A screening method for pesticide spray adjuvant and its application

Abstract

The present invention provides a method for screening pesticide spray adjuvants and its application, and relates to the technical field of pesticide preparations and adjuvant use. After adding a spray adjuvant to the pesticide preparation liquid, the present invention screens a spray adjuvant suitable for the pesticide preparation by measuring the dynamic contact angle, dynamic impact behavior, deposition morphology and other indicators of the liquid. The present invention also evaluates the performance of the spray adjuvant by measuring and analyzing the physicochemical properties of the pesticide liquid to which the spray adjuvant is added, the evaporation performance of the liquid, the dynamic deposition behavior of the liquid on the plant leaf surface, the wetting and spreading behavior and the deposition morphology. The present invention comprehensively evaluates the effects of different spray adjuvants on the dosage delivery behavior of the diluted droplets of the preparation at low dilution multiples, which not only helps to reduce the development cost of adjuvant products and shorten the research and development cycle, but also can quickly screen spray adjuvants that match the pesticide preparation, which helps to further achieve the "reduced application and increased efficiency" of pesticides.

Description

Technical Field

[0001] The invention belongs to the technical field of pesticide preparation and adjuvant use, and specifically relates to a method for screening a pesticide spray adjuvant and application thereof. Background Art

[0002] Spray adjuvants are additives added to the pesticide barrel when spraying pesticides in the field and used with pesticide formulations. They are currently a powerful tool for reducing the use of pesticides and increasing their efficiency. Spray adjuvants can improve the physical and chemical properties of pesticide solutions and the biological activity of active ingredients. The addition of spray adjuvants can reduce the surface tension of the solution, affect the dosage delivery behavior of the solution, improve the wetting and spreading of the solution on the leaf surface, the ability to resist rain erosion, the ability to resist evaporation, the ability to penetrate wax, and the ability to absorb and conduct, and ultimately improve the target deposition efficiency of the solution.

[0003] At present, commonly used pesticide spray adjuvants include oils, surfactants, inorganic salts and polymer adjuvants. Oil adjuvants mainly include mineral oils, vegetable oils and their derivatives. Oil adjuvants are composed of one or more long-chain hydrocarbons, which are similar to the wax layer composition on the surface of plant leaves. Therefore, they have good affinity with plant stems and leaves and can enhance the adhesion of the liquid medicine on the plant leaf surface. At the same time, the boiling point of oil adjuvants is high, which can delay the evaporation and drying time of the liquid medicine, providing the liquid medicine with a longer time to penetrate into the leaves. Surfactant molecules have a unique amphiphilic structure, which can be adsorbed on the interface between the two phases, reduce interfacial tension, and enhance the stability of emulsions and suspensions, and enhance the surface activity of the liquid medicine. Among them, the addition of silicone surfactants to the liquid medicine can make the liquid medicine diffuse and penetrate quickly on the plant leaf surface, and is widely used. Inorganic salt adjuvants are mainly suitable for herbicides such as glyphosate and glufosinate ammonium that are easily affected by cations in hard water, and can appropriately adjust the pH of the liquid medicine. Polymer additives are mainly polymer additives. Compared with small molecule surfactants, the steric hindrance of polymer additives can reduce the surface tension of the solution to a certain extent, increase the viscosity of the system, increase the droplet diameter, and reduce spray drift.

[0004] Pesticide formulations require different solvents and adjuvants as well as specific processing technologies, which may lead to different physical and chemical properties of the diluted solution. According to reports, the most registered pesticide formulations in my country include emulsifiable concentrates, wettable powders, suspensions, aqueous solutions, water-dispersible granules, water-emulsions, microemulsions, dispersible oil suspensions, etc. In general, the solution after the pesticide formulation is diluted with water can be divided into emulsion systems, suspension systems, and true solutions. Emulsions belong to liquid-liquid dispersion systems, which are a liquid dispersed in another immiscible liquid in the form of tiny droplets. Emulsifiable concentrates, water-emulsions, and microemulsions are emulsions after being diluted with water. Suspension systems are solid particles suspended and dispersed in the water phase. Wettable powders, water-dispersible granules, suspensions, and dispersible oil suspensions are suspension systems after being diluted with water. A true solution is obtained after the aqueous solution is diluted with water. If the pesticide formulation itself is diluted with water for spraying, the deposition performance of the solution is often poor, and the solution cannot be well attached to the leaves of the target plants. Therefore, spray adjuvants need to be added to increase the adhesion of the solution. Due to the lack of industry standards and market supervision, there are many types of spray adjuvants on the market and the quality of adjuvant products varies greatly. Therefore, it is extremely important to correctly select and use pesticide spray adjuvants. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a method for screening pesticide spray adjuvants, which can quickly screen spray adjuvants that match the pesticide formulation liquid.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The invention provides a method for screening a spray adjuvant, comprising the following steps: after adding the spray adjuvant to the liquid of a pesticide preparation, measuring the dynamic contact angle of a diluted liquid droplet on a target plant leaf surface, and screening a spray adjuvant that makes the liquid droplet contact angle less than 90 degrees; measuring the dynamic impact behavior of the liquid droplets, and screening a spray adjuvant that inhibits or weakens the bouncing and splashing of the liquid droplets; measuring the deposition morphology of the liquid on the target leaf surface, and screening a spray adjuvant that makes the liquid droplets have a uniform deposition morphology, so as to obtain a spray adjuvant suitable for the pesticide preparation.

[0008] Preferably, before measuring the dynamic contact angle, the type and concentration of the spraying aid are preliminarily screened by measuring the physical and chemical properties of the diluted liquid.

[0009] More preferably, the physicochemical properties include surface tension, viscosity, particle size and dynamic surface tension.

[0010] Preferably, the dosage form of the pesticide preparation includes one of water dispersible granules, suspension concentrates, wettable powders, emulsifiable concentrates, water emulsions or microemulsions.

[0011] The present invention also provides a method for evaluating the performance of pesticide spray adjuvants. After adding the spray adjuvants, the physical and chemical properties of the diluted drug solution, the evaporation performance of the drug solution, the dynamic deposition behavior of the drug solution on the plant leaf surface, the wetting and spreading behavior and the deposition morphology are measured and analyzed to evaluate the performance of the spray adjuvant.

[0012] Preferably, the physicochemical properties include surface tension, viscosity, particle size and dynamic surface tension of the diluted drug solution.

[0013] Preferably, the dynamic deposition behavior analysis includes measuring the dynamic impact process of the drug solution droplets after reaching the target plant leaf surface after adding the spray adjuvant.

[0014] Preferably, the wetting and spreading behavior analysis includes measuring the change in contact angle of the drug droplets on the plant leaf surface using a contact angle meter after adding a spray adjuvant.

[0015] Preferably, the deposition morphology includes a uniform deposition morphology and a non-uniform deposition morphology.

[0016] The present invention also provides an application of the method for screening the spray adjuvant or the method for evaluating the performance of the spray adjuvant in screening pesticide preparations.

[0017] Compared with the prior art, the present invention has the following technical effects:

[0018] Pyraclostrobin has a good control effect on various fungal diseases of wheat. In addition to its fungicidal effect, relevant reports show that pyraclostrobin has an intervention effect on CO2 assimilation, water and nitrogen absorption, abscisic acid and other plant hormones in plant leaves. Therefore, pyraclostrobin is considered to have a "greening" or "plant health" effect, which can promote rapid crop growth and increase crop yields. In addition, pyraclostrobin has been registered for the production of various dosage forms, suspensions, emulsifiable concentrates, microcapsule suspensions, water emulsions and microemulsions. The invention takes mineral oil (MO), silicone adjuvant Silwet L-77, amino acid surfactant sodium lauroyl sarcosinate and high molecular weight hydroxypropyl methylcellulose (HPMC) polymer adjuvant as examples, selectively adds these adjuvants into a 10-fold diluted solution of water dispersible granules (WG), suspensions (SC), wettable powders (WP), emulsifiable concentrates (EC), emulsions in water (EW) and microemulsions (ME), studies the wetting, spreading and dynamic deposition behavior of diluted solution droplets on the surface of wheat leaves and the final deposition morphology on the leaf surface, and comprehensively evaluates and compares the effects of different spray adjuvants on the dosage delivery behavior of diluted solution droplets of the preparation at a low dilution multiple. Based on the spatial evaporation process of fungicide solution during use and its interaction with the target crop leaves, a method for quickly evaluating the performance of agricultural spray adjuvants was established. On the one hand, it helps to reduce the development cost of adjuvant products, shorten the research and development cycle, and reduce the blindness of adjuvant research and development. On the other hand, based on the selected pesticide formulation, it can quickly select the spray adjuvant that matches it, reduce the number of field tests, and help further achieve the "reduced application and increased efficiency" of pesticides. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is the dynamic surface tension of the liquid after emulsifiable concentrate, microemulsion, emulsion in water, water dispersible granules, suspension concentrate and wettable powder are diluted with water;

[0020] Figure 2 The impact dynamics of droplets of diluted emulsion formulation on wheat leaves;

[0021] Figure 3 The impact dynamics of droplets of diluted suspension formulation on wheat leaves;

[0022] Figure 4 Wetting and spreading of droplets of diluted emulsion preparation on wheat leaves;

[0023] Figure 5 Wetting and spreading of droplets of diluted suspension system preparation on wheat leaves;

[0024] Figure 6 This is the deposition morphology of droplets of diluted emulsion preparation on wheat leaves;

[0025] Figure 7This is the deposition morphology of droplets of diluted suspension preparation on wheat leaves;

[0026] Figure 8 The figure is a flow chart of the screening method for pesticide spray adjuvants. DETAILED DESCRIPTION

[0027] The invention provides a method for screening a spray adjuvant, comprising the following steps: after adding the spray adjuvant to the liquid of a pesticide preparation, measuring the dynamic contact angle of a diluted liquid droplet on a target plant leaf surface, and screening a spray adjuvant that makes the liquid droplet contact angle less than 90 degrees; measuring the dynamic impact behavior of the liquid droplets, and screening a spray adjuvant that inhibits or weakens the bouncing and splashing of the liquid droplets; measuring the deposition morphology of the liquid on the target leaf surface, and screening a spray adjuvant that makes the liquid droplets have a uniform deposition morphology, so as to obtain a spray adjuvant suitable for the pesticide preparation.

[0028] In a specific embodiment of the present invention, for the diluted liquid system of the emulsion preparation, high concentrations of mineral oil additives and polymer additives can inhibit and / or weaken the breakage of the droplet edges, and the inhibitory effect of the high concentration of polymer additives is more obvious, the droplets are almost not broken, and the deposition effect is good; for the diluted liquid of the suspension system, silicone additives and amino acid surfactant additives can inhibit the bouncing of the droplets.

[0029] In a specific embodiment of the present invention, for the droplets of the emulsion system, the initial contact angle of all the droplets is less than 90°, but the high concentration of polymer additives can increase the viscosity of the liquid medicine, limiting the spreading of the droplets. For the liquid medicine of the suspension system, the contact angle of the liquid medicine on the plant leaf surface is relatively large, and the appropriate concentration of silicone additives, amino acid surfactant additives, and mineral oil additives can reduce the contact angle of the liquid medicine.

[0030] In a specific embodiment of the present invention, for the droplets of emulsion preparations, after adding a mineral oil adjuvant, the spreading speed of the liquid medicine is significantly accelerated, the spreading area is increased, and the evaporation time is shortened. The addition of a polymer adjuvant can make the diluted droplets of the emulsifiable concentrate preparation spread completely, but it does not improve the wetting and spreading of the droplets of the diluted liquid medicine of the water emulsion and microemulsion. For the liquid medicine of the suspension system, the appropriate concentration of mineral oil adjuvant and amino acid surfactant adjuvant can slightly increase the spreading area of ​​the liquid medicine, and the appropriate concentration of silicone adjuvant can make the liquid medicine spread completely on the plant leaf surface.

[0031] In the present invention, before measuring the dynamic contact angle, the type and concentration of the spraying adjuvant are preliminarily screened by measuring the physical and chemical properties of the diluted liquid.

[0032] In the present invention, the physicochemical properties include surface tension, viscosity, particle size and dynamic surface tension. In a specific embodiment of the present invention, for the liquid medicine of the emulsion system, the mineral oil additive and the polymer additive have no effect on the liquid surface tension; for the liquid medicine of the suspension system, the mineral oil additive, the silicone additive and the amino acid surfactant additive of appropriate concentration can reduce the surface tension of the liquid medicine.

[0033] In a specific embodiment of the present invention, high-concentration polymer additives can significantly increase the viscosity of the drug solution, while mineral oil additives, silicone additives and amino acid surfactant additives have no effect of increasing the viscosity of the drug solution.

[0034] In the specific embodiment of the present invention, the appropriate concentration of mineral oil additives can significantly affect the particle size of emulsion and microemulsion emulsion droplets, and a certain concentration of polymer additives can significantly increase the particle size of emulsion and water emulsion emulsion droplets. The increase in the particle size of the emulsion droplets after adding the additives indicates that the added additives destroy the interfacial stability of the emulsion droplets and the droplets coalesce. The particle size of the suspended particles is not affected by the mineral oil additives, silicone additives and amino acid surfactant additives.

[0035] In the specific embodiment of the present invention, since pesticide spraying is a dynamic process, the results of the dynamic surface tension of the pesticide solution are also of reference value for the analysis of droplet behavior. For the liquid of the emulsion system, although the concentration of the adjuvant does not affect the static surface tension of the diluted liquid, the adjuvant shows a difference in the rate of reduction of the dynamic surface tension of the liquid. Polymeric adjuvants can make the dynamic surface tension of emulsifiable concentrates and water emulsion liquids decrease faster. For the liquid of the suspension system, silicone adjuvants and amino acid surfactants can reduce the dynamic surface tension of the liquid.

[0036] In the present invention, the dosage form of the pesticide preparation includes one of water dispersible granules, suspension concentrates, wettable powders, emulsifiable concentrates, aqueous emulsions or microemulsions.

[0037] The present invention also provides a method for evaluating the performance of pesticide spray adjuvants. After adding the spray adjuvant, the physical and chemical properties of the diluted liquid, the evaporation performance of the liquid, the dynamic deposition behavior of the liquid on the plant leaf surface, the wetting and spreading behavior and the deposition morphology are measured and analyzed to evaluate the performance of the spray adjuvant. In a specific embodiment of the present invention, the evaporation performance of the liquid can be measured indoors using a contact angle measuring instrument to control the temperature and measure the evaporation of the liquid in a hanging drop state.

[0038] In the present invention, the physicochemical properties include the surface tension, viscosity, particle size and dynamic surface tension of the diluted liquid. The physicochemical properties of the liquid mainly refer to the surface tension, viscosity, particle size and density of the liquid. The addition of adjuvants may change the properties of the liquid, thereby affecting the subsequent dosage delivery behavior. Among them, since pesticide spraying is a dynamic process, the results of the dynamic surface tension of the pesticide solution are also of reference value for the analysis of droplet behavior. The present invention evaluates the performance of the spray adjuvant by measuring the physicochemical properties of the liquid, and can preliminarily determine the type and concentration of the spray adjuvant suitable for the pesticide formulation. In the present invention, a surface tension meter (DCAT 21, DataPhysics Co., Ltd., Germany) is used to measure the static surface tension of the diluted liquid by the Wilhelmy plate method. The dynamic surface tension of the diluted liquid is measured by the maximum bubble pressure method at 25°C using a bubble pressure tensiometer BP100 (Kruss Co., Ltd., Germany). The capillary diameter is 0.347mm, and the life of the bubble surface is 10 to 10000ms. The viscosity of the diluted solution was measured at 25°C using a viscometer DV-III (Brookfield Co., Ltd., USA). The particle size of the emulsion droplets or suspended particles of the diluted solution was measured using a BeNano180 nanoparticle size and Zeta potential analyzer (Beite Instrument Co., Ltd., Dandong, China). Each sample was repeated three times, and the values ​​are expressed as mean ± standard deviation.

[0039] In the present invention, the dynamic deposition behavior analysis includes measuring the dynamic impact process of the droplets of the pesticide solution after they reach the target plant leaf surface after adding the spray adjuvant. The dynamic impact process of the pesticide droplets after they reach the target plant leaf surface determines the deposition effect of the pesticide. When the droplets hit the solid surface, due to the kinetic energy of the droplets, the droplets first spread to the maximum and then shrink. In the present invention, a high-speed camera (FASTCAM Mini UX100, Photron) was used to record the dynamic behavior of the diluted droplets of the drug solution hitting the surface of the plant leaves. The camera frequency was set to 20000fps and the resolution was 1280×616. The syringe (inner diameter 0.33mm, Shanghai Becton Dickinson Medical Devices Co., Ltd.) was pushed by a syringe pump (KDScientific Syringe Pump Company, USA) to generate droplets, which were then released to hit the wheat leaves. The plant leaves were fixed on a glass slide using double-sided tape. In a specific embodiment of the present invention, the droplet release height is 0.3m, and the water droplets hit the wheat leaves at approximately the same speed (ν=2.42m / s). The injection pump is turned on to allow the droplets to fall freely, and the video of the droplets hitting the plant leaves is captured at the moment of the droplets falling. The present invention simulates the process of field spray droplets hitting the surface of plant leaves, which is closely related to the surface tension and viscosity parameters of the liquid medicine.

[0040] In the present invention, the wetting and spreading behavior analysis includes using a contact angle meter to measure the change in contact angle of the liquid medicine droplets on the plant leaf surface after adding a spray adjuvant. The present invention uses a contact angle meter to measure the change in contact angle of the liquid medicine droplets on the plant leaf surface to reflect the wetting and spreading behavior of the liquid medicine droplets on the plant leaf surface. During the experiment, after the pesticide droplets hit the plant leaves and spread, they are finally deposited on the leaves and evaporate on the leaf surface. This process is evaluated by measuring the dynamic contact angle and is closely related to the surface tension and viscosity of the liquid medicine. In the present invention, by using a contact angle meter (OCA 20, Data Physics, Germany), the automatic injection unit of the instrument is used to inject 3μL droplets into the plant leaves. The contact angle of the droplet is calculated by the Young-Laplace equation, and the contact angle of the diluted liquid medicine droplet on the wheat leaf is measured to evaluate the wetting and spreading properties of the liquid medicine.

[0041] In the present invention, the deposition morphology includes uniform deposition morphology and non-uniform deposition morphology. In the present invention, plant leaves are attached to a glass slide with double-sided tape, and 2 μL droplets are injected into wheat leaves using a 5 μL micro-injector (Shanghai Anting Micro-injector Factory). At 25°C, wait for the droplets to evaporate completely, use a VHX-2000 ultra-depth three-dimensional microscope system (Keyence Corporation, Japan) to photograph the deposition morphology of the dilution droplets on the wheat leaves, and use the instrument's measurement software to measure the final deposition area of ​​the droplets.

[0042] The present invention also provides an application of the method for screening the spray adjuvant or the method for evaluating the performance of the spray adjuvant in screening pesticide preparations.

[0043] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0044] Example 1

[0045] Experimental materials: Wheat seeds (Jimai No. 22) were provided by the Institute of Plant Protection, Chinese Academy of Agricultural Sciences. After sowing, the plants were grown in a greenhouse environment with 16 hours of light / 8 hours of darkness. The day and night temperatures were 22°C and 18°C, respectively, and the relative humidity was 70%.

[0046] Test method:

[0047] 1. Preparation of emulsion system preparations and suspension system preparations:

[0048] According to the formula composition in Tables 1-3, the preparation process of EC and ME is to dissolve the original drug in an organic solvent, add an emulsifier and other ingredients, and stir at a constant rate to obtain 15% pyraclostrobin EC and ME preparations. The preparation process of EW is to dissolve the original drug in an organic solvent, add other ingredients, and use a high-speed shear emulsifier to shear at 10,000 r / min for 5 minutes to obtain a 15% pyraclostrobin EW preparation.

[0049] Table 1 Formula composition of 15% pyraclostrobin emulsifiable concentrate

[0050] Element content(%) 98% Pyraclostrobin TC 15％ S-150 65％ Sol1000 10％ 602# 4.5％ 500# 5.5％

[0051] Table 2 Formula composition of 15% pyraclostrobin microemulsion

[0052]

[0053]

[0054] Table 3 Composition of 15% pyraclostrobin emulsion in water

[0055] Element content(%) 98% Pyraclostrobin TC 15％ S-150 33％ 1,2-Propanediol 5％ 602# 3％ 500# 3％ Deionized water 41％

[0056] According to the formulation in Table 4, weigh the technical, wetting agent, dispersant, magnesium aluminum silicate, ethylene glycol and deionized water into a beaker. Weigh three groups of samples and transfer the mixture to the sand mill silo. Add the beads at a ratio of sample mass: zirconium bead mass = 1:1.2, and set the sand milling speed to 10000r / min. According to the conditions in Table 5, by changing the particle size of the zirconium beads and the sand milling time, the D of the suspended particles was measured using a laser particle size analyzer during the grinding process. 50 If the measured D 50 The values ​​were consistent with those in Table 5, and the grinding was stopped. Xanthan gum was added according to the formula ratio, and the mixture was sheared for 10 min using a high-speed shearing machine. Samples were collected to obtain 25% pyraclostrobin WP, WG and SC suspension system preparations.

[0057] Table 4 Formula composition of 25% pyraclostrobin suspension preparation

[0058] Element content 98% Pyraclostrobin TC 25％ Wetting agent SP-28R 1％ Dispersant SP3275 5％ Magnesium Aluminum Silicate 1％ Ethylene glycol 4％ Deionized water 64％

[0059] Table 5 Sand milling conditions of 25% pyraclostrobin suspension preparation

[0060]

[0061] 2. Preparation of dilute solutions of pyraclostrobin emulsion and suspension preparations:

[0062] Suspension system preparations WG, SC and WP, ​​and emulsion system preparations EC, ME and EW were diluted into liquids with deionized water at a ratio of 1:10. The concentrations of adjuvants added to EC, ME and EW solutions were 0.1, 1 and 5 g / L. The treatment without adjuvant addition was used as the control group CK.

[0063] Table 6 Additive type and concentration of pyraclostrobin formulation system

[0064]

[0065] 3. Analysis of test results:

[0066] (1) Effects of spray adjuvants on the physicochemical properties of the solution

[0067] The physicochemical properties of the drug solution mainly refer to the surface tension, viscosity, particle size and density of the drug solution. The addition of adjuvants may change the properties of the drug solution, thereby affecting the subsequent dose delivery behavior. The physicochemical properties of EC, EW and ME preparations and the diluted drug solution with the addition of MO and HPMC adjuvants are shown in Table 7. The physicochemical properties of WG, SC and WP preparations and the diluted drug solution with the addition of MO, Silwet and sodium lauroyl sarcosinate adjuvants are shown in Table 8.

[0068] 1) Surface tension: For the emulsion system, the surface tension of the liquid is maintained at about 31-32 mN / m after the addition of MO and HPMC additives, indicating that mineral oil additives and polymer additives have almost no effect on the surface tension of the liquid. For the suspension system, 5g / L MO additive, 1g / L Silwet additive, and 1g / L and 5g / L sodium lauroyl sarcosinate additives can reduce the surface tension of the liquid. The effect of reducing the surface tension cannot be achieved when the concentration is lower than the corresponding concentration of these additives.

[0069] 2) Viscosity: When the polymer additives are added at a concentration of 5g / L, they can significantly increase the viscosity of the liquid. MO additives, Silwet additives and lauroyl sarcosine additives have no effect on increasing the viscosity of the liquid.

[0070] 3) Particle size: Adding 1g / L and 5g / L of MO additive can significantly affect the particle size of emulsion and microemulsion droplets, and 5g / L concentration can affect the particle size of water-based emulsion droplets; after adding 5g / L of HPMC additive, the particle size of emulsion and water-based emulsion droplets increased significantly. The increase in the particle size of emulsion droplets after adding additives indicates that the added additives destroyed the interfacial stability of the emulsion droplets and the droplets coalesced. The particle size of suspended particles is not affected by MO additives, Silwet additives and lauroyl sarcosine additives.

[0071] 4) Dynamic surface tension: Since pesticide spraying is a dynamic process, the results of the dynamic surface tension of the pesticide solution are also of reference value for the analysis of droplet behavior. For the emulsion system solution, although the concentration of the adjuvant does not affect the static surface tension of the diluted solution, the adjuvant shows a difference in the rate of reduction of the dynamic surface tension of the solution. For EC and EW preparations, the HPMC adjuvant has a faster reduction rate of the dynamic surface tension of the solution at a concentration of 1g / L and 5g / L, and the curve trend of the ME preparation is almost the same. For the suspension system solution, the addition of 1g / L of Silwet adjuvant has the strongest ability to reduce the dynamic surface tension of the solution, followed by 1g / L and 5g / L of sodium lauroyl sarcosinate, and the other concentrations of the three adjuvants have poor ability to reduce the dynamic surface tension of the solution.

[0072] Table 7 Physical and chemical properties of the emulsifiable concentrate, water emulsion and microemulsion after dilution with water

[0073] Emulsion system Static surface tension Viscosity (mPa·s) Average particle size (nm) EC 31.51±0.07 1.12±0.04 330.61±37.39 EC+MO 0.1g / L 31.48±0.36 1.12±0.00 286.39±28.59 EC+MO 1g / L 31.22±0.15 1.09±0.02 1647.02±232.79 EC+MO 5g / L 31.40±0.05 1.11±0.02 3404.27±185.09 EC+HPMC 0.1g / L 32.07±0.13 2.05±0.57 257.31±29.73 EC+HPMC 1g / L 31.74±0.06 2.24±0.04 347.98±21.32 EC+HPMC 5g / L 31.76±0.24 11.19±0.05 19727.52±1956.42 ME 31.93±0.20 1.04±0.04 123.09±5.16 ME+MO 0.1g / L 30.46±0.30 1.15±0.02 263.85±108.42 ME+MO 1g / L 31.52±0.32 1.13±0.02 5210.86±1048.21 ME+MO 5g / L 31.58±0.11 1.04±0.00 7778.26±1638.21 ME+HPMC 0.1g / L 32.38±0.03 1.20±0.04 166.73±17.27 ME+HPMC 1g / L 31.78±0.07 2.91±0.02 138.55±16.61 ME+HPMC 5g / L 31.90±0.17 26.41±0.06 93.35±0.66 EW 31.88±0.07 0.96±0.00 235.30±7.62 EW+MO 0.1g / L 31.88±0.08 0.96±0.00 205.62±1.71 EW+MO 1g / L 31.45±0.16 1.00±0.00 211.59±3.65 EW+MO 5g / L 30.86±0.01 0.92±0.00 2065.75±774.40 EW+HPMC 0.1g / L 31.96±0.08 1.16±0.00 157.95±1.93 EW+HPMC 1g / L 32.29±0.17 2.15±0.02 356.01±3.09 EW+HPMC 5g / L 33.12±0.13 12.22±0.12 11254.1±692.40

[0074] Table 8 Physical and chemical properties of the water dispersible granules, suspension concentrates and wettable powders after dilution with water

[0075] Suspension system Static surface tension Viscosity (mPas) Average particle size (μm) WG 36.10±0.31 1.37±0.02 2.29±0.53 WG+MO 0.1g / L 39.81±0.17 1.47±0.02 2.22±0.13 WG+MO 1g / L 33.56±0.32 1.55±0.05 2.08±0.29 WG+MO 5g / L 31.27±0.21 1.63±0.06 2.23±0.45 WG+Silwet 0.01g / L 37.31±0.67 1.41±0.02 2.35±0.13 WG+Silwet 0.1g / L 35.31±0.47 1.52±0.00 5.27±0.99 WG+Silwet 1g / L 20.05±0.48 1.56±0.00 2.46±0.44 WG+Sarkosyl 0.1g / L 36.14±0.63 1.53±0.09 2.35±0.11 WG+Sarkosyl 1g / L 30.68±0.31 1.52±0.04 1.633±0.24 WG+Sarkosyl 5g / L 30.22±0.37 1.61±0.02 1.59±0.15 SC 37.26±0.25 1.61±0.02 6.23±0.39 SC+MO 0.1g / L 37.48±0.16 1.41±0.02 5.87±0.72 SC+MO 1g / L 35.06±0.53 1.56±0.00 4.93±0.69 SC+MO 5g / L 32.70±0.67 1.56±0.00 5.01±0.45 SC+Silwet 0.01g / L 36.57±0.60 1.64±0.00 5.28±0.88 SC+Silwet 0.1g / L 28.44±0.62 1.56±0.00 5.27±0.99 SC+Silwet 1g / L 20.82±0.46 1.57±0.02 5.03±0.85 SC+Sarkosyl 0.1g / L 37.37±0.49 1.65±0.02 4.98±0.98 SC+Sarkosyl 1g / L 28.63±0.52 1.55±0.02 3.08±0.29 SC+Sarkosyl 5g / L 29.93±0.13 1.45±0.02 3.90±0.53 WP 37.04±0.38 1.00±0.03 12.30±0.01 WP+MO 0.1g / L 39.33±0.63 0.93±0.02 13.15±0.05 WP+MO 1g / L 36.61±0.12 0.90±0.01 13.55±0.08 WP+MO 5g / L 32.95±0.21 0.91±0.01 12.62±0.12 WP+Silwet 0.01g / L 34.85±0.20 0.91±0.04 13.38±0.19 WP+Silwet 0.1g / L 26.83±0.12 0.95±0.03 13.61±0.09 WP+Silwet 1g / L 21.39±0.02 1.09±0.01 13.17±0.07 WP+Sarkosyl 0.1g / L 37.10±0.48 0.93±0.04 12.69±0.42 WP+Sarkosyl 1g / L 30.21±0.39 0.97±0.00 12.77±0.30 WP+Sarkosyl 5g / L 30.18±0.11 0.90±0.01 12.17±0.01

[0076] (2) Effect of spray adjuvants on the dynamic deposition behavior of the spray solution on plant leaves

[0077] The dynamic impact process of pesticide droplets after reaching the target plant leaf surface determines the deposition effect of pesticides. When droplets hit the solid surface, due to the kinetic energy of the droplets, the droplets first spread to the maximum and then shrink. Using a high-speed camera, we simulated the process of field spray droplets hitting the surface of wheat leaves. This process is closely related to the surface tension and viscosity parameters of the pesticide solution.

[0078] 1) For the diluted liquid system of emulsion preparations, droplets without additives and with low concentrations of MO and HPMC additives, splashing of varying degrees occurs at the edge of the liquid film ( Figure 2 ). The droplet diffuses to a maximum value of about 1.25ms. Tiny droplets are generated at the edge of the liquid film and eventually separate from the droplet. When the additive concentrations of MO and HPMC are increased to 5g / L, the phenomenon of droplet edge fragmentation is suppressed and weakened. At a concentration of 5g / L, the inhibitory effect of HPMC is more obvious, the droplets are almost not broken, and the deposition effect is good.

[0079] 2) For the diluted liquid of the suspension system, the liquid droplets without additives bounced after hitting the wheat leaves. The addition of mineral oil additives did not inhibit the droplet bounce. The addition concentrations of 1g / L silicone additives and 1g / L and 5g / L sodium lauroyl sarcosinate could inhibit the droplet bounce, but small droplets inevitably broke off the edge of the droplets ( Figure 3 ).

[0080] (3) Effect of spray adjuvants on the wetting and spreading behavior of the spray solution

[0081] After the droplets hit the wheat leaves and spread, they eventually deposited on the leaves and evaporated on the leaf surface. By using a contact angle meter to measure the change in the contact angle of the droplets of the drug solution on the wheat leaves, the wetting behavior of the droplets of the drug solution on the surface of the wheat leaves can be reflected. This process is evaluated by measuring the dynamic contact angle and is closely related to the surface tension and viscosity of the drug solution.

[0082] 1) For the droplets of the emulsion system, the initial contact angle of all droplets is less than 90°. Previous studies on the spreading and wetting of the liquid medicine on the crop leaf surface mainly focused on the influence of the surface tension of the solution, while there were fewer studies on the influence of the viscosity of the liquid medicine. When the concentration of the HPMC additive reached 5g / L, the initial contact angle of the droplet was larger and the spreading was slower, while the droplet contact angles of other treatment groups of EC, EW and ME formulations almost all dropped to 20-30° within 100 seconds. This is because the added HPMC additive increases the viscosity of the liquid medicine, limiting the spreading of the droplets ( Figure 4 ).

[0083] 2) For the suspension system solution, the contact angle of the solution on the wheat leaves is relatively large. Except for the addition of 1g / L Silwet adjuvant, 1g / L and 5g / L sodium lauroyl sarcosinate adjuvant, and 5g / L mineral oil adjuvant, which can reduce the contact angle of the solution, the other treatment solutions cannot wet and spread on the surface of the wheat leaves. Among them, the solution with 1g / L Silwet L-77 adjuvant can quickly wet and spread on the surface of the wheat leaves ( Figure 5 ).

[0084] (4) Effect of spray adjuvants on the deposition morphology of the drug solution

[0085] Figure 6 It directly reflects the wetting and spreading process of the diluted drug solution in the emulsion system (emulsifiable concentrate, microemulsion and water emulsion) and the final deposition morphology; Figure 7 It intuitively reflects the wetting and spreading process of the diluted solution of suspension additives (water dispersible granules, suspension concentrates and wettable powders) and the final deposition form. This process is related to the surface tension, viscosity and particle size of droplets or suspended particles of the solution.

[0086] 1) For the droplets of the emulsion preparation, since the emulsion preparation contains more oil, it has a stronger affinity for the wax layer on the surface of the wheat leaves. All the treated diluted solutions finally achieved uniform deposition on the leaf surface and completely evaporated in a short time. The droplets of the water emulsion and microemulsion dilutions without the addition of adjuvants completely evaporated in about 11 minutes and 7 minutes, respectively, and finally formed a nearly circular uniform deposition. After adding 1g / L and 5g / L MO adjuvants, the spreading speed of the solution was significantly accelerated, the spreading area was increased, and the evaporation time was shortened. The droplets wetted and spread along the stripe structure on the surface of the wheat leaves. The solution with the addition of HPMC adjuvant was deposited on the leaves in the form of a thin film. Even at higher concentrations, the effect of HPMC adjuvant on improving the spreading performance of the solution was not obvious. Only the diluted droplets of the emulsion preparation could still be completely spread after adding HPMC adjuvant, and HPMC adjuvant did not improve the wetting and spreading of the droplets of the water emulsion and microemulsion dilution solutions.

[0087] 2) For the suspension system, the water dispersible granules, suspensions and wettable powders without additives had a smaller spreading area on the wheat leaf surface. When 5g / L MO additive, 1g / L and 5g / L sodium lauroyl sarcosinate were added, the spreading area of ​​the solution increased slightly. Only when the concentration of Silwet L-77 additive reached 1g / L, the solution could be fully spread on the surface of wheat leaves. For the diluted solution of water dispersible granules and suspensions, the solution showed a "coffee ring" state after complete evaporation on the wheat leaves, and the diluted solution of wettable powder showed a central deposition morphology after evaporation.

[0088] The present invention takes mineral oil additives, silicone additives, polymer additives and amino acid surfactant additives as examples, and experimentally determines the effects of the above spray additives on the evaporation, impact, and wetting and spreading behaviors of the liquid medicine at low dilution multiples, and evaluates the performance of the spray additives. Adding spray additives can change the static and dynamic surface tension and viscosity of the liquid medicine, and these parameters are the main influencing factors of the wetting and spreading, dynamic impact and evaporation and deposition behaviors of the liquid medicine on the leaf surface of the target plant.

[0089] The spatial evaporation of the liquid medicine is related to the chemical composition and temperature of the liquid medicine. In the present invention, after adding the spray adjuvant, the surface tension and viscosity values ​​of the diluted liquid medicine can be measured first to preliminarily screen out the better adjuvant type and concentration. Then, referring to the temperature of the preparation use scene, the evaporation of the liquid medicine in the hanging drop state is measured indoors using a contact angle meter to control the temperature. By using an ultra-high-speed camera to simulate the dynamic impact behavior of droplets, the adjuvant type and concentration that can suppress the bouncing and splashing of droplets can be further screened out. Generally speaking, the surface tension of the liquid medicine is low, the viscosity is high, and the liquid medicine is not easy to bounce or splash. By using a contact angle meter to measure the dynamic contact angle of the liquid medicine on the leaf surface of the target plant and using an ultra-depth of field microscope to observe the wetting and spreading of the liquid medicine, the adjuvant and concentration that can increase the wetting performance of the liquid medicine can be screened out. Generally speaking, the lower the surface tension value of the liquid medicine, the better the spreading performance of the liquid medicine, but it should be noted that the viscosity will inhibit the spreading of the liquid medicine. The spreading of the drug solution is accompanied by evaporation and deposition. The final deposition form of the drug solution on the leaf surface of the target plant can be used to screen out additives that can make the drug solution deposited and dispersed evenly. The results of this part are related to the wetting and spreading of the drug solution.

[0090] During the preparation process of emulsion preparations, a high content of emulsifier is added. Therefore, without adding adjuvants, the surface tension of the preparation at a low dilution multiple is already low, and it can wet and spread on the leaves of hydrophobic crops. However, after hitting the leaf surface, the droplets will break and separate into small droplets. Therefore, considering adding oil adjuvants or high molecular polymer adjuvants, the evaporation of the solution can be delayed. The addition of high molecular polymer adjuvants can increase the overall viscosity of the solution system and reduce the occurrence of droplet splashing.

[0091] The wetting agent content added to the suspension system during the preparation process is low, and the surfactant content is low when the liquid is diluted without adding adjuvants. Therefore, the liquid cannot wet the leaf surface even at a low dilution multiple, and the droplets form a ring-shaped deposit after evaporating completely on the leaf surface. The aggregation of active ingredients limits the efficacy of the drug, and the droplets bounce after hitting the surface of wheat leaves, resulting in poor liquid deposition. Therefore, it is necessary to select an adjuvant that can increase the wetting performance of the liquid, and the concentration of the adjuvant should also be appropriate. Too low an addition concentration has no effect on improving the performance of the liquid.

[0092] The test results of the present invention fully illustrate that different types of adjuvants play different roles in the dosage delivery behavior of the liquid medicine, and fully illustrate the importance of establishing a spray adjuvant performance evaluation method in the present invention based on the effects of the spray adjuvant on the physical and chemical properties of the liquid medicine, evaporation, leaf impact, wetting and spreading, and deposition behavior.

[0093] The above is only a preferred embodiment 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 principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for screening pesticide spray adjuvants, characterized in that: The steps include: (1) After adding the spray adjuvant to the pesticide formulation dilution, the dynamic contact angle of the pesticide droplets on the target plant leaf surface is measured, and the spray adjuvant that makes the pesticide droplet contact angle less than 90° is screened; (2) measuring the dynamic impact behavior of the drug droplets screened in step (1) to screen a spray adjuvant that inhibits or weakens the bouncing and splashing of the drug droplets; (3) Determining the deposition morphology of the pesticide droplets obtained by screening in step (2) on the target leaf surface, and screening a spray adjuvant that enables the pesticide droplets to have a uniform deposition morphology, that is, obtaining a spray adjuvant suitable for the pesticide formulation; Before measuring the dynamic contact angle, the type and concentration of spray adjuvants were preliminarily screened by measuring the physical and chemical properties of the diluted solution; The physicochemical properties include surface tension, viscosity, particle size and dynamic surface tension; The dosage form of the pesticide preparation includes one of water dispersible granules, suspensions, wettable powders, emulsifiable concentrates, aqueous emulsions or microemulsions.

2. Application of the method for screening spray adjuvants according to claim 1 in screening pesticide spray adjuvants.

Images