Salicylic acid derivative-based loosening and recovering agent as well as preparation method and application thereof

Abstract

The invention discloses a loosening and recovering agent based on salicylic acid derivatives and a preparation method and application thereof, and belongs to the technical field of forestry pest control and plant immune regulation. The loosening and recovering agent is characterized by being prepared from the following components in percentage by mass: 8 to 12 percent of salicylic acid SA, 5 to 8 percent of sulfonated salicylic acid, 3 to 6 percent of ferric salicylate Fe-SA, 2 to 4 percent of ammonium salicylate NH4-SA, 15 to 18 percent of methanol, 0.5 to 1.2 percent of sulfonic acid, 0.2 to 0.8 percent of ferric chloride FeCl3, 0.5 to 1.5 percent of cationic surface active agent, 1 to 3 percent of phenylalanine and the balance of sodium bicarbonate. According to the invention, derivatives such as sulfonated salicylic acid and iron salicylate are compounded, and the synergistic interaction of phenylalanine and metal ions is combined, so that a composite system with immune activation, nematode killing and pine tree rejuvenation functions is formed, and the limitation of a traditional prevention and treatment technology is broken through.

Description

Technical Field

[0001] The invention relates to a pine compound based on salicylic acid derivatives, a preparation method and application thereof, and belongs to the technical field of forestry pest control and plant immune regulation. Background Art

[0002] Prior art CN116548458B discloses a highly effective compound nematicide for pine wood nematode disease and its preparation method. The compound nematicide comprises a nematicide and adjuvants, wherein the adjuvants include a synergist, a surfactant, a solvent, and a rejuvenating agent. The nematicide is a mixture of emamectin benzoate and linalool, the synergist is piperonyl butoxide, the solvent includes DMF and a chloride solution, and the rejuvenating agent includes an aqueous solution of amino oligosaccharides. The compound nematicide contains 10-20% linalool by mass, 0.5-3.5% emamectin benzoate by mass, and 2-8% linalool by mass.

[0003] Pine wilt disease is a devastating disease of pine trees. Traditional chemical agents (such as fumigants and insecticides) severely damage the ecological environment and are unable to restore the physiological functions of infected pine trees. Salicylic acid (SA), a key inducer of plant systemic resistance (SAR), enhances plant disease resistance by activating the jasmonic acid (JA) and salicylic acid (SA) signaling pathways. However, its direct killing effect on nematodes when used alone is limited. Summary of the Invention

[0004] The purpose of the present invention is to overcome the technical defects of the prior art, solve the above technical problems, and propose a loosening agent based on salicylic acid derivatives and its preparation method and application.

[0005] The present invention specifically adopts the following scheme: a loosening agent based on a salicylic acid derivative, which includes the following components by mass fraction: 8-12% of salicylic acid SA, 5-8% of sulfonated salicylic acid, 3-6% of iron salicylate Fe-SA, 2-4% of ammonium salicylate NH4-SA, 15-18% of methanol, 0.5-1.2% of sulfonic acid, 0.2-0.8% of ferric chloride FeCl3, 0.5-1.5% of a cationic surfactant, 1-3% of phenylalanine, and the balance is sodium bicarbonate.

[0006] As a preferred embodiment, the iron salicylate is produced by chelating FeCl3 with sulfonated salicylic acid under sulfonic acid catalysis, and the chelation ratio is 1:1.5-2.0.

[0007] As a preferred embodiment, the cationic surfactant is cetyltrimethylammonium chloride.

[0008] The present invention also provides a method for preparing a loosening agent based on salicylic acid derivatives, comprising the following steps:

[0009] Step SS1: Chelating reaction step, comprising: dissolving 8-12% salicylic acid SA and 5-8% sulfonated salicylic acid in 15-18% methanol, adding 0.5-1.2% sulfonic acid and 0.2-0.8% ferric chloride FeCl3, stirring at 60°C for 40 minutes to generate SA-Fe 3+ chelates;

[0010] Step SS2: a mixing and dispersing step, comprising: adding 2-4% by mass of ammonium salicylate, 1-3% by mass of phenylalanine, and 0.5-1.5% by mass of a cationic surfactant to the solution obtained in step SS1, and ultrasonically treating the solution for 30 minutes until homogeneous;

[0011] Step SS3: pH adjustment step, comprising: slowly adding sodium bicarbonate solution to adjust the pH to 6.2±0.3, filtering, sealing and storing in the dark.

[0012] As a preferred embodiment, the cationic surfactant is cetyltrimethylammonium chloride.

[0013] The present invention also proposes an application of a pine repair agent based on salicylic acid derivatives, which includes: drilling a hole at a 45° angle at the base of a pine tree, with a hole diameter of 6 mm and a depth of 8-10 cm, injecting 30-50 ml of the pine repair agent, and sealing the hole with a tree healing agent after injection.

[0014] The present invention also proposes an application of a pine compound based on salicylic acid derivatives, which includes: diluting the pine compound 80 times, spraying 500L per hectare on the pine tree leaves, and combining it with rhizosphere irrigation of 20L per pine tree, once every 30 days.

[0015] The present invention also proposes an application of a pine compound based on salicylic acid derivatives, which comprises: mixing the pine compound with a slow-release granular carrier, and spreading it at 10 kg / mu around the periphery of the nematode epidemic area to form a chemical-immune barrier.

[0016] As a preferred embodiment, the slow-release particle carrier is diatomaceous earth.

[0017] The beneficial effects achieved by the present invention are as follows: First, triple protection: the nematodes targeted by the pine compound of the present invention include pine wood nematodes, root-knot nematodes, cyst nematodes, bright nematodes, short-bodied nematodes, and root-knot nematodes (southern root-knot nematodes, northern root-knot nematodes), and immune activation (disease resistance) + physical killing (quick-acting) + reproduction inhibition (long-acting). By compounding derivatives such as sulfonated salicylic acid and ferric salicylate, and combining phenylalanine with metal ions for synergistic enhancement, a composite system with the functions of immune activation, nematode killing and pine tree rejuvenation is formed, breaking through the limitations of traditional prevention and control technologies; second, rapid rejuvenation. By using the pine compound of the present invention, the yellow-greening period of moderately and lightly infected pine trees is shortened to 7-15 days, and the annual timber volume growth is restored to more than 90%; third, broad-spectrum anti-nematode, the pine compound of the present invention has a killing rate of 95% or more for pine wood nematodes, root-knot nematodes (Meloidogyne spp.), etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is an electron micrograph of oxidative damage to the body wall of pine wood nematode at 800-fold dilution for 2 minutes;

[0019] Figure 2 This is an electron micrograph of oxidative damage to the body wall of pine wood nematode at 800-fold dilution for 10 minutes;

[0020] Figure 3 These are electron micrographs of oxidative damage to the body wall of pine wood nematode at 800-fold dilution for 30 minutes;

[0021] Figure 4 This is an electron micrograph of oxidative damage to the body wall of pine wood nematode at 800-fold dilution for 1 hour;

[0022] Figure 5 This is an electron micrograph of oxidative damage to the body wall of pine wood nematode after 3 hours at 800-fold dilution;

[0023] Figure 6 This is an electron micrograph of oxidative damage to the body wall of pine wood nematode at 800-fold dilution after 3 days;

[0024] Figure 7 This is an electron micrograph of oxidative damage to the body wall of pine wood nematode at 15 days old at 800 times dilution;

[0025] Figure 8 This is an electron micrograph of eggshell rupture at 800-fold dilution for 10 minutes;

[0026] Figure 9 This is an electron micrograph of eggshell rupture at 3 days after dilution 800 times. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0028] Example 1: The present invention proposes a loosening agent based on salicylic acid derivatives, which comprises the following components by mass fraction: salicylic acid SA 8%, sulfonated salicylic acid 5%, iron salicylate Fe-SA 3%, ammonium salicylate NH4-SA 2%, methanol 15%, sulfonic acid 0.5%, ferric chloride FeCl3 0.2%, cationic surfactant 0.5%, phenylalanine 1%, and the balance is sodium bicarbonate; wherein salicylic acid SA is used to induce the synthesis of pine disease-resistant proteins and activate immune response; sulfonated salicylic acid is used to enhance the permeability of the agent and destroy the lipid layer of the nematode body wall; iron salicylate Fe-SA is used to slowly release Fe 3+ It catalyzes oxidative stress in nematodes and promotes the repair of pine xylem; ammonium salicylate NH4-SA is used to regulate the pH of plant cell sap and inhibit nematode enzyme activity; methanol is used as a solvent to promote the transmembrane transport of active ingredients; sulfonic acid is used to catalyze the chelation reaction between salicylic acid SA and phenylalanine; ferric chloride FeCl3 is used to synergistically generate reactive oxygen species ROS with salicylic acid SA, which directly damages nematode DNA; the cationic surfactant is hexadecyltrimethylammonium chloride, which is used to enhance the attachment and absorption of the agent in the pine phloem; phenylalanine is used to induce pine trees to synthesize anti-nematode peptides and interfere with nematode feeding behavior; sodium bicarbonate is used to adjust the pH of the preparation to 6.0-6.5 and neutralize soil acidity.

[0029] Example 2: The present invention proposes a loosening agent based on salicylic acid derivatives, which includes the following components by mass fraction: salicylic acid SA 10%, sulfonated salicylic acid 5%, iron salicylate Fe-SA 3%, ammonium salicylate NH4-SA2%, methanol 15%, sulfonic acid 0.5%, ferric chloride FeCl3 0.2%, cationic surfactant 0.5%, phenylalanine 1%, and the balance is sodium bicarbonate.

[0030] Example 3: The present invention proposes a loosening agent based on salicylic acid derivatives, which includes the following components in mass fraction: salicylic acid SA 12%, sulfonated salicylic acid 5%, iron salicylate Fe-SA 3%, ammonium salicylate NH4-SA2%, methanol 15%, sulfonic acid 0.5%, ferric chloride FeCl3 0.2%, cationic surfactant 0.5%, phenylalanine 1%, and the balance is sodium bicarbonate.

[0031] Example 4: The present invention proposes a loosening agent based on salicylic acid derivatives, which includes the following components in mass fraction: salicylic acid SA 8%, sulfonated salicylic acid 7%, iron salicylate Fe-SA 3%, ammonium salicylate NH4-SA 2%, methanol 15%, sulfonic acid 0.5%, ferric chloride FeCl3 0.2%, cationic surfactant 0.5%, phenylalanine 1%, and the balance is sodium bicarbonate.

[0032] Example 5: The present invention proposes a loosening agent based on salicylic acid derivatives, which includes the following components in mass fraction: salicylic acid SA 8%, sulfonated salicylic acid 8%, iron salicylate Fe-SA 3%, ammonium salicylate NH4-SA 2%, methanol 15%, sulfonic acid 0.5%, ferric chloride FeCl3 0.2%, cationic surfactant 0.5%, phenylalanine 1%, and the balance is sodium bicarbonate.

[0033] Example 6: The present invention proposes a loosening agent based on salicylic acid derivatives, which includes the following components in mass fraction: salicylic acid SA 10%, sulfonated salicylic acid 7%, iron salicylate Fe-SA 3%, ammonium salicylate NH4-SA2%, methanol 15%, sulfonic acid 0.5%, ferric chloride FeCl3 0.2%, cationic surfactant 0.5%, phenylalanine 1%, and the balance is sodium bicarbonate.

[0034] Example 7: The present invention proposes a loosening agent based on salicylic acid derivatives, which includes the following components in mass fraction: salicylic acid SA 10%, sulfonated salicylic acid 8%, iron salicylate Fe-SA 3%, ammonium salicylate NH4-SA2%, methanol 15%, sulfonic acid 0.5%, ferric chloride FeCl3 0.2%, cationic surfactant 0.5%, phenylalanine 1%, and the balance is sodium bicarbonate.

[0035] Example 8: The present invention proposes a loosening agent based on salicylic acid derivatives, which includes the following components in mass fraction: salicylic acid SA 12%, sulfonated salicylic acid 7%, iron salicylate Fe-SA 3%, ammonium salicylate NH4-SA2%, methanol 15%, sulfonic acid 0.5%, ferric chloride FeCl3 0.2%, cationic surfactant 0.5%, phenylalanine 1%, and the balance is sodium bicarbonate.

[0036] Example 9: The present invention proposes a loosening agent based on salicylic acid derivatives, which includes the following components in mass fraction: salicylic acid SA 12%, sulfonated salicylic acid 8%, iron salicylate Fe-SA 3%, ammonium salicylate NH4-SA2%, methanol 15%, sulfonic acid 0.5%, ferric chloride FeCl3 0.2%, cationic surfactant 0.5%, phenylalanine 1%, and the balance is sodium bicarbonate.

[0037] Optionally, the iron salicylate is generated by chelating FeCl3 with sulfonated salicylic acid under sulfonic acid catalysis, with a chelation ratio of 1:1.5-2.0.

[0038] Optionally, the cationic surfactant is cetyltrimethylammonium chloride.

[0039] The mechanism of action of the pine compound based on salicylic acid derivatives of the present invention includes: (1) immune activation, salicylic acid SA activates pine NPR1 protein, triggers the expression of PR proteins (such as chitinase and β-1,3-glucanase), and enhances the cell wall's ability to resist nematode infection; phenylalanine synthesizes phenolic substances through the shikimic acid pathway, inhibiting the secretion of cellulase by the nematode's stylet; (2) direct killing of nematodes, Fe 3+ The salicylic acid SA chelate releases ROS in the pine ducts, destroying the nematode's body wall cuticle and mitochondrial function; sulfonated salicylic acid dissolves the nematode's cuticular lipids, leading to osmotic imbalance of body fluids and death; (3) Reproduction inhibition, ammonium salicylate NH4-SA interferes with the alkaline phosphatase activity required for nematode egg hatching, reducing the larval survival rate by ≥90%; cationic surfactants wrap the nematode fertilized eggs, blocking their respiratory metabolism.

[0040] The present invention also provides a method for preparing a loosening agent based on salicylic acid derivatives, comprising the following steps:

[0041] Step SS1: Chelating reaction step, comprising: dissolving 8-12% salicylic acid SA and 5-8% sulfonated salicylic acid in 15-18% methanol, adding 0.5-1.2% sulfonic acid and 0.2-0.8% ferric chloride FeCl3, stirring at 60°C for 40 minutes to generate SA-Fe 3+ chelates;

[0042] Step SS2: a mixing and dispersing step, comprising: adding 2-4% by mass of ammonium salicylate, 1-3% by mass of phenylalanine, and 0.5-1.5% by mass of a cationic surfactant to the solution obtained in step SS1, and ultrasonically treating the solution for 30 minutes until homogeneous;

[0043] Step SS3: pH adjustment step, comprising: slowly adding sodium bicarbonate solution to adjust the pH to 6.2±0.3, filtering, sealing and storing in the dark.

[0044] Optionally, the cationic surfactant is cetyltrimethylammonium chloride.

[0045] The present invention also proposes a pine remediation agent based on a salicylic acid derivative for use in moderately to lightly infected pine trees. The application involves drilling a 45° angled hole at the base of the pine tree, with a diameter of 6 mm and a depth of 8-10 cm. 30-50 ml of the pine remediation agent is then injected, and the hole is sealed with a tree healing agent. The results: A 70% or greater yellow leaf greening rate is achieved within 7 days, the number of xylem nematodes is reduced by 95% within 15 days, and the tree resumes normal growth within 30 days.

[0046] The present invention also proposes the use of a salicylic acid derivative-based pine nematode remediation agent for preventing the spread of nematodes and controlling soil nematodes. The application involves diluting the agent 80-fold and spraying it on pine leaves at a rate of 500 L per hectare. This is combined with rhizosphere irrigation of 1 L per pine tree every 30 days. The results: the number of nematodes carried by Monochamus alternatus decreased by 85%, and the hatching rate of nematode eggs in the soil was suppressed by ≥80%.

[0047] The present invention also proposes an application of a pine compound based on a salicylic acid derivative for treating the edge isolation zone of a nematode epidemic area. The application includes: mixing the pine compound with a slow-release granular carrier, and applying it at a rate of 10 kg / mu to the periphery of the nematode epidemic area to form a chemical-immune barrier.

[0048] As a preferred embodiment, the slow-release particle carrier is diatomaceous earth.

[0049] Test project name: Indoor control test of pine wood nematodes with pine compound based on salicylic acid derivatives; Test purpose: To determine the killing rate and killing concentration of pine compound based on salicylic acid derivatives (abbreviated as: pine compound) on pine wood nematodes, and provide a basis for the prevention and control of pine wood nematode disease in pine forests; The standard complied with is: NY / T1833.1 2009-Nematicides-Part 1: Test for inhibition of plant pathogenic nematodes-Insect immersion method.

[0050] Experimental conditions: The target organism, pine wood nematode (Bursaphelenchus xylophilus), was collected from Minqing County and cultured in the laboratory. Culture conditions: Pine wood nematodes were cultured with Botrytis cinerea for 3 weeks and then used. Instruments and equipment included an electronic balance, centrifuge, biochemical test plate, pipette, counter, biological microscope, and constant temperature incubator.

[0051] Experimental design: The test agents are as follows.

[0052] Pharmacy content source Pine complex Example 1 Provided by the client

[0053] Preparation: Dilute the pine compound directly with water 800-fold, 1500-fold, 3500-fold, and 5000-fold. Test nematode preparation: Elute pine wood nematodes from the Botrytis cinerea culture medium with deionized water, filter, and centrifuge at 1000 rpm for 2 minutes. Discard the supernatant, resuspend in water, and centrifuge again. Adjust the nematode concentration in the suspension to ≥100 nematodes / mL after resuspension with water and set aside. Treatment: Use a pipette to pipette 5 mL of the drug solution into a centrifuge tube, starting from low to high concentrations, and add an equal volume of the prepared nematode suspension. After mixing thoroughly, pipette the mixture into the wells of a biochemical test plate, cover, and incubate at 25°C. Repeat each treatment four times, with a control containing no drug added. Results: The condition of the pine wood nematodes was observed 2 minutes, 10 minutes, 30 minutes, and 1 hour after treatment, and the time of death was recorded. The nematodes were cultured and observed for 3, 10, and 15 days. Investigation method: 1 mL of the mixture was taken from each treatment group and observed for nematode mortality under a dissecting microscope. At least 100 nematodes were observed in each replicate, and the total number of threads and dead nematodes was recorded. Nematodes were considered dead if they were rigid and unable to bend or move when touched with a bamboo needle.

[0054] Data Statistics and Analysis: Based on the survey data, the adjusted mortality rate of each treatment group was calculated. The adjusted mortality rate was calculated using formula (1) and formula (2). The results were rounded to two significant figures.

[0055]

[0056] Where,

[0057] P1—mortality rate;

[0058] K——the number of dead insects;

[0059] N——total number of insects treated;

[0060]

[0061] Where,

[0062] P2——adjusted mortality rate, in percentage (%);

[0063] Pt – treatment mortality;

[0064] P0——blank control mortality rate;

[0065] Experimental results and analysis: As shown in Table 1, when pine wood nematodes were treated with an 800-fold dilution of pine compound, the nematodes went from a rapidly swimming state to a state of rigor mortis within 2 minutes of application, with a mortality rate of 99.05%. After 10 minutes of treatment, the mortality rate was 100%. After three days of observation, the pine wood nematodes showed no signs of resuscitation and gradually decomposed. After 15 days, the pine wood nematodes were basically decomposed into residue. When diluted 1500 times, some pine wood nematodes went into rigor mortis and died 2 minutes after application, with a mortality rate of 39.62%. Most pine wood nematodes gradually became restricted from swimming, reducing their feeding and swimming speeds. After 10 minutes of treatment, the vast majority of pine wood nematodes gradually straightened their bodies and stopped moving, with a mortality rate of 99.36%. After 30 minutes of treatment, all nematodes were dead. After three days, there was no sign of resuscitation and the nematodes gradually decomposed, and all decomposed within 15 days. When the pine wood nematode (Pine Wood Nematode) was treated with a 3500-fold dilution, the mortality rate increased with treatment time, reaching 9.46% at 2 minutes, 41.93% at 10 minutes, and 98.59% at 30 minutes. All nematodes were dead within 1 hour of treatment, reaching 100% mortality. After three days, there was no resurgence and the nematodes gradually decomposed, reaching complete decomposition within 15 days. Nematode mortality after treatment with a 5000-fold dilution showed a similar trend: after 1 hour, most nematodes became rigid and inactive, with a mortality rate of 81.99%. After 3 hours, all nematodes became rigid and inactive, reaching 100% mortality. After three days, there was no sign of resurgence and the nematodes began to decompose. Within 15 days, most of the decomposition was complete, with no possibility of resurgence.

[0066] Table 1 The killing effect of pine compound on pine wood nematodes at different dilution multiples

[0067]

[0068] like Figures 1 to 7 The electron micrographs of the oxidative damage to the body wall of pine wood nematodes at 2 min, 10 min, 30 min, 1 h, 3 h, 3 d and 15 d after 800-fold dilution are shown. The oxidative damage and decomposition processes of the nematode body wall can be seen from the figures. Figure 8 and Figure 9 The electron micrographs of the egg shell rupture at 10 minutes and 3 days show that the egg shell gradually becomes transparent and thinner at 10 minutes, and the egg shell completely decomposes at 3 days, and the nematodes no longer hatch.

[0069] The results of this study demonstrate that pine compound has excellent efficacy against pine wood nematodes. 800-1500-fold dilutions of pine compound exhibited significant and rapid killing effects against pine wood nematodes, achieving 100% nematode mortality within 30 minutes of treatment. While the effectiveness of pine compound against nematodes remained unchanged with increasing dilution, the killing rate decreased. A 3500-fold dilution achieved 100% nematode killing within one hour, and a 5000-fold dilution required three hours of treatment to achieve 100% nematode killing. Because insecticide activity measured in efficacy trials is typically higher than in field trials, companies are required to conduct further pine forest pine wood nematode control trials to confirm the scientific validity and practical effectiveness of the killing concentrations obtained in this study. The raw data from Table 1 are shown in Table 2.

[0070] Table 2: Raw data

[0071]

[0072]

[0073] Note: ——Indicates that all pine wood nematodes are dead and their bodies have begun to decompose.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A loosening agent based on salicylic acid derivatives, characterized in that: The loosening agent comprises the following components by mass fraction: 8-12% of salicylic acid SA, 5-8% of sulfonated salicylic acid, 3-6% of iron salicylate Fe-SA, 2-4% of ammonium salicylate NH4-SA, 15-18% of methanol, 0.5-1.2% of sulfonic acid, 0.2-0.8% of ferric chloride FeCl3, 0.5-1.5% of cationic surfactant, 1-3% of phenylalanine, and the balance is sodium bicarbonate.

2. The decongestant based on salicylic acid derivatives according to claim 1, characterized in that: The iron salicylate is generated by chelating FeCl3 with sulfonated salicylic acid under the catalysis of sulfonic acid, and the chelation ratio is 1:1.5-2.

0.

3. The decongestant based on salicylic acid derivatives according to claim 1, characterized in that: The cationic surfactant is cetyltrimethylammonium chloride.

4. A method for preparing a loosening agent based on salicylic acid derivatives, characterized in that: The steps include: Step SS1: Chelating reaction step, comprising: dissolving 8-12% salicylic acid SA and 5-8% sulfonated salicylic acid in 15-18% methanol, adding 0.5-1.2% sulfonic acid and 0.2-0.8% ferric chloride FeCl3, stirring at 60°C for 40 minutes to generate SA-Fe 3+ chelates; Step SS2: a mixing and dispersing step, comprising: adding 2-4% by mass of ammonium salicylate, 1-3% by mass of phenylalanine, and 0.5-1.5% by mass of a cationic surfactant to the solution obtained in step SS1, and ultrasonically treating the solution for 30 minutes until homogeneous; Step SS3: pH adjustment step, comprising: slowly adding sodium bicarbonate solution to adjust the pH to 6.2±0.3, filtering, sealing and storing in the dark.

5. The method for preparing a loosening agent based on salicylic acid derivatives according to claim 4, characterized in that: The cationic surfactant is cetyltrimethylammonium chloride.

6. An application of a loosening agent based on a salicylic acid derivative, characterized in that: The application comprises: drilling a hole at a 45° angle at the base of a pine tree, wherein the hole diameter is 6 mm and the depth is 8-10 cm, injecting 30-50 ml of a pine compound, and sealing the hole with a tree healing agent after the injection.

7. An application of a loosening agent based on salicylic acid derivatives, characterized in that: The application comprises: diluting the pine compound 80 times, spraying 500L per hectare on the pine tree leaves, and irrigating the pine tree root zone with 20L per plant once every 30 days.

8. An application of a loosening agent based on salicylic acid derivatives, characterized in that: The application includes: mixing the pine compound with a slow-release granular carrier, and spreading it at 10 kg / mu on the periphery of the nematode epidemic area to form a chemical-immune barrier.

9. The use of a loosening agent based on salicylic acid derivatives according to claim 8, characterized in that: The slow-release particle carrier is diatomaceous earth.

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