A nano-scale isolation and slow-release film preparation applicable to the prevention and control of plant diseases and insect pests and post-harvest preservation, and its preparation method and application

Abstract

The present invention discloses a modified film-forming agent and a preparation method thereof, and also discloses a nano-scale isolation and slow-release film preparation for plant pest control and post-harvest preservation, and a preparation method thereof, as well as the application of the nano-scale isolation and slow-release film preparation in plant pest control, the application in the apple bag-free technology as a substitute for apple bagging raw materials, and the application as a post-harvest preservation and antiseptic for fruits and vegetables. The nano-scale isolation and slow-release film preparation of the present invention has the dual effects of long-term leaf surface isolation and drug slow release. The attachment time on plant leaves can be up to 60 days at most, and the slow-release period of thymol and fluid iodine is 20-40 days. It has outstanding effects of comprehensive pest control, reducing pesticides and labor, saving costs, improving quality and increasing efficiency, and provides a safe, efficient, broad-spectrum and stable new material for green plant protection in agriculture and post-harvest anti-corrosion and preservation of fruits and vegetables.

Description

Technical Field

[0001] The present invention belongs to the fields of preparation of polymer materials and plant protection, and particularly relates to a nano-scale isolation and slow-release film preparation for plant pest control and post-harvest preservation, its preparation method and application. Background Art

[0002] As an important agricultural input, pesticides have made great contributions to ensuring food security. In 2022, the output of chemical pesticide technicals (converted to 100% active ingredient) in China was nearly 2.5 million tons, mainly in conventional pesticide formulations such as emulsifiable concentrates, wettable powders and emulsions. Due to the limitations and influences of traditional pesticide components, formulations, environmental conditions, application methods, application equipment, etc., the utilization rate of pesticides is not high. Currently, the effective utilization rate of pesticides on crops in China is only about 20% - 30%. More than 70% of the pesticides are lost to the non-target environment in the form of volatilization, drift, etc. The long-term and large-scale and inefficient application of pesticides has led to excessive pesticide residues in agricultural products, soil and water bodies, which not only poses a threat to non-target organisms and human health, but also causes damage to the structure and function of the ecosystem.

[0003] Therefore, promoting the development of new technologies and products for green prevention and control of crop pests and diseases is a strategic requirement for realizing pesticide reduction and harm control and promoting the overall green transformation of agricultural development. Using advanced functional materials and preparation processes to develop new green prevention and control products for pests and diseases, and to develop new application materials with both physical isolation and slow-release of pesticides, increasing the deposition rate on the target, regulating the release of pesticides, and synergistically reducing the amount of chemical pesticides and increasing efficiency are the current research frontiers and hotspots, and will also promote the innovation of new green prevention and control products and technologies.

[0004] The green control of plant pests and diseases requires the agent to have the advantages of leaf surface isolation, slow release, and resistance to rain erosion, so as to achieve external prevention of pest sucking, internal slow release and conduction of drugs, and effectively overcome the problems of low utilization rate and environmental pollution caused by the rolling of pesticide droplets, fast volatilization, rain erosion, etc., and help to reduce the amount of pesticide application and increase efficiency and ensure the quality and safety of agricultural products.

[0005] Currently, there are few green control preparations for pests and diseases with these functions. Summary of the Invention

[0006] The purpose of the present invention is to address the above problems and provide a nano-scale isolation and slow-release film preparation for plant pest control and post-harvest preservation, its preparation method and application.

[0007] The technical solution adopted by the present invention to achieve its purpose is:

[0008] The first aspect of the present invention provides a modified film-forming agent, which comprises, by weight, 10 to 20 parts of polyvinyl acetate emulsion or vinyl acetate emulsion, 5 to 10 parts of 1 to 2.5 wt % chitosan acetate solution, and 1 to 5 parts of 9 to 11 wt % ammonium persulfate solution.

[0009] The second aspect of the present invention provides a method for preparing the modified film-forming agent, comprising adding 10 to 20 parts of polyvinyl acetate emulsion or vinyl acetate emulsion and 5 to 10 parts of 1 to 2.5 wt% chitosan acetate solution into a stirred reactor and heating the reactor to 60 to 90° C., performing an emulsification reaction at a stirring speed of 150 to 300 r / min for 30 min to 1 h, and then dripping 1 to 5 parts of 9 to 11 wt% ammonium persulfate solution, and after the dripping is complete, heat-keeping the reaction for 40 min to 90 min to obtain the modified film-forming agent, preferably heat-keeping the reaction for 60 min to 90 min.

[0010] The solid content of the polyvinyl acetate emulsion is 18-45%, preferably 20-40% or 25-35%;

[0011] The solid content of the acetic acid acrylate emulsion is 40-60%, preferably 45-60% or 50-58%.

[0012] The third aspect of the present invention provides a nano-isolation slow-release film preparation suitable for plant disease and insect pest control and post-harvest preservation, and its preparation method and application, which comprises the following components by weight: 5 to 10 parts of the modified film-forming agent according to claim 1, 1 to 5 parts of active microemulsion, 5 to 10 parts of filler, and 5 to 10 parts of water; the active microemulsion comprises the following components: by weight, 10 to 30 parts of emulsifier, 10 to 20 parts of 5-10wt% alkaline solution, 5 to 10 parts of thymol, and 2 to 5 parts of nanofluid iodine;

[0013] Preferably, the emulsifier is OP-10 emulsifier, and the alkaline solution is KOH solution or NaOH solution;

[0014] Preferably, the filler is selected from nano calcium carbonate, calcium sulfate, superphosphate, and lime powder.

[0015] The fourth aspect of the present invention provides the above-mentioned nano-isolation sustained-release film preparation suitable for plant disease and insect pest control and post-harvest preservation, and its preparation method and application, comprising the following steps:

[0016] Step 1: preparing an active microemulsion: taking 10 to 30 parts of an emulsifier and mixing with 10 to 20 parts of a 5 to 10 wt % alkaline solution, then adding 5 to 10 parts of thymol, stirring at a speed of 150 to 400 r / min to fully dissolve, and then adding 2 to 5 parts of nanofluid iodine and stirring to fully dissolve to obtain an active microemulsion;

[0017] Step 2: Take 5 - 10 parts of the modified film-forming agent and mix it with 5 - 10 parts of water, and stir well to dissolve to form a film matrix solution; take 10 - 20 parts of the film matrix solution and mix it with 1 - 5 parts of the active microemulsion, stir evenly, add 5 - 10 parts of the filler, and stir well and mix evenly to obtain the isolation and slow-release film; or,

[0018] Step 2 is: Take 5 - 10 parts of the modified film-forming agent, 5 - 10 parts of water and 1 - 5 parts of the active microemulsion, mix and stir evenly, add 5 - 10 parts of the filler, and stir well and mix evenly to obtain the isolation and slow-release film.

[0019] In the technical solution of the preparation method described above,

[0020] The preparation method of the nano-fluid iodine is: Mix elemental iodine and a solvent in a mass ratio of 1:1 - 3, stir and react at a temperature of 120 - 170 °C for 10 - 60 min, let the product cool and then stand for stratification, and the obtained lower layer liquid is nano-fluid iodine; the solvent is selected from one or more of dimethyl sulfoxide, diphenyl sulfone, triethanolamine, N-methylpyrrolidone, sulfolane, N,N-dimethylformamide;

[0021] Preferably, the atomic iodine content in the nano-fluid iodine is 80 - 93 wt%, it is stable to light and heat, and does not sublime or degrade.

[0022] The fifth aspect of the present invention provides the application of the above-mentioned nano-state isolation and slow-release film preparation in the prevention and control of plant diseases and pests. The diseases include various plant bacterial or fungal diseases, and the pests include psyllids, planthoppers, spider mites, leafhoppers, rust mites, thrips and aphids;

[0023] Preferably, the spider mites include Panonychus citri and Empoasca vitis, the planthoppers include rice planthoppers, and the psyllids include Diaphorina citri;

[0024] Preferably, the dosage of the nano-state isolation and slow-release film preparation for preventing and controlling rice planthoppers is 25 - 100 g·hm -1 , preferably 50 - 100 g·hm -1 ;

[0025] Preferably, the concentration of the nano-state isolation and slow-release film preparation for field control of Panonychus citri is 5 - 20 g / kg, preferably 10 - 20 g / kg.

[0026] In the technical solution of the application of the above-mentioned nano-state isolation and slow-release film preparation in the prevention and control of plant diseases and pests, the application of the nano-state isolation and slow-release film preparation in combination with other pesticides in the preparation of pesticides for preventing and controlling plant pests; the other pesticides include carvacrol;

[0027] Preferably, the mixed pesticide with the combined use of the nano-state isolation and slow-release film preparation and carvacrol contains 45 - 90 mg / kg of the nano-state isolation and slow-release film preparation + 30 - 35 mg / kg of carvacrol; preferably, it contains 45 - 90 mg / kg of the nano-state isolation and slow-release film preparation + 31.25 mg / kg of carvacrol.

[0028] In the application technical solution of the above-mentioned nano-state isolation and slow-release film preparation in the prevention and control of plant diseases and pests, the plant bacterial diseases include cucumber bacterial angular leaf spot, and the fungal diseases include tomato gray mold, tobacco powdery mildew, and potato late blight.

[0029] Preferably, when preventing and controlling plant bacterial or fungal diseases in the field, the dosage of the nano-state isolation and slow-release film preparation is 50 - 120 ml / mu or 50 - 100 ml / mu or 100 - 120 ml / mu.

[0030] The sixth aspect of the present invention provides the application of the above-mentioned nano-state isolation and slow-release film preparation in the apple bag-free technology as a substitute for apple bagging raw materials. The fruits sprayed with the nano-state isolation and slow-release film preparation do not need to be bagged throughout the growth period; preferably, the nano-state isolation and slow-release film preparation with a concentration of 100 - 500 times or 100 - 400 times or 200 - 300 times is sprayed before apple bagging, and then sprayed once again during the fruit expansion period or when it is washed away by rain.

[0031] The seventh aspect of the present invention provides the application of the above-mentioned nano-state isolation and slow-release film preparation as a post-harvest fresh-keeping and anti-corrosion preservative for fruits and vegetables. Preferably, the concentration of the film preparation in the fresh-keeping and anti-corrosion preservative prepared by the film preparation is 800 - 1200 mg·L -1 , preferably 900 - 1100 mg·L -1 ;

[0032] Preferably, the application method is: immerse the harvested fruits in an aqueous solution of the film preparation with a concentration of 800 - 1200 mg·L -1 for 2 - 5 min, preferably 2 - 3 min, then take out and air-dry and store.

[0033] Preferably, the fruit is mango.

[0034] The nano-state isolation and slow-release film preparation of the present invention can be applied to the area to be placed and the crop parts (the whole plant, including stems, leaves, and fruits) by conventional spraying methods, spraying, or drone aerial spraying to apply the isolation and slow-release film.

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

[0036] The nano - state isolation and slow - release film preparation of the present invention has the dual effects of long - term leaf surface isolation and drug slow - release. The attachment time on plant leaves can reach up to 60 days at most. The slow - release period of thymol and liquid iodine is 20 - 40 days. It has outstanding effects of comprehensive prevention and control of pests and diseases, reducing the amount of pesticides and labor, saving costs, improving quality and efficiency, and provides a safe, efficient, broad - spectrum and stable new material for green plant protection in agriculture and post - harvest anti - decay and fresh - keeping of fruits and vegetables.

[0037] It can also be used as a barrel - mixing spray adjuvant to improve the rain - erosion resistance of pesticides, prevent the drift and evaporation of liquid medicine, improve the persistence of pesticides, and slow down the occurrence of pesticide phytotoxicity. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Shows the nano - particle size distribution after the film preparation of the present invention is diluted 200 times.

[0039] Figure 2 Shows the emulsion particle size of the film preparation of the present invention (diluted 200 times).

[0040] Figure 3 Is the scanning electron microscope image of the adhesion of the film preparation of the present invention (diluted 200 times) on citrus leaves 1 day after spraying.

[0041] Figure 4 Is the scanning electron microscope image of the adhesion of the film preparation of the present invention (diluted 200 times) on citrus leaves 60 days after spraying.

[0042] Figure 5 Is the scanning electron microscope image of the adhesion of the film preparation of the present invention (diluted 200 times) on citrus leaves.

[0043] Figure 6 Is the transmission electron microscope scanning image of the film preparation of the present invention (diluted 200 times).

[0044] Figure 7 Shows the adhesion effect of the film preparation of the present invention on citrus leaves (20 days after spraying).

[0045] Figure 8 Shows the adhesion effect of the film preparation of the present invention on citrus leaves (60 days after spraying).

[0046] Figure 9 Shows the influence of the water treatment and the film preparation treatment of the present invention on the apparent phenomenon of mangoes.

[0047] Figure 10 Shows the influence of the water treatment and the film preparation treatment of the present invention on the incidence rate and disease index of mangoes.

[0048] Figure 11 Shows the influence of the water treatment and the film preparation treatment of the present invention on the softening of mangoes. DETAILED DESCRIPTION OF THE INVENTION

[0049] The present invention will be further described below in conjunction with embodiments, but the present invention is not limited thereby.

[0050] The experimental methods in the following embodiments are all conventional methods unless otherwise specified.

[0051] Sources of main raw materials and materials:

[0052] Elemental iodine: English name iodine, molecular formula I2, CAS No. 7553-56-2.

[0053] Dimethyl sulfoxide (DMSO): CAS No. 67-68-5.

[0054] OP-10 emulsifier (alkylphenol polyoxyethylene ether): CAS No. 9002-93-1, and the content of OP-10 emulsifier used in the embodiments of the present invention is 99%.

[0055] Thymol: 5-methyl-2-isopropylphenol (English name 5-methyl-2-Isopropylphenol), CAS No.: 89-83-8.

[0056] Polyvinyl acetate emulsion: Polyvinyl acetate emulsion, CAS NO: 9003-20-7, a water-soluble adhesive, a thermoplastic adhesive prepared by the polymerization reaction of vinyl acetate monomer under the action of an initiator; usually called white latex or simply PVAC emulsion. The solid content of the polyvinyl acetate emulsion in the research of the present invention is 30±1%.

[0057] Chitosan acetate solution: Prepared by dissolving chitosan acetate (CAS No.: 70694-72-3) in water.

[0058] Vinyl acetate-acrylate emulsion: Also known as ethylene-propylene emulsion, it is a water-based polymer resin copolymerized with vinyl acetate and butyl acrylate as the main functional monomers; the solid content of the vinyl acetate-acrylate emulsion used in the embodiments of the present invention is 55±1 wt%.

[0059] Example 1 Preparation of the isolation and sustained-release film preparation of the present invention

[0060] Operate according to the following steps:

[0061] S1. Prepare the film matrix solution

[0062] S1.1. Preparation of modified film-forming agent: Add 10 - 20 parts of polyvinyl acetate emulsion or vinyl acetate - propylene emulsion and 5 - 10 parts of 1 - 2.5% chitosan acetate solution into a stirring reactor, heat up to 60 - 90 °C, carry out emulsification reaction for 30 min - 1 h at a stirring speed of 150 - 300 r / min, then dropwise add 1 - 5 parts of 10 wt% ammonium persulfate aqueous solution. After the dropping is completed, keep the temperature for reaction for 40 min - 90 min to obtain the modified film-forming agent.

[0063] S1.2. Preparation of film matrix solution: Take 10 - 30 parts of the modified film-forming agent and mix it with an equal amount of water, stir well to dissolve to form a film matrix solution. This step can also be omitted, and directly in step S3, mix the modified film-forming agent with an equal amount of water, active microemulsion, and filler.

[0064] S2. Preparation of active microemulsion

[0065] S2.1. Preparation of nanofluid iodine:

[0066] The nanofluid iodine used in the present invention is the atomic state fluid iodine or atomic state nano-iodine disclosed in Chinese Patent ZL 201710388396.5 (Patent Name: An Atomic State Fluid Iodine and Its Derived Nano-Iodine and Preparation Method and Use), and it can be prepared by the method disclosed in ZL 201710388396.5.

[0067] In the embodiment of the present invention, the preparation method is specifically: Mix elemental iodine and solvent dimethyl sulfoxide according to a mass ratio of 1 - 3:1, stir and react at a temperature of 120 - 170 °C for 10 - 60 min. After the product is cooled, it is allowed to stand for stratification, and the obtained lower layer liquid is nanofluid iodine, in which the atomic iodine content is 80 - 93 wt%, and it is stable to light and heat, does not sublime and does not degrade.

[0068] S2.2. Preparation of active microemulsion: Take 10 - 30 parts of OP-10 emulsifier and mix it with 10 - 20 parts of 5 - 10 wt% KOH solution, then add 5 - 10 parts of thymol, stir and dissolve thoroughly at a speed of 150 - 400 r / min, and then add 2 - 5 parts of nanofluid iodine and stir and dissolve thoroughly to obtain the active microemulsion;

[0069] S3. Preparation of isolation and sustained-release film preparation: Take 10 - 20 parts of the film matrix solution and mix it with 1 - 5 parts of the active microemulsion, stir evenly, add 5 - 10 parts of filler, stir and mix evenly to obtain the isolation and sustained-release film preparation of the present invention, which is in the form of an emulsion. The filler is nano calcium carbonate, calcium sulfate, superphosphate or hydrated lime powder.

[0070] According to the above method, prepare the isolation and sustained-release film preparation samples of Examples 1 - 4, and the specific ratios and process parameters of each example are shown in Tables 1 - 3 as follows:

[0071] Table 1 Formulation and Process Parameters of Step S1.1

[0072]

[0073] Table 2 Formulation and Process Parameters of Step S2

[0074]

[0075] Table 3 Formulation of Step S3

[0076]

[0077] The particle size distribution of the membrane preparation prepared in Example 1 after being diluted 200 times is shown in Figure 1 , and the particle size distribution range is 50 - 1000 nm, where the median is around 100 nm. Figure 2 Figure is the scanning electron micrograph of the particle size of the membrane preparation emulsion in Example 1. The scanning electron micrograph of the adhesion of the membrane preparation in Example 1 on citrus leaves is shown in Figures 3 to 5 , where Figure 3 is the adhesion situation of the membrane preparation on the leaves 1 day after spraying, Figure 4 is the adhesion situation 60 days after spraying, Figure 5 It can be seen the adhesion effect of the active particles in the membrane preparation on the leaves. Figure 6 Figure is the transmission electron micrograph of the membrane preparation in Example 1 after being diluted 200 times. Nearly circular micelle particles can be observed, and there is a transparent structure outside most of the particles, indicating that the micelle particles should belong to the core - shell structure. Hydrophobic thymol and fluid - state nano - iodine are encapsulated in the core of the micelle particles, and in this way, the effect of drug sustained release can be achieved. Figures 7 to 8 Figure is the field characterization effect diagram of the adhesion of the membrane preparation in Example 1 on citrus leaves within 20 - 60 days after spraying. Through experiments, it can be known that the membrane preparation of the present invention has the dual effects of long - term foliar isolation and drug sustained release. The adhesion time on plant leaves can be up to 60 days at most, and the sustained release period of thymol and fluid iodine is 20 - 40 days.

[0078] In the following Application Examples 1 - 7, the membrane preparations prepared in Examples 1 - 4 are formulated with water to the use concentration or diluted to the corresponding multiple for application. For example, a membrane preparation with a concentration of 10 g / L means taking 10 g of the membrane preparation of the present invention and adding water to a volume of 1 L. Control effect of the membrane preparation in Application Example 1 against Panonychus citri McGregor

[0079] (I) Indoor Activity

[0080] Test agents: The membrane preparation prepared in Example 1; Control agent: 1.8% abamectin.

[0081] Test method: Five different series of mass concentrations were set for the two agents. The mass concentrations of the film preparation were 10.00, 5.00, 2.50, 1.25, and 0.63 g / L in sequence, and the mass concentrations of abamectin were 8.00, 4.00, 2.00, 1.00, and 0.50 mg / L in sequence. 100 mL of the liquid medicine was prepared for each mass concentration for standby.

[0082] Activity determination method: The leaf mite slide dipping method was adopted. Each treatment was repeated 4 times, with 30 mites in each repetition. At the same time, a treatment containing organic solvent but no agent was set as the blank control. The results were checked 48 h after the treatment. The mite body was gently touched with a No. 0 writing brush, and those with immobile chelicerae were considered dead, and the mortality rate was calculated.

[0083] Taking the logarithm of the agent concentration (mg / L) as the independent variable x and the probit value of the corrected mortality rate as the dependent variable y, the virulence regression equations were established respectively, and the LC of the single agent and each mixed agent ratio was calculated using DPS software 50 、LC 90 and the 95% confidence limit to compare the activities of the two agents against the target.

[0084] Activity determination results:

[0085] The results of indoor bioactivity determination are shown in Table 4. The LC 50 of the film preparation against Panonychus citri for 48 h was 7.22 mg / L, and the LC 90 was 35.64 mg / L, higher than 1.8% abamectin.

[0086] Table 4 Toxicity determination results of the ecological film against Panonychus citri (treatment for 48 h)

[0087]

[0088] (2) Field efficacy:

[0089] The experimental plot was set in a certain Citrus reticulata cv. Chachiensis plantation in Muzhou Town, Xinhui District, Jiangmen City. A total of 5 treatments were set in the experiment: the mass concentrations of the film preparation were 20.00, 10.00, and 5.00 g / kg, the control agent was 35 times the liquid of 29% lime sulfur mixture, and another clear water blank control (CK) was set. There were 2 citrus trees in each plot, with 1 liter of water used for each tree. Each treatment was randomly arranged in blocks and repeated 4 times, with a total of 20 experimental treatment plots and 40 citrus trees. The medicine was applied once at the beginning of the peak period of young and weak mites (on November 10, 2022). A Lino HD400 type sprayer was used to evenly spray the liquid medicine on the front and back of the citrus leaves, and the spraying volume was 900 L / hm 2, with the criterion of no dripping of the liquid medicine. No other pesticides were applied to control other pests and diseases during the test period. Investigations were carried out once before the application of the medicine and on the 1st, 3rd, 10th, 15th, 20th, and 30th days after the application. In each plot, 2 trees were investigated. Five young shoots were marked at the east, west, south, north, and middle positions of each tree. Five leaves were fixed on each young shoot. The number of live mites on the front and back sides of a total of 25 leaves was investigated, and the reduction rate of the pest population and the control effect were calculated. The results are shown in Table 5.

[0090] Table 5 Experimental results of the film preparation for controlling citrus red spider mites

[0091]

[0092] The results showed that the film preparation had excellent control effects on citrus red spider mites. The control effects of each treatment group of the film preparation reached over 80% on the 1st day after the application of the medicine, which were significantly higher than that of the 29% lime sulfur mixture aqueous solution, and the quick-acting property was good. Within 3 - 20 days after the application of the medicine, the highest control effect of the film preparation on red spider mites reached 97.74%, and the control effect persistence period of each treatment concentration was over 20 days.

[0093] Application Example 2 Control effect of the film preparation on rice planthoppers

[0094] (I) Indoor activity

[0095] Tested pesticides: The film preparation prepared in Example 2; Control pesticide thiamethoxam. Pesticide concentrations: The film preparation at 10.00, 5.00, 2.50, 1.25, 0.63 g / L, and thiamethoxam at 28.00, 14.00, 7.00, 3.50, 1.75 mg / L. 100 mL of the liquid medicine was prepared for each mass concentration for standby.

[0096] The indoor activity determination was carried out by the rice stem dipping method. Rice plants at the late tillering stage to the early booting stage with consistent growth were pulled out with roots, washed, and cut into rice stems about 10 cm long with roots. They were respectively soaked in the liquid medicine of different concentrations for 30 s. After the rice stems were taken out and dried, the roots were wrapped with absorbent cotton soaked with distilled water, and then inserted into a mineral water bottle with the bottom cut off from the bottle mouth for fixation. 20 test insects were introduced into each bottle, and the bottle mouth was sealed with a 200 - mesh gauze. Then it was placed in an RHZ intelligent artificial light climate chamber at 27 ± 1 °C, RH 70 - 80%, and a light cycle of 14:10 for cultivation. Each treatment was repeated 4 times, and at the same time, a treatment containing the organic solvent without the pesticide was set as the blank control.

[0097] The death situation of the test insects was investigated every day after the treatment. After 5 days, statistics were carried out, and the total number of insects and the cumulative number of dead insects were recorded. According to the investigation data, the corrected mortality of each treatment was calculated. Taking the logarithm of the pesticide concentration (mg / L) as the independent variable x and the probit value of the corrected mortality as the dependent variable y, the toxicity regression equations were respectively established, and the LC50, LC90, and 95% confidence limits of the single agent and each ratio mixture were calculated using DPS software to compare the activities of the two pesticides against the target. The results are shown in Table 6.

[0098] Result determination: After 120 h of treatment, the LC 50 of the membrane preparation against rice planthoppers was 17.35 mg·L -1 , and the LC 90 was 57.69 mg·L -1 . The LC 50 of the control agent, 98% thiamethoxam, against rice planthoppers was 4.70 mg·L -1 , and the LC 90 was 32.84 mg·L -1 . Although the membrane preparation was less effective than the control thiamethoxam, it contains no chemical pesticide ingredients, causes little environmental pollution, has strong selectivity, low toxicity to humans, livestock, and natural enemies, and pests are less likely to develop resistance. Therefore, it can be used as a green control agent for rice planthoppers.

[0099] Table 6 Toxicity determination results of the membrane preparation against rice planthoppers (treatment for 120 h)

[0100]

[0101] (2) Field efficacy

[0102] Experimental method: The experimental field was set in a paddy field in Shishan Town, Xiuying District, Haikou City, Hainan Province. The first pesticide application was carried out during the mid - growth stage of rice (before heading), at the peak hatching period of rice planthoppers. A total of 5 treatments were set up: the mass concentration of the membrane preparation was 100 g / hm 2 (sprayed with a 600 - fold solution during treatment), 50 g / hm 2 (1200 - fold solution), 25 g / hm 2 (2400 - fold solution), the effective ingredient dosage of the control agent, 1.5% matrine soluble concentrate, was 5 g / hm 2 , and another clear - water blank control (CK) was set. The area of each plot was 20 m 2 . Each treatment was arranged in a randomized block design with 4 replicates, for a total of 20 experimental treatment plots. The first pesticide application was on September 14, 2023, and the second application was 7 days after the first application (September 22), with a total of 2 applications. Surveys were conducted 1, 3, and 7 days after the second application (September 23, 25, and 29), for a total of 4 surveys. In each plot, 10 points were surveyed using the parallel jump method, with 2 rice plants at each point. The side of a white porcelain plate was placed close to the rice plants, and the rice plants were slapped towards the porcelain plate to make the insects fall onto the white porcelain plate. The number of rice planthoppers on the white porcelain plate was counted, and the reduction rate and control effect were calculated.

[0103] The test results are shown in Table 7. The highest control effect of the treatment with an effective ingredient dosage of 50 g·hm -1 of the membrane preparation could reach 89.75%. It had good long - term control efficacy against rice planthoppers, was safe for the growth of rice plants, and was safe for natural enemies. It can be applied to the green control of rice planthoppers.

[0104] Table 7 Test results of the membrane preparation in controlling rice planthoppers

[0105]

[0106] Application Example 3: Effect of film preparation on the prevention and treatment of bacterial and fungal diseases of crops

[0107] In order to further clarify the control effect of the film preparation on viral, bacterial and fungal diseases of crops, tomato gray mold, tobacco powdery mildew, potato late blight and cucumber bacterial angular leaf spot were taken as control objects, and their field control effects were investigated: the film preparation of Example 3 was applied to spray plants in tomato, tobacco, potato and cucumber planting fields at the early stage of the disease, and the medicine was used twice in total. The field control effect was investigated 7 days and 10 days after the second application.

[0108] Calculate the disease index (referred to as disease index) and control effect (referred to as control effect). The leaf damage classification standard refers to the classification standard of each disease, calculate the disease index according to the classification, and then calculate the control effect based on the disease index:

[0109]

[0110]

[0111] The results are shown in Table 8. The film preparation of Example 3 has significant control effects on various crop pathogens. The control effects are all above 80% 7 days after the second application, and the long-lasting effect is good.

[0112] Table 8 Test results of film preparations for preventing and controlling various crop diseases

[0113]

[0114] * Note: The film preparations in Table 8 were diluted 1200 times with water before application.

[0115] Application Example 4: Effect of film preparation on control of tea green leafhopper (Empoascapirisuga Matumura) and its effect on reducing pesticide dosage and increasing efficiency

[0116] The experimental site was Gaoqiao Town, Changsha County, Hunan Province, in an adult tea garden with 12 years of age. The field spray method was used and three treatments were set up for test agent: the film preparation of Example 4 (180 ml / mu, diluted to 500 times liquid for application), control agent: 5% carvacrol aqueous solution (180 ml / mu, 800 times liquid), and combination agent: film preparation (90 ml / mu, 1000 times liquid) + 5% carvacrol aqueous solution (90 ml / mu, 1600 times liquid).

[0117] The application time of the pesticide was June 15, 2023. The population base of pests was investigated before pesticide application, and the pest population was investigated at 1 day, 7 days, 14 days, and 20 days after pesticide application. The reduction rate of pest population and the control effect were calculated. The control ability of the film preparation against Empoasca vitis and its ability to reduce the dosage and enhance the efficacy of the botanical pesticide carvacrol were evaluated. As can be seen from Table 9, the control effect of the film preparation against the target was comparable to that of the biogenic pesticide 5% carvacrol aqueous solution. The control effect against the target reached 81.56% at 1 day after pesticide application, with a maximum of 85.75%, and remained above 80% within 20 days after pesticide application. It can be applied to the control of Empoasca vitis in tea production and has high safety for tea growth. By compounding and spraying the film preparation with 5% carvacrol aqueous solution, it was found that the control effect of the compounded liquid against the target reached up to 94.52%, and the control effect remained above 90% at 20 days after pesticide application. This shows that the film preparation has a significant effect of reducing the dosage and enhancing the efficacy of pesticides such as carvacrol. While reducing the dosage of carvacrol pesticide by 50%, the control effect was significantly improved by 5-6 percentage points (p < 0.05). This indicates that the film preparation has great potential for individual use or as an adjuvant for reducing pesticide dosage and enhancing efficacy in the control of Empoasca vitis.

[0118] Table 9 Test results of the film preparation for controlling Empoasca vitis

[0119]

[0120] Application Example 5 Control effect of the film preparation against Diaphorina citri Kuwayama. and its effect on reducing pesticide dosage and enhancing efficacy

[0121] The experimental site was an orchard in Xinhui District, Jiangmen City, Guangdong Province. The adult citrus reticulata Blanco cv. Chachiensis trees were 8 years old. The field spray method was used, and 3 treatments were set up with the test agents: the film preparation of Example 1 (90 mg / kg), 5% carvacrol aqueous solution (62.5 mg / kg), and film preparation (45 mg / kg) + 5% carvacrol aqueous solution (31.25 mg / kg). The first application time was August 31, 2023 (the peak hatching period of psyllid eggs), and the second application time was September 10, 2023. The pest population base was investigated before applying the medicine, and the pest population was investigated 5 days, 10 days after the first application, and 5 days, 10 days, 15 days after the second application. The pest population reduction rate and control effect were calculated. The control ability of the film preparation against Diaphorina citri and the ability to reduce the amount and increase the efficiency of the plant oil pesticide carvacrol were evaluated. As can be seen from Table 10, the control effect of the film preparation on the target was equivalent to that of the biogenic pesticide 5% carvacrol aqueous solution. The control effect on the target reached 81.56% on the 1st day after applying the medicine, and the highest reached 85.75%. Moreover, it remained above 80% within 20 days after applying the medicine. It can be applied to the control of Empoasca flavescens in tea production, and it has high safety for tea growth. Through the compound spraying of the film preparation and 5% carvacrol aqueous solution, it was found that the control effect of the compound liquid on the target reached up to 100%, and the control effect remained above 98% 20 days after applying the medicine. It shows that the film preparation has a significant effect of reducing the amount and increasing the efficiency of pesticides such as carvacrol. While reducing the amount of carvacrol pesticide by 50%, the control effect was significantly increased by 18 percentage points (p < 0.01). It shows that the film preparation has great potential when used alone or as an adjuvant for reducing the amount and increasing the efficiency of pesticides in the control of Diaphorina citri.

[0122] Table 10 Test results of the film preparation for controlling Diaphorina citri

[0123]

[0124] Application Example 6 Application effect of the film preparation in the apple bag-free cultivation technology

[0125] The test was set up in the demonstration orchard of standard dwarfing red Fuji in the west of Lubai Village, Fengqi Sub-district Office, Luochuan County, Shaanxi Province, which is the apple research and development center of Yan'an City. The test object was the standard dwarfing red Fuji trees with a tree age of 10 years. 4 treatments (the film preparation of Example 2) were set up. The concentrations of the film preparation were 100-fold solution (Treatment 1), 200-fold solution (Treatment 2), 300-fold solution (Treatment 3), 400-fold solution (Treatment 4) and 1 clear water control. There were 5 replicates. Each treatment and the control started spraying the test agent before bagging the apples. When the fruit swelled and burst the outer film of the apple or was washed off by rain, it was sprayed again once. A total of 2 sprays were made.

[0126] During the fruit ripening period, apple fruits were sampled, and the photosynthesis and respiration of the leaves of each treatment and the control apple trees were measured. The sampled apple fruits were measured for indicators such as the weight of 100 fruits, fruit shape index, fruit surface color, fruit firmness, and soluble solid content, and the sampled leaves were measured for the fresh weight of 100 leaves. The results are shown in Tables 11 to 13. The statistical results in Table 11 show that the film preparation has no obvious effect on the photosynthetic rate of the leaves of Red Fuji apple trees, can significantly increase the fresh weight of 100 leaves, and reduce the defoliation rate of the fruit trees; Table 12 shows that there is no significant difference in the fruit surface color between the film preparation treatment and the conventional bagging (control 1) apples, and it has a certain promoting effect on the fruit firmness and soluble solid content.

[0127] Table 11 Effects on the Leaves of Red Fuji Apple Trees

[0128]

[0129] Table 12 Effects on the Fruit Surface Color of Apples

[0130]

[0131] Table 13 Effects on the Single Fruit Weight and Fruit Quality of Red Fuji Apples

[0132]

[0133] Application Example 7 Inhibitory Effect of Film Preparation on Anthracnose of Postharvest Mangoes

[0134] 1 Test Method

[0135] 1.1 Sample Preparation and Treatment

[0136] Take the film preparation prepared in Example 3 and add it to water to prepare an aqueous solution with a concentration of 1000 mg·L -1 (Take the fluid film preparation prepared in Example 1, add 1000 mg of water and make up the volume to 1 liter)

[0137] Select fruits with uniform size, no mechanical damage on the surface, and no pests and diseases. Set two treatment groups, with the film preparation treatment as the experimental group and the water treatment as the control group. The specific treatment methods are as follows:

[0138] Film Preparation Treatment Group: Prepare 60 mangoes, soak the fresh mangoes in the film preparation aqueous solution for 2 - 3 minutes, then take them out and drain until there is no dripping, and lay them flat in a fruit and vegetable storage box. During normal temperature storage, set the storage conditions of the box, maintain the humidity at 90% - 95%, and maintain the storage temperature at (25 ± 1)°C.

[0139] Water Treatment Group: Soak 60 fresh mangoes in water for 15 seconds, then take them out and air-dry them, and place them in a fruit and vegetable storage box. The storage conditions are exactly the same as those of the film preparation treatment group.

[0140] During the experiment, 4 time points were set for sampling (as shown in Table 14). The mango storage period was 12 days, and then the post-ripening quality of mangoes was measured. Among them, each time of mango sampling was not less than 10 pieces for quality determination. The treatment group and the control group were measured 3 times repeatedly, and the results were averaged.

[0141] Table 14 Setting of mango sampling time points

[0142]

[0143] 1.2 Determination of disease index

[0144] According to the ratio of fruit lesion area, it was stipulated as 4 levels: no lesion was level 0; the ratio of lesion area less than 10% was level 1, the ratio of lesion area 10% - 20% was level 2, the ratio of lesion area 20% - 50% was level 3; the ratio of lesion area greater than 50% was level 4.

[0145] 1.3 Determination of hardness

[0146] Select 1 cm thick fruit cuttings near the equator of each fruit, and use a texture analyzer to measure the hardness of mango fruits in the water treatment group and the film preparation treatment group. Measurement conditions: the probe model is P / 10 cylindrical probe, the mode is TPA, 12 fruits are measured in each group, the hardness unit is gf, and the measurement results are averaged.

[0147] 2 Results

[0148] 2.1 Effects of water treatment and film preparation treatment on the appearance of mangoes

[0149] From Figure 9 It can be visually seen that with the extension of the storage time, different degrees of anthracnose spots appeared in the water treatment group, and a large number of link phenomena of anthracnose spots appeared on the 12th day of normal temperature storage; while the film preparation treatment could significantly inhibit the ripening and yellowing of mangoes and inhibit the rotting of mangoes, and no obvious anthracnose spots were observed on the 12th day.

[0150] 2.2 Effects of water treatment and film preparation treatment on the incidence and disease index of mangoes

[0151] Figure 10 It shows that during the storage period, the incidence and disease index of mangoes in the film preparation treatment group were significantly lower than those in the water treatment group (p < 0.05). On the 8th day of normal temperature storage, the incidence and disease index of mangoes treated with the film preparation were 25.0% and 18.18% lower than those in the water treatment group respectively. It shows that during the storage process, the film preparation treatment can inhibit the disease of mangoes and delay the post-ripening and senescence of fruits.

[0152] 2.3 Effects of water treatment and film preparation treatment on the softening of mangoes

[0153] Softening is also a manifestation of rapid ripening and anthracnose rot in mangoes. As the storage time prolongs, the hardness of mangoes shows a downward trend. Figure 11 The results showed that from 4 to 12 days, the hardness of mangoes in the film preparation treatment group was significantly higher than that in the water treatment group (p < 0.05). The decreasing rates of mango hardness in the water treatment group and the film preparation treatment group were 54.24% and 52.87% respectively, and the decreasing rate of the film preparation treatment group was 1.37% lower than that of the water treatment group. This indicates that the film preparation treatment can effectively maintain the hardness of mangoes and prevent rapid softening and rot.

Claims

1. A nano-isolation slow-release film preparation suitable for plant disease and insect pest control and post-harvest preservation, characterized in that: The composition comprises the following components by weight: 5 to 10 parts of a modified film-forming agent, 1 to 5 parts of an active microemulsion, 5 to 10 parts of a filler, and 5 to 10 parts of water; The active microemulsion comprises the following components: by weight, 10 to 30 parts of emulsifier, 10 to 20 parts of 5-10wt% alkaline solution, 5 to 10 parts of thymol, and 2 to 5 parts of nanofluid iodine; the alkaline solution is KOH solution or NaOH solution; The filler is selected from nano calcium carbonate, calcium sulfate, superphosphate, and lime powder; The modified film-forming agent comprises, by weight, 10 to 20 parts of polyvinyl acetate emulsion or acetic acid acrylic emulsion, 5 to 10 parts of 1 to 2.5 wt% chitosan acetic acid solution, and 1 to 5 parts of 9 to 11 wt% ammonium persulfate solution; the solid content of the polyvinyl acetate emulsion is 18-45%; the solid content of the acetic acid acrylic emulsion is 40-60%; The preparation method of the modified film-forming agent comprises the following steps: adding polyvinyl acetate emulsion or vinyl acetate emulsion and chitosan acetic acid solution into a stirring reactor and heating to 60-90° C., fully emulsifying and reacting under stirring, then dripping ammonium persulfate solution, and after dripping, keeping the temperature to react until fully reacted; The preparation method of the active microemulsion comprises the following steps: mixing an emulsifier with an alkaline solution, then adding thymol, stirring to fully dissolve, and then adding nanofluid iodine, stirring to fully dissolve, to obtain the active microemulsion.

2. The nano-isolation sustained-release film preparation suitable for plant disease and insect pest control and post-harvest preservation according to claim 1, characterized in that: The emulsifier is OP-10 emulsifier.

3. The nano-isolation sustained-release film preparation suitable for plant disease and insect pest control and post-harvest preservation according to claim 1, characterized in that: The preparation method of the modified film-forming agent comprises the following steps: adding polyvinyl acetate emulsion or vinyl acetate emulsion and chitosan acetic acid solution into a stirring reactor and heating the reactor to 60-90°C, performing emulsification reaction for 30min-1h at a stirring speed of 150-300r / min, then dripping ammonium persulfate solution, and after the dripping is completed, keeping the temperature for reaction for 40min-90min to obtain the film-forming agent.

4. The method for preparing the nano-isolation sustained-release film preparation suitable for plant disease and insect pest control and post-harvest preservation according to claim 1, characterized in that: The steps include: Step 1: preparing an active microemulsion: taking 10 to 30 parts of an emulsifier and mixing with 10 to 20 parts of a 5 to 10 wt % alkaline solution, then adding 5 to 10 parts of thymol, stirring at a speed of 150 to 400 r / min to fully dissolve, and then adding 2 to 5 parts of nanofluid iodine and stirring to fully dissolve to obtain an active microemulsion; Step 2: Mix 5 to 10 parts of the modified film-forming agent with 5 to 10 parts of water, stir and dissolve them thoroughly to form a membrane matrix solution; mix 10 to 20 parts of the membrane matrix solution with 1 to 5 parts of the active microemulsion and stir them evenly, add 5 to 10 parts of filler, stir and mix them evenly to obtain the isolation sustained-release membrane; or, Step 2 is: take 5-10 parts of modified film-forming agent, 5-10 parts of water and 1-5 parts of active microemulsion, mix them and stir them evenly, add 5-10 parts of filler, stir and mix them evenly, and then obtain the isolation sustained-release membrane.

5. The preparation method according to claim 4, characterized in that: The preparation method of the nanofluid iodine is as follows: elemental iodine and a solvent are mixed in a mass ratio of 1:1 to 3, and the mixture is stirred and reacted at a temperature of 120 to 170° C. for 10 to 60 minutes. The product is cooled and then statically separated to obtain a lower layer of nanofluid iodine; the solvent is selected from one or more of dimethyl sulfoxide, diphenyl sulfone, triethanolamine, N-methylpyrrolidone, sulfolane, and N,N-dimethylformamide.

6. Application of the nano-isolation slow-release membrane preparation according to claim 1 in plant disease and insect pest control, characterized in that: Diseases include bacterial or fungal plant diseases, and insect pests include psyllids, plant hoppers, spider mites, leafhoppers, thrips and aphids.

7. The use according to claim 6, characterized in that: The spider mites include citrus red spider mites, the planthoppers include rice planthoppers, and the psyllids include citrus psyllids.

8. The use according to claim 7, characterized in that: The dosage of the nano-isolation slow-release film preparation for controlling rice planthoppers is 25-100 g·hm -1 ; The concentration of the nano-isolation sustained-release film preparation for controlling citrus red spider in the field is 5-20 g / kg.

9. The use according to claim 6, characterized in that: The nano-isolation slow-release membrane preparation is used in combination with other pesticides in the preparation of pesticides for preventing and controlling plant pests; the other pesticides include carvacrol.

10. The use according to claim 9, characterized in that: The mixed pesticide using the nano-state isolation sustained-release membrane preparation and carvacrol contains 45-90 mg / kg of the nano-state isolation sustained-release membrane preparation and 30-35 mg / kg of carvacrol.

11. The use according to claim 6, characterized in that: The plant bacterial diseases include cucumber bacterial angular leaf spot, and the fungal diseases include tomato gray mold, tobacco powdery mildew and potato late blight.

12. The use according to claim 11, characterized in that: When controlling bacterial or fungal diseases of plants in the field, the dosage of the nano-isolation slow-release film preparation is 50-120 ml / mu.

13. Use of the nano-isolation sustained-release film preparation according to claim 1 as a substitute for apple bagging raw materials in apple bagging-free technology, characterized in that: Fruits sprayed with nano-isolation sustained-release film preparations do not need to be bagged during the entire growing period.

14. The use according to claim 13, characterized in that: Before bagging apples, spray the nano-isolation sustained-release membrane preparation at a concentration of 100 to 500 times, and spray again when the fruit is in the expansion stage or washed away by rain.

15. Use of the nano-isolation sustained-release film preparation according to claim 1 as a preservative for post-harvest vegetables and fruits.

16. Use according to claim 15, characterized in that: The concentration of the film preparation in the fresh-keeping preservative prepared by the film preparation is 800-1200 mg·L -1 ; Application method: Soak the picked fruits in 800-1200mg·L -1 Soak the membrane in the aqueous solution of the membrane preparation for 2 to 5 minutes, then take out, dry and store.

Images