hot storage kept below 5%.

[0018] In order to screen the optimal dosage of auxiliary agents such as sodium p-toluenesulfonate, sodium polynaphthalene formaldehyde sulfonate, and sodium methanesulfinate, three contents of 0.5%, 1.5%, and 3.0% were set for screening. The specific results are shown in Table 2.

[0019] Table 2 Selection of additive dosage

[0020] As shown in Table 2, the decomposition rate of pleuromutilin after hot storage was less than 5% at three different concentrations. Sodium methanesulfinate is relatively expensive and has average water dispersibility. The addition of sodium polynaphthalene formaldehyde sulfonate causes the suspension concentrate to turn yellow, affecting its appearance. However, the addition of sodium p-toluenesulfonate not only improves the stability of the technical product but is also relatively affordable and improves the appearance of the suspension concentrate. Therefore, considering both cost and properties, the preferred wetting and dispersing agent formulation is SC29: HAS040: NNO: sodium p-toluenesulfonate = 2:2:2:1.5.

[0021] 2. Screening of thickeners

[0022] Aqueous suspension concentrates often face storage stability issues, such as particle agglomeration, sedimentation, and thickening. The aforementioned formulation is prone to sedimentation upon prolonged storage. This can be addressed by increasing viscosity to improve sedimentation stability. Excessive viscosity can make the product difficult to pour and result in significant sticking, complicating processing and use. An appropriate viscosity ensures good stability and a high suspension efficiency. Based on relevant theory and the chemical instability of pleuromutilin, this experiment maintained the required additives from the previously screened formulation. Instead, the viscosity was modified by adjusting the dosages of magnesium aluminum silicate and xanthan gum. However, increased viscosity can reduce the self-dispersibility of the aqueous suspension concentrate. Therefore, the amount of the dispersant NNO was increased to improve water dispersibility. The results are shown in Table 3.

[0023] Table 3 Selection of thickeners

[0024] As shown in Table 3, excessive addition of xanthan gum affects the fluidity and water dispersibility of the formulation. Therefore, without compromising water dispersibility, 2% magnesium aluminum silicate was used as a thickener, or a combination of 1% magnesium aluminum silicate and 0.05% xanthan gum was used to improve the sedimentation stability of the suspension concentrate. Furthermore, increasing the NNO content enhanced the water dispersibility of the formulation.

[0025] 3. Selection of defoamer dosage

[0026] The wetting and dispersing agents described in this application are mostly sulfonates, which can cause a large number of bubbles to form during processing, affecting the grinding effect. Therefore, some organosilicon defoamers such as polydimethylsiloxane are usually added to the suspending agent, but the defoamer should be added in moderation. Too much addition can reduce the surface tension of the system and make the stratification phenomenon more obvious. If too little is added, the defoaming effect is not obvious. In this experiment, a universal organosilicon defoamer was selected for testing, and the specific results are shown in Table 4.

[0027] Table 4 Selection of defoamer dosage

[0028] As shown in Table 4, when the defoaming agent dosage is too low, it cannot effectively solve the large amount of bubbles generated during the grinding process. When the dosage is controlled at 0.3-0.5%, fewer bubbles are generated during the preparation process, which is conducive to grinding.

[0029] 4. Selection of antifreeze

[0030] Pesticide suspension concentrates using water as the dispersion medium need to maintain stability in extremely cold conditions during storage, and therefore typically require the addition of a suitable antifreeze. Using glycerol as the antifreeze increases system viscosity and poor fluidity. Using ethylene glycol as the antifreeze improves formulation stability and fluidity, but increases the decomposition rate of the technical product after hot storage. Using sodium chloride as the antifreeze, although very little precipitation will occur at the bottom of the product after cold storage, this does not increase the degree of decomposition of the technical product. Therefore, sodium chloride is the optimal antifreeze.

[0031] 5. Effect of particle size on the stability of the technical after hot storage

[0032] After determining the above-mentioned adjuvants, aqueous suspension concentrates of pleuromutilin with different particle sizes (numbered 1-6) were prepared. After heat storage, the content of the technical drug was determined using the pesticide thermal stability determination method GB / T19136-2003, and the decomposition rate of the technical drug after heat storage was analyzed. The specific results are shown in Table 5.

[0033] Table 5 Effect of particle size on the stability of the original drug

[0034] As shown in Figure 1 and Table 5, the 20% pleuromutilin aqueous suspension prepared using the above-mentioned adjuvants met stability requirements when the particle size was between 5 and 8 μm. This indicates that, under this formulation, the formulation and particle size have a significant impact on the chemical stability of the pleuromutilin aqueous suspension. Smaller particle sizes improve the chemical stability of the technical drug, but too small a particle size makes industrial production difficult.

[0035] 6. Determination of the optimal formula and preparation method

[0036] Table 6 Determination of the preferred formula

[0037] 7.20% Pleuromutilin Suspension Concentrate Control Items, Indicators, and Specifications

[0038] The main properties of the suspension concentrate were tested in accordance with the national standard for pesticide suspension concentrates (GB / T19136-2003), as shown in Table 7. The results show that, under this formulation, the pleuromutilin aqueous suspension concentrate exhibits a milky white, uniform dispersion with good dispersibility and suspension efficiency. The technical product is relatively stable after heat storage and is also stable at low temperatures.

[0039] Table 7 Control Items of 20% Pleuromutilin Aqueous Suspension Concentrate BRIEF DESCRIPTION OF THE DRAWINGS

[0040] FIG1 is a particle size distribution diagram of a 20% pleuromutilin suspension concentrate;

[0041] FIG2 is a particle size distribution table of 20% pleuromutilin suspension concentrate;

[0042] FIG3 is the protective activity of 20% pleuromutilin suspension concentrate against rice bacterial blight at 200 μg / mL;

[0043] FIG4 shows the therapeutic activity of 20% pleuromutilin suspension concentrate against rice bacterial blight at 200 μg / mL;

[0044] FIG5 is the protective activity of 20% pleuromutilin suspension concentrate against rice bacterial leaf streak at 200 μg / mL;

[0045] FIG6 shows the therapeutic activity of 20% pleuromutilin suspension concentrate against rice bacterial leaf streak at 200 μg / mL;

[0046] FIG7 is the protective activity of 20% pleuromutilin suspension concentrate against citrus canker at 200 μg / mL;

[0047] FIG8 shows the therapeutic activity of 20% pleuromutilin suspension at 200 μg / mL against citrus canker. Example

[0048] The present invention is further illustrated by the following examples. It should be understood that the methods described in the examples are merely illustrative of the present invention and are not intended to limit the present invention. Simple modifications to the preparation methods of the present invention, based on the concepts of the present invention, fall within the scope of the present invention. All raw materials and solvents used in the examples are commercially available products of corresponding purity.

[0049] Example 1: Preparation of 20% pleuromutilin suspension

[0050] 2.0 g of sodium diphenylmethanesulfonate HAS040, 2.0 g of sodium naphthalenesulfonate formaldehyde condensate NNO, 1.5 g of sodium p-toluenesulfonate, 4.0 g of sodium chloride and 2.0 g of high molecular weight amphiphilic anionic nonionic surfactant complex SC29 were weighed into a beaker containing 66.1 g of secondary water, stirred and dissolved, and then 20.0 g of truncated pleuromutilin and 2.0 g of magnesium aluminum silicate were added. After shearing and homogenization, the mixture was poured into a sand mill containing zirconium beads in a volume mass ratio of 1:1 to the suspending agent, 0.4 g of polydimethylsiloxane was added, and sand milling was started in an ice-water bath. The particle size was tested every 1 h. After about 4 h, the particle size was tested using a laser particle size analyzer. When D90 was about 6 μm, stirring was stopped and 20% truncated pleuromutilin suspension was obtained after filtration.

[0051] Example 2: Preparation of 10% pleuromutilin suspension

[0052] Table 8 10% pleuromutilin suspension formulation

[0053] (1) Weigh 2.0 g of sodium diphenylmethanesulfonate HAS040, 2.0 g of sodium naphthalenesulfonate formaldehyde condensate NNO, 1.5 g of sodium p-toluenesulfonate, 4.0 g of sodium chloride and 2.0 g of high molecular weight amphiphilic anionic nonionic surfactant complex SC29 into a beaker containing 66.1 g of secondary water, stir and dissolve, add 10.0 g of pleuromutilin and 2.0 g of magnesium aluminum silicate, shear and homogenize, pour into a sand mill containing zirconium beads in a volume mass ratio of 1:1 to the suspension agent, add 0.4 g of silicone defoaming agent polydimethylsiloxane, start sand milling in an ice water bath, and test the particle size every 1 h. After about 4 h, test the particle size with a laser particle size analyzer. When D90 is about 6 μm, stop stirring and filter to obtain a 10% pleuromutilin suspension.

[0054] Example 3: Main performance test of pleuromutilin aqueous suspension

[0055] According to the relevant national standards or industry standards of my country for pesticides (GB / T14825-2006 Method for Determining Suspension Rate of Pesticides, GB / T19136-2003 Method for Determining Thermal Storage Stability of Pesticides, GB / T19137-2003 Method for Determining Low-Temperature Stability of Pesticides, HG / T2467.5-2003 Specifications for the Preparation of Product Standards for Pesticide Suspension Concentrates), the main technical indicators of the pleuromutilin suspension concentrate of the present invention were measured.

[0056] As shown in Table 5, when the particle size of the 20% pleuromutilin aqueous suspension concentrate prepared using the above-mentioned adjuvants was greater than 10 μm, the decomposition rate of the technical drug was high, exceeding 20%, after heat storage (54°C ± 2). When the particle size of the suspension concentrate technical drug was between 5 and 8 μm, the decomposition rate was approximately between 5% and 10%, meeting the stability requirements. This indicates that, under this formulation, the formulation and particle size have a significant impact on the chemical stability of the technical drug of the pleuromutilin aqueous suspension concentrate, with smaller particle sizes improving the chemical stability of the technical drug.

[0057] The main properties of the suspension concentrate were tested in accordance with the national standard for pesticide suspension concentrates (GB / T19136-2003), as shown in Table 7. The results showed that, under this formulation, the pleuromutilin aqueous suspension concentrate exhibited a milky white, uniform dispersion with good dispersibility and suspension efficiency. The decomposition rate of the technical product after heat storage was less than 10%.

[0058] Example 4: In vitro test of pesticide efficacy

[0059] The turbidity method was used to test the antibacterial EC of pleuromutilin suspension concentrate against 10 fungi, including X. oryzae (Xoo), X. oryzae (Xoc), X. citrus canker (Xac), B. oleracea, X. oleracea, X. oleracea var. pekinensis, X. oleracea var. chin ... 50Value test:

[0060] 1. Test materials: pipette tips (5 mL, 1 mL, 200 μL), 15 mL centrifuge tubes, secondary water, 2 mL EP tubes, NB culture medium, all need to be sterilized.

[0061] 2. NB medium: 3g beef peptone, 5g peptone, 1g yeast powder, 10g glucose, 1L secondary water. Dispense into test tubes (4mL / tube), pH = 7.0-7.2

[0062] 3. Operation steps:

[0063] (1) Weigh a certain amount of the preparation to be tested and dissolve it in a corresponding volume (200 μL) of DMSO. Prepare a 5% solution system and dilute it proportionally to the required concentration. Dose the solution to 4 mL with 0.1% Tween solution.

[0064] (2) Use a pipette to draw 1 mL of the drug-Tween water mixture into a test tube containing 4 mL of culture medium.

[0065] (3) Use a pipette to aspirate 200 μL of the mixed solution (culture solution) and measure its OD value using a 96-well plate and record it.

[0066] (4) Add 50 μL of bacterial suspensions of rice bacterial blight (Xoo), rice bacterial leaf streak (Xoc), citrus canker (Xac), cabbage black rot, peach punch hole disease, Chinese cabbage soft rot, melon fine corner disease, tobacco bacterial wilt, watermelon fruit rot, and tomato bacterial wilt pathogens into each test tube.

[0067] (5) Place the sample in a shaker set at 28°C and 180 rpm.

[0068] (6) After 24h-36h (the OD value of CK is 0.6-0.8 (which means that the bacteria we made are not contaminated and are growing normally)), measure its OD value, record it, and then calculate its inhibition rate.

[0069] Corrected OD value = OD value of bacterial culture medium - OD value of sterile culture medium

[0070] Inhibition rate % = (corrected OD value of control culture medium - corrected OD value of culture medium containing bacteria) / corrected OD value of control culture medium * 100

[0071] 4. Activity data:

[0072] 20% pleuromutilin suspension concentrate showed excellent antibacterial activity against ten bacterial diseases including X. oryzae (Xoo). 50 The values ​​were better than those of the control drugs 20% zinc thiazole suspension, 20% thiazole copper suspension and 95% pleuromutilin original drug.

[0073] Table 9 EC values ​​of pleuromutilin suspension etc. for Xoo 50 value

[0074] As can be seen from Table 9, the EC values ​​of the 20% pleuromutilin suspension concentrate and the 98% pleuromutilin technical of the present invention against bacterial blight pathogenic bacteria of rice are 50 The values ​​were 0.79 μg / mL and 1.33 μg / mL respectively. 50 The activity values ​​were better than those of the control drugs 20% zinc thiazole suspension (13 μg / mL), 20% thiophanate-methyl suspension (76.27 μg / mL), 12% zhongshengmycin powder (85.16 μg / mL) and 98% pleuromutilin original drug (1.33 μg / mL).

[0075] Table 10 EC values ​​of pleuromutilin suspension concentrate for Xoc 50 value

[0076] As can be seen from Table 10, the EC values ​​of the 20% pleuromutilin suspension concentrate and the 98% pleuromutilin technical drug against Psoralea oryzae 50 The values ​​were 0.65 μg / mL and 0.88 μg / mL respectively. 50 The activity values ​​were better than those of the control drugs 20% zinc thiazole suspension (29.11 μg / mL), 20% thiophanate-methyl suspension (77.30 μg / mL), 12% zhongshengmycin powder (60.75 μg / mL) and 98% pleuromutilin original drug (1.04 μg / mL).

[0077] Table 11 EC of pleuromutilin suspension etc. for Xac 50 value

[0078] As can be seen from Table 11, the EC values ​​of the 20% pleuromutilin suspension concentrate and the 95% pleuromutilin original drug against citrus canker pathogens are 50 The values ​​were 1.13 μg / mL and 2.87 μg / mL respectively. 50 The activity values ​​were better than those of the control drugs 20% zinc thiazole suspension (41.97 μg / mL), 20% thiophanate-methyl suspension (104.89 μg / mL), 12% zhongshengmycin powder (108.51 μg / mL) and 98% pleuromutilin original drug (2.87 μg / mL).

[0079] Table 12 EC of pleuromutilin suspension concentrate against cabbage black rot pathogen 50 value

[0080] As can be seen from Table 12, the EC values ​​of the 20% pleuromutilin suspension concentrate and the 98% pleuromutilin original drug against cabbage black rot fungus are 50 The values ​​were 11.69 μg / mL and 14.48 μg / mL respectively. 50 The activity values ​​were better than those of the control drugs 20% zinc thiazole suspension (55.41 μg / mL), 20% thiophanate-methyl suspension (82.27 μg / mL), 12% zhongshengmycin powder (92.61 μg / mL) and 98% pleuromutilin original drug (14.48 μg / mL).

[0081] Table 13 EC of pleuromutilin suspension concentrate against peach perforator 50 value

[0082] As can be seen from Table 13, the EC values ​​of the 20% pleuromutilin suspension concentrate and the 98% pleuromutilin original drug against peach perforator pathogens are 50 The values ​​were 16.93 μg / mL and 24.80 μg / mL respectively. 50 The activity values ​​were better than those of the control drugs 20% zinc thiazole suspension (82.54 μg / mL), 20% thiophanate-methyl suspension (263.87 μg / mL), 12% zhongshengmycin powder (146.78 μg / mL) and 98% pleuromutilin original drug (24.80 μg / mL).

[0083] Table 14 EC of pleuromutilin suspension concentrate against Chinese cabbage soft rot pathogens 50 value

[0084] As can be seen from Table 14, the EC values ​​of the 20% pleuromutilin suspension concentrate and the 98% pleuromutilin technical drug against Chinese cabbage soft rot pathogens are 50 The values ​​were 18.50 μg / mL and 21.30 μg / mL respectively. 50 The activity values ​​were better than those of the control drugs 20% zinc thiazole suspension (30.56 μg / mL), 20% thiophanate-methyl suspension (131.32 μg / mL), 12% zhongshengmycin powder (136.50 μg / mL) and 98% pleuromutilin original drug (28.89 μg / mL).

[0085] Table 15 EC of pleuromutilin suspension concentrate against melon keratinosis 50 value

[0086] As can be seen from Table 15, the EC values ​​of the 20% pleuromutilin suspension concentrate and the 98% pleuromutilin original drug against the melon sclerotinia pestis were 50 The values ​​were 40.43 μg / mL and 52.17 μg / mL respectively. 50 The activity values ​​were better than those of the control drugs 20% zinc thiazole suspension (65.41 μg / mL), 20% thiophanate-methyl suspension (156.40 μg / mL), 12% zhongshengmycin powder (135.42 μg / mL) and 98% pleuromutilin original drug (52.17 μg / mL).

[0087] Table 16 EC of pleuromutilin suspension concentrate against tobacco bacterial wilt pathogen 50 value

[0088] As can be seen from Table 16, the EC values ​​of the 20% pleuromutilin suspension concentrate and the 98% pleuromutilin original drug against tobacco bacterial wilt pathogens are 50 The values ​​were 27.03 μg / mL and 33.31 μg / mL respectively. 50 The activity values ​​were better than those of the control drugs 20% zinc thiazole suspension (50.50 μg / mL), 20% thiophanate-methyl suspension (101.23 μg / mL), 12% zhongshengmycin powder (122.95 μg / mL) and 98% pleuromutilin original drug (33.31 μg / mL).

[0089] Table 17 EC of pleuromutilin suspension concentrate against watermelon fruit rot pathogens 50 value

[0090] As can be seen from Table 17, the EC values ​​of the 20% pleuromutilin suspension concentrate and the 98% pleuromutilin original drug against watermelon fruit rot pathogens are 50 The values ​​were 56.50 μg / mL and 60.99 μg / mL respectively. 50 The activity values ​​were better than those of the control drugs 20% zinc thiazole suspension (88.81 μg / mL), 20% thiophanate-methyl suspension (97.46 μg / mL), 12% zhongshengmycin powder (110.33 μg / mL) and 98% pleuromutilin original drug (60.99 μg / mL).

[0091] Table 18 EC of pleuromutilin suspension concentrate against tomato bacterial wilt pathogen 50 value

[0092] As can be seen from Table 18, the EC values ​​of the 20% pleuromutilin suspension concentrate and the 98% pleuromutilin original drug against tomato bacterial wilt pathogens are 50 The values ​​were 22.62 μg / mL and 43.29 μg / mL respectively. 50 The activity values ​​were better than those of the control drugs 20% zinc thiazole suspension (88.13 μg / mL), 20% thiazole copper suspension (141.25 μg / mL) and 98% pleuromutilin original drug (43.29 μg / mL).

[0093] Example 5: Pesticide efficacy test on rice bacterial blight in living potted plants

[0094] This time, the leaf clipping method was used to test the protective and therapeutic effects of the pleuromutilin preparation of the present invention on rice bacterial blight in living pot plants at a concentration of 200 μg / mL.

[0095] Therapeutic activity:

[0096] Using scissors dipped in a bacterial solution of bacterial blight pathogenic bacteria, a 1 / 3 cm portion of the tip of a rice leaf was cut off. Twenty-four hours later, a 20% pleuromutilin suspension concentrate and a 98% pleuromutilin stock solution of the present invention were dissolved in DMSO, then prepared with a 0.1% Tween-80 solution to a concentration of 200 μg / mL. The solution was evenly sprayed onto the rice leaves until droplets appeared. A control of untreated water was also provided. Ten to 15 leaves per rice plant were treated. Fourteen days after application, the length of the lesions on the rice leaves was measured, and the control efficacy was calculated based on the lesion length.

[0097] Protective activity:

[0098] A 20% pleuromutilin suspension concentrate and a 98% pleuromutilin original drug of the present invention were each dissolved in 200 μL of DMSO and prepared with a 0.1% Tween-80 solution to a concentration of 200 μg / mL. The mixture was evenly sprayed onto rice leaves until droplets appeared. 24 hours later, the leaves were cut and inoculated with scissors containing the bacterial pathogen Bacterial blight of rice. The bacterial solution was applied to the tip of the rice leaves at one-third of the surface. A control containing no bacterial blight was also established. Ten to 15 leaves were treated for each treatment, with three replicates. Fourteen days after application, the length of the lesions on the rice leaves was measured, and the control efficacy was calculated based on the lesion length.

[0099] Table 19 In vivo protective activity of 20% pleuromutilin suspension concentrate of the present invention against rice bacterial blight

[0100] As can be seen from Table 19 and Figure 2, at a concentration of 200 μg / mL, the therapeutic activities of the 20% pleuromutilin suspension concentrate of the present invention and the 98% pleuromutilin original drug were 62.8% and 59.9%, respectively. The 20% pleuromutilin suspension concentrate (62.8%) of the present invention was more active than the 98% pleuromutilin original drug (59.9%), the 20% zinc thiazole suspension concentrate (56.0%), the 20% thiophanate-methyl suspension concentrate (44.8%), and the 12% zhongshengmycin wettable powder.

[0101] Table 20 In vivo therapeutic activity of 20% pleuromutilin suspension concentrate of the present invention against rice bacterial blight

[0102] As can be seen from Table 20 and Figure 3, at a concentration of 200 μg / mL, the therapeutic activities of the 20% pleuromutilin suspension concentrate of the present invention and the 98% pleuromutilin original drug were 50.5% and 48.7%, respectively. The 20% pleuromutilin suspension concentrate (50.5%) of the present invention was more active than the 98% pleuromutilin original drug (48.7%), the 20% zinc thiazole suspension concentrate (47.7%), the 20% thiophanate-methyl suspension concentrate (37.6%), and the 12% zhongshengmycin wettable powder (21.3%).

[0103] Example 6: Pesticide efficacy test on rice bacterial leaf streak in living potted plants

[0104] At a concentration of 200 μg / mL, the protective effect of 20% pleuromutilin suspension concentrate against rice bacterial leaf streak in living pot plants was determined by pressure osmosis method.

[0105] Protective activity:

[0106] Using an analytical balance, accurately weigh 20% pleuromutilin suspension concentrate, 98% pleuromutilin technical, 10% pleuromutilin wettable powder, and a control agent into a 1.5 mL centrifuge tube. Dissolve each agent in 200 μL of DMSO and adjust each agent to a concentration of 200 μg / mL using 0.1% Tween-20 solution. Spray the agent evenly onto rice leaves until droplets form. After 24 hours, fill a needleless syringe with the bacterial solution and inject it into the rice plants approximately one-third of the way from the leaf tip. A control containing no agent and plain water was also provided. Ten to 15 leaves were treated for each treatment, with three replicates. Fourteen days after application, the lesion length on the rice leaves was measured, and the disease index and control efficacy were calculated.

[0107] Control effect = (lesion length of negative control group - lesion length of treatment group) / lesion length of negative control group × 100%

[0108] Therapeutic activity:

[0109] Fill a needleless syringe with the bacterial solution and inject it into rice plants approximately one-third of the way from the leaf tip. 24 hours later, use an analytical balance to accurately weigh a 20% pleuromutilin suspension concentrate, 98% pleuromutilin technical concentrate, 10% pleuromutilin wettable powder, and a control agent into a 1.5 mL centrifuge tube. Dissolve each agent in 200 μL of DMSO and adjust each agent to a concentration of 200 μg / mL using 0.1% Tween-20 solution. Spray the solution evenly onto rice leaves until droplets form. A control containing no agent and plain water should also be provided. Each treatment involves 10-15 leaves, with three replicates. Fourteen days after application, measure the length of the lesions on the rice leaves, and calculate the disease index and control efficacy.

[0110] Control effect = (lesion length of negative control group - lesion length of treatment group) / lesion length of negative control group × 100%

[0111] Table 21 In vivo protective activity of 20% pleuromutilin suspension concentrate of the present invention against rice bacterial leaf streak

[0112] As can be seen from Table 21 and Figure 4, at a concentration of 200 μg / mL, the therapeutic activity of the 20% pleuromutilin suspension concentrate of the present invention was 44.1%. Among them, the 20% pleuromutilin suspension concentrate of the present invention (44.1%) was more active against rice bacterial leaf streak than 98% pleuromutilin technical (41.8%), 20% zinc thiazole suspension concentrate (38.5%), 20% thiophanate-methyl suspension concentrate (34.4%), and 12% zhongshengmycin wettable powder (18.7%).

[0113] Table 22 In vivo therapeutic activity of 20% pleuromutilin suspension concentrate of the present invention against rice bacterial leaf streak

[0114] As can be seen from Table 22 and Figure 5, at a concentration of 200 μg / mL, the therapeutic activity of the 20% pleuromutilin suspension concentrate of the present invention was 45.3%. The 20% pleuromutilin suspension concentrate of the present invention (45.3%) was more active against rice bacterial leaf streak than 98% pleuromutilin technical (44.0%), 20% zinc thiazole suspension concentrate (42.5%), 20% thiophanate-copper suspension concentrate (30.0%), and 12% zhongshengmycin wettable powder (19.3%).

[0115] Example 7: Pesticide efficacy test on citrus canker in living potted plants

[0116] At a concentration of 200 μg / mL, the protective and therapeutic effects of the pleuromutilin suspension preparation of the present invention on citrus canker in living potted plants were tested using the acupuncture method.

[0117] Protective activity

[0118] 18.0 mg of 20% pleuromutilin suspension was accurately weighed using an analytical balance, dissolved in 200 μL of DMSO, and prepared with 0.1% Tween-80 solution to a concentration of 200 μg / mL. The mixture was evenly sprayed on rice leaves until droplets appeared. After 24 hours, a disposable syringe containing citrus canker bacteria was used for inoculation. 18 small holes were pierced on each leaf and inoculated with Xac suspension (OD 595 =0.6) was applied to the wound for 24 hours. The drug-containing filter paper was discarded and a control of water without drug was set up. 10-15 leaves were treated for each treatment, and repeated 3 times. The disease status of citrus leaves was measured 21 days after application, and the control index was calculated based on the disease index.

[0119] Therapeutic activity

[0120] A disposable syringe containing citrus canker was used for inoculation. 18 small holes were made on each leaf and the Xac suspension (OD 595 = 0.6) was applied to the wound surface for 24 hours. Then, 18.0 mg of a 20% pleuromutilin suspension concentrate and the like were accurately weighed using an analytical balance. Dissolved separately in DMSO, the mixture was then prepared with a 0.1% Tween-80 solution to a concentration of 200 μg / mL. The mixture was evenly sprayed onto the citrus leaves until droplets appeared. A control of untreated water was also provided. Ten to 15 leaves per citrus plant were treated. Twenty-one days after application, the disease status of the citrus leaves was measured, and the control efficacy was calculated based on the disease index.

[0121] Table 23 In vivo protective activity of 20% pleuromutilin suspension concentrate of the present invention against citrus canker

[0122] As can be seen from Table 23 and Figure 7, at a concentration of 200 μg / mL, the protective activity of the 20% pleuromutilin suspension concentrate of the present invention was 48.7%. Among them, the 20% pleuromutilin suspension concentrate of the present invention (48.7%) was more active against citrus canker than 98% pleuromutilin original drug (44.9%), 20% zinc thiazole suspension concentrate (45.8%), 20% thiophanate-methyl suspension concentrate (39.7%), and 12% zhongshengmycin wettable powder (20.1%).

[0123] Table 24 In vivo therapeutic activity of 20% pleuromutilin suspension of the present invention against citrus canker

[0124] As can be seen from Table 24 and Figure 8, at a concentration of 200 μg / mL, the protective activity of the 20% pleuromutilin suspension concentrate of the present invention was 50.8%. Among them, the 20% pleuromutilin suspension concentrate of the present invention (50.8%) was more active against citrus canker than 98% pleuromutilin technical (47.9%), 20% zinc thiazole suspension concentrate (48.2%), 20% thiophanate-copper suspension concentrate (36.5%), and 12% zhongshengmycin wettable powder (37.4%).

Claims

1. A suspension concentrate of pleuromutilin, characterized in that: The invention comprises: 5-25 wt% of pleuromutilin; 3-12 wt% of a surfactant; 0.5-2.5 wt% of a thickener; 2-6 wt% of an antifreeze agent; 0.3-0.5 wt% of an organosilicon defoaming agent; and the balance is deionized water.

2. The pleuromutilin suspension according to claim 1, characterized in that: The particle size of the suspending agent is 5-8 μm.

3. The pleuromutilin suspension according to claim 1, characterized in that: The surfactant is selected from ionic or non-ionic dispersants or wetting agents; preferably, the weight percentage of the dispersant or wetting agent is 7.5%.

4. The pleuromutilin suspension according to claim 3, characterized in that: The dispersant and wetting agent are composed of a polymer amphiphilic anionic nonionic surfactant complex SC29, sodium diphenylmethanesulfonate HAS040, naphthalenesulfonic acid sodium salt formaldehyde condensate NNO and sodium p-toluenesulfonate in a weight ratio of 2:2:2:1.

5.

5. The pleuromutilin suspension according to claim 1, characterized in that: The thickener is selected from one or both of magnesium aluminum silicate SF-40 and xanthan gum.

6. The pleuromutilin suspension according to claim 1, characterized in that: The antifreeze agent is selected from sodium chloride, and the silicone defoaming agent is selected from polydimethylsiloxane.

7. The method for preparing the pleuromutilin suspension according to claim 1, characterized in that: Take a surfactant, an antifreeze agent and water according to the weight percentage, stir and dissolve them, add pleuromutilin and a thickener according to the weight percentage, mix them evenly under the action of a shearing machine, then pump the mixed slurry into a sander for grinding, add an organosilicon defoaming agent according to the weight percentage, perform a particle size test every 1 hour, stop stirring when D90 is less than 8μm, and obtain a 5-25% pleuromutilin suspension after filtering.

8. Use of any of the suspension concentrates of claims 1-6 for preventing and controlling agricultural pests and diseases, wherein the agricultural pests and diseases are Xanthoceras oryzae (Xoo), Xanthoceras oxysporum (Xoc), Xanthoceras citrus (Xac), black rot of cabbage, perforation of peach, soft rot of Chinese cabbage, fine corner pathogen of melon, bacterial wilt of tobacco, fruit rot of watermelon, bacterial wilt of tomato, bacterial blight of cucumber, bacterial blight of konjac, grape canker, tomato canker, kiwi canker, apple canker, gray mold of cucumber, fusarium wilt of pepper, sclerotinia of rape, fusarium head blight of wheat, late blight of potato, and root rot of blueberry.

9. A method for preventing and controlling agricultural pests and diseases, characterized in that: The suspension concentrate of any one of claims 1 to 6 is made to act on a pest or its living environment, wherein the pest is Xanthoceras oryzae (Xoo), Xanthoceras oxysporum (Xoc), Xanthoceras citrus (Xac), black rot of cabbage, perforation of peach, soft rot of Chinese cabbage, fine corner pathogen of melon, bacterial wilt of tobacco, fruit rot of watermelon, bacterial wilt of tomato, bacterial blight of cucumber, bacterial blight of konjac, grape canker, tomato canker, kiwi canker, apple canker, gray mold of cucumber, fusarium wilt of pepper, sclerotinia of rapeseed, fusarium head blight of wheat, late blight of potato, and root rot of blueberry.

10. A method for protecting plants from agricultural pests and diseases, comprising the step of contacting the agricultural pests and diseases with the suspension concentrate according to any one of claims 1 to 6, wherein the agricultural pests and diseases are Xanthoceras oryzae (Xoo), Xanthoceras oxysporum (Xoc), Xanthoceras citri (Xac), black rot of cabbage, perforation of peaches, soft rot of Chinese cabbage, schizoctonia solani, bacterial wilt of tobacco, fruit rot of watermelon, bacterial wilt of tomato, bacterial wilt of cucumber, bacterial leaf blight of cucumber, bacterial leaf blight of konjac, grape canker, tomato canker, kiwi canker, apple canker, gray mold of cucumber, fusarium wilt of pepper, sclerotinia sclerotiorum of rape, fusarium head blight of wheat, late blight of potato, and root rot of blueberry.

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