A fruit tree antiviral powder and method of application

Abstract

The application discloses a kind of fruit tree antiviral powder and application method, belong to fruit tree disease green prevention and control technical field.The powder includes following component weight part: chitosan oligosaccharide 5-15 parts, algal polysaccharide 3-10 parts, betaine 2-8 parts, complex trace element 10-20 parts, anti-caking agent 1-2 parts;The chitosan oligosaccharide molecular weight is less than or equal to 3200Da, and degree of deacetylation is greater than or equal to 85%;The algal polysaccharide is from brown algae, and molecular weight is 10000-20000Da;The complex trace element is EDTA chelate state, and the weight ratio of each element is Zn:B:Mn:Fe=3:2:1:1.5;The fruit tree antiviral powder and application method of the application, by the four-component compounding of specific parameters, construct multi-layer closed loop prevention and control, eliminate polysaccharide compounding static complex inactivation, film forming and permeability cannot be obtained, active component proportion is low, crushing thermal degradation and other technical problems, realize the green, efficient, whole cycle systematic prevention and control of fruit tree virus disease, while giving consideration to nutrition supplement and fruit quality improvement.

Description

Technical Field

[0001] This invention specifically relates to an antiviral powder for fruit trees and its application method, belonging to the field of green prevention and control technology for fruit tree diseases. Background Technology

[0002] Fruit tree viral diseases are key factors restricting the improvement of quality and efficiency in the fruit industry. They are characterized by strong latency, wide transmission routes, and the lack of specific treatments. After fruit trees are infected with viruses, symptoms such as weakened tree vigor, yellowing and curling of leaves, deformed fruit, and reduced yield will appear. In severe cases, it can lead to the complete loss of the entire orchard. Moreover, the virus can spread through multiple routes such as scions, seedlings, insects, and sap, and is mostly a systemic infection. It can remain latent in the tree for a long time and be transported with the tree's metabolism, making prevention and control extremely difficult. Currently, the prevention and control of fruit tree viral diseases mainly relies on two types of technical means, both of which have obvious shortcomings: Chemical pesticide control: Most of the chemical pesticides used are virus inhibitors. Although they can inhibit virus replication in the short term, they are prone to pesticide residues and induce virus resistance. They also damage the orchard micro-ecology and natural enemy populations, which is not in line with the development trend of green agriculture and organic agriculture. Moreover, most chemical antiviral agents are water-based, which have high storage and transportation costs and the active ingredients are easily degraded and inactivated, making them unsuitable for mechanized spraying operations in large-scale orchards. Nutritional induced resistance products for prevention and control: Existing products mostly use single polysaccharide components such as chitosan oligosaccharide or seaweed polysaccharide. This is because chitosan oligosaccharide and seaweed polysaccharide are both macromolecular polysaccharide inducers. When combined, they will compete for plant cell receptors and absorption channels, which can easily lead to functional redundancy or even absorption antagonism. In addition, due to electrostatic complexation, macromolecular flocculation and precipitation can occur, making it difficult to significantly improve the prevention and control efficacy. However, the defense system of single polysaccharide components is limited, with weak induced resistance and unstable prevention and control efficacy.

[0003] In addition, existing nutrient-induced resistance products are all in aqueous formulation because the biostimulants in powder formulation dissolve slowly and have poor leaf penetration, resulting in lower actual bioavailability and efficacy compared to aqueous formulations. Therefore, almost all existing antiviral induced resistance products are in aqueous formulation, sacrificing storage and transportation stability and shelf life. Summary of the Invention

[0004] To address the aforementioned issues, this invention proposes an antiviral powder for fruit trees and its application method. By constructing a multi-layered closed-loop control system through the compounding of four components with specific parameters, it eliminates technical problems such as electrostatic complexation inactivation of polysaccharides, the incompatibility between film formation and permeability, low proportion of active components, and thermal degradation during pulverization. This achieves green, efficient, and full-cycle systematic control of viral diseases in fruit trees, while also taking into account nutritional supplementation and fruit quality improvement.

[0005] The present invention relates to an antiviral powder for fruit trees, comprising the following components by weight: 5-15 parts chitosan oligosaccharide, 3-10 parts seaweed polysaccharide, 2-8 parts betaine, 10-20 parts complex trace elements, and 1-2 parts anti-caking agent; wherein the chitosan oligosaccharide has a molecular weight ≤3200 Da and a degree of deacetylation ≥85%; the seaweed polysaccharide is derived from brown algae and has a molecular weight of 10000-20000 Da; and the complex trace elements are in EDTA chelated form, with a weight ratio of Zn:B:Mn:Fe = 3:2:1:1.5. The preparation steps of the powder are as follows: chitosan oligosaccharide, seaweed polysaccharide and betaine are ultra-finely pulverized to a particle size ≤100μm and then mixed evenly. Compound trace elements and anti-caking agent are added, and after stirring evenly, the mixture is dried at 45-50℃ until the moisture content is ≤5%.

[0006] I. The functions of each component in the antiviral powder for fruit trees of the present invention are as follows: Chitosan oligosaccharides, as a core plant immune elicitor, can specifically recognize pattern recognition receptors (PRRs) on the cell membranes of fruit tree leaves and roots, triggering a dual resistance signaling pathway mediated by salicylic acid (SA) and jasmonic acid (JA), inducing the synthesis and accumulation of disease resistance-related substances such as pathogenesis-associated proteins (PR proteins), phytoalexins, and phenylalanine ammonia-lyase (PAL); simultaneously, they can directly bind to the active site of viral RNA replicase, interfering with viral replication and assembly within cells, blocking viral proliferation at the endogenous level, and inducing plants to acquire systemic resistance; (Molecular weight is limited) ≤3200Da and degree of deacetylation ≥85% are the basic parameters to ensure its membrane permeability and receptor binding activity. Further optimization is to select components with a degree of polymerization of 3-10 with a proportion of ≥70%. Chitosan oligosaccharides in this degree of polymerization range have the strongest affinity for plant cell membrane receptors and the highest immune-stimulating activity. This is the precise control for achieving efficient induction of resistance. That is, if the degree of polymerization is lower than 3, the half-life is short and the duration of efficacy is poor. If the degree of polymerization is higher than 10, it is difficult to penetrate the cell wall and the activity drops sharply. This solves the problem that traditional antiviral powders cannot achieve stable and efficient induction of resistance because they do not have precise control over the degree of polymerization range of activity. Seaweed polysaccharides: Utilizing seaweed polysaccharides derived from brown algae, these polysaccharides possess dual defense functions: extracellular barrier and immune induction. On one hand, they can rapidly form a dense, continuous biopolysaccharide membrane on the surface of fruit tree leaves and fruits, physically blocking the contact between virus particles and cell surface receptors, preventing virus adsorption and invasion, and constructing the first line of extracellular defense. On the other hand, they can induce lignification of fruit tree cell walls and pectin cross-linking, thickening the cell wall structure and enhancing the physical defense capabilities of cells. Simultaneously, as an immune elicitor, they induce a defensive response in plants, complementing the immune pathway of chitosan oligosaccharides and strengthening systemic resistance levels. The preferred formulation is brown algae oligosaccharides and... The alginate is compounded in a 1:2 weight ratio: small molecular weight alginate (3000-5000 Da) can quickly penetrate into the mesophyll tissue to exert an immune-inducing effect, and its immune pathway is superimposed with that of chitosan oligosaccharide; large molecular weight alginate (15000-20000 Da) remains on the plant surface to form a continuous and dense barrier film, exerting a physical barrier effect. The dual molecular weight compound solves the problem that single molecular weight seaweed polysaccharides cannot simultaneously achieve film-forming properties and permeability, realizing the dual functions of surface blocking and internal induction of resistance. By combining with chitosan oligosaccharide, the synergistic effect of internal and external defense can be further enhanced. Betaine: As a small molecule osmotic regulator and synergist, it can regulate the osmotic pressure of leaf epidermal cells, soften the gaps in the lipid bilayer of the cuticle, and promote the rapid penetration of macromolecular active ingredients such as chitosan oligosaccharides and seaweed polysaccharides into the mesophyll and phloem through the leaf cuticle, significantly improving the absorption and utilization rate of effective ingredients and the whole-plant translocation efficiency, thus solving the problem of low leaf absorption efficiency of macromolecular polysaccharides. On the other hand, it can stabilize the spatial structure of intracellular proteins and enzymes, maintain the normal physiological metabolism of cells under viral stress, alleviate photosynthetic inhibition and physiological disorders caused by viral infection, enhance the tree's abiotic resistance, and prevent the explosive aggravation of viral diseases when accompanied by stresses such as high temperature and drought. In addition, betaine is an amphoteric compound. When it is pre-coated on the surface of chitosan oligosaccharide particles in the preparation process, it can prevent electrostatic complexation between chitosan oligosaccharides and seaweed polysaccharides during dissolution through charge shielding, thereby achieving the effects of promoting penetration, resisting stress, and preventing complexation. Compound micronutrients: EDTA chelation is used to avoid chemical reactions and absorption antagonism between elements, ensuring efficient absorption and utilization of each element and providing precise nutritional support for the fruit tree's antiviral process. Zinc is a coenzyme factor for various disease-resistant enzymes, participating in the synthesis of phytoalexins and defense enzymes, and enhancing the strength of the immune response. Boron maintains the integrity of cell membrane structure and pollen tube development, reducing the pathways for viral infection through floral organs. Manganese and iron participate in plant photosynthesis and the construction of antioxidant enzyme systems (SOD, POD, CAT), clearing reactive oxygen species generated by viral stress, maintaining normal energy metabolism in the tree, providing sufficient material and energy support for the immune defense response, and preventing tree vigor decline during the induced resistance process. The compound micronutrients are precisely matched to the nutrient consumption rhythm during the fruit tree's antiviral process, achieving a balance between nutrient supply and immune requirements. Anti-caking agent: selected from magnesium aluminum silicate or diatomaceous earth, used to improve the storage stability of powder, prevent the product from getting damp and clumping, and ensure the solubility and use effect within the shelf life.

[0007] II. The synergistic effects of the components of the antiviral powder for fruit trees of the present invention are as follows: 1. Synergistic Internal and External Defense: External blocking and internal inhibition, a double-layered barrier to prevent viral infection. Seaweed polysaccharides construct a continuous physical barrier on the extracellular surface and plant surface, blocking the adsorption and invasion of viral particles, which constitutes the first line of extracellular defense. Chitosan oligosaccharides enter the cell to activate immune signaling pathways and directly inhibit viral replication, which constitutes the second line of intracellular defense. The two form a double-layered defense structure that blocks extracellular invasion and inhibits intracellular proliferation. Compared with single components, this achieves complementary prevention and control dimensions and greatly improves the blocking efficiency of viral infection. At the same time, through precise molecular weight matching, it avoids absorption competition and functional redundancy between macromolecules, and breaks through the technical problem of easy antagonism in polysaccharide complexes. Even if a small number of viruses break through the physical barrier, they will be quickly inhibited by the intracellular immune system and will not be able to complete replication and systemic spread. 2. Synergistic Absorption and Transduction: Enhancing Penetration and Amplifying the Activity of Core Components. Betaine, by regulating the permeability of the cuticle, fundamentally solves the technical problems of low absorption efficiency and slow transduction of macromolecular components such as chitosan oligosaccharides and seaweed polysaccharides on the leaf surface. This allows both to quickly enter the plant and be transduced to all tissues of the plant through the phloem, fully exerting their immune-stimulating activity and avoiding the residue and waste of effective components on the leaf surface due to photosynthesis. At the same time, the stress-resistant effect of betaine itself can alleviate the damage to cells caused by viral stress, providing a stable cellular physiological environment for immune components to exert their effects, and indirectly improving the prevention and control effect.

[0008] 3. Synergistic effect of immunity and nutrition: Inducing resistance and supplementing nutrition to form a positive defense cycle: The immune defense response induced by chitosan oligosaccharide and seaweed polysaccharide consumes a lot of nutrients and energy in plants. If the nutrient supply is insufficient, not only will the inducing resistance effect be difficult to sustain, but it may also lead to tree decline and viral disease rebound. The specific ratio of chelated trace elements in this invention can specifically supplement the key mineral elements required in the disease resistance process, strengthen the antioxidant system and photosynthetic efficiency, and provide continuous material and energy support for the immune response. At the same time, after the tree vigor is improved, the plant's own basic resistance is further enhanced, which in turn amplifies the effect of immune induction and resistance, forming a positive cycle of inducing resistance activation, nutrient supply and resistance enhancement, making the prevention effect more stable and lasting, and solving the problem of short duration of prevention effect of existing products.

[0009] 4. Synergistic effect of stress resistance and disease prevention: It alleviates stress and reduces the risk of viral outbreaks. The osmotic regulation effect of betaine and the nutritional effect of trace elements work together to enhance the abiotic stress resistance of fruit trees (high temperature, drought, low temperature, etc.). In field production, environmental stress often exacerbates the occurrence and damage of viral diseases. The weakened tree vigor under stress leads to massive viral replication and rapid onset of symptoms. Existing antiviral products usually experience a drop in efficacy of more than 50% under stress. This invention indirectly reduces the risk and severity of viral disease outbreaks by alleviating environmental stress and maintaining normal cellular physiological metabolism. It forms an indirect synergy with the core antiviral components, ensuring the stability of efficacy under stress conditions.

[0010] 5. Preventing electrostatic complexation: When betaine is pre-coated on the surface of chitosan oligosaccharide particles during the preparation process, it can prevent electrostatic complexation between chitosan oligosaccharide and seaweed polysaccharide during dissolution through charge shielding, thereby achieving the effects of promoting penetration, resisting stress and preventing complexation.

[0011] Furthermore, the powder comprises the following components in parts by weight: 8-12 parts chitosan oligosaccharide, 5-8 parts seaweed polysaccharide, 4-6 parts betaine, and 12-18 parts complex trace elements.

[0012] Furthermore, the anti-caking agent is magnesium aluminum silicate or diatomaceous earth.

[0013] Further, the preparation steps are as follows: first, chitosan oligosaccharide and betaine are mixed in a certain proportion and then ultra-finely pulverized to a particle size ≤100μm, so that betaine is uniformly coated on the surface of chitosan oligosaccharide particles to form composite micro powder; then, the composite micro powder is stirred and mixed evenly with seaweed polysaccharide, composite trace elements, and anti-caking agent, and dried to a moisture content ≤5%; in view of the problems of easy electrostatic complexation and thermal degradation during the pulverization process when chitosan oligosaccharide and seaweed polysaccharide are directly compounded, the preparation of the fruit tree antiviral powder of the present invention adopts a step-by-step coating process: first, chitosan oligosaccharide and betaine are mixed in a certain proportion and then ultra-finely pulverized together to control the particle size ≤100μm; during the co-pulverization process, small molecule betaine will be uniformly adsorbed and coated on the surface of chitosan oligosaccharide particles, and by utilizing its own zwitterionic properties, the positive charge on the surface of chitosan oligosaccharide is completely shielded to form betaine. The process involves combining chitosan oligosaccharide with micro-powder. This step utilizes the zwitterionic properties of betaine components, which promote penetration and resist stress, to achieve the complexation of chitosan oligosaccharide and seaweed polysaccharide at the formulation level through co-pulping and coating. No additional dispersants or anti-flocculation agents are required. After this step, the chitosan oligosaccharide and seaweed polysaccharide do not undergo electrostatic complexation when the powder dissolves, maintaining a single-molecule dispersion state. This ensures no precipitation or nozzle clogging during spraying and fully preserves the bioactivity of both, maximizing their synergistic effect. The aforementioned micro-powder, along with seaweed polysaccharide, EDTA-chelated trace elements, and an anti-caking agent, are added to a mixer and mixed at 200 rpm for 15 minutes until the material is uniform. The mixed material is then dried at 45-50℃ until the moisture content is ≤5%, yielding the finished powder.

[0014] Furthermore, the mass ratio of chitosan oligosaccharide to betaine is 2:1. At this ratio, betaine forms a monolayer that completely coats the surface of the chitosan oligosaccharide particles, achieving the best charge shielding effect. If the ratio is too low, the shielding will be incomplete, and complexation will still occur. If the ratio is too high, it will cause betaine redundancy, which will change the osmotic pressure of the solution and affect the absorption efficiency.

[0015] Furthermore, the ultrafine pulverization is a low-temperature airflow ultrafine pulverization, in which the material temperature is always ≤40℃ during the pulverization process. Compared with ordinary mechanical pulverization, airflow pulverization achieves ultrafine powder through high-speed airflow collision, without mechanical friction generating heat. Combined with low-temperature control, it can completely avoid the thermal degradation of heat-sensitive active ingredients such as chitosan oligosaccharides and seaweed polysaccharides, while preventing betaine from melting and agglomerating when heated, ensuring uniform powder particle size, consistent coating effect, and high retention of active ingredients.

[0016] A method for applying an antiviral powder to fruit trees, wherein the application of the antiviral powder to fruit trees completes the full-cycle protection based on the complete infection cycle of fruit tree virus overwintering in the roots, initial infection at bud break, transmission during flowering, and symptoms appearing in young fruit, combined with the physiological characteristics and virus infection risk of fruit trees at different growth stages, thereby maximizing the control effect of the antiviral powder to fruit trees of this invention; the application method includes the following steps: S1 Pre-budding root irrigation: Dilute the powder at a ratio of 1:100-200, and apply 100-250 grams of powder per diseased tree around the drip line of the fruit tree; This step targets the characteristics of fruit tree virus systemic infection and root overwintering with the virus, activates the tree's overall immunity through root absorption, promotes the growth of new roots, eliminates overwintering viruses from the endogenous source, and enhances the tree's basic resistance; S2 Pre-budding spray: Dilute the powder at a ratio of 1:1000-1200 and spray it on the entire fruit tree. The amount of spray should be enough to moisten the branches and buds, that is, spray the entire fruit tree evenly. The amount of spray should be enough to moisten the surface of the branches and buds without dripping. This step is used to clean the orchard and disinfect the overwintering virus base on the surface of the branches, activate the disease resistance system of the tree during the dormant period, and reduce the risk of initial virus infection during the budding period. S3 application before and after flowering: Dilute the powder at a ratio of 1:800-1000 and spray it once 7 days before flowering and once 10 days after flowering. Focus on spraying the flower spikes and the back of the leaves. The flowering period is a high-risk period for insect transmission of viruses and infection of flower parts. Applying it at this stage can block the virus from infecting through flower parts and also has the effect of protecting flowers and fruits.

[0017] S4 application during the young fruit enlargement stage: Dilute the powder at a ratio of 1:600-800 and spray 1-2 times, with an interval of 10-15 days between the two applications. Focus on spraying the fruit and leaves to inhibit virus replication and reduce deformed fruit. This stage is the critical period for fruit deformity caused by viral symptoms. After application, it can enhance the resistance and defense capabilities of fruit cells, inhibit virus replication in the fruit, reduce deformed fruit caused by viral diseases, and improve the appearance quality and marketability of the fruit.

[0018] Furthermore, the optimal spraying time for each step is 6-8 am or 6-8 pm to avoid periods of high temperature and strong sunlight, thereby reducing photolysis and evaporation of active ingredients and improving absorption efficiency. When diluting the powder, use warm water at 25-30℃, control the stirring speed at 150-200 r / min, and dissolve for 10-15 minutes to ensure that the powder is completely dissolved without precipitation, which is suitable for large-scale operations.

[0019] Furthermore, the spraying time for each step of the application method is 6-8 am or 6-8 pm; the powder is dissolved in warm water at 25-30℃, the stirring speed is 150-200 r / min, and the dissolution time is 10-15 minutes.

[0020] Compared with the prior art, the antiviral powder for fruit trees and its application method of the present invention have the following advantages: 1. Synergistic effect of compound polysaccharides, betaine and trace elements: By combining chitosan oligosaccharides with a specific degree of polymerization, dimolecular-weight seaweed polysaccharides, betaine and chelated trace elements, the technical problems of easy antagonism in the compounding of polysaccharide inducers and the lower efficacy of powdered formulations compared to aqueous formulations are solved. The efficacy of viral disease control is increased by more than 30% compared to single chitosan oligosaccharide products and by more than 20% compared to compound products of binary polysaccharides. Field trials show that under normal conditions, the incidence of fruit tree viral diseases is reduced by 40%-50%, the rate of deformed fruit is reduced by more than 35%, and the efficacy can still be maintained at more than 80% under high temperature and drought adversity.

[0021] 2. Solving the problem of mutual interference between compound formulations and improving the quality of formulation application: A step-by-step coating mixing method is adopted, utilizing the zwitterionic properties of betaine to completely solve the technical problem of electrostatic complexation and inactivation when compounding chitosan oligosaccharides and seaweed polysaccharides without adding new components, so as to fully release the synergistic activity of polysaccharide compounding; the dual molecular weight seaweed polysaccharide components solve the technical problem of the incompatibility between film-forming properties and permeability; combined with low-temperature airflow pulverization process, the heat-sensitive active ingredients are maximized to retain them; thus, the formulation's solubility stability, bioavailability, and activity retention rate are all significantly improved.

[0022] 3. Precise control of active components significantly improves efficacy and stability: The active polymerization range (3-10 polymers) of chitosan oligosaccharide is precisely optimized, changing the common average molecular weight structure, ensuring high efficiency and stability of immune-inducing activity, solving the problem of large batch-to-batch efficacy fluctuations in existing products, and forming a positive match with the overall synergistic system.

[0023] 4. Comprehensive and systematic prevention and control throughout the entire growth cycle, significantly enhancing long-term effectiveness: Targeting the complete infection cycle of fruit tree viruses, a sequential system of root drenching for disinfection, orchard sanitation for prevention, flowering interruption, and young fruit consolidation is applied. This combines above-ground control with underground disinfection, avoiding the problems of foliar protection alone, inability to eliminate endogenous viruses, and easy rebound of prevention efficacy. The concentration gradient application at different growth stages precisely matches the physiological characteristics and infection risks of fruit trees at each stage, achieving precise prevention and control throughout the entire growth cycle, with stable and long-lasting efficacy.

[0024] 5. Green and safe, with dual benefits of disease prevention and quality improvement: The product contains no chemical pesticides, leaves no residue, does not cause drug resistance, and does not damage the orchard ecosystem, meeting the production requirements of green food and organic agriculture; while controlling viral diseases, it can supplement the fruit trees with a variety of key trace elements needed for growth, improve tree vigor, and increase the sugar content of the fruit by 1-2 degrees, achieving synergistic benefits of disease prevention and quality improvement. Detailed Implementation

[0025] The present invention relates to an antiviral powder for fruit trees, comprising the following components by weight: 5-15 parts chitosan oligosaccharide, 3-10 parts seaweed polysaccharide, 2-8 parts betaine, 10-20 parts complex trace elements, and 1-2 parts anti-caking agent; wherein the chitosan oligosaccharide has a molecular weight ≤3200 Da and a degree of deacetylation ≥85%; the seaweed polysaccharide is derived from brown algae and has a molecular weight of 10000-20000 Da; and the complex trace elements are in EDTA chelated form, with a weight ratio of Zn:B:Mn:Fe = 3:2:1:1.5. The preparation steps of the powder are as follows: chitosan oligosaccharide, seaweed polysaccharide and betaine are ultra-finely pulverized to a particle size ≤100μm and then mixed evenly. Compound trace elements and anti-caking agent are added, and after stirring evenly, the mixture is dried at 45-50℃ until the moisture content is ≤5%.

[0026] I. The functions of each component in the antiviral powder for fruit trees of the present invention are as follows: Chitosan oligosaccharides, as a core plant immune elicitor, can specifically recognize pattern recognition receptors (PRRs) on the cell membranes of fruit tree leaves and roots, triggering a dual resistance signaling pathway mediated by salicylic acid (SA) and jasmonic acid (JA), inducing the synthesis and accumulation of disease resistance-related substances such as pathogenesis-associated proteins (PR proteins), phytoalexins, and phenylalanine ammonia-lyase (PAL); simultaneously, they can directly bind to the active site of viral RNA replicase, interfering with viral replication and assembly within cells, blocking viral proliferation at the endogenous level, and inducing plants to acquire systemic resistance; (Molecular weight is limited) ≤3200Da and degree of deacetylation ≥85% are the basic parameters to ensure its membrane permeability and receptor binding activity. Further optimization is to select components with a degree of polymerization of 3-10 with a proportion of ≥70%. Chitosan oligosaccharides in this degree of polymerization range have the strongest affinity for plant cell membrane receptors and the highest immune-stimulating activity. This is the precise control for achieving efficient induction of resistance. That is, if the degree of polymerization is lower than 3, the half-life is short and the duration of efficacy is poor. If the degree of polymerization is higher than 10, it is difficult to penetrate the cell wall and the activity drops sharply. This solves the problem that traditional antiviral powders cannot achieve stable and efficient induction of resistance because they do not have precise control over the degree of polymerization range of activity. Seaweed polysaccharides: Utilizing seaweed polysaccharides derived from brown algae, these polysaccharides possess dual defense functions: extracellular barrier and immune induction. On one hand, they can rapidly form a dense, continuous biopolysaccharide membrane on the surface of fruit tree leaves and fruits, physically blocking the contact between virus particles and cell surface receptors, preventing virus adsorption and invasion, and constructing the first line of extracellular defense. On the other hand, they can induce lignification of fruit tree cell walls and pectin cross-linking, thickening the cell wall structure and enhancing the physical defense capabilities of cells. Simultaneously, as an immune elicitor, they induce a defensive response in plants, complementing the immune pathway of chitosan oligosaccharides and strengthening systemic resistance levels. The preferred formulation is brown algae oligosaccharides and... The alginate is compounded in a 1:2 weight ratio: small molecular weight alginate (3000-5000 Da) can quickly penetrate into the mesophyll tissue to exert an immune-inducing effect, and its immune pathway is superimposed with that of chitosan oligosaccharide; large molecular weight alginate (15000-20000 Da) remains on the plant surface to form a continuous and dense barrier film, exerting a physical barrier effect. The dual molecular weight compound solves the problem that single molecular weight seaweed polysaccharides cannot simultaneously achieve film-forming properties and permeability, realizing the dual functions of surface blocking and internal induction of resistance. By combining with chitosan oligosaccharide, the synergistic effect of internal and external defense can be further enhanced. Betaine: As a small molecule osmotic regulator and synergist, it can regulate the osmotic pressure of leaf epidermal cells, soften the gaps in the lipid bilayer of the cuticle, and promote the rapid penetration of macromolecular active ingredients such as chitosan oligosaccharides and seaweed polysaccharides into the mesophyll and phloem through the leaf cuticle, significantly improving the absorption and utilization rate of effective ingredients and the whole-plant translocation efficiency, thus solving the problem of low leaf absorption efficiency of macromolecular polysaccharides. On the other hand, it can stabilize the spatial structure of intracellular proteins and enzymes, maintain the normal physiological metabolism of cells under viral stress, alleviate photosynthetic inhibition and physiological disorders caused by viral infection, enhance the tree's abiotic resistance, and prevent the explosive aggravation of viral diseases when accompanied by stresses such as high temperature and drought. In addition, betaine is an amphoteric compound. When it is pre-coated on the surface of chitosan oligosaccharide particles in the preparation process, it can prevent electrostatic complexation between chitosan oligosaccharides and seaweed polysaccharides during dissolution through charge shielding, thereby achieving the effects of promoting penetration, resisting stress, and preventing complexation. Compound micronutrients: EDTA chelation is used to avoid chemical reactions and absorption antagonism between elements, ensuring efficient absorption and utilization of each element and providing precise nutritional support for the fruit tree's antiviral process. Zinc is a coenzyme factor for various disease-resistant enzymes, participating in the synthesis of phytoalexins and defense enzymes, and enhancing the strength of the immune response. Boron maintains the integrity of cell membrane structure and pollen tube development, reducing the pathways for viral infection through floral organs. Manganese and iron participate in plant photosynthesis and the construction of antioxidant enzyme systems (SOD, POD, CAT), clearing reactive oxygen species generated by viral stress, maintaining normal energy metabolism in the tree, providing sufficient material and energy support for the immune defense response, and preventing tree vigor decline during the induced resistance process. The compound micronutrients are precisely matched to the nutrient consumption rhythm during the fruit tree's antiviral process, achieving a balance between nutrient supply and immune requirements. Anti-caking agent: selected from magnesium aluminum silicate or diatomaceous earth, used to improve the storage stability of powder, prevent the product from getting damp and clumping, and ensure the solubility and use effect within the shelf life.

[0027] II. The synergistic effects of the components of the antiviral powder for fruit trees of the present invention are as follows: 1. Synergistic Internal and External Defense: External blocking and internal inhibition, a double-layered barrier to prevent viral infection. Seaweed polysaccharides construct a continuous physical barrier on the extracellular surface and plant surface, blocking the adsorption and invasion of viral particles, which constitutes the first line of extracellular defense. Chitosan oligosaccharides enter the cell to activate immune signaling pathways and directly inhibit viral replication, which constitutes the second line of intracellular defense. The two form a double-layered defense structure that blocks extracellular invasion and inhibits intracellular proliferation. Compared with single components, this achieves complementary prevention and control dimensions and greatly improves the blocking efficiency of viral infection. At the same time, through precise molecular weight matching, it avoids absorption competition and functional redundancy between macromolecules, and breaks through the technical problem of easy antagonism in polysaccharide complexes. Even if a small number of viruses break through the physical barrier, they will be quickly inhibited by the intracellular immune system and will not be able to complete replication and systemic spread. 2. Synergistic Absorption and Transduction: Enhancing Penetration and Amplifying the Activity of Core Components. Betaine, by regulating the permeability of the cuticle, fundamentally solves the technical problems of low absorption efficiency and slow transduction of macromolecular components such as chitosan oligosaccharides and seaweed polysaccharides on the leaf surface. This allows both to quickly enter the plant and be transduced to all tissues of the plant through the phloem, fully exerting their immune-stimulating activity and avoiding the residue and waste of effective components on the leaf surface due to photosynthesis. At the same time, the stress-resistant effect of betaine itself can alleviate the damage to cells caused by viral stress, providing a stable cellular physiological environment for immune components to exert their effects, and indirectly improving the prevention and control effect.

[0028] 3. Synergistic effect of immunity and nutrition: Inducing resistance and supplementing nutrition to form a positive defense cycle: The immune defense response induced by chitosan oligosaccharide and seaweed polysaccharide consumes a lot of nutrients and energy in plants. If the nutrient supply is insufficient, not only will the inducing resistance effect be difficult to sustain, but it may also lead to tree decline and viral disease rebound. The specific ratio of chelated trace elements in this invention can specifically supplement the key mineral elements required in the disease resistance process, strengthen the antioxidant system and photosynthetic efficiency, and provide continuous material and energy support for the immune response. At the same time, after the tree vigor is improved, the plant's own basic resistance is further enhanced, which in turn amplifies the effect of immune induction and resistance, forming a positive cycle of inducing resistance activation, nutrient supply and resistance enhancement, making the prevention effect more stable and lasting, and solving the problem of short duration of prevention effect of existing products.

[0029] 4. Synergistic effect of stress resistance and disease prevention: It alleviates stress and reduces the risk of viral outbreaks. The osmotic regulation effect of betaine and the nutritional effect of trace elements work together to enhance the abiotic stress resistance of fruit trees (high temperature, drought, low temperature, etc.). In field production, environmental stress often exacerbates the occurrence and damage of viral diseases. The weakened tree vigor under stress leads to massive viral replication and rapid onset of symptoms. Existing antiviral products usually experience a drop in efficacy of more than 50% under stress. This invention indirectly reduces the risk and severity of viral disease outbreaks by alleviating environmental stress and maintaining normal cellular physiological metabolism. It forms an indirect synergy with the core antiviral components, ensuring the stability of efficacy under stress conditions.

[0030] 5. Preventing electrostatic complexation: When betaine is pre-coated on the surface of chitosan oligosaccharide particles during the preparation process, it can prevent electrostatic complexation between chitosan oligosaccharide and seaweed polysaccharide during dissolution through charge shielding, thereby achieving the effects of promoting penetration, resisting stress and preventing complexation.

[0031] The powder comprises the following components in parts by weight: 8-12 parts chitosan oligosaccharide, 5-8 parts seaweed polysaccharide, 4-6 parts betaine, and 12-18 parts complex trace elements.

[0032] The anti-caking agent is magnesium aluminum silicate or diatomaceous earth.

[0033] The specific preparation steps are as follows: First, chitosan oligosaccharide and betaine are mixed in a certain proportion and then ultra-finely pulverized to a particle size ≤100μm, so that betaine is uniformly coated on the surface of chitosan oligosaccharide particles to form composite micro powder; then, the composite micro powder is stirred and mixed evenly with seaweed polysaccharide, composite trace elements, and anti-caking agent, and dried to a moisture content ≤5%; In view of the problems of easy electrostatic complexation and thermal degradation during the pulverization process when chitosan oligosaccharide and seaweed polysaccharide are directly compounded, the preparation of the fruit tree antiviral powder of the present invention adopts a step-by-step coating process: First, chitosan oligosaccharide and betaine are mixed in a certain proportion and then ultra-finely pulverized together to control the particle size ≤100μm; during the co-pulverization process, small molecule betaine will be uniformly adsorbed and coated on the surface of chitosan oligosaccharide particles, and by utilizing its own zwitterionic properties, the positive charge on the surface of chitosan oligosaccharide is completely shielded, forming betaine and chitosan oligosaccharide. Sugar-composite micro powder: This step utilizes the zwitterionic properties of betaine components, which promote penetration and resist stress, to achieve the complexation of chitosan oligosaccharide and seaweed polysaccharide at the formulation level through co-pulping and coating. No additional dispersants or anti-flocculation agents are needed. After this step, chitosan oligosaccharide and seaweed polysaccharide will not undergo electrostatic complexation when the powder dissolves, and will always maintain a single-molecule dispersion state. This ensures that there is no precipitation or nozzle clogging during spraying, and fully preserves the biological activity of both, so as to give full play to the synergistic effect. The above-mentioned composite micro powder, seaweed polysaccharide, EDTA chelated trace element combination, and anti-caking agent are put into a mixer and mixed at a stirring speed of 200r / min for 15min until the material is uniform. The mixed material is then dried at 45-50℃ until the moisture content is ≤5% to obtain the finished powder.

[0034] The mass ratio of chitosan oligosaccharide to betaine is 2:1. At this ratio, betaine forms a monolayer that completely coats the surface of the chitosan oligosaccharide particles, achieving the best charge shielding effect. If the ratio is too low, the shielding will be incomplete, and complexation will still occur. If the ratio is too high, it will cause betaine redundancy, which will change the osmotic pressure of the solution and affect the absorption efficiency.

[0035] The ultrafine pulverization is a low-temperature airflow ultrafine pulverization, in which the material temperature is always ≤40℃ during the pulverization process. Compared with ordinary mechanical pulverization, airflow pulverization achieves ultrafine powder through high-speed airflow collision, without mechanical friction generating heat. Combined with low temperature control, it can completely avoid the thermal degradation of heat-sensitive active ingredients such as chitosan oligosaccharides and seaweed polysaccharides, while preventing betaine from melting and agglomerating when heated, ensuring uniform powder particle size, consistent coating effect, and high retention of active ingredients.

[0036] A method for applying an antiviral powder to fruit trees, wherein the application of the antiviral powder to fruit trees completes the full-cycle protection based on the complete infection cycle of fruit tree virus overwintering in the roots, initial infection at bud break, transmission during flowering, and symptoms appearing in young fruit, combined with the physiological characteristics and virus infection risk of fruit trees at different growth stages, thereby maximizing the control effect of the antiviral powder to fruit trees of this invention; the application method includes the following steps: S1 Pre-budding root irrigation: Dilute the powder at a ratio of 1:100-200, and apply 100-250 grams of powder per diseased tree around the drip line of the fruit tree; This step targets the characteristics of fruit tree virus systemic infection and root overwintering with the virus, activates the tree's overall immunity through root absorption, promotes the growth of new roots, eliminates overwintering viruses from the endogenous source, and enhances the tree's basic resistance; S2 Pre-budding spray: Dilute the powder at a ratio of 1:1000-1200 and spray it on the entire fruit tree. The amount of spray should be enough to moisten the branches and buds, that is, spray the entire fruit tree evenly. The amount of spray should be enough to moisten the surface of the branches and buds without dripping. This step is used to clean the orchard and disinfect the overwintering virus base on the surface of the branches, activate the disease resistance system of the tree during the dormant period, and reduce the risk of initial virus infection during the budding period. S3 application before and after flowering: Dilute the powder at a ratio of 1:800-1000 and spray it once 7 days before flowering and once 10 days after flowering. Focus on spraying the flower spikes and the back of the leaves. The flowering period is a high-risk period for insect transmission of viruses and infection of flower parts. Applying it at this stage can block the virus from infecting through flower parts and also has the effect of protecting flowers and fruits.

[0037] S4 application during the young fruit enlargement stage: Dilute the powder at a ratio of 1:600-800 and spray 1-2 times, with an interval of 10-15 days between the two applications. Focus on spraying the fruit and leaves to inhibit virus replication and reduce deformed fruit. This stage is the critical period for fruit deformity caused by viral symptoms. After application, it can enhance the resistance and defense capabilities of fruit cells, inhibit virus replication in the fruit, reduce deformed fruit caused by viral diseases, and improve the appearance quality and marketability of the fruit.

[0038] The optimal spraying time for each step is 6-8 am or 6-8 pm to avoid high temperature and strong light periods, reduce photolysis and evaporation of active ingredients, and improve absorption efficiency. When diluting the powder, use warm water at 25-30℃, control the stirring speed at 150-200 r / min, and dissolve for 10-15 minutes to ensure that the powder is completely dissolved without precipitation, which is suitable for large-scale operation.

[0039] The application method involves spraying at 6-8 AM or 6-8 PM; the powder is diluted with warm water at 25-30°C, with a stirring speed of 150-200 r / min and a dissolution time of 10-15 minutes.

[0040] Example 1: The antiviral powder for fruit trees in this embodiment comprises the following components by weight: 5 parts chitosan oligosaccharide, 3 parts seaweed polysaccharide, 2 parts betaine, 10 parts trace element combination, and 1 part magnesium aluminum silicate; wherein the chitosan oligosaccharide has a molecular weight of 3200 Da and a degree of deacetylation of 85%; the seaweed polysaccharide is derived from brown algae and has a molecular weight of 10000 Da; the trace element combination is in EDTA chelated form, with a Zn:B:Mn:Fe weight ratio of 3:2:1:1.5; the preparation method is as follows: (1) Chitosan oligosaccharide, seaweed polysaccharide and betaine were respectively ultra-finely pulverized by ordinary machinery to a particle size ≤100μm; (2) Put the three pulverized materials into a mixer, stir at 200 r / min for 15 min, add the trace element combination and magnesium aluminum silicate, and continue stirring for 10 min until uniform; (3) Dry the mixture at 45°C until the moisture content is 4.8% to obtain the finished powder.

[0041] Example 2: The antiviral powder for fruit trees in this embodiment comprises the following components by weight: 10 parts chitosan oligosaccharide, 6 parts seaweed polysaccharide, 5 parts betaine, 15 parts trace element combination, and 1.5 parts diatomaceous earth; wherein the chitosan oligosaccharide has a molecular weight of 2800 Da and a degree of deacetylation of 90%; the seaweed polysaccharide is derived from brown algae and has a molecular weight of 15000 Da; the trace element combination is the same as in Example 1; the preparation method is the same as in Example 1, the drying temperature is 48℃, and the moisture content of the finished product is 4.2%.

[0042] Example 3: The antiviral powder for fruit trees in this embodiment comprises the following components by weight: 15 parts chitosan oligosaccharide, 10 parts seaweed polysaccharide, 8 parts betaine, 20 parts trace element combination, and 2 parts magnesium aluminum silicate; wherein the chitosan oligosaccharide has a molecular weight of 3000 Da and a degree of deacetylation of 88%; the seaweed polysaccharide is derived from brown algae and has a molecular weight of 20000 Da; the trace element combination is the same as in Example 1; the preparation method is the same as in Example 1, the drying temperature is 50℃, and the moisture content of the finished product is 3.9%.

[0043] Example 4: The raw material formula of the antiviral powder for fruit trees in this embodiment is exactly the same as that in Example 2. The difference lies in the preparation process, which adopts a step-by-step coating mixing method, as follows: S1. Chitosan oligosaccharide and betaine are mixed and then subjected to ordinary mechanical ultra-fine grinding to a particle size ≤100μm to obtain betaine-coated chitosan oligosaccharide composite micro powder. S2. Add the composite micro powder, seaweed polysaccharide, trace element combination and diatomaceous earth into the mixer and stir at 200r / min for 15min until uniform; S3, dry at 48℃ to a moisture content of 4.1% to obtain the finished product.

[0044] Example 5: The only difference between this embodiment and Example 4 is that the seaweed polysaccharide is composed of fucoidan oligosaccharide and fucoidan in a weight ratio of 1:2, wherein the fucoidan oligosaccharide has a molecular weight of 4000 Da and the fucoidan has a molecular weight of 18000 Da; the rest of the formulation and preparation process are the same as in Example 4.

[0045] Example 6: The only difference between this embodiment and Example 5 is that the components with a degree of polymerization of 3-10 in the chitosan oligosaccharide account for 75% of the total mass; the rest of the formulation and preparation process are the same as in Example 5.

[0046] Example 7: The only difference between this embodiment and Example 6 is that: the ultrafine grinding adopts low-temperature airflow ultrafine grinding, the material temperature is controlled at 35℃ during the grinding process, and the particle size D90 after grinding is ≤100μm; the rest of the formula and preparation steps are the same as those in Example 6.

[0047] Comparative Example 1: The only difference between this comparative example and Example 2 is that the raw materials do not contain betaine; all other raw materials, proportions, and preparation methods are the same as in Example 2.

[0048] Comparative Example 2: The only difference between this comparative example and Example 2 is that the raw materials do not contain seaweed polysaccharides; the other raw materials, proportions, and preparation methods are the same as in Example 2.

[0049] Comparative Example 3: This comparative example is a commercially available single chitosan oligosaccharide aqueous solution (5% chitosan oligosaccharide by mass), which is a conventional product of existing technology.

[0050] Comparative Example 4: This comparative example is a binary compound aqueous solution of chitosan oligosaccharide and seaweed polysaccharide, with 5 parts chitosan oligosaccharide, 6 parts seaweed polysaccharide, and the remainder being water. The preparation method is conventional water-soluble mixing.

[0051] Comparative Example 5: The only difference between this comparative example and Example 2 is that chitosan oligosaccharide and seaweed polysaccharide were mixed and pulverized first, and then betaine was added; that is, a step-by-step coating process was not used, but all other conditions were the same.

[0052] Dissolution stability and complexation degree test: Take 1g of each of the finished powders from Examples 2, 4, and 5, dissolve them in 25℃ warm water at a ratio of 1:800, stir for 10 minutes, and then let them stand for observation. Measure the transmittance and precipitation rate of the solutions. The results are shown in Table 1.

[0053] The results showed that Example 4, which adopted a stepwise coating process, completely solved the electrostatic complexation problem between chitosan oligosaccharide and seaweed polysaccharide, and significantly improved the clarity and stability of the solution. Conventional one-step mixing methods all had varying degrees of complexation and flocculation, which directly affected the application and biological activity.

[0054] Active ingredient retention rate test: Using Example 2 (ordinary mechanical pulverization) and Example 7 (low-temperature airflow pulverization) as samples, the activity retention rates of chitosan oligosaccharides and seaweed polysaccharides before and after pulverization were determined, and the results are shown in Table 2:

[0055] The results showed that low-temperature airflow milling can significantly reduce the thermal degradation of heat-sensitive polysaccharides, increase the activity retention rate by more than 15%, and make the powder particle size more uniform. When combined with the stepwise coating process, it can maximize the bioactivity and uniformity of the product.

[0056] Field efficacy trials: Experimental materials: The test fruit trees were 8-year-old Red Fuji apples, and the test area was an apple orchard in Yantai, Shandong Province, where apple mosaic virus was evenly distributed and the degree of disease was consistent; the test agents were the products of Examples 1-7 and Comparative Examples 1-5.

[0057] Experimental testing: The experiment consisted of 13 treatment groups, plus a water control group; each group was replicated 3 times, with 3 trees per replicate, arranged in randomized blocks; Application method: All examples and comparative examples adopted the time-sequential application method of the present invention; comparative examples 3 and 4 were applied according to the conventional spraying method recommended in the product instructions; the blank control group was sprayed with an equal amount of water.

[0058] Investigation and Measurement: During the fruit ripening period, the incidence rate of apple mosaic virus and the rate of deformed fruit were investigated in each treatment group. For each tree, 100 leaves and 50 fruits were randomly collected from five directions (east, south, west, north, and center) to calculate the incidence rate and rate of deformed fruit. Simultaneously, fruits were randomly collected to measure the soluble solids content (sugar content), and the average value was taken. A high-temperature and drought stress subgroup was also established to statistically analyze the incidence rate under stress conditions and calculate the retention rate of control efficacy. The experimental results are shown in Table 3 below.

[0059] The experimental results show that the incidence of viral diseases and the rate of deformed fruit in Examples 1-3 of this invention are significantly lower than those in the blank control group and each comparative example. Among them, Example 2 has the best effect, with the incidence of viral diseases reduced by 53.5% and the rate of deformed fruit reduced by 55.1% compared with the blank control. The prevention efficacy is 41.6% higher than that of the single chitosan oligosaccharide product (Comparative Example 3) and 30.8% higher than that of the binary compound product (Comparative Example 4), proving that the compounding of each component produces a significant synergistic effect. Example 4, after employing a stepwise coating process, showed a 14.6% increase in efficacy compared to Example 2, demonstrating that the synergistic activity of polysaccharides was fully released after resolving the complexation inactivation issue. Example 5, using dual-molecular-weight seaweed polysaccharides, further enhanced efficacy, demonstrating that the structure of small-molecule permeation immunity and large-molecule film-forming barrier further strengthened the synergistic defense effect both internally and externally. Example 6 limited the active polymerization degree range of chitosan oligosaccharides, and Example 7, after employing low-temperature airflow pulverization, showed a gradual increase in efficacy, indicating a continuous leap in product performance. Comparative Example 5, which did not employ a stepwise coating process, showed significantly lower efficacy than Example 4, indicating the negative impact of complexation inactivation on the compounding effect. The fruit sugar content in all examples of this invention was significantly increased compared to the blank control, by 1.2-2.2 degrees, indicating the nutritional and quality-improving effect brought about by the synergistic effect of trace elements and active ingredients, achieving both disease prevention and quality improvement.

[0060] The above embodiments are merely preferred embodiments of the present invention. Therefore, all equivalent changes or modifications made to the structure, features and principles described in the claims of the present invention are included within the scope of the present invention.

Claims

1. A fruit tree antiviral powder, characterized in that, The powder comprises the following components by weight: 5-15 parts chitosan oligosaccharide, 3-10 parts seaweed polysaccharide, 2-8 parts betaine, 10-20 parts complex trace elements, and 1-2 parts anti-caking agent; the chitosan oligosaccharide has a molecular weight ≤3200 Da and a degree of deacetylation ≥85%; the seaweed polysaccharide is derived from brown algae and has a molecular weight of 10000-20000 Da; the complex trace elements are in EDTA chelated form, and the weight ratio of each element is Zn:B:Mn:Fe=3:2:1:1.5; the preparation steps of the powder are as follows: the chitosan oligosaccharide, seaweed polysaccharide, and betaine are ultra-finely pulverized to a particle size ≤100 μm and then mixed evenly, the complex trace elements and anti-caking agent are added, and after stirring evenly, the powder is dried at 45-50℃ until the moisture content is ≤5%.

2. The antiviral powder for fruit trees according to claim 1, characterized in that: The powder comprises the following components in parts by weight: 8-12 parts chitosan oligosaccharide, 5-8 parts seaweed polysaccharide, 4-6 parts betaine, and 12-18 parts complex trace elements.

3. The antiviral powder for fruit trees according to claim 1, characterized in that: The anti-caking agent is magnesium aluminum silicate or diatomaceous earth.

4. The antiviral powder for fruit trees according to claim 1, characterized in that: The preparation steps are as follows: First, chitosan oligosaccharide and betaine are mixed in proportion and then ultra-finely pulverized to a particle size ≤100μm, so that betaine is uniformly coated on the surface of chitosan oligosaccharide particles to form composite micro powder; then, the composite micro powder is stirred and mixed evenly with seaweed polysaccharide, composite trace elements and anti-caking agent, and dried to a moisture content ≤5%.

5. The antiviral powder for fruit trees according to claim 4, characterized in that: The mass ratio of chitosan oligosaccharide to betaine is 2:

1.

6. The antiviral powder for fruit trees according to claim 1, characterized in that: The seaweed polysaccharide is composed of a mixture of fucoidan oligosaccharide and fucoidan in a weight ratio of 1:2; the fucoidan oligosaccharide has a molecular weight of 3000-5000 Da, and the fucoidan has a molecular weight of 15000-20000 Da.

7. The antiviral powder for fruit trees according to claim 1, characterized in that: The components with a degree of polymerization of 3-10 in the chitosan oligosaccharide account for more than 70% of the total mass.

8. The antiviral powder for fruit trees according to claim 1, characterized in that: The ultrafine pulverization is a low-temperature airflow ultrafine pulverization, and the material temperature is always ≤40℃ during the pulverization process.

9. A method for applying an antiviral powder for fruit trees, used for applying the antiviral powder for fruit trees according to any one of claims 1 to 8, characterized in that: The application method includes the following steps: S1 Pre-budding root irrigation: Dilute the powder at a ratio of 1:100-200, and apply 100-250 grams of powder per diseased tree around the drip line of the fruit tree. S2 pre-budding spray: Dilute the powder at a ratio of 1:1000-1200 and spray it on the entire fruit tree. The amount of spray should be enough to moisten the branches and buds. S3 application before and after flowering: Dilute the powder at a ratio of 1:800-1000 and spray it once 7 days before flowering and once 10 days after flowering, focusing on spraying the flower spikes and the back of the leaves to block the spread of the virus during the flowering period. S4 application during the fruit enlargement stage: Dilute the powder at a ratio of 1:600-800, spray 1-2 times, with an interval of 10-15 days between the two applications, focusing on spraying the fruit and leaves to inhibit virus replication and reduce deformed fruit.

10. The method for applying the antiviral powder for fruit trees according to claim 9, characterized in that: The application method involves spraying at 6-8 AM or 6-8 PM; the powder is diluted with warm water at 25-30°C, with a stirring speed of 150-200 r / min and a dissolution time of 10-15 minutes.

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