Nanometer liquid spraying film-forming agent for fruit planting disease and insect pest resistance and preparation method of nanometer liquid spraying film-forming agent

Abstract

The invention relates to the technical field of agriculture, and discloses a nano liquid spray film-forming agent for fruit planting and disease and insect pest resistance and a preparation method thereof. The nano liquid spray film-forming agent has good disease-resistant and insect-resistant effects, has good film-forming property after being sprayed on the surfaces of plant leaves or fruits and air-dried, can well attach the pesticide to the leaves, can improve the utilization rate of the pesticide, and can be used as a long-acting slow-release disease-resistant and insect-resistant agent. The material is simple in preparation method and low in raw material cost, can be stored for 1-3 months after long-term application, can also solve the problem of pesticide residues, and can be used for producing green organic food. The nano liquid spray film-forming agent disclosed by the invention can jointly realize safety, environmental friendliness and functionality, is harmless to a human body and the environment while ensuring a fruit preservation effect, and is suitable for environments such as orchards and comprehensive fruit and vegetable gardens in wet areas.

Description

Technical Field

[0001] The invention belongs to the field of agricultural technology, and specifically relates to a nano liquid spray film-forming agent for resisting diseases and insect pests in fruit and vegetable planting and a preparation method thereof. The nano liquid spray film-forming agent can simultaneously resist diseases and insect pests and promote crop growth. Background Art

[0002] China's mango planting industry has a long history and broad development prospects. China's mangoes are mainly grown in tropical and subtropical areas in the south, especially in Guangdong, Guangxi Zhuang Autonomous Region, Yunnan, Hainan, Fujian and Sichuan provinces. According to statistics, there are more than 300 mango pests and diseases reported at home and abroad. In the past 10 years, more than 90 new mango pests and diseases have been reported, and about 20 species can cause serious economic losses. There are 1 to 2 important pests and diseases during the mango shoot, flowering and fruiting periods, resulting in a 10% to 30% drop in yield, which seriously affects the development of the mango industry. Anthracnose is the most common and most harmful fungal disease in mango production. Mango anthracnose is a common disease caused by a fungus, and its main pathogen is Colletotrichum gloeosporioides. This disease may affect the leaves, flowers, fruits and branches of mangoes. In the early stage, small water stains appear on the surface of the fruit, which gradually expand into round or irregular black spots. These spots may become larger and merge over time, causing depressions or pits on the surface of the fruit, and in severe cases, the fruit rots. The pathogen of bacterial angular leaf spot is Xanthomonas campestris pv. Mangiferaeindicae. Bacterial angular leaf spot is a disease caused by a bacterium. The symptoms of this disease include the appearance of black or dark brown spots on the leaves, which gradually expand to form angular or irregular patches. When mango fruits are infected, they appear as stain-like black spots with yellow halos at the edges of the spots. In severe cases, the fruit cracks, resulting in a decrease in fruit quality, affecting yield and quality, and being unfavorable for sales. Mango thrips are more harmful to young fruits. The larvae will suck the juice of young fruits, resulting in the inability of the fruit to grow normally and a reduction in the commercial rate. Thrips have multiple generations a year, and the generations overlap. The damage is serious in orchards with uneven shoots and in drought and high temperature weather.

[0003] At present, more than 10 species of thrips have been reported, including Thrips flavus Schrank and Thripshawaiiensis (Morgan), among which Scirtothrips dorsalis Hood and Thrips dorsalis Hood are dominant species. Thrips can cause great damage to the leaves, spikes and fruits of mangoes, and can induce diseases such as sooty mold and gummosis, seriously reducing the yield and quality of mangoes. Bactrocera dorsalis Hendel is one of the most harmful insect pests in the mango fruit-bearing period. The adult lays eggs in the fruit, and the larvae eat the flesh after hatching, causing the fruit to rot and deteriorate. Bactrocera dorsalis Hendel mainly eats fruits, which is the main restrictive factor for the export of fresh mangoes. The female fly lays eggs in the fruit, and the larvae eat the fruit after hatching, causing the fruit to rot, crack and fall. Fruits can also rot during storage and transportation, and maggots can be found in rotten fruits.

[0004] Mango trees will encounter a variety of diseases during their cultivation. During the growth process, mango fruits are susceptible to various diseases. If these diseases are not prevented and controlled in time, they will seriously affect the yield and quality of mangoes. Mango disease prevention and control requires a combination of agricultural measures and chemical control methods, timely detection and identification of diseases, and the adoption of scientific and effective prevention and control measures to ensure the healthy growth, high yield and high quality of mangoes. The application of nano-liquid spray film-forming agents in agriculture provides an efficient and environmentally friendly way of plant protection. The current status of research on nanopesticides shows that significant progress has been made in this field, especially in improving the effectiveness of pesticides, reducing the amount of use, and enhancing the ability to prevent and control crop diseases. However, there are also some technical and safety challenges in the research and application of nanopesticides. The persistence of the effect of nanopesticides may be a problem that needs attention compared with traditional pesticides. Due to the small particle size and large specific surface area of ​​nanopesticides, they have a high coverage rate on the leaves of plants or the surface of pests, which helps to improve the bioavailability of pesticides and reduce the amount of pesticides used. However, this high efficiency may also lead to an increase in the persistence of nanopesticides in the environment, thereby increasing the potential risk to non-target organisms and ecosystems. Currently, nanomaterials can be used to construct long-acting sustained-release systems, which can match the release characteristics of pesticides with the occurrence patterns of harmful organisms, extend the effective period, and reduce the dosage and frequency of pesticide application.

[0005] The application of nano-liquid spray film-forming agents on fruits is an effective means of prevention and control. In-depth research and technological progress provide feasible solutions for the sustainable development of pesticides and for addressing the problems exposed in the application of traditional pesticides. Therefore, in-depth research and application of nano-liquid spray film-forming agents in agriculture is a problem that needs to be solved at present. Summary of the invention

[0006] In view of this, fruit disease prevention and control needs to combine agricultural measures and chemical control methods, timely discover and identify diseases, and take scientific and effective prevention and control measures to ensure the healthy growth, high yield and high quality of fruits. To this end, the present invention discloses a nano liquid spray film-forming agent for fruit planting to resist diseases and insect pests and a preparation method thereof, which can not only avoid the shortcomings of nano pesticides that the effect durability may not be as good as traditional pesticides and need more frequent spraying or higher concentrations to maintain the same prevention and control effect, but also avoid the shortcomings of pesticides and fertilizers in the use process, such as waste of agents, environmental pollution, and unsustainable drug effects.

[0007] Furthermore, in order to improve the performance and application effect of nanopesticides, the present invention combines polyurethane with polysaccharide nanoparticles to form a film-forming spray for fruit application, which can provide effective protection measures and improve fruit quality. It also has the advantages of environmental protection and controlled release effect, and is an innovative and efficient agricultural technology.

[0008] It should be noted that polysaccharide compounds are biodegradable polymers with good biocompatibility and low toxicity, so they are widely used in the agricultural field as carriers or additives for pesticides. In agriculture, they can be used as plant growth regulators, soil conditioners and pesticide carriers, which can improve plant disease resistance and promote crop growth. Polyurethane is a multifunctional synthetic material with excellent physical properties and chemical stability. It can form a film with good encapsulation and protection, covering the surface of plants or fruits to prevent the invasion of pathogenic microorganisms, pests and external factors, and help protect the growth and development of crops. Polyurethane film has strong durability and weathering resistance, can be maintained on the surface of plants or in the soil for a long time, provide continuous protection effect, and reduce the need for frequent application of pesticides. Polyurethane materials are biodegradable and can be degraded by microorganisms under certain conditions, reducing pollution to the environment, which is in line with the concept of green agriculture. Polyurethane has the advantages of encapsulation, durability, controlled release function, biodegradability and synergistic effect in agriculture. It can be combined with polysaccharide compounds to form a composite material with synergistic effects such as antibacterial, antioxidant, and growth promotion, which helps to improve crop yield and quality. It can be used as an important agricultural material to increase crop yields, protect the environment and promote sustainable agricultural development.

[0009] In order to achieve the above object, the present invention adopts the following technical solution:

[0010] The first object of the present invention is to provide a nano liquid spray film-forming agent for fruit planting against pests and diseases, wherein the nano liquid spray film-forming agent mainly comprises the following raw materials in terms of mass percentage:

[0011] 2-20% polysaccharide compound, 0.5-5% cross-linking agent, 0.1-5% surfactant, 0.1-10% insecticide, 0.1-10% fungicide, 0.1-5% isocyanate, 0.5-10% polyol, 0.1-5% hydrophilic chain extender, 0.1-10% neutralizer, 0.1-7% antioxidant, 0.1-6% light stabilizer, 0.01-20% organic solvent, balance water.

[0012] Optionally, the nano liquid spray film-forming agent mainly comprises the following raw materials in terms of mass percentage:

[0013] 2-20% polysaccharide compound, 0.5-5% cross-linking agent, 0.1-5% surfactant, 0.1-10% insecticide, 0.1-10% fungicide, 0.5-3% isocyanate, 0.5-7.5% polyol, 0.1-3% hydrophilic chain extender, 0.1-5% neutralizer, 0.1-5% antioxidant, 0.1-1% light stabilizer, 0.01-10% organic solvent, balance water.

[0014] Furthermore, the nano liquid spray film-forming agent mainly comprises the following raw materials in terms of mass percentage:

[0015] 5% polysaccharide compound, 1.2% cross-linking agent, 0.2% surfactant, 0.4% insecticide, 0.15% fungicide, 0.8% isocyanate, 1.5% polyol, 0.2% hydrophilic chain extender, 0.7% neutralizer, 0.5% antioxidant, 0.1% light stabilizer, 0.01% organic solvent, and the balance is water.

[0016] Furthermore, the polysaccharide compound is one or a combination of chitosan, sodium alginate, quaternized chitosan, oxidized carboxymethyl chitosan, quaternized alginic acid, and quaternized cellulose.

[0017] Furthermore, the organic solvent is one or a combination of methanol, ethanol, propanol and acetonitrile.

[0018] Furthermore, the cross-linking agent is any one of trimethylolpropane, sodium tripolyphosphate, genipin, glutaraldehyde, and diethylenetriamine.

[0019] Furthermore, the surfactant is any one of lecithin, saponin, Tween 80, and polyethylene glycol.

[0020] Furthermore, the isocyanate is any one of 4,4'-diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate and 1,6-hexamethylene diisocyanate.

[0021] Furthermore, the polyol is any one of castor oil-based polyol, soybean oil-based polyol, fructose-based polyol, lactic acid-based polyol, and polycaprolactone.

[0022] Furthermore, the neutralizing agent is any one of ammonia water and potassium hydroxide.

[0023] Furthermore, the hydrophilic chain extender is any one of dimethylolpropionic acid, citric acid, succinic acid, glycerol, 1,4-butanediol, 1,3-propylene glycol, and glycerol.

[0024] Furthermore, the insecticide is any one of cyhalothrin, avermectin benzoate, acetamiprid, ivermectin, spinosad, methyl phoxim, and trichlorfon, and the fungicide is any one of azoxystrobin, kasugamycin, prochloraz, pyraclostrobin, copper hydroxide, and fluazinam.

[0025] The second object of the present invention is to provide a method for preparing the nano liquid spray film-forming agent for fruit planting against pests and diseases as described above.

[0026] A method for preparing a nano liquid spray film-forming agent for fruit planting against pests and diseases comprises the following steps:

[0027] (1) dissolving a polysaccharide compound in a solution to prepare a solution; then adding a surfactant, a fungicide and an insecticide and stirring the mixture to obtain a liquid medicine;

[0028] It should be noted that the solution includes deionized water, low concentration saline, 1% acetic acid water, ethanol dilution, isopropanol dilution, dilute hydrochloric acid (pH <6), and different solutions can be selected according to the type of polysaccharide compound, such as chitosan (1% acetic acid water, 1% acetic acid water and other acidic solutions), quaternized fiber (35-60°C, 1% acetic acid water and other acidic solutions), oxidized carboxymethyl chitosan (medium or alkaline, low concentration saline), quaternized alginic acid (ethanol dilution), quaternized chitosan (ethanol, isopropanol dilution), etc.

[0029] (2) using a dropwise addition method, slowly adding the crosslinking agent solution to the stirred drug solution of step (1) through a syringe or dropper to form nanoparticles; or using an ultrasonic method, utilizing ultrasonic self-assembly to uniformly disperse the polysaccharide compound molecules in the solution to form nanoparticles; continuing to stir the mixed solution at 30-40° C. to perform a crosslinking reaction to form a stable nano solution;

[0030] (3) mixing isocyanate and polyol in proportion, heating and reacting to form a prepolymer; cooling the prepolymer, adding a hydrophilic chain extender to carry out a chain extension reaction to form a waterborne polyurethane prepolymer; adding a neutralizing agent, adjusting the pH value to 6.0-6.9, and gradually adding the neutralized prepolymer into water, stirring at high speed for 2 hours to form a stable aqueous dispersion; after all reactions are completed, completely removing the residual solvent by a rotary evaporator at 40° C.;

[0031] (4) Adding polyurethane as an additive to the nano-solution with pesticide as the core and sugar-based carrier prepared in step (2) to increase the adhesion of the final product on the surface of plants and harmful organisms, enhance the material's drug loading performance, targeted adhesion, and stability of the active ingredient, and greatly reduce environmental pollution by enhancing the physical and chemical properties of the product.

[0032] Furthermore, the method of using the nano liquid spray film-forming agent for fruit planting against pests and diseases disclosed in the present invention is:

[0033] Do a good job of pesticide protection, spray the prepared anti-disease and insect pest nano-liquid spray film-forming agent directly on the surface of plants and harmful organisms, and after the spray liquid dries, form a composite film to cover the surface of the fruit. The mass ratio of the anti-disease and insect pest nano-liquid spray film-forming agent to water is 1:50-500.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1) The present invention provides a nano liquid spray film-forming agent for fruit disease and insect resistance that can simultaneously play a role in disease and insect resistance, which has good film-forming properties and a lasting protective effect, while reducing the amount of pesticides and fertilizers used and reducing environmental pollution. Nanoparticles have a controlled release function, which can slowly release plant protection factors, extend the duration of the protective effect, and reduce the need for frequent spraying. The addition of polyurethane can enhance the adhesion of the spray liquid, so that it forms a more uniform and stable film layer on the surface of the fruit, improve the protective effect, and will not cause pollution to the environment after application, which is in line with the development trend of green agriculture.

[0036] The polyurethane-polysaccharide composite film can be formed on the surface of the fruit, providing a protective film. The formation of the protective film can reduce the evaporation and respiration of water on the surface of the fruit, prevent the fruit from being invaded by pathogenic microorganisms, climatic factors and mechanical damage, delay the aging and decay of the fruit, and help improve the quality and shelf life of the fruit.

[0037] 2) The nano liquid spray film-forming agent of the present invention adopts a water solvent system to reduce the emission of volatile organic compounds to achieve low VOCs emission; selects low-toxic or non-toxic raw materials to improve the biocompatibility and safety of the product; uses renewable resources and bio-based raw materials to reduce environmental burden, increase degradability, and designs components and structures to ensure degradability in the natural environment; and the coating has air permeability, waterproofness and antibacterial properties, has the advantages of good comprehensive prevention and control effect, strong durability, convenient operation, etc., and is suitable for disease and pest control and growth promotion of various crops. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] The word "embodiment" used here as an "exemplary" does not necessarily mean that any embodiment described is superior to or better than other embodiments. Unless otherwise specified, the performance index tests in the embodiments of this application are performed using conventional test methods in the art. It should be understood that the terms described in this application are only used to describe specific implementation methods and are not used to limit the content disclosed in this application.

[0040] Unless otherwise specified, the technical and scientific terms used in this document have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs; other experimental methods and technical means not specifically specified in this application refer to experimental methods and technical means commonly used by ordinary technicians in this field.

[0041] In order to better illustrate the content of the present application, numerous specific details are provided in the specific examples below. It should be understood by those skilled in the art that the present application can also be implemented without certain specific details. In the embodiments, some methods, means, instruments, equipment, etc. well known to those skilled in the art are not described in detail in order to highlight the main purpose of the present application.

[0042] Under the premise of no conflict, the technical features disclosed in the embodiments of the present application can be combined arbitrarily, and the resulting technical solutions belong to the contents disclosed in the embodiments of the present application.

[0043] The invention discloses a nano liquid spray film-forming agent for resisting diseases and insect pests in fruit planting and a preparation method thereof.

[0044] In order to better understand the present invention, the present invention is further specifically described below through the following examples, but it should not be understood as a limitation of the present invention. Some non-essential improvements and adjustments made by technicians in this field based on the above invention content are also considered to fall within the protection scope of the present invention.

[0045] Example 1

[0046] 1) Dissolve 50.0 g of chitosan in 1000 mL of water, and add 2.0 g of polyethylene glycol under stirring; add 4.0 g of kasugamycin and 4.0 g of acetamiprid dissolved in 4 mL of acetonitrile to the above solution and stir for 0.5 h, add 5 mL of glutaraldehyde solution through a syringe and slowly add it dropwise to the stirring solution, stir for 2 h to form nanoparticles.

[0047] 2) In a reaction kettle, 4.0 g of 4,4'-diphenylmethane diisocyanate and 3.0 g of castor oil-based polyol were mixed in proportion and heated to react to form a prepolymer; after the prepolymer was cooled, 7.0 g of citric acid was added to carry out a chain extension reaction to form a waterborne polyurethane prepolymer; then 7 mL of ammonia water was added to adjust the pH value to 6.0-6.9, and after all reactions were completed, the solvent was evaporated and removed at 40° C. using a rotary evaporator.

[0048] 3) The nano solution obtained in step 1) and the polyurethane obtained in step 2) are uniformly mixed to obtain a nano liquid spray film-forming agent.

[0049] Example 2

[0050] 1) Dissolve 50.0 g of sodium alginate in 1000 mL of water, and add 0.8 g of Tween 80 while stirring. Add 4.0 g of azoxystrobin and 4.0 g of cyhalothrin dissolved in 4 mL of acetonitrile to the above solution, stir for 0.5 h, then add 7.4 mL of sodium tripolyphosphate and ultrasonicate for 0.5 h, and use ultrasonic self-assembly to evenly disperse the polysaccharide compound molecules in the solution to form nanoparticles.

[0051] 2) 6.0 g of dicyclohexylmethane diisocyanate and 3.0 g of polycaprolactone were mixed in a reaction kettle in proportion and heated to react to form a prepolymer. After the prepolymer was cooled, 8.2 g of 1,4-butanediol was added to carry out a chain extension reaction to form a waterborne polyurethane prepolymer. 7.0 mL of ammonia water was added to adjust the pH value to 6.0-6.9. After all reactions were completed, the solvent was evaporated and removed at 40° C. using a rotary evaporator.

[0052] 3) The nano solution obtained in step 1) and the polyurethane obtained in step 2) are uniformly mixed to obtain a nano liquid spray film-forming agent.

[0053] Example 3

[0054] 1) 62.0 g of quaternary ammonium cellulose was dissolved in 1000 mL of water, and 3.2 g of lecithin was added under stirring. 4.0 g of pyraclostrobin and 4.0 g of avermectin benzoate dissolved in 4 mL of methanol were added to the above solution and stirred for 0.5 h, and then 5 mL of trimethylolpropane was added and ultrasonicated for 1 h. Ultrasonic self-assembly was used to uniformly disperse the polysaccharide compound molecules in the solution to form nanoparticles.

[0055] 2) 4.0 g of adipic acid diisocyanate and 3.0 g of castor oil-based polyol were mixed in a reaction kettle in proportion and heated to react to form a prepolymer. After the prepolymer was cooled, 8.2 g of 1,3-propylene glycol was added to carry out a chain extension reaction to form a waterborne polyurethane prepolymer. 15.0 mL of potassium hydroxide was added to adjust the pH value to 6.0-6.9. After all reactions were completed, the solvent was evaporated and removed at 40° C. using a rotary evaporator.

[0056] 3) The nano solution obtained in step 1) and the polyurethane obtained in step 2) are uniformly mixed to obtain a nano liquid spray film-forming agent.

[0057] Example 4

[0058] 1) Dissolve 50.0g chitosan in 1000mL water, add 3.0g saponin under stirring. Add 4.0g methyl phoxim and 4.0g prochloraz dissolved in 4mL propanol to the above solution and stir for 0.5h. Slowly add 6.4mL diethylenetriamine to the stirred solution through a syringe and stir for 2h to form nanoparticles.

[0059] 2) In a reaction kettle, 7.7 g of adipic acid diisocyanate and 6.3 g of fructose-based polyol were mixed in proportion and heated to react to form a prepolymer. After the prepolymer was cooled, 7.5 g of propylene glycol was added to carry out a chain extension reaction to form a waterborne polyurethane prepolymer. 7.0 mL of ammonia water was added to adjust the pH value to 6.0-6.9. After all reactions were completed, the solvent was evaporated and removed at 40° C. using a rotary evaporator.

[0060] 3) The nano solution obtained in step 1) and the polyurethane obtained in step 2) are uniformly mixed to obtain a nano liquid spray film-forming agent.

[0061] Example 5

[0062] 1) Dissolve 50.0 g of quaternized alginic acid in 1000 mL of water, and add 5.0 g of saponin under stirring. Add 4.0 g of spinosad and 4.0 g of copper hydroxide dissolved in 7 mL of ethanol to the above solution, stir for 0.5 h, then add 5 mL of genipin and perform ultrasonication for 1 h. Use ultrasonic self-assembly to evenly disperse the polysaccharide compound molecules in the solution to form nanoparticles.

[0063] 2) 4.0 g of 4,4'-diphenylmethane diisocyanate and 3.8 g of lactic acid-based polyol were mixed in a reaction kettle in proportion and heated to react to form a prepolymer. After the prepolymer was cooled, 12.0 g of glycerol was added to carry out a chain extension reaction to form a waterborne polyurethane prepolymer. 7.0 mL of ammonia water was added to adjust the pH value to 6.0-6.9. After all reactions were completed, the solvent was evaporated and removed at 40°C using a rotary evaporator.

[0064] 3) The nano solution obtained in step 1) and the polyurethane obtained in step 2) are uniformly mixed to obtain a nano liquid spray film-forming agent.

[0065] Example 6

[0066] 1) Dissolve 50.0g chitosan in 1000mL water, and add 2.0g Tween 80 under stirring. Add 4.0g ivermectin and 4.0g fluazinam dissolved in 5mL acetonitrile to the above solution and stir for 0.5h. Slowly add 5mL trimethylolpropane dropwise to the stirred solution through a syringe and stir for 2h to form nanoparticles.

[0067] 2) 4.0 g of dicyclohexylmethane diisocyanate and 3.0 g of polycaprolactone were mixed in a reaction kettle in proportion and heated to react to form a prepolymer. After the prepolymer was cooled, 8.2 g of 1,4-butanediol was added to carry out a chain extension reaction to form a waterborne polyurethane prepolymer. 7.0 mL of ammonia water was added to adjust the pH value to 6.0-6.9. After all reactions were completed, the solvent was evaporated and removed at 40° C. using a rotary evaporator.

[0068] 3) The nano solution obtained in step 1) and the polyurethane obtained in step 2) are uniformly mixed to obtain a nano liquid spray film-forming agent.

[0069] Example 7

[0070] 1) Dissolve 40.0 g of oxycarboxymethyl chitosan in 1000 mL of water, and add 2.8 g of polyethylene glycol while stirring. Add 4.0 g of trichlorfon and 4.0 g of fluazinam dissolved in 5 mL of methanol to the above solution and stir for 0.5 h. Add 5 mL of glutaraldehyde solution through a syringe and slowly dropwise add it to the stirred solution, and stir for 2 h to form nanoparticles.

[0071] 2) 4.0 g of dicyclohexylmethane diisocyanate and 3.0 g of soybean oil-based polyol were mixed in a reaction kettle in proportion and heated to react to form a prepolymer. After the prepolymer was cooled, 8.2 g of dimethylol propionic acid was added to carry out a chain extension reaction to form a waterborne polyurethane prepolymer. 7.0 mL of ammonia water was added to adjust the pH value to 6.0-6.9. After all reactions were completed, the solvent was evaporated and removed at 40° C. using a rotary evaporator.

[0072] 3) The nano solution obtained in step 1) and the polyurethane obtained in step 2) are uniformly mixed to obtain a nano liquid spray film-forming agent.

[0073] Example 8

[0074] 1) 60.0 g of quaternary ammonium cellulose was dissolved in 1000 mL of water, and 2.2 g of Tween 80 was added under stirring. 4.0 g of spinosad and 4.0 g of pyraclostrobin dissolved in 5 mL of acetonitrile were added to the above solution, stirred for 0.5 h, and then 5 mL of genipin was added and ultrasonicated for 1 h. The polysaccharide compound molecules were uniformly dispersed in the solution by ultrasonic self-assembly to form nanoparticles.

[0075] 2) 4.0 g of dicyclohexylmethane diisocyanate and 3.0 g of castor oil-based polyol were mixed in a reaction kettle in proportion and heated to react to form a prepolymer. After the prepolymer was cooled, 8.2 g of succinic acid was added to carry out a chain extension reaction to form a waterborne polyurethane prepolymer. 7.0 mL of ammonia water was added to adjust the pH value to 6.0-6.9. After all reactions were completed, the solvent was evaporated and removed at 40° C. using a rotary evaporator.

[0076] 3) The nano solution obtained in step 1) and the polyurethane obtained in step 2) are uniformly mixed to obtain a nano liquid spray film-forming agent.

[0077] In order to further demonstrate the beneficial effects of the present invention and to better understand the present invention, the following experiments are further used to illustrate the technical features disclosed in the present invention, but they should not be construed as limiting the present invention. Other improvements made by those skilled in the art based on the above invention without inventive work are also considered to fall within the scope of protection of the present invention.

[0078] Experiment 1: Control effect of nano-liquid spray film-forming agent on Bactrocera dorsalis

[0079] 1) Methods of applying pesticides to crops and test methods

[0080] The field efficacy test was conducted in Yangdong District, Guangdong Province. The nano-liquid spray film-forming liquid prepared by implementing particles 1-8 was sprayed on the surface of mango fruit to form a uniform film coverage. After the spray liquid dried, a polyurethane-chitosan composite film was formed to cover the surface of the mango fruit. Selective test: 20 healthy female insects aged 20-25 days at the peak of egg laying were randomly selected and placed in a test cage (30cm×30cm×30cm) with adult feed and water, and the test insects were allowed to adapt for 24 hours. The positive control group was sprayed with commercial drugs for the prevention and control of citrus fruit flies sold on the market. The control group was sprayed with an equal amount of water. After natural drying, the mangoes of the treatment group and the control group were placed in a test cage at the same time, repeated 3 times, and marked. After 24 hours, the mangoes in the test cage were taken out, the number of egg-laying holes and the amount of eggs laid on the fruit were checked and recorded, and the egg-laying repellency rate of each agent was calculated.

[0081] Methodology:

[0082] Non-selective test: Spray the prepared nano-liquid spray film-forming liquid on the surface of mango fruit to form a uniform film coverage, and put it in a fresh-keeping box after natural drying. The temperature is controlled at (26±1)℃ and the humidity is controlled at 60%±10%. The control group is sprayed with an equal amount of water. The mangoes of the treatment group and the control group are placed in different test cages and marked. After 24 hours, take out the fruits in the test cages and check and record the number of ovipositor holes and the amount of eggs laid on the fruits. The test is repeated 3 times. Calculate the ovipositor repellency rate.

[0083] Selective test: Put mangoes of the treatment group and the control group into the same test cage, and other conditions are the same as the non-selective test, and calculate the oviposition avoidance rate.

[0084] The calculation formula of the egg-laying repellency rate is as follows:

[0085]

[0086] (2) Test results

[0087] Table 1 Control effect of disease-resistant and insect-resistant nano liquid spray film-forming agent on citrus fruit fly

[0088]

[0089]

[0090] Experiment 2: Effect of Nano-liquid Spray Film-Forming Agent on Thrips Control

[0091] (1) Preparation method and test method

[0092] The field efficacy test was conducted in Yangdong District, Guangdong Province. The nano-liquid spray film-forming agent obtained in implementation cases 1-8 was used to form a uniform film coverage. After the spray liquid dried, a polyurethane-chitosan composite film was formed, which covered the surface of the mango tree to achieve the effect of prevention and control. The positive control selected a certain brand of registered thrips pesticide on the market and diluted it 50 times to spray the flower branches to achieve the effect of prevention and control. The control group was not treated. The insect population base was investigated before the drug was used, and the number of thrips was investigated 7 and 14 days after the drug was used. The investigation method was: 3 trees were selected in each plot, and 1 inflorescence with the same growth period was randomly selected from the 5 directions of each tree in the southeast, northwest and middle. The inflorescence was tapped 3 times, and the number of thrips was collected and counted using a tray (with coordinate paper), and the insect population reduction rate and control effect were calculated. The calculation formulas are as follows ① and ②.

[0093]

[0094] (2) Test results

[0095] Table 2 Control effect of nano liquid spray film-forming agent on thrips 7 days after treatment

[0096]

[0097]

[0098] Table 3 Control effect of nano liquid spray film-forming agent on thrips 14 days after treatment

[0099]

[0100] Experiment 3: Effect of Nano-liquid Spray Film-Forming Agent on Anthracnose Control

[0101] (1) Preparation method and test method

[0102] Mango samples were treated as follows. The nano-liquid spray film-forming agent obtained in Example 1-8 was diluted 50 times and sprayed on the diseased mango fruit and dried at 25°C. The nano-liquid spray film-forming agent obtained in Example 1-8 was applied to form a uniform film coverage. After the spray liquid dried, a polyurethane-chitosan composite film was formed, which covered the surface of the mango sample to achieve the effect of prevention and control. For the positive control, a certain brand of registered anthracnose pesticide on the market was diluted by the same multiple and sprayed on the sample to achieve the effect of prevention and control. Blank control group (CK): spray clean water on the diseased mango fruit and dry it. The treated mangoes were placed at (25±1)°C for 7 days, and 12 mangoes were selected from each group for mixed measurement. Observe the anthracnose spots and the inhibition of anthracnose by different treatments. There are four levels based on the ratio of the anthracnose lesion area on the fruit: no lesions is level 0; lesion area ratio less than 10% is level 1; lesion area ratio 10%-20% is level 2; lesion area ratio 20%-50% is level 3; lesion area ratio greater than 50% is level 4.

[0103] Calculation formula:

[0104]

[0105] (2) Test results

[0106] Table 4 Anthracnose incidence 7 days after the first treatment with nano-liquid spray film-forming agent

[0107]

[0108] Experiment 4: Effect of Nano-liquid Spray Film-Forming Agent on the Prevention and Treatment of Bacterial Angular Spot Disease

[0109] (1) Preparation method and test method

[0110] The field efficacy test was conducted in Yangdong District, Guangdong Province, when bacterial angular leaf spot initially occurred. The method was carried out in accordance with the GB / T17980.98-2004 test criteria, and a backpack electric sprayer was used for application. The test agent selected the nano-liquid spray film-forming agent of case 1-9, and clean water was used as the control. Each treatment plot had 5 plants, repeated 3 times, and the application began in mid-October 2018, with an interval of 7 days, for a total of 3 applications. 15 and 30 days after the last application of the drug, 3 plants were surveyed in each plot, and 5 treetops were selected from different directions of the mango canopy for each plant. The total number of leaves and the number of diseased leaves at each level were recorded, the disease index was calculated, and the control effect of the drug was calculated.

[0111] The disease is graded as follows: Grade 0: no lesions; Grade 1: lesion area accounts for less than 5% of the total leaf area; Grade 3: lesion area accounts for 6%-15% of the total leaf area; Grade 5: lesion area accounts for 16%-25% of the total leaf area; Grade 7: lesion area accounts for 26%-50% of the total leaf area; Grade 9: lesion area accounts for more than 50% of the total leaf area. Efficacy calculation formula:

[0112]

[0113] Table 5 Field control effect of nano liquid spray film-forming agent on mango bacterial angular spot disease

[0114]

[0115] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A nano liquid spray film-forming agent for fruit planting against pests and diseases, characterized in that: The nano liquid spray film-forming agent mainly includes the following raw materials in terms of mass percentage: 2-20% polysaccharide compound, 0.5-5% cross-linking agent, 0.1-5% surfactant, 0.1-10% insecticide, 0.1-10% fungicide, 0.1-5% isocyanate, 0.5-10% polyol, 0.1-5% hydrophilic chain extender, 0.1-10% neutralizer, 0.1-7% antioxidant, 0.1-6% light stabilizer, 0.01-20% organic solvent, balance water.

2. The nano liquid spray film-forming agent for fruit planting against pests and diseases according to claim 1, characterized in that: The nano liquid spray film-forming agent mainly includes the following raw materials in terms of mass percentage: 2-20% polysaccharide compound, 0.5-5% cross-linking agent, 0.1-5% surfactant, 0.1-10% insecticide, 0.1-10% fungicide, 0.5-3% isocyanate, 0.5-7.5% polyol, 0.1-3% hydrophilic chain extender, 0.1-5% neutralizer, 0.1-5% antioxidant, 0.1-1% light stabilizer, 0.01-10% organic solvent, balance water.

3. The nano liquid spray film-forming agent for fruit planting against pests and diseases according to claim 1 or 2, characterized in that: The nano liquid spray film-forming agent mainly includes the following raw materials in terms of mass percentage: 5% polysaccharide compound, 1.2% cross-linking agent, 0.2% surfactant, 0.4% insecticide, 0.15% fungicide, 0.8% isocyanate, 1.5% polyol, 0.2% hydrophilic chain extender, 0.7% neutralizer, 0.5% antioxidant, 0.1% light stabilizer, 0.01% organic solvent, and the balance is water.

4. The nano liquid spray film-forming agent for fruit planting against pests and diseases according to claim 1, characterized in that: The polysaccharide compound is one or a combination of chitosan, sodium alginate, quaternized chitosan, oxidized carboxymethyl chitosan, quaternized alginate, and quaternized cellulose, and the organic solvent is one or a combination of methanol, ethanol, propanol, and acetonitrile.

5. The nano liquid spray film-forming agent for fruit planting against pests and diseases according to claim 1, characterized in that: The cross-linking agent is any one of trimethylolpropane, sodium tripolyphosphate, genipin, glutaraldehyde, and diethylenetriamine; the surfactant is any one of lecithin, saponin, Tween 80, and polyethylene glycol.

6. The nano liquid spray film-forming agent for fruit planting against pests and diseases according to claim 1, characterized in that: The isocyanate is any one of 4,4'-diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, and 1,6-hexamethylene diisocyanate; and the polyol is any one of castor oil-based polyol, soybean oil-based polyol, fructose-based polyol, lactic acid-based polyol, and polycaprolactone.

7. The nano liquid spray film-forming agent for fruit planting against pests and diseases according to claim 1, characterized in that: The neutralizing agent is any one of ammonia water and potassium hydroxide.

8. The nano liquid spray film-forming agent for fruit planting against pests and diseases according to claim 1, characterized in that: The hydrophilic chain extender is any one of dimethylol propionic acid, citric acid, succinic acid, glycerol, 1,4-butanediol, 1,3-propylene glycol, and glycerol.

9. The nano liquid spray film-forming agent for fruit planting against pests and diseases according to claim 1, characterized in that: The insecticide is any one of cyhalothrin, avermectin benzoate, acetamiprid, ivermectin, spinosad, methyl phoxim, and trichlorfon; the fungicide is any one of azoxystrobin, kasugamycin, prochloraz, pyraclostrobin, copper hydroxide, and fluazinam.

10. A method for preparing a nano liquid spray film-forming agent for fruit planting against pests and diseases as claimed in any one of claims 1 to 9, characterized in that: The following steps are involved: (1) dissolving a polysaccharide compound in a solution to prepare a solution; then adding a surfactant, a fungicide and an insecticide and stirring the mixture to obtain a liquid medicine; (2) using a dropwise addition method, slowly adding the crosslinking agent solution to the stirred drug solution of step (1) through a syringe or dropper to form nanoparticles; or using an ultrasonic method, utilizing ultrasonic self-assembly to uniformly disperse the polysaccharide compound molecules in the solution to form nanoparticles; continuing to stir the mixed solution at 30-40° C. to perform a crosslinking reaction to form a stable nano solution; (3) mixing isocyanate and polyol in proportion, heating and reacting to form a prepolymer; cooling the prepolymer, adding a hydrophilic chain extender to carry out a chain extension reaction to form a waterborne polyurethane prepolymer; adding a neutralizing agent, adjusting the pH value to 6.0-6.9, and gradually adding the neutralized prepolymer into water, stirring at high speed for 2 hours to form a stable aqueous dispersion; after all reactions are completed, completely removing the residual solvent by a rotary evaporator at 40° C.; (4) Adding polyurethane as an additive to the nano-solution with pesticide as the core and sugar-based carrier prepared in step (2) to increase the adhesion of the final product on the surface of plants and harmful organisms, enhance the material's drug loading performance, targeted adhesion, and stability of the active ingredient, and greatly reduce environmental pollution by enhancing the physical and chemical properties of the product.

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