A bactericidal composition containing mancozeb and pyraclostrobin and preparation method thereof

Abstract

The invention discloses a fungicide composition containing mancozeb and pyraclostrobin. The fungicide composition has pyraclostrobin and mancozeb as effective ingredients and contains titanium dioxide; the mass ratio of pyraclostrobin to mancozeb is 1:3-1:9, and the mass ratio of pyraclostrobin to titanium dioxide is 6:1-2:1. The invention uses pyraclostrobin and mancozeb to prepare a fungicide composition, and utilizes the synergistic effect between the two to improve the control effect of the fungicide composition on citrus scab. At the same time, using anatase nano-grade titanium dioxide to pre-adsorb pyraclostrobin and modify it, it can not only effectively reduce the Ostwald ripening that occurs when pyraclostrobin and mancozeb are compounded, but also enhance the synergistic effect of pyraclostrobin and mancozeb.

Description

Technical Field

[0001] The invention belongs to the field of pesticides and relates to a bactericidal composition containing mancozeb and pyraclostrobin and a preparation method thereof. Background Art

[0002] Mancozeb, English common name: Mancozeb, chemical name: ethylenebisdithiocarbamate manganese and zinc complex salt. Mancozeb is a protective fungicide with a broad fungicidal spectrum. It mainly inhibits the oxidation of pyruvic acid in bacteria and is effective against many diseases such as anthracnose and early blight on fruit trees and vegetables. At the same time, it is often mixed with systemic fungicides to delay the development of resistance.

[0003] Pyraclostrobin is also known as pyraclostrobin, English common name: Pyraclostrobin, molecular formula C 19 H 18 ClN3O4, chemical name is N-[2-[[1-(4-chlorophenyl)pyrazol-3-yl]oxymethyl]phenyl]-N-methoxycarbamic acid methyl ester. Pyraclostrobin is a new broad-spectrum fungicide, and its mechanism of action is mitochondrial respiration inhibitor, with protective, therapeutic, and leaf penetration and conduction effects. The results of field efficacy tests of pyraclostrobin emulsifiable concentrate showed that it has a good control effect on cucumber powdery mildew, downy mildew and banana black spot, leaf spot, and sclerotinia, and has protective, therapeutic, systemic conductivity, and rainwater erosion resistance, and has a wide range of applications.

[0004] Although pyraclostrobin is a new and highly effective agent for controlling powdery mildew, anthracnose, late blight, brown spot and sheath blight of crops, especially powdery mildew and anthracnose; however, pyraclostrobin has a single site of action. If used alone for a long time, resistance will inevitably occur. In addition, the cost of this agent is high, making it difficult to promote in plant protection. In actual use, the single preparation of mancozeb has a weak ability to withstand rain erosion, and a larger dose is required to achieve the purpose of protecting crops. It has a greater impact on the environment, increases the cost of medication, and increases the risk of crop resistance to mancozeb. When pyraclostrobin and mancozeb are simply compounded into an aqueous suspension, the steric hindrance and van der Waals forces brought by traditional adjuvants cannot solve the problems of pyraclostrobin's Ostrea ripening, but instead seriously amplify the problems of Ostrea ripening.

[0005] Citrus scab, also known as resin disease and stem rot, is a disease caused by the infection of the citrus fungus, which occurs on citrus. It mainly harms branches, fruits, leaves and other parts. The symptoms of damage in citrus orchards can be summarized into four types, namely gum flow type, dry type, scab and stem rot type. When it occurs seriously, it will cause large-scale orchard destruction, shorten the life of the trees or cause a large number of rotten fruits during storage and transportation, affecting the commercial value of the fruits.

[0006] In order to reduce or prevent citrus from being infected by Aspergillus fungi, the measures currently used mainly include agricultural control and chemical control.

[0007] The results of fungicide control on citrus sorrel showed that the concentration of 16% prochloraz·isoproonyl was 320 mg / L, the concentration of 325 g / L benzoxazin·pyraclostrobin was 435.5 mg / L, the concentration of 42.4% trifloxystrobin·flutolanil was 211.8 mg / L, the concentration of 430 g / L tebuconazole was 71.6 mg / L, the concentration of 27.8% thiofuran·hexaconazole was 184.8 mg / L, and 10% hexaconazole had a significant inhibitory effect on the growth of citrus sorrel at its highest concentration of 70 mg / L.

[0008] However, agricultural control is a purely defensive measure, and its efficiency and effectiveness are not satisfactory and reliable, especially when the prevailing climatic conditions are conducive to fungal infection. Similarly, with the emergence of drug resistance, the effectiveness of the above-mentioned chemical control in actual use has been continuously reduced over time. Summary of the invention

[0009] In view of the above technical problems, the present invention provides a fungicide composition containing mancozeb and pyraclostrobin, wherein the fungicide composition further comprises titanium dioxide, which is used to solve the shortcomings of high cost and easy drug resistance of single use of pyraclostrobin, large dosage of mancozeb and weak resistance to rainwater erosion, and serious problems of Ostrea ripening and paste formation caused by the combination of pyraclostrobin and mancozeb.

[0010] The objective of the present invention is achieved through the following technical solutions:

[0011] A fungicide composition containing mancozeb and pyraclostrobin, wherein the fungicide composition takes pyraclostrobin and mancozeb as active ingredients and contains titanium dioxide; the mass ratio of pyraclostrobin to mancozeb is 1:3-1:9, and the mass ratio of pyraclostrobin to titanium dioxide is 6:1-2:1.

[0012] Preferably, the mass ratio of pyraclostrobin to mancozeb is 1:4 to 1:9.

[0013] The titanium dioxide is anatase type nano-grade titanium dioxide.

[0014] Another object of the present invention is to provide a method for preparing a fungicidal composition containing mancozeb and pyraclostrobin, comprising the following steps:

[0015] Step (1), dissolving pyraclostrobin in N,N-dimethylformamide to obtain a pyraclostrobin solution;

[0016] Step (2), adding titanium dioxide to the pyraclostrobin solution, stirring at a temperature of 26 to 30° C. and a rotation speed of 300 to 500 r / min for 4 to 6 hours;

[0017] Step (3) The solid-liquid phase obtained in step (2) is subjected to rotary evaporation to remove the solvent at a temperature of 29 to 40° C. and a pressure of 0.29 to 0.42 mbar to obtain pyraclostrobin-titanium dioxide;

[0018] Step (4), mixing the mancozeb technical with pyraclostrobin-titanium dioxide uniformly to obtain a fungicide composition.

[0019] In step (2), the temperature is preferably 28°C.

[0020] As a further preferred embodiment of the fungicide composition containing mancozeb and pyraclostrobin of the present invention, the dosage form of the fungicide composition is an aqueous suspension.

[0021] The invention discloses an aqueous suspension containing a fungicide composition of mancozeb and pyraclostrobin. The aqueous suspension is prepared from the following raw materials in mass fractions: 20-35% of mancozeb, 4-8% of pyraclostrobin, 4-8% of a dispersant, 0.1-2% of titanium dioxide, 0.11-1.2% of a thickener, 1-5% of an antifreeze agent, 0.76-1.35% of a stabilizer, 0.2% of a defoamer, and water is added to 100%.

[0022] Preferably, the aqueous suspension is made of the following raw materials in mass fractions: mancozeb 20-35%, pyraclostrobin 4-8%, dispersant 4-8%, titanium dioxide 0.75-2%, thickener 0.3-1.2%, antifreeze 3-5%, stabilizer 0.8-1.35%, defoamer 0.2%, and water is supplemented to 100%.

[0023] The dispersant is one or more of modified calcium lignin sulfonate and modified sodium lignin sulfonate.

[0024] The thickener is one or more of xanthan gum, magnesium aluminum silicate and sodium carboxymethyl cellulose.

[0025] The antifreeze agent is one or more of glycerol and ethylene glycol.

[0026] The stabilizer is one or more of urotropine, 3-mercapto-1,2,4-triazole and epichlorohydrin.

[0027] The defoamer is a GPES type polyether defoamer, a polyether modified silicone type defoamer, or a silicone type defoamer.

[0028] Another object of the present invention is to provide a method for preparing an aqueous suspension concentrate of a fungicidal composition containing mancozeb and pyraclostrobin, comprising the following steps:

[0029] Step (1), dissolving pyraclostrobin in N,N-dimethylformamide to obtain a pyraclostrobin solution;

[0030] Step (2), adding titanium dioxide to the pyraclostrobin solution, stirring at a temperature of 26 to 30° C. and a rotation speed of 300 to 500 r / min for 4 to 6 hours;

[0031] Step (3) The solid-liquid phase obtained in step (2) is subjected to rotary evaporation to remove the solvent at a temperature of 29 to 40° C. and a pressure of 0.29 to 0.42 mbar to obtain pyraclostrobin-titanium dioxide;

[0032] Step (4), mixing the mancozeb technical with the dispersant uniformly, and pulverizing the mixture using a jet mill to obtain a mother powder;

[0033] Step (5), uniformly mixing pyraclostrobin-titanium dioxide, mother powder, thickener, antifreeze agent, stabilizer, defoamer and water to obtain an aqueous suspension.

[0034] Another object of the present invention is to provide the use of the fungicide composition containing pyraclostrobin and mancozeb in preventing and treating citrus scab.

[0035] The beneficial effects of the present invention are:

[0036] The present invention uses pyraclostrobin and mancozeb to prepare a fungicide composition, and utilizes the synergistic effect between the two to improve the fungicide composition's control effect on citrus scab. At the same time, we surprisingly found that using anatase nano-grade titanium dioxide to pre-adsorb pyraclostrobin and modify it can not only effectively reduce the Ostwald ripening that occurs when pyraclostrobin and mancozeb are compounded, but also can enhance the synergistic effect of pyraclostrobin and mancozeb.

[0037] When the bactericidal composition and the aqueous suspension are prepared by the present invention, the raw materials do not need to be sanded, and the dimethylformamide used when titanium dioxide adsorbs pyraclostrobin can be recycled, thereby responding to the national concept of emission and carbon reduction, sustainable development, green environmental protection and energy saving. DETAILED DESCRIPTION

[0038] The technical solution of the present invention is described below using preferred embodiments. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0039] “%” refers to mass fraction.

[0040] Example 1

[0041] 20% Mancozeb + 4% Pyraclostrobin SC

[0042]

[0043] The preparation method of 20% mancozeb + 4% pyraclostrobin SC is as follows:

[0044] Step (1), dissolving pyraclostrobin in dimethylformamide according to a mass ratio of pyraclostrobin to N,N-dimethylformamide of 2:1;

[0045] Step (2), adding titanium dioxide to the solution obtained in step (1), stirring at a temperature of 28° C. and a speed of 500 r / min for 4 h;

[0046] Step (3), at a temperature of 31° C. and a pressure of 0.32 mbar, the solid-liquid phase obtained in step (2) is subjected to rotary evaporation to remove N,N-dimethylformamide to obtain pyraclostrobin-titanium dioxide; and the dimethylformamide is recycled;

[0047] Step (4), mixing the mancozeb technical and modified sodium lignin sulfonate (Borregaard LignoTech) uniformly, and crushing them under a pressure of 8 kg using a jet mill to obtain a mother powder;

[0048] Step (5), mixing the pyraclostrobin-titanium dioxide obtained in step (3), the mother powder obtained in step (4), xanthan gum, magnesium aluminum silicate, glycerol, GPES type polyether defoamer B-299, and water at high speed to obtain 20% mancozeb + 4% pyraclostrobin SC.

[0049] Example 2

[0050] 24% Mancozeb + 4% Pyraclostrobin SC

[0051]

[0052] Step (1), dissolving pyraclostrobin in dimethylformamide according to a mass ratio of pyraclostrobin to N,N-dimethylformamide of 2:1;

[0053] Step (2), adding titanium dioxide to the solution obtained in step (1), stirring at a temperature of 28° C. and a speed of 500 r / min for 4 h;

[0054] Step (3), at a temperature of 31° C. and a pressure of 0.32 mbar, the solid-liquid phase obtained in step (2) is subjected to rotary evaporation to remove the solvent to obtain pyraclostrobin-titanium dioxide;

[0055] Step (4), mixing the mancozeb technical and modified calcium lignin sulfonate (Borregaard LignoTech) uniformly, and crushing them under a pressure of 8 kg using a jet mill to obtain a mother powder;

[0056] Step (5), mixing the pyraclostrobin-titanium dioxide obtained in step (3), the mother powder obtained in step (4), xanthan gum, magnesium aluminum silicate, glycerol, and a polyether-modified silicone defoamer The mixture was uniformly mixed by high-speed shearing with water to obtain 24% mancozeb + 4% pyraclostrobin SC.

[0057] Example 3

[0058] 28% Mancozeb + 4% Pyraclostrobin SC

[0059]

[0060]

[0061] Step (1), dissolving pyraclostrobin in dimethylformamide according to a mass ratio of pyraclostrobin to N,N-dimethylformamide of 2:1;

[0062] Step (2), adding titanium dioxide to the solution obtained in step (1), stirring at a temperature of 28° C. and a speed of 500 r / min for 4 h;

[0063] Step (3), at a temperature of 31° C. and a pressure of 0.32 mbar, the solid-liquid phase obtained in step (2) is subjected to rotary evaporation to remove the solvent to obtain pyraclostrobin-titanium dioxide;

[0064] Step (4), mixing the mancozeb technical with the modified calcium lignin sulfonate uniformly, and crushing them under a pressure of 8 kg using a jet mill to obtain a mother powder;

[0065] Step (5), mixing the pyraclostrobin-titanium dioxide obtained in step (3), the mother powder obtained in step (4), xanthan gum, magnesium aluminum silicate, glycerol, and a polyether-modified silicone defoamer The mixture was mixed evenly with water at high speed shearing to obtain 30% mancozeb + 5% pyraclostrobin SC.

[0066] Example 4

[0067] 32% Mancozeb + 8% Pyraclostrobin SC

[0068]

[0069] Step (1), dissolving pyraclostrobin in dimethylformamide according to a mass ratio of pyraclostrobin to N,N-dimethylformamide of 2:1;

[0070] Step (2), adding titanium dioxide to the solution obtained in step (1), stirring at a temperature of 28° C. and a speed of 500 r / min for 4 h;

[0071] Step (3), at a temperature of 31° C. and a pressure of 0.32 mbar, the solid-liquid phase obtained in step (2) is subjected to rotary evaporation to remove the solvent to obtain pyraclostrobin-titanium dioxide;

[0072] Step (4), mixing the mancozeb technical with the modified calcium lignin sulfonate uniformly, and crushing them under a pressure of 8 kg using a jet mill to obtain a mother powder;

[0073] Step (5), uniformly mixing the pyraclostrobin-titanium dioxide obtained in step (3), the mother powder obtained in step (4), xanthan gum, magnesium aluminum silicate, glycerin, silicone defoamer S-29, and water under high-speed shearing to obtain 32% mancozeb + 8% pyraclostrobin SC.

[0074] Example 5

[0075] 32% Mancozeb + 4% Pyraclostrobin SC

[0076]

[0077] Step (1), dissolving pyraclostrobin in dimethylformamide according to a mass ratio of pyraclostrobin to N,N-dimethylformamide of 2:1;

[0078] Step (2), adding titanium dioxide to the solution obtained in step (1), stirring at a temperature of 28° C. and a speed of 500 r / min for 4 h;

[0079] Step (3), at a temperature of 31° C. and a pressure of 0.32 mbar, the solid-liquid phase obtained in step (2) is subjected to rotary evaporation to remove the solvent to obtain pyraclostrobin-titanium dioxide;

[0080] Step (4), mixing the mancozeb technical with the modified calcium lignin sulfonate uniformly, and crushing them under a pressure of 8 kg using a jet mill to obtain a mother powder;

[0081] Step (5), mixing the pyraclostrobin-titanium dioxide obtained in step (3), the mother powder obtained in step (4), xanthan gum, magnesium aluminum silicate, glycerol, and a polyether-modified silicone defoamer The mixture was mixed evenly with water at high speed shearing to obtain 32% mancozeb + 8% pyraclostrobin SC.

[0082] Stability test:

[0083] Titanium dioxide in the formula of Example 1 to Example 5 was removed respectively to prepare water suspension concentrates of Comparative Example 1 to Comparative Example 5; anatase nano-grade titanium dioxide in the formula of Example 4 was replaced with rutile nano-grade titanium dioxide, and the remaining components and process remained unchanged to prepare water suspension concentrate of Comparative Example 6. Stability tests were conducted on samples of Example 1 to Example 5 and Comparative Example 1 to Comparative Example 6, and the samples were heat stored at 54°C for two weeks. The content and suspension rate before and after heat storage were determined by liquid phase, and the experimental data are shown in the following table.

[0084] Table 1. Stability test results

[0085]

[0086]

[0087] From the above results, it can be found that the stability of the water suspension concentrate of mancozeb and pyraclostrobin is significantly improved by first using anatase nano-sized titanium dioxide to adsorb pyraclostrobin and then compounding it with mancozeb, which solves the problem of reduced suspension rate due to increased particle size caused by Ostwald ripening. Due to the limitation of spatial structure, the effect of diamond nano-sized titanium dioxide in preventing Ostwald ripening is obviously not as good as that of anatase nano-sized titanium dioxide.

[0088] Bioassay experiment:

[0089] Indoor toxicity determination of pyraclostrobin and mancozeb against Diaporthe citri.

[0090] Metarhizium citrinum: complete genome sequences of the ZJUD2 and ZJUD14 species complex.

[0091] The test culture medium used PDA medium: 200 g potato, 20 g glucose, 20 g agar, and distilled water to 1000 mL.

[0092] The activity of single agents and binary compound compositions against citrus scab pathogen was determined indoors by the mycelial growth rate method. Single preparations and compound compositions were prepared using DMSO, and the corresponding concentrations of agents were added to the preheated sterilized PDA medium to prepare drug-containing plates of different concentrations, with blank PDA plates without agents as controls. A 5mm diameter puncher was used to punch holes at the edge of a citrus scab colony cultured at 28°C in the dark for 7 days to prepare a bacterial cake, and then the bacterial cake was picked up with an inoculation needle and inoculated on PDA plates of different concentrations containing mancozeb, pyraclostrobin, and compound compositions. Each plate was placed in a biochemical incubator and cultured at 28°C in the dark for 7 days, and the colony diameter was measured and recorded. Each treatment was repeated 3 times, and the test was repeated 3 times.

[0093] According to the linear growth rate of Citrus citrinum on the plates with different concentrations of the agent, the growth inhibition rate of each concentration of the agent on the pathogen was calculated, and the EC of the single agent and the mixed agent of each treatment ratio was calculated using DPS software. 50 According to the Wadley (1945) method, the synergistic coefficient SR under different ratios was calculated, and the SR value was used to judge the combined action mode of the mixed agents: SR < 0.5 was antagonistic; 1.5 ≥ SR ≥ 0.5 was additive; SR > 1.5 was synergistic.

[0094] Table 2. Results of indoor toxicity test of pyraclostrobin and mancozeb against Aspergillus citri

[0095]

[0096]

[0097] Analysis and evaluation: Mancozeb and pyraclostrobin mixed with each other have high fungicidal activity against citrus scab. EC 50 They were 0.0136, 0.0166, 0.0180, 0.0203, 0.0220, 0.0254, 0.0387, 0.0614, and 0.1094, respectively, and the synergistic coefficients were 0.94, 1.92, 2.13, 2.21, 2.33, 2.27, 1.65, 1.56, and 0.99, respectively. According to the Wadley (1945) method, 1.5 ≥ SR ≥ 0.5 is additive, and SR > 1.5 is synergistic. The synergistic coefficients SR of the mass ratio of mancozeb to pyraclostrobin of 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, and 14:1 are all greater than 1.5, indicating a synergistic effect; the synergistic coefficients of the mass ratio of mancozeb to pyraclostrobin of 1:1 and 16:1 are between 0.5 and 1.5, indicating an additive effect. However, in actual production, specific environment, processing technology and other factors are still needed for further comprehensive consideration.

[0098] The Aspergillus citrinum (complex species of full genome sequences ZJUD2 and ZJUD14) used in the examples of the present invention is only to illustrate that "mancozeb and pyraclostrobin have a synergistic effect on Aspergillus citrinum after compounding", but the Aspergillus citrinum used is not limited to this source. It should be clear to those skilled in the art that as long as it is identified as Aspergillus citrinum, the mancozeb and pyraclostrobin of the present invention have a synergistic effect on it after compounding.

[0099] Biological Control Examples:

[0100] Experimental example: Field trial to control citrus scab

[0101] Crop and target: Citrus (Sandang tangerine), scab disease

[0102] Agents: water suspension prepared in Examples 1 to 5, 25% pyraclostrobin suspension (Shandong Kangqiao Biotechnology Co., Ltd.), 430 g / L mancozeb suspension (Corteva Agricultural Technology Co., Ltd.).

[0103] Use a backpack electric sprayer 3WBD-20L with a pressure of 0.5-0.6MPa. Apply the pesticide once every ten days for a total of three times. The preparations prepared in Examples 1 to 5 were diluted 500 times, with a water consumption of 1 kg per tree; 430g / L mancozeb SC was diluted 200 times, with a water consumption of 1 kg per tree; 25% pyraclostrobin SC was diluted 1000 times, with a water consumption of 6 kg per tree.

[0104] Survey time and frequency: Survey once before spraying to ensure that the test tree area has not been treated with any pesticides; survey once 14 days after three sprayings.

[0105] The survey time before pesticide application is April 15, 2020; the first pesticide application time is April 16, 2020; the survey time after three pesticide applications is May 20, 2020.

[0106] Survey method: 2 plants per plot, sampling method of 5 points in east, west, south, north and center, 2 tips per point, 4 leaves under the top leaf and all fruits of each branch, calculate disease index and control effect. Grading method: Level 0: no lesions on leaves and fruits; Level 1: the area of ​​sandy skin lesions on leaves and fruits accounts for less than 5% of the area of ​​leaves and fruits; Level 3: the area of ​​sandy skin lesions on leaves and fruits accounts for 6%-10% of the area of ​​leaves and fruits; Level 5: the area of ​​sandy skin lesions on leaves and fruits accounts for 11%-25% of the area of ​​leaves and fruits; Level 7: the area of ​​sandy skin lesions on leaves and fruits accounts for 26%-50% of the area of ​​leaves and fruits; Level 9: the area of ​​sandy skin lesions on leaves and fruits accounts for more than 51% of the area of ​​leaves and fruits.

[0107] This test complies with the "Quality Management Specifications for Pesticide Registration Tests", "Pesticide Field Efficacy Test Guidelines", and SOP-TM-073a "Citrus Gum Disease Test". The calculation formula is as follows:

[0108]

[0109]

[0110] Table 3. Field control results of pyraclostrobin and mancozeb water suspension on citrus scab

[0111]

[0112] The test results show that the water suspension prepared by compounding pyraclostrobin and mancozeb in Examples 1 to 5 has a control effect of 85.90-88.51%, which is significantly higher than the control effect of 67.37% when mancozeb is used alone, and also higher than the control effect of 80.98% when pyraclostrobin is used alone, showing a significant synergistic effect.

[0113] The aqueous suspension concentrates of Example 4 and Comparative Example 4 were selected, both of which were heat-stored at 54°C for two weeks. The same test scheme as above was used to carry out field tests to test the control effects of the two. The results are shown in Table 4.

[0114] Table 4. Field control results of pyraclostrobin and mancozeb SCs against citrus scab after hot storage

[0115]

[0116] The test results show that after the water suspension concentrates of Example 4 and Comparative Example 4 were hot stored at 54°C for two weeks, the control effect of Example 4 was much better than that of Comparative Example 4. Further explanation: The present invention uses anatase nano-grade titanium dioxide to pre-adsorb pyraclostrobin, which can not only effectively reduce the Ostwald ripening that occurs when pyraclostrobin and mancozeb are compounded, effectively solve the problems of reduced suspension rate and reduced efficacy caused by Ostwald ripening, but also enhance the synergistic effect of pyraclostrobin and mancozeb.

[0117] Those skilled in the art can understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions recorded in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A fungicidal composition containing mancozeb and pyraclostrobin, characterized in that: The bactericidal composition has pyraclostrobin and mancozeb as active ingredients and contains titanium dioxide; the mass ratio of pyraclostrobin to mancozeb is 1:3-1:9, and the mass ratio of pyraclostrobin to titanium dioxide is 6:1-2:1; the titanium dioxide is anatase nano-grade titanium dioxide.

2. The fungicidal composition containing mancozeb and pyraclostrobin according to claim 1, characterized in that: The mass ratio of pyraclostrobin to mancozeb is 1:4 to 1:

9.

3. A method for preparing the bactericidal composition containing mancozeb and pyraclostrobin according to claim 1, characterized in that: The following steps are involved: Step (1), dissolving pyraclostrobin in dimethylformamide to obtain a pyraclostrobin solution; Step (2), adding titanium dioxide to the pyraclostrobin solution, stirring at a temperature of 26 to 30° C. and a speed of 300 to 500 r / min for 4 to 6 hours; Step (3): the solid-liquid phase obtained in step (2) is subjected to rotary evaporation at a temperature of 29 to 40° C. and a pressure of 0.29 to 0.42 mbar to remove the solvent, thereby obtaining pyraclostrobin-titanium dioxide; Step (4), mixing the mancozeb technical with pyraclostrobin-titanium dioxide to obtain a fungicide composition.

4. An aqueous suspension containing the fungicidal composition of mancozeb and pyraclostrobin according to claim 1, characterized in that: The water suspension is prepared from the following raw materials in mass fractions: 20-35% of mancozeb, 4-8% of pyraclostrobin, 4-8% of dispersant, 0.1-2% of titanium dioxide, 0.11-1.2% of thickener, 1-5% of antifreeze agent, 0.76-1.35% of stabilizer, 0.2% of defoamer, and water is added to 100%.

5. The aqueous suspension concentrate according to claim 4, characterized in that: The water suspension is prepared from the following raw materials in mass fractions: 20-35% of mancozeb, 4-8% of pyraclostrobin, 4-8% of dispersant, 0.75-2% of titanium dioxide, 0.3-1.2% of thickener, 3-5% of antifreeze agent, 0.8-1.35% of stabilizer, 0.2% of defoamer, and water is added to 100%.

6. The suspending agent according to claim 4 or 5, characterized in that: The dispersant is one or more of modified calcium lignin sulfonate and modified sodium lignin sulfonate; the thickener is one or more of xanthan gum, magnesium aluminum silicate, and sodium carboxymethyl cellulose; the antifreeze is one or more of glycerol and ethylene glycol; the stabilizer is one or more of urotropine, 3-mercapto-1,2,4-triazole, and epichlorohydrin; the defoamer is GPES type polyether defoamer, polyether modified silicone type defoamer, and silicone type defoamer.

7. A method for preparing an aqueous suspension concentrate of a fungicidal composition containing mancozeb and pyraclostrobin as claimed in claim 4, characterized in that: The following steps are involved: Step (1), dissolving pyraclostrobin in dimethylformamide to obtain a pyraclostrobin solution; Step (2), adding titanium dioxide to the pyraclostrobin solution, stirring at a temperature of 26 to 30° C. and a speed of 300 to 500 r / min for 4 to 6 hours; Step (3): the solid-liquid phase obtained in step (2) is subjected to rotary evaporation at a temperature of 29 to 40° C. and a pressure of 0.29 to 0.42 mbar to remove the solvent, thereby obtaining pyraclostrobin-titanium dioxide; Step (4), mixing the mancozeb technical and the dispersant evenly, and pulverizing them using a jet mill to obtain a mother powder; Step (5), uniformly mixing pyraclostrobin-titanium dioxide, mother powder, thickener, antifreeze agent, stabilizer, defoamer and water to obtain an aqueous suspension.

8. Use of the fungicidal composition containing pyraclostrobin and mancozeb according to claim 1 in preventing and treating citrus scab.

9. Use of the aqueous suspension concentrate according to claim 4 in preventing and treating citrus scab.

Images