Physical and chemical combined pesticide application method for guava nematode prevention and control
By combining physical and chemical application methods with soil environment regulation, high-temperature suffocation, and the synergistic use of chemical agents and biological agents, the problem of diminishing chemical control efficacy has been solved, achieving continuous control of guava nematodes and improving plant health.
Patent Information
- Application Number
- CN202511541391.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-27
- Publication Date
- 2025-12-16
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
In current technologies, the control of guava nematodes mainly relies on chemical nematicides, which leads to a decrease in control effectiveness with the increase of planting years, a rebound in nematode populations, and an impact on fruit yield and fruit quality.
A combined physical and chemical application method was adopted, including physical regulation of the soil environment, high-temperature suffocation pretreatment, chemical drenching, and synergistic application of biological agents. By implementing multiple control measures during the key periods of the guava growth cycle, a combination of physical, chemical, and biological control measures was formed, resulting in a temporal complementarity and synergistic effect of physical, chemical, and biological control.
This method achieves continuous and sustained control of guava nematode populations, curbs nematode population expansion, improves plant health, and reduces chemical residues and damage to the soil microecological environment.
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Figure CN121128520A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application relates to the technical field of pest control, in particular to a physical-chemical combined pesticide application method for guava nematode control. BACKGROUND
[0002] Pest control refers to a comprehensive technical measure for controlling the population number of pests and reducing the damage degree of pests, so as to protect the safety of agricultural production, reduce economic losses, maintain ecological balance and human health, by means of physical, chemical, biological, agricultural and comprehensive management, and is widely applied to agricultural planting, forestry conservation, warehousing logistics, urban sanitation and family protection. The control methods include physical control, chemical control, biological control, agricultural control and modern comprehensive control. The guava nematode control is one of the pest control methods.
[0003] The related guava nematode control mainly uses chemical nematicides, but this method has the problems of single target, short effective period, difficulty in effectively covering the entire life history of nematodes, and easy to cause nematode resistance, pesticide residues and soil micro-ecological environment damage after long-term continuous use. Therefore, the control effect decreases with the increase of planting years, and the nematode population rebounds in the middle and late stages of crop growth, causing continuous damage to the root system of guava trees, and finally affecting the yield and quality of fruit trees. SUMMARY
[0004] In order to solve the problems of decreasing control effect with the increase of planting years, affecting the yield and quality of fruit trees caused by the related guava nematode control mainly using chemical nematicides, the application provides a physical-chemical combined pesticide application method for guava nematode control.
[0005] The application provides a physical-chemical combined pesticide application method for guava nematode control, which adopts the following technical scheme: A physical-chemical combined pesticide application method for guava nematode control comprises the following steps: S1, soil environment physical regulation: after pruning the guava tree, alkaline microbial fertilizer is applied within the tree crown drip line range, and the application amount is 4-6 kg per plant; S2, high-temperature smothering pretreatment: in the season when the daily maximum temperature is continuously higher than 35℃, transparent plastic film is used to cover the ground under the tree crown projection, and the covering time is 4-6 weeks, so that the cultivated layer soil temperature is increased to 45-55℃; S3, chemical agent root irrigation: during the fruiting period of guavas or at the initial stage of nematode damage, a nematocide composition is diluted with water and uniformly irrigated to the soil near the drip line of the tree crown; the nematocide composition is composed of ingredients including, by mass percentage, abamectin: 2.4%-2.6%, fluopyram: 2.4%-2.6%, and the balance being water; the amount of nematocide composition is 500 ml / acre, and 1000 liters of water is used to uniformly irrigate the soil near the drip line of the tree crown; S4, biological agent synergistic application: before and after the chemical agent root irrigation treatment, a paecilomyces lilacinus preparation is applied at a dosage of 1 kg / acre, diluted with 1000 liters of water for root irrigation or trench application; S5, prevention cycle implementation: the combined prevention and control operations of S1 to S4 are implemented three times a year, with the time points of the three operations being set in March, June and September.
[0006] By using the above technical solution, since the alkaline microbial fertilizer is concentratedly applied within the drip line of the tree crown, which is the area where the guava root system is densely distributed, the alkaline environment can neutralize the acidic substances secreted by the root system due to nematode damage, and the active microorganisms in the microbial fertilizer can quickly colonize the rhizosphere soil, inhibit the activity of nematode larvae through nutrient competition and space occupation, and create a favorable soil micro-ecological environment for subsequent high-temperature smothering, thus achieving the effects of improving the rhizosphere micro-ecology and reducing the nematode base; Since the thin film is covered in the summer high-temperature season, the transparent plastic film can effectively block the loss of soil heat and produce a greenhouse effect, so that the temperature of the plough layer soil is stably maintained at 45-55℃ for more than four weeks, which can cause the denaturation and inactivation of the cuticle protein on the surface of the nematode, and damage the enzyme system function in the body, especially the inactivation of the egg mass which has strong cold tolerance, thus achieving the effect of completely killing the residual nematode population in the soil by physical means; Due to the specific combination of abamectin and fluopyram, abamectin causes nerve conduction block by acting on the gamma-aminobutyric acid system of nematode synapses, while fluopyram interferes with energy metabolism by inhibiting the succinate dehydrogenase activity of nematode mitochondrial complex II, and the two components produce a synergistic effect on the nervous system and energy metabolism system, respectively, and the dilution concentration of 1000 liters of water can ensure that the pesticide solution forms a uniform concentration gradient in the soil, thus obtaining a high nematocidal effect under the dual action mechanism; at the same time, the Paecilomyces lilacinus fungus is a specific parasitic fungus, its mycelium can recognize and wrap around the surface of nematodes, and through the secretion of chitinase to degrade the nematode body wall, and then invade the body to absorb nutrients, the biological control effect is complementary in time and space with the chemical agent, and can continue to maintain the control effect after the concentration of the chemical agent decreases, and the plant hormones produced by the microbial agent can promote the repair of damaged roots, thus obtaining the benefits of continuous control of nematode population and promotion of plant growth; according to the growth cycle of guavas and the occurrence of nematodes, the control is carried out at three nodes before sprouting in spring, during fruiting in summer and after fruit picking in autumn, the operation in March can control the base number of nematodes after overwintering, the operation in June is at the peak of nematode reproduction, which can block the population expansion, and the operation in September can reduce the number of overwintering worms, thus obtaining the effect of continuous control of nematode population throughout the year.
[0007] Preferably, before the S1 step, a pretreatment step of the water content of the orchard soil is further included: keeping the orchard soil in a wet state, and the relative water content of the soil is controlled at 60%-80%.
[0008] By adopting the above technical solution, since the relative water content of the soil is adjusted to the appropriate range of 60%-80% in advance, this humidity condition not only ensures that the active bacteria in the microbial fertilizer can quickly germinate and proliferate, but also provides medium conditions for heat conduction in the subsequent high-temperature smothering stage, and the moderate soil humidity can induce the nematode larvae to change from the dormant state to the active state, increasing their contact opportunities with the control measures, thus obtaining a synergistic effect of improving the control efficiency of the subsequent steps.
[0009] Preferably, in the S1 step, the alkaline microbial fertilizer is a microbial fertilizer containing Bacillus subtilis.
[0010] By adopting the above technical solution, since Bacillus subtilis has strong alkali tolerance and enzyme production capacity, it can still maintain high metabolic activity in an alkaline environment, and the antibacterial peptide substances secreted by it can inhibit the hatching of nematode egg masses, and the exopolysaccharides produced during the growth of the bacteria can help improve the soil aggregate structure, creating a suitable growth environment for the root system of guavas, and thus enhancing the soil improvement effect and biological control effect.
[0011] Preferably, in the S1 step, the alkaline microbial fertilizer is applied, and 1-3% of amino acid powder is added as a microbial growth promoter, based on the mass of the microbial fertilizer.
[0012] By adopting the above technical solution, since the amino acid powder provides the microorganisms with an easily absorbed organic nitrogen source and small molecule carbon source, the adaptation period of Bacillus subtilis in the soil can be shortened, and the rapid formation of dominant flora is promoted. The specific amino acid components such as glycine and proline can induce the bacteria to produce more antibacterial substances. At the same time, the amino acid and the inorganic salt in the microbial fertilizer form chelated nutrients, improving the effectiveness of trace elements, thus achieving the promotion effect of accelerating the colonization of the flora and enhancing the insect inhibiting activity.
[0013] Preferably, in the S2 step, the soil is flattened before being covered with the transparent plastic film to ensure that there is no gap between the film and the ground.
[0014] By adopting the above technical solution, since the soil surface is flattened and the film is tightly attached, heat loss from the edges is reduced, the temperature distribution in the soil is uniform, and the existence of local low-temperature areas that allow nematodes to survive is avoided. In addition, tight coverage can block the entry of external oxygen, providing a local oxygen-deficient environment that can further inhibit the survival of nematodes, thus achieving the effects of improving heat conduction efficiency and efficiently killing pests.
[0015] Preferably, in the S3 step, the nematocide composition is subjected to a pre-treatment of oscillation before use, with an oscillation frequency of 150-200 revolutions per minute and an oscillation time of 5-10 minutes.
[0016] By adopting the above technical solution, since the mechanical oscillation at a specific frequency and time can form a uniform and stable microemulsion system of abamectin and fluopyram in the aqueous phase, avoiding the stratification phenomenon caused by the difference in solubility of the active ingredients, and the oscillation process promotes the dispersion of the adjuvant, improving the permeability and adhesion of the pesticide solution in the soil, thus ensuring that the active ingredients can exert biological activity.
[0017] Preferably, in the S3 step, the depth of the liquid pesticide is controlled to be 20-40 cm.
[0018] By adopting the above technical solution, since the depth of the liquid pesticide is controlled to be 20-40 cm, which corresponds to the distribution layer of the main absorbing roots of Guavaberry, the nematocide can act on the root area where the nematodes are severely damaged. Too shallow application will result in the inability of the pesticide solution to cover the deep root system, and too deep application will cause waste of the pesticide and potential environmental pollution, thus achieving the effects of targeted pesticide application and improving the utilization rate of the pesticide.
[0019] Preferably, in the S3 step, the liquid pesticide also contains the plant growth adjuvant alginic acid, and the addition amount of alginic acid is 0.01-0.05% of the total mass of the liquid pesticide.
[0020] By adopting the above technical scheme, due to the natural plant growth regulating substances and trace elements contained in the alginate, the potential stress effect of the chemical agent on the root system can be alleviated, the growth and development of the new root hairs are promoted, and at the same time, the colloid film formed by the alginate molecules can prolong the retention time of the agent on the root surface, improve the persistence of the control effect, so as to obtain the effects of reducing the risk of phytotoxicity and enhancing the stress resistance of the plant.
[0021] Preferably, in the S4 step, the application of the Paecilomyces lilacinus preparation is performed at an interval from the root irrigation treatment of the chemical agent, and the interval time is 5-10 days.
[0022] By adopting the above technical scheme, due to the setting of a reasonable interval of 5-10 days, the inhibition effect of the chemical agent residue on the activity of the Paecilomyces lilacinus can be avoided, and the biological control means can be introduced when the chemical control effect begins to weaken. The time window just corresponds to the connection point of the half-life period of the chemical agent and the germination period of the preparation, so that the seamless connection effect of the chemical and biological control means is obtained.
[0023] Preferably, in the S4 step, when the Paecilomyces lilacinus preparation is applied, the soil temperature is controlled to be 15-35℃, and the soil humidity is controlled to be 40%-60% of the field water holding capacity.
[0024] By adopting the above technical scheme, due to the control of the soil temperature and humidity in the optimum growth range of the Paecilomyces lilacinus, the temperature condition of 15-35℃ ensures the normal growth of the mycelium and the spore germination, and the field water holding capacity of 40%-60% avoids the lack of oxygen of the bacteria caused by excessive humidity and the influence of the mycelium expansion caused by excessive dryness. The combination of the environmental parameters can exert the control potential of the biological preparation, so that the effects of improving the action of the preparation and ensuring the efficiency of the biological control are obtained.
[0025] In summary, the present application has the following beneficial effects: 1. Since the present application adopts the physical and chemical combined application method, integrates the soil environment physical regulation, high-temperature smothering pretreatment, root irrigation of the chemical agent and the synergistic application of the biological preparation, and continuously implements the above-mentioned means in three key periods of the guavas growth cycle, synergistically intervenes in different life stages of the nematodes, forms the time sequence complementation and mechanism superposition of the physical, chemical and biological control, and therefore obtains the effects of uninterrupted and continuous control on the nematode population of the guavas and improvement of the plant health level.
[0026] 2、Preferably, a pretreatment step of controlling the soil moisture content before applying the alkaline microbial fertilizer is adopted in the present application. Since the soil humidity is maintained within an appropriate range, the active bacteria in the microbial fertilizer are provided with conditions for rapid germination and proliferation, the heat conduction efficiency of the subsequent high-temperature smothering stage is improved, and the nematode larvae are induced to change from a dormant state to an active state to increase their contact opportunities with the control measures, thereby enhancing the synergistic effect of the overall control process and improving the execution efficiency and control consistency of each step.
[0027] 3、The method of the present application avoids the inhibition of the activity of biological agents by chemical residues by setting the time interval between chemical root irrigation and the application of P. lilacinum preparations, and ensures the timely connection of biological control when the chemical control effect is weakened. This timing arrangement is in line with the half-life of the agent and the germination period of the agent, thus achieving seamless integration of chemical and biological control methods, prolonging the duration of the control effect, promoting the repair of damaged roots, and achieving efficient and environmentally friendly nematode control benefits. BRIEF DESCRIPTION OF DRAWINGS
[0028] Figure 1 A flowchart of a physical-chemical combined application method for guava nematode control is provided for the present application. DETAILED DESCRIPTION
[0029] The present application is further described in detail below in conjunction with the drawings and examples.
[0030] Technical ideas: Related guava nematode control is mainly achieved by applying chemical nematicides, but this method has a single target and a short duration, and cannot effectively cover the entire life cycle of nematodes. Long-term continuous use can lead to nematode resistance, pesticide residues, and soil microecological environment destruction, resulting in a decrease in control effect with increasing planting years, and a rebound of nematode populations in the middle and late stages of crop growth, causing persistent damage to guava root systems and ultimately affecting fruit tree yield and fruit quality.
[0031] The present application discloses a physical-chemical combined application method for guava nematode control, comprising the following steps: S1, soil environment physical regulation; S2, high-temperature smothering pretreatment; S3, chemical agent root irrigation: during the fruiting period of guava or at the beginning of nematode damage, a nematicide composition is diluted with water and uniformly applied to the soil near the drip line of the tree crown; S4, biological agent application: before and after the chemical agent root irrigation treatment, P. lilacinum preparation is applied, with an application amount of 1 kg / mu, diluted with 1000 liters of water for root irrigation or trenching; S5, control cycle implementation.
[0032] This application employs a combined physical and chemical application method, integrating multiple control measures such as physical regulation of the soil environment, high-temperature suffocation pretreatment, root irrigation with chemical agents, and synergistic application of biological agents. By continuously implementing the above measures during three key periods in the guava growth cycle, synergistic intervention is carried out against different life stages of nematodes, forming a temporal complementarity and mechanistic superposition of physical, chemical, and biological control. Therefore, it achieves uninterrupted and continuous control of the guava nematode population, curbing the expansion of the nematode population and improving the health level of the plant.
[0033] Example 1 This embodiment provides a combined physicochemical application method for controlling guava nematodes, comprising the following steps: Pre-treatment of orchard soil moisture content: Keep the orchard soil moist, and control the relative soil moisture content at 60%.
[0034] S1. Physical regulation of soil environment: After pruning the guava tree, apply alkaline microbial fertilizer within the drip line of the canopy at a rate of 4 kg / tree.
[0035] Among them, alkaline microbial fertilizer is a microbial fertilizer containing Bacillus subtilis.
[0036] In addition to applying alkaline microbial fertilizer, amino acid powder, accounting for 1% of the fertilizer's mass, is added as a microbial growth promoter.
[0037] S2. High-temperature suffocation pretreatment: During the summer season when the daily maximum temperature is consistently above 35℃, cover the ground under the tree canopy projection with transparent plastic film for 4 weeks to raise the soil temperature of the cultivated layer to 45-55℃.
[0038] Before covering, the soil is leveled to ensure there are no gaps between the film and the ground.
[0039] S3. Chemical drenching: During the guava fruiting period or the early stage of nematode damage, dilute the nematicide composition with water and apply it evenly to the soil near the drip line of the tree canopy. The nematicide composition consists of the following ingredients by weight percentage: abamectin: 2.4%, fluopyram: 2.4%, and the remainder is water. The dosage of the nematicide composition is 500 mL / acre, diluted with 1000 L of water and applied evenly to the soil near the drip line of the tree canopy.
[0040] The nematicide composition is pretreated by shaking before use, with a shaking frequency of 150 rpm and a shaking time of 5 minutes.
[0041] The depth of pesticide application should be controlled at 20cm.
[0042] The plant growth promoter alginic acid is added to the solution, with the amount of alginic acid added being 0.01% of the total mass of the solution.
[0043] S4. Synergistic application of biological agents: Before and after chemical agent root irrigation treatment, apply Paecilomyces lilacinus preparation at a rate of 1 kg / mu, diluted with 1000L of water for root drenching or furrow application.
[0044] The application of Paecilomyces lilacinus preparations and the root irrigation treatment with chemical agents were carried out at intervals of 5 days.
[0045] When applying Paecilomyces lilacinus preparations, the soil temperature should be controlled at 15℃ and the soil moisture at 40% field capacity.
[0046] S5. Implementation of the prevention and control cycle: Three rounds of joint prevention and control operations from S1 to S4 will be carried out each year, with the three rounds of operations scheduled for March, June and September respectively.
[0047] Example 2 This embodiment provides a combined physicochemical application method for controlling guava nematodes, comprising the following steps: Pre-treatment of orchard soil moisture content: Keep the orchard soil moist, with the relative soil moisture content controlled at 70%.
[0048] S1. Physical regulation of soil environment: After pruning the guava tree, apply alkaline microbial fertilizer within the drip line of the canopy at a rate of 5 kg / tree.
[0049] Among them, alkaline microbial fertilizer is a microbial fertilizer containing Bacillus subtilis.
[0050] In addition to applying alkaline microbial fertilizer, amino acid powder, accounting for 2% of the fertilizer's mass, is added as a microbial growth promoter.
[0051] S2. High-temperature suffocation pretreatment: During the summer season when the daily maximum temperature is consistently above 35℃, cover the ground under the tree canopy projection with transparent plastic film for 5 weeks to raise the soil temperature of the cultivated layer to 45-55℃.
[0052] Before covering, the soil is leveled to ensure there are no gaps between the film and the ground.
[0053] S3. Chemical drenching: During the fruiting period of guava or the early stage of nematode damage, dilute the nematicide composition with water and apply it evenly to the soil near the drip line of the tree canopy. The nematicide composition consists of the following ingredients in the indicated weight percentages: abamectin: 2.5%, fluopyram: 2.5%, and the remainder is water. The dosage of the nematicide composition is 500 mL / acre, diluted with 1000 L of water and applied evenly to the soil near the drip line of the tree canopy.
[0054] The nematicide composition is pretreated by shaking before use, with a shaking frequency of 175 rpm and a shaking time of 7.5 minutes.
[0055] The depth of the pesticide application solution should be controlled to 30cm.
[0056] The plant growth promoter alginic acid is also added to the solution, with the amount of alginic acid added being 0.03% of the total mass of the solution.
[0057] S4. Synergistic application of biological agents: Before and after chemical agent root irrigation treatment, apply Paecilomyces lilacinus preparation at a rate of 1 kg / mu, diluted with 1000L of water for root drenching or furrow application.
[0058] The application of Paecilomyces lilacinus preparation and the root drenching treatment with chemical agents were carried out at an interval of 7.5 days.
[0059] When applying Paecilomyces lilacinus preparations, the soil temperature should be controlled at 25℃ and the soil moisture at 50% field capacity.
[0060] S5. Implementation of the prevention and control cycle: Three rounds of joint prevention and control operations from S1 to S4 will be carried out each year, with the three rounds of operations scheduled for March, June and September respectively.
[0061] Example 3 This embodiment provides a combined physicochemical application method for controlling guava nematodes, comprising the following steps: Pre-treatment of orchard soil moisture content: Keep the orchard soil moist, and control the relative soil moisture content at 80%.
[0062] S1. Physical regulation of soil environment: After pruning the guava tree, apply alkaline microbial fertilizer within the drip line of the canopy at a rate of 6 kg / tree.
[0063] Among them, alkaline microbial fertilizer is a microbial fertilizer containing Bacillus subtilis.
[0064] In addition to applying alkaline microbial fertilizer, amino acid powder, accounting for 3% of the fertilizer's mass, is added as a microbial growth promoter.
[0065] S2. High-temperature suffocation pretreatment: During the summer season when the daily maximum temperature is consistently above 35℃, cover the ground under the tree canopy projection with transparent plastic film for 6 weeks to raise the soil temperature of the cultivated layer to 45-55℃.
[0066] Before covering, the soil is leveled to ensure there are no gaps between the film and the ground.
[0067] S3. Chemical drenching: During the guava fruiting period or the early stage of nematode damage, dilute the nematicide composition with water and apply it evenly to the soil near the drip line of the tree canopy. The nematicide composition consists of the following ingredients by weight percentage: abamectin: 2.6%, fluopyram: 2.6%, and the remainder is water. The dosage of the nematicide composition is 500 mL / acre, diluted with 1000 L of water and applied evenly to the soil near the drip line of the tree canopy.
[0068] The nematicide composition is pretreated by shaking before use, with a shaking frequency of 200 rpm and a shaking time of 10 minutes.
[0069] The depth of pesticide application should be controlled at 40cm.
[0070] The plant growth promoter alginic acid is added to the solution, with the amount of alginic acid added being 0.05% of the total mass of the solution.
[0071] S4. Synergistic application of biological agents: Before and after chemical agent root irrigation treatment, apply Paecilomyces lilacinus preparation at a rate of 1 kg / mu, diluted with 1000L of water for root drenching or furrow application.
[0072] The application of Paecilomyces lilacinus preparations and the root irrigation treatment with chemical agents were carried out at intervals of 10 days.
[0073] When applying Paecilomyces lilacinus preparations, the soil temperature should be controlled at 35℃ and the soil moisture at 60% field capacity.
[0074] S5. Implementation of the prevention and control cycle: Three rounds of joint prevention and control operations from S1 to S4 will be carried out each year, with the three rounds of operations scheduled for March, June and September respectively.
[0075] Comparative Example 1 The comparative example refers to the content of Example 1, except that when pretreating the soil moisture content in the orchard, the relative soil moisture content is controlled at 40%, and the rest is the same as in Example 1.
[0076] Comparative Example 2 The comparative example refers to the content of Example 1, except that the amount of alkaline microbial fertilizer applied in step S1 is 2.5 kg / plant, and the rest is the same as in Example 1.
[0077] Comparative Example 3 The comparative example is based on the content of Example 1, except that the amino acid powder added in step S1 accounts for 0.5% of the mass of the microbial fertilizer, and the rest is the same as in Example 1.
[0078] Comparative Example 4 The comparative example refers to the content of Example 1, except that the covering time of the transparent plastic film in step S2 is 2.5 weeks, and the rest is the same as Example 1.
[0079] Comparative Example 5 The comparative example refers to the content of Example 1, except that the nematicide composition in step S3 consists of the following components by mass percentage: 1.7% abamectin, 1.7% fluopyram, and the balance being water. The rest of the contents are the same as in Example 1.
[0080] Comparative Example 6 The comparative example is the same as that in Example 1, except that the interval between the application of Paecilomyces lilacinus preparation and the root irrigation treatment with chemical agent in step S4 is 3 days. The rest of the content is the same as that in Example 1.
[0081] Performance testing Sample preparation: The experiment was conducted in a guava orchard with a 3-year history of nematode infestation. The soil in the orchard was clay loam, and the initial nematode population was found to be at a high density of more than 300 nematodes per 100 grams of soil. Multiple treatment groups were set up, namely, following Examples 1-3 and Comparative Examples 1-6 for pest control. Each treatment group had 3 replicate plots, and each plot contained 5 guava trees of uniform growth. All agricultural operations, such as pruning and fertilization, were kept consistent except for the control measures specified in this method. The experimental period was one full year, that is, 3 rounds of control operations were carried out.
[0082] Detection of nematode population density decline rate: The detection procedure follows the industry standard "Guidelines for Field Efficacy Trials of Pesticides (I) Control of Root-Knot Nematodes in Vegetables with Nematicides" (NY / T1464.26-2010). Before each round of control operations and 30 days after, soil samples were collected from the rhizosphere at a depth of 0 to 40 cm near the drip line of each test tree using a 5-point sampling method. Soil samples from the same replicate plot were mixed evenly, and nematodes were separated and collected from the soil using a modified Bellman funnel method. The separated nematodes were counted under an optical microscope, and the number of second-instar larvae of root-knot nematodes was accurately identified. The nematode population density decline rate was calculated using the following formula: Reduction rate = (Insect population density before control - Insect population density after control) / Insect population density before control × 100%.
[0083] Evaluation of root health status and root knot index: At the end of the experimental period, the main absorbing roots of each experimental tree were dug up and rinsed with clean water. An evaluation team composed of three plant protection experts conducted an independent blind evaluation of root health status based on the typical symptoms of root-knot nematode damage, namely the size, number and distribution of root nodules formed on the root system. A grade of 0 indicates that the root system is healthy and there are no root knots, and a grade of 5 indicates that the root system is severely deformed and more than 75% of the root surface area is covered by root knots. The average root knot index of each tree was used as the evaluation basis.
[0084] Soil microbial community activity detection: The detection method refers to the triphenyltetrazolium chloride (TTC-dehydrogenase activity) determination method in "Methods for Determination of Soil Microbial Biomass". The specific procedure is as follows: Fresh rhizosphere soil samples from each treatment group are taken and co-cultured with glucose solution and TTC staining solution in a constant temperature incubator. During the metabolism of soil microorganisms, dehydrogenases are produced, which reduce colorless TTC to red triphenylformazan. Then, formazan is extracted with methanol, and its absorbance is measured under a spectrophotometer. The absorbance value reflects the total activity and metabolic intensity of the soil microbial community.
[0085] Physiological growth indicators of plants were measured using the methods described in the agricultural industry standard "Description Specification for Fruit Tree Germplasm Resources - Guava" (NY / T2327-2013). During the autumn fruit harvest season, the growth of new shoots, the relative chlorophyll content of leaves, and the yield per tree were measured and recorded for each experimental tree. The growth of new shoots was measured using a measuring tape to measure the length of the current year's spring shoots. The relative chlorophyll content of leaves was measured using a chlorophyll meter on healthy leaves on the sunny side of the central canopy. The measurement process followed the instrument operating procedures and was completed at a unified time from 9:00 AM to 11:00 AM. The yield per tree was obtained by weighing all mature fruits at harvest.
[0086] Table 1:
[0087] Example Conclusion: As can be seen from Examples 1-3 and Comparative Example 1, and Table 1, pre-adjusting the relative soil moisture content to a suitable moist state is the foundation for ensuring the synergistic effect of subsequent stages. Suitable humidity not only provides favorable conditions for the rapid germination and colonization of functional microbial communities in alkaline microbial fertilizer, thereby improving the rhizosphere microecological environment, but also enhances the heat transfer efficiency during the high-temperature suffocation stage and effectively induces the activity of nematode larvae. Conversely, when the soil moisture is too low, both microbial activity and heat transfer are inhibited, resulting in a weakening of the synergistic effect of the entire control system, and ultimately a decline in all performance indicators. Based on Examples 1-3 and Comparative Example 2, and in conjunction with Table 1, it can be seen that applying sufficient alkaline microbial fertilizer can create a soil environment unfavorable to nematode survival; sufficient fertilizer application can ensure that functional microorganisms form a dominant population in the rhizosphere, effectively suppressing nematode larvae through strong nutrient and space competition, and creating favorable conditions for subsequent treatments; while insufficient fertilizer application leads to a decrease in the ability to regulate the rhizosphere microecology, which cannot effectively reduce the nematode population, thus affecting the overall control effect. Based on Examples 1-3 and Comparative Example 3, and in conjunction with Table 1, it can be seen that adding an appropriate proportion of amino acid powder as a microbial growth promoter can accelerate the colonization process of functional microorganisms in the soil. Amino acids provide microorganisms with easily absorbed carbon and nitrogen nutrients, shorten their growth lag phase, and promote the microorganisms to quickly enter the logarithmic growth phase and exert an insect-suppressing effect. If the growth promoter is insufficient, the adaptation period of microorganisms in the microbial fertilizer is prolonged, making it difficult to quickly establish population dominance and weakening the initial biological regulation effect. As can be seen from Examples 1-3 and Comparative Example 4, and Table 1, ensuring sufficient film covering time is the basis for high-temperature suffocation of nematodes; while continuous high-temperature action can destroy the protein structure and enzyme system in the nematodes, achieving physical removal; if the covering time is insufficient, enough heat energy will not be accumulated, resulting in uneven temperature distribution in the soil and insufficient duration, allowing some nematodes to survive in local low-temperature areas, becoming the source of reinfection. As can be seen from Examples 1-3 and Comparative Example 5, and Table 1, maintaining the concentrations of abamectin and fluopyram within a specific range is a way to achieve synergistic chemical control through a dual-mechanism approach. This formulation can simultaneously act on the nervous and energy metabolism systems of nematodes, producing a synergistic insecticidal effect. A decrease in the effective concentration will result in insufficient active ingredients per unit volume of pesticide solution, making it difficult to form an effective concentration gradient in the soil to kill nematodes, thus reducing the control effect. Based on Examples 1-3 and Comparative Example 6, and in conjunction with Table 1, it can be seen that setting an interval between chemical root irrigation and the application of biological agents is a sequential design that achieves seamless integration of chemical and biological control and maintains continuous control efficacy. This interval avoids the inhibition of Paecilomyces lilacinus activity by chemical residues and ensures that biological control can be promptly resumed when the efficacy of chemical agents begins to decline. If the interval is too short, the activity of biological agents will be impaired, and an effective biological population cannot be established. If the interval is too long, a control gap will occur, during which the nematode population will recover.
[0088] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.
Claims
1. A combined physicochemical application method for controlling guava nematodes, characterized in that, Includes the following steps: S1. Physical regulation of soil environment: After pruning the guava tree, apply alkaline microbial fertilizer within the drip line of the canopy, at a rate of 4-6 kg / tree. S2. High-temperature suffocation pretreatment: During the summer season when the daily maximum temperature is consistently above 35℃, cover the ground under the tree canopy projection with transparent plastic film for 4-6 weeks to raise the soil temperature of the cultivated layer to 45-55℃. S3. Chemical Root Drenching: During the guava fruiting period or the early stage of nematode damage, dilute the nematicide composition with water and apply it evenly to the soil near the drip line of the tree canopy. The nematicide composition consists of the following ingredients in the indicated weight percentages: abamectin: 2.4%-2.6%, fluopyram: 2.4%-2.6%, with the remainder being water. The dosage of the nematicide composition is 500 ml / acre, diluted with 1000 liters of water and applied evenly to the soil near the drip line of the tree canopy. S4. Synergistic application of biological agents: Before and after chemical agent root irrigation treatment, apply Paecilomyces lilacinus preparation at a rate of 1 kg / mu, diluted with 1000 liters of water for root drenching or furrow application. S5. Implementation of the prevention and control cycle: Three rounds of joint prevention and control operations described in S1 to S4 shall be carried out each year, with the three rounds of operations scheduled for March, June and September respectively.
2. The physicochemical combined application method for controlling guava nematodes according to claim 1, characterized in that, Before step S1, there is a pretreatment step for the soil moisture content in the orchard: keep the orchard soil moist, and control the relative soil moisture content at 60%-80%.
3. The physicochemical combined application method for controlling guava nematodes according to claim 1, characterized in that, In step S1, the alkaline microbial fertilizer is a microbial fertilizer containing Bacillus subtilis.
4. The physicochemical combined application method for controlling guava nematodes according to claim 1, characterized in that, While applying the alkaline microbial fertilizer in step S1, add 1%-3% of amino acid powder by weight of the fertilizer as a microbial growth promoter.
5. The physicochemical combined application method for controlling guava nematodes according to claim 1, characterized in that, In step S2, the soil is leveled before the transparent plastic film is applied to ensure that there are no gaps between the film and the ground.
6. The physicochemical combined application method for controlling guava nematodes according to claim 1, characterized in that, In step S3, the nematicide composition is subjected to a shaking pretreatment before use, with a shaking frequency of 150-200 rpm and a shaking time of 5-10 minutes.
7. The physicochemical combined application method for controlling guava nematodes according to claim 1, characterized in that, In step S3, the depth of the pesticide application should be controlled to be 20-40 cm.
8. The physicochemical combined application method for controlling guava nematodes according to claim 1, characterized in that, In step S3, a plant growth promoter, alginic acid, is added to the solution. The amount of alginic acid added is 0.01%-0.05% of the total mass of the solution.
9. The physicochemical combined application method for controlling guava nematodes according to claim 1, characterized in that, In step S4, the application of the Paecilomyces lilacinus preparation and the root irrigation treatment with chemical agents are carried out at intervals of 5-10 days.
10. The physicochemical combined application method for controlling guava nematodes according to claim 1, characterized in that, In step S4, when applying Paecilomyces lilacinus preparations, the soil temperature should be controlled at 15-35℃ and the soil moisture at 40%-60% of field capacity.