Method for preventing and treating diseases and insect pests of bitter gourd seedlings

Abstract

The application discloses a balsam pear seedling disease and pest control method, and aims to solve the problems of pesticide resistance of diseases and pests caused by blind use of chemical pesticides, pesticide residue affecting quality safety, high risk of plant pesticide injury, lack of pertinence of prevention and treatment and insufficient comprehensive prevention and control. The method comprises six steps of seedbed disinfection treatment, seed coating treatment, seedling environment regulation, biological prevention implementation, precise chemical prevention and treatment and strong seedling cultivation management. The seedbed is disinfected by combining physical heat disinfection with biological bacteria, a protective barrier is formed by seed coating, suitable growth conditions are created by environment regulation, a natural defense system is constructed by biological prevention, pesticide residue is reduced by precise use of pesticides, and the resistance of strong seedlings is enhanced by strong seedling management. The application can effectively reduce the disease and pest source base, reduce pesticide dependence, enhance the disease resistance of seedlings, improve the survival rate, guarantee the quality and safety of balsam pear, and meet the requirements of green agricultural development.

Description

Technical Field

[0001] This invention relates to the field of agricultural technology, and in particular to a method for controlling diseases and pests in bitter gourd seedlings. Background Technology

[0002] Bitter gourd, an annual climbing herbaceous plant belonging to the Cucurbitaceae family, is widely cultivated in my country due to its heat-clearing, detoxifying, and nutrient-rich properties. The seedling stage is the most critical growth phase in bitter gourd cultivation. During this period, the plant tissues are tender and have weak resistance, making them susceptible to various diseases and pests. Common seedling diseases include fungal diseases such as damping-off, seedling blight, and wilt, as well as viral diseases; common pests include aphids, whiteflies, and leaf miners. If these diseases and pests are not effectively controlled during the seedling stage, they will seriously affect the later growth and final yield of bitter gourd, and may even lead to the death of the entire field of plants, causing significant economic losses to growers. Therefore, how to conduct scientific and effective disease and pest control during the bitter gourd seedling stage is an important technical issue for ensuring high-quality and high-yield bitter gourd.

[0003] Among these, pest and disease control during the seedling stage is a core technical aspect of bitter gourd cultivation management, directly affecting plant survival rate and subsequent yield. Current production practices primarily rely on chemical pesticide spraying for seedling pest and disease control, using fungicides and insecticides such as carbendazim, chlorothalonil, and imidacloprid to control their occurrence. However, the long-term and excessive use of chemical pesticides not only easily leads to pesticide resistance in pests and diseases, reducing control effectiveness, but also causes pesticide residue problems, affecting the quality and safety of bitter gourd and threatening consumer health. Furthermore, the tender tissues of bitter gourd seedlings are highly sensitive to chemical pesticides, and improper application can easily cause phytotoxicity, further exacerbating the difficulty of control.

[0004] Current technologies for controlling pests and diseases in bitter gourd seedlings have significant shortcomings. First, the indiscriminate use of chemical pesticides lacks specificity, failing to provide precise control based on the occurrence patterns and specific conditions of seedling pests and diseases, resulting in pesticide waste and environmental pollution. Second, the reliance on chemical pesticides ignores the principle of integrated pest management, lacking a systematic control solution encompassing agricultural cultivation practices and biological control. Third, existing technologies fail to fully consider the unique physiological characteristics of bitter gourd seedlings, resulting in a mismatch between control methods and seedling growth needs, leading to unstable control effects and failing to meet the requirements of modern green agriculture. Therefore, developing a control method that effectively manages bitter gourd seedling pests and diseases while also ensuring plant safety and environmental friendliness has become a pressing technical challenge for the bitter gourd cultivation industry. Summary of the Invention

[0005] The purpose of this invention is to provide a method for controlling diseases and pests in bitter gourd seedlings, which solves the problems mentioned in the background art.

[0006] This invention is implemented as follows: a method for controlling diseases and pests in bitter gourd seedlings, comprising the following specific steps: Step 1: Seedbed disinfection treatment: Before sowing bitter gourd, the seedbed soil is disinfected using a combination of physical heat disinfection and biological agents; Step 2: Seed coating treatment: Bitter gourd seeds are coated with a seed coating agent containing probiotics and plant extracts to form a protective layer; Step 3: Seedling environment control: By adjusting the temperature, humidity, and light conditions of the seedbed, an environment unfavorable to the occurrence of diseases and pests but favorable to the healthy growth of seedlings is created; Step 4: Implementation of biological control: Natural enemy insects are released or microbial agents are sprayed at appropriate times during the seedling stage to establish a natural defense system; Step 5: Precision chemical control: When the trend of disease and pest occurrence is monitored, low-toxicity and high-efficiency agents are selected for precise application, and the dosage and application time are strictly controlled; Step 6: Strong seedling cultivation and management: Through reasonable water and fertilizer regulation and the use of plant immune inducers, the stress resistance and disease resistance of bitter gourd seedlings are enhanced.

[0007] Preferably, the soil disinfection treatment in step 1 includes: first, tilling the seedbed soil to a preset depth, then laying a transparent plastic film of a preset thickness, using solar energy to raise the soil temperature to a preset temperature and maintain it for a preset time, and then uniformly spraying Bacillus subtilis wettable powder with a preset concentration and a preset dosage.

[0008] Preferably, the seed coating agent in step 2 comprises the following components by weight: a predetermined number of parts of Bacillus subtilis powder, a predetermined number of parts of chitosan, a predetermined number of parts of neem extract, a predetermined number of parts of sodium alginate, and a predetermined number of parts of polyvinyl alcohol. The mass ratio of the seed coating agent to the seed is a predetermined ratio. After coating, the seed is air-dried until the moisture content is lower than the predetermined moisture content.

[0009] Preferably, the environmental control parameters in step 3 are: daytime temperature controlled within a preset temperature range, nighttime temperature controlled within a preset temperature range, soil relative humidity maintained within a preset humidity range, air relative humidity controlled within a preset humidity range, daily sunshine duration set to a preset duration, and sunshine intensity set to a preset intensity.

[0010] Preferably, the biological control in step 4 includes: releasing predatory mites at the one-leaf-one-heart stage of seedlings, with a preset number released per square meter; spraying Trichoderma harzianum wettable powder at the two-leaf-one-heart stage of seedlings, diluted to a preset multiple, and spraying again after a preset number of days, for a preset number of consecutive applications.

[0011] Preferably, the monitoring method for precise chemical control in step 5 is as follows: conduct field inspections every morning during the seedling stage and record the occurrence of diseases and pests; when the disease rate exceeds the preset threshold or the insect population density exceeds the preset density, initiate chemical control; use carbendazim wettable powder at a preset multiple or chlorothalonil wettable powder at a preset multiple to control fungal diseases, and use imidacloprid wettable powder at a preset multiple to control aphids. Spraying time is selected after dusk, and the dosage is controlled within the preset dosage.

[0012] Preferably, the seedling cultivation management in step 6 includes: spraying chitosan oligosaccharide inducer once a week, diluted to a preset ratio; applying organic fertilizer once at the three-leaf stage of the seedlings, applying a preset amount of decomposed cake fertilizer per square meter of seedbed, and irrigating with amino acid water-soluble fertilizer diluted to a preset ratio.

[0013] Preferably, it also includes establishing a seedling disease and pest forecasting archive, recording the weather conditions, seedling condition, types and extent of diseases and pests, control measures and effects of each inspection, forming a data archive to guide subsequent control decisions.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. Effective comprehensive prevention and control Disinfecting seedbeds by combining physical heat disinfection with biological agents effectively kills pathogens and insect eggs in the soil, reducing the initial source of pests and diseases; seed coating treatment forms a protective barrier during seed germination, reducing the chance of seedling disease infection; the introduction of biological control measures builds a natural defense system, reducing dependence on chemical pesticides.

[0015] 2. Precision medication reduces residues By adopting a pest and disease monitoring and early warning mechanism, chemical pesticides are only applied when the control threshold is reached, thus avoiding blind and excessive use of pesticides. Low-toxicity and high-efficiency pesticides are selected and the dosage and application time are strictly controlled, which significantly reduces pesticide residues and ensures the quality and safety of bitter gourd.

[0016] 3. Enhances stress resistance and improves survival rate By creating suitable conditions for seedling growth through environmental regulation and combining strong seedling cultivation management measures, the stress resistance and disease resistance of bitter gourd seedlings were enhanced. The use of plant immune inducers activated the seedlings' own defense system, improved the plant's resistance to various diseases and pests, and significantly increased the seedling survival rate.

[0017] 4. Environmentally friendly and sustainable This invention comprehensively utilizes agricultural control, biological control, and precision chemical control measures, embodying the core concept of integrated pest management, reducing the negative impact of chemical pesticides on the ecological environment, meeting the requirements of modern green agricultural development, and possessing good value for promotion and application. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall technical solution architecture of the bitter gourd seedling disease and pest control method proposed in this invention; Figure 2 This is a schematic diagram of the core integrated pest management principle framework of the present invention, which combines physical thermal disinfection with biological agents, seed coating treatment, and the synergistic effect of biological control and precision chemical control. Detailed Implementation

[0019] Example 1 To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0020] This embodiment elaborates on a method for controlling diseases and pests in bitter gourd seedlings. The method includes six core steps: soil pretreatment combining physical thermal disinfection and biological agents; seed coating with the synergistic effect of probiotics and plant-derived extracts; seedbed management with intelligent environmental parameter regulation; a natural defense system constructed by natural enemy insects and microbial agents; precise chemical application based on disease and pest monitoring and early warning; and robust seedling cultivation management based on plant immune induction and nutrient regulation. This forms a complete and systematic integrated prevention and control technology system for diseases and pests in bitter gourd seedlings.

[0021] Regarding step 1, seedbed disinfection, soil disinfection of the seedbed before bitter gourd sowing is the primary step in pest and disease control. Its core lies in employing a dual mechanism combining physical heat disinfection and biological agents to reduce the initial number of pathogens and insect eggs in the soil, creating a low-pest-pressure starting environment for bitter gourd seedlings. The specific operating procedure is as follows: First, the seedbed soil is tilled to a depth of 25 to 30 centimeters. During tilling, crop residues, stones, and debris are removed to ensure the soil is loose and well-aerated, which facilitates heat transfer to deeper soil layers during subsequent heat treatment. After tilling, the seedbed surface is raked smooth and leveled, creating raised beds 120 to 150 centimeters wide and with a length determined by the number of seedlings to be cultivated. The beds should be 10 to 15 centimeters above ground level to facilitate drainage and subsequent management.

[0022] Next, physical heat sterilization is performed. A transparent plastic film with a thickness of 0.08 to 0.12 mm is used to cover the prepared seedbed surface. The edges of the film are then sealed tightly with soil to ensure a relatively enclosed space for warming. After covering with the film, the soil temperature is gradually increased by sunlight. Under sunny weather conditions, after 7 to 10 days of continuous sunlight, the temperature at a depth of 10 cm can rise to 55 to 65 degrees Celsius. This temperature can effectively kill most fungal pathogens, bacterial pathogens, insect eggs, and weed seeds in the soil. During the heat preservation period, the film should be kept intact; any damage should be repaired promptly. After the heat preservation is completed, the film is removed to allow the soil to cool naturally to room temperature.

[0023] Then, apply the biological agent. After the soil temperature drops to normal, use 8 to 12 grams of Bacillus subtilis wettable powder per square meter of seedbed area. Dilute the agent with water at a ratio of 1:200 to 1:300 to prepare a bacterial solution with a concentration of 1×10⁶ live spores per milliliter. 8 Up to 5×10 8 Apply the bacterial solution evenly to the surface of the seedbed soil using a sprayer, ensuring the soil surface is thoroughly moistened without causing runoff. After spraying, lightly rake the soil surface to ensure the bacterial agent is fully mixed with the soil. Once applied to the soil, Bacillus subtilis can rapidly colonize the rhizosphere, forming a dominant microbial community. It inhibits the growth and reproduction of soil-borne pathogens through multiple mechanisms, including competitive site occupation, secretion of antimicrobial substances, and induction of plant resistance.

[0024] Regarding step 2, seed coating treatment, bitter gourd seeds are coated with a seed coating agent containing probiotics and plant-derived extracts. This forms a protective barrier during seed germination, achieving an active defense effect of inhibiting bacteria with beneficial bacteria and repelling insects with plant-derived active substances. The specific operation of this step is as follows: The seed coating agent is formulated as follows: 15 to 25 parts by weight of Bacillus subtilis powder, 8 to 12 parts by weight of chitosan, 5 to 10 parts by weight of neem extract, 3 to 6 parts by weight of sodium alginate, 2 to 5 parts by weight of polyvinyl alcohol, with the remainder being fillers. The effective viable count of Bacillus subtilis powder is not less than 2 × 10¹ per gram. 0 The degree of deacetylation of chitosan is 85% to 95%, and the molecular weight is 5 × 10⁻⁶. 4 Up to 3×10 5 The Dalton extract contains azadirachtin at a content of not less than 0.3%, sodium alginate with a viscosity of 200 to 800 mPa·s, and polyvinyl alcohol with a degree of polymerization of 1700 to 1900 and a degree of alcoholysis of 88% to 90%.

[0025] Before seed coating, bitter gourd seeds are carefully selected, removing diseased, insect-infested, deformed, and impurity seeds, and choosing plump, uniformly sized seeds for coating. The selected seeds are then placed in a well-ventilated, shady place to dry for 2 to 3 hours, reducing the seed moisture content to below 8%, thus improving the adhesion of the seed coating agent.

[0026] During the coating process, the prepared seed coating agent is mixed with bitter gourd seeds at a mass ratio of 1:40 to 1:60, meaning 1.67 to 2.5 grams of seed coating agent are used per 100 grams of seeds. Using a seed coating machine or by manual stirring, the seed coating agent is evenly coated onto the surface of each seed, forming a coating layer with a thickness of 0.5 to 1.2 millimeters. After coating, the seeds are spread out in a cool, well-ventilated place to air dry naturally, avoiding direct sunlight. The air drying time is usually 8 to 12 hours, until the coating layer solidifies and the seed moisture content drops below 10%. Coated seeds should be stored in a dry, well-ventilated, and cool place, avoiding moisture and direct sunlight, which can affect the coating effect and seed germination rate.

[0027] In this coating agent, Bacillus subtilis can colonize the seedling roots during seed germination, forming a rhizosphere protective barrier; chitosan has good film-forming and antibacterial activity, and can form a protective film on the seed surface to inhibit pathogen infection; azadirachtin and other active ingredients in neem extract have broad-spectrum insecticidal and insecticidal effects, and can repel or kill pests in the soil; sodium alginate and polyvinyl alcohol serve as film-forming agents to ensure that each active ingredient can adhere firmly to the seed surface and be released slowly.

[0028] Regarding step 3, seedling stage environmental control, this involves adjusting the temperature, humidity, and light conditions of the seedbed to create an environmental parameter range that is both unfavorable to the occurrence of pests and diseases and promotes robust seedling growth, thus achieving optimal configuration of environmental factors. Specific environmental control parameters are set as follows: Regarding temperature management, daytime temperatures should be controlled within the range of 25 to 32 degrees Celsius, with the optimal temperature being 28 to 30 degrees Celsius; nighttime temperatures should be controlled within the range of 18 to 22 degrees Celsius, with the optimal temperature being 20 to 22 degrees Celsius. Maintaining a day-night temperature difference between 6 and 12 degrees Celsius is beneficial for seedlings to accumulate organic matter through photosynthesis during the day, while appropriately lowering the temperature at night reduces respiration. Simultaneously, a low-temperature environment is unfavorable for the active reproduction of most pathogens and pests. When the outside temperature is below the set range, the seedbed temperature should be increased by using electric heating wires or covering with insulation blankets; when the outside temperature is above the set range, the seedbed temperature should be reduced by increasing ventilation, covering with shade nets, and using misting for cooling.

[0029] Regarding humidity management, the relative humidity of the soil should be maintained within the range of 65% to 80%, with the optimal humidity being 70% to 75%; the relative humidity of the air should be controlled within the range of 60% to 75%, with the optimal humidity being 65% to 70%. Soil moisture can be regulated by irrigation time and amount. Drip irrigation or frequent small waterings should be used to maintain uniform and stable soil moisture, avoiding sudden changes in water content that could lead to poor seedling root development. Air humidity can be controlled by spraying and ventilation. On sunny days, ventilation should be increased appropriately around midday to reduce air humidity and prevent high humidity environments from inducing diseases such as gray mold and downy mildew. During dry periods, spraying around the seedbed can increase air humidity and prevent seedlings from wilting due to excessively dry air.

[0030] Regarding light management, the daily light duration should be controlled between 10 and 14 hours, with the optimal duration being 12 to 13 hours; the light intensity should be controlled within the range of 20,000 to 40,000 lux, with the optimal intensity being 25,000 to 35,000 lux. From emergence until the seedlings have one leaf and one bud, appropriately increase the light intensity and duration to promote photosynthesis and rapid growth. After the seedlings reach the two-leaf and one-bud stage, if the light is too strong, cover them with shade netting for moderate shading to prevent sunburn on the seedling leaves. During periods of continuous cloudy or rainy weather, supplemental lighting can be used with plant growth lamps to ensure the seedlings receive sufficient light to maintain normal photosynthesis and growth.

[0031] Regarding step 4, biological control, natural enemy insects are released at the appropriate time during the seedling stage, or microbial agents are sprayed to construct a natural defense system of using insects to control insects and using microorganisms to suppress microorganisms, reducing dependence on chemical pesticides and achieving ecological regulation of pests and diseases. Specific implementation is as follows: During the seedling stage (one leaf and one bud), predatory mites are released as natural enemies for biological pest control. *Neoseiuyes barkii* or *Neoseiuyes cucumeris* are selected as the release species, with a release rate of 80 to 120 mites per square meter. During release, the release device containing the predatory mites is evenly placed on the seedling leaves or the surface of the seedbed substrate, allowing the mites to disperse and find prey. Predatory mites can prey on the eggs and nymphs of common small pests in the seedbed, such as spider mites, thrips, and aphids, effectively controlling pest populations. Avoid using any insecticides for one week before and after release to prevent toxicity to the predatory mites.

[0032] At the two-leaf-one-heart stage of seedlings, begin spraying with Trichoderma harzianum wettable powder for microbial control. The active ingredient content of Trichoderma harzianum wettable powder is 1×10⁻⁶ live spores per gram. 9 For applications involving more than one spore, dilute according to a ratio of 1:800 to 1:1000, i.e., dilute 10 grams of Trichoderma harzianum wettable powder with 8 to 10 liters of water to prepare a Trichoderma harzianum spore concentration of 1 × 10⁻⁶ spores per milliliter. 6 Up to 1×10 7Prepare a bacterial suspension. Apply evenly to both sides of the seedling leaves and the base of the stem using a sprayer, ensuring the leaves are thoroughly moistened without dripping. Repeat the application every 7 to 10 days, for a total of 3 to 4 applications. *Trichoderma harzianum* effectively inhibits the pathogens of fungal diseases such as gray mold, damping-off, and seedling blight through mechanisms such as hyperparasitism, competition for nutrients and space, and secretion of antibacterial substances.

[0033] Regarding step 5, precision chemical control, based on pest and disease monitoring and early warning, when pest and disease occurrence reaches the control threshold, select low-toxicity, high-efficiency pesticides for precise application, strictly controlling the dosage and application time to achieve effective pest and disease control while minimizing pesticide residues. Specific monitoring and control procedures are as follows: The monitoring method involved daily morning field inspections during the seedling stage, using a magnifying glass to examine the upper and lower surfaces of seedling leaves, the base of stems, and the soil around the roots, recording the occurrence of pests and diseases. Monitoring content included: the type, area, and number of lesions on seedling leaves; the species, population density, and severity of pest damage; and abnormal symptoms such as wilting, yellowing, and deformity of seedlings. Weather conditions for each inspection were recorded, including temperature, humidity, and rainfall. A pest and disease occurrence record was established, with detailed records of each inspection, providing data support for prevention and control decisions.

[0034] The control measures are initiated when the disease incidence rate exceeds 5% or the insect population density exceeds 30 insects per 100 seedlings. The disease incidence rate is calculated by dividing the number of diseased seedlings by the total number of seedlings surveyed and multiplying by 100%. The insect population density is determined by randomly surveying 100 seedlings per row and recording the number of pests.

[0035] For chemical control, for fungal diseases such as damping-off, seedling blight, and gray mold, use carbendazim wettable powder at a dilution ratio of 1:500 to 1:600 ​​(25 grams of carbendazim wettable powder to 12.5 to 15 liters of water); or use chlorothalonil wettable powder at a dilution ratio of 1:600 ​​to 1:800 (25 grams of chlorothalonil wettable powder to 15 to 20 liters of water). For piercing-sucking pests such as aphids and whiteflies, use imidacloprid wettable powder at a dilution ratio of 1:2000 to 1:3000 (10 grams of imidacloprid wettable powder to 20 to 30 liters of water). Spraying should be done in the late afternoon or evening when temperatures are lower and transpiration is weaker, allowing the pesticide to remain on the leaves for a longer period to exert its effect. Strong sunlight should be avoided to prevent pesticide decomposition and inactivation.

[0036] Regarding dosage control, the dosage of carbendazim wettable powder should not exceed 50 grams of active ingredient per mu (667 square meters), chlorothalonil wettable powder should not exceed 80 grams of active ingredient per mu, and imidacloprid wettable powder should not exceed 20 grams of active ingredient per mu. The number of chemical control applications during the entire seedling stage should be limited to three times, and different pesticides should be used alternately to prevent the development of pesticide resistance in pests and diseases.

[0037] Regarding step 6, seedling cultivation and management, through reasonable water and fertilizer regulation and the use of plant immunity inducers, the stress resistance and disease resistance of bitter gourd seedlings are enhanced, resulting in robust seedlings and improved transplant survival rate and later yield. Specific management measures are as follows: Regarding the use of plant immune inducers, spray chitosan oligosaccharide inducers once a week. The concentration of the chitosan oligosaccharide inducer is 0.5% to 1%, that is, diluted at a ratio of 1:100 to 1:200, with 100 to 150 ml of diluted solution per square meter of seedbed. As a plant immune inducer, chitosan oligosaccharide can activate the plant's own defense system and improve the plant's resistance to pathogens. When spraying, evenly cover both sides of the seedling leaves. Avoid rainfall or irrigation within 4 hours after spraying to prevent affecting the inducement effect.

[0038] For water and fertilizer management, topdressing should be applied once at the three-leaf stage of the seedlings. Apply 80 to 120 grams of well-rotted cake fertilizer per square meter of seedbed as base fertilizer, supplemented with amino acid water-soluble fertilizer. The amino acid water-soluble fertilizer should be diluted at a ratio of 1:500 to 1:800, that is, 1 liter of concentrate to 500 to 800 liters of water, and 200 to 300 ml of diluted solution should be applied per square meter of seedbed. Well-rotted cake fertilizer is rich in protein and organic matter, which can continuously provide nutrients for seedlings; amino acid water-soluble fertilizer contains a variety of free amino acids and trace elements, which can quickly supplement seedling nutrition, promote the development of seedling roots, thick stems, and dark green leaves.

[0039] Throughout the seedling stage, keep the seedbed clean, promptly remove diseased plants, residual leaves, and weeds to reduce the initial sources of infection and transmission vectors of pests and diseases. Harden off the seedlings 3 to 5 days before transplanting by gradually reducing the temperature and humidity of the seedbed, while increasing ventilation and light intensity to improve the seedlings' adaptability to transplanting stress.

[0040] Regarding the establishment of a seedling disease and pest forecasting archive, this archive will be established simultaneously during the aforementioned prevention and control process. The archive will include: the date of each field inspection, weather conditions (temperature, humidity, precipitation, wind, etc.), seedling condition (seedling height, leaf age, leaf color, growth vigor, etc.), types and severity of diseases and pests, control measures adopted, and their effectiveness evaluation. This data will be organized and archived chronologically to form a complete database of disease and pest occurrence and control. Through analysis and summarization of historical data, the patterns of disease and pest occurrence and key influencing factors will be identified, providing a scientific basis for subsequent prevention and control decisions and achieving precise and intelligent disease and pest control.

[0041] The parameters and operating steps in the above embodiments are specific implementations by those skilled in the art under conventional technical conditions. The scope of protection of this invention is not limited thereto. Any appropriate adjustment or substitution of the above parameters without departing from the spirit of the technical solution of this invention shall fall within the protection scope of this invention.

[0042] Example 2 To further illustrate the technical solution of the present invention, another embodiment is provided below. The main difference between this embodiment and embodiment 1 lies in the specific operation method of soil disinfection treatment and the difference in the setting of some environmental parameters. Other identical parts will not be described again.

[0043] This embodiment elaborates on the methods for preventing and controlling diseases and pests in bitter gourd seedlings under facility-based seedling cultivation conditions, and is applicable to facility-based seedling cultivation scenarios such as greenhouses or seedling factories.

[0044] In step 1, the seedbed disinfection process, facility-based seedling cultivation typically employs substrate cultivation. The substrate disinfection process is as follows: First, peat moss, perlite, and vermiculite are mixed evenly in a volume ratio of 4:3:3 to create a composite seedling substrate. Then, the substrate is piled into a mound 30 to 40 cm thick. Saturated steam is introduced into the mound using a steam generator to raise the substrate temperature to 70 to 80 degrees Celsius and maintain this temperature for 30 to 45 minutes. This steam heat kills pathogens, pests, and weed seeds in the substrate. After steam disinfection, the substrate is spread out to cool to room temperature. Finally, Bacillus subtilis wettable powder is evenly mixed into the substrate at a dosage of 50 to 80 grams per cubic meter of substrate, ensuring that the effective viable count of Bacillus subtilis is not less than 2 × 10¹ per gram. 0 indivual.

[0045] In step 3, seedling stage environmental control, the environment for facility-based seedling cultivation is precisely regulated using an automated control system. Temperature parameters are set as follows: daytime temperature controlled at 26-30 degrees Celsius, nighttime temperature controlled at 18-20 degrees Celsius; substrate temperature controlled within the range of 20-24 degrees Celsius. Humidity parameters are set as follows: substrate relative humidity maintained at 70%-80%, air relative humidity controlled at 65%-75%. Light parameters are set as follows: light intensity controlled at 30,000-40,000 lux, light duration 12-14 hours. When natural light is insufficient, full-spectrum plant growth lights are used for supplemental lighting, with the light source suspended 50-80 cm above the seedlings.

[0046] In step 4, biological control, the relatively enclosed environment of facility-based seedling cultivation makes it more suitable for the use of microbial agents. In addition to the *Trichoderma harzianum* application scheme described in Example 1, *Bacillus subtilis* agents can be used in conjunction for synergistic control. Seven to ten days after seedling emergence, apply *Bacillus subtilis* wettable powder at a dilution of 1:500 as a foliar spray, using 150 to 200 ml of the diluted solution per square meter of seedbed. Repeat the spray after 10 to 15 days, for a total of 2 to 3 applications. *Bacillus subtilis* effectively inhibits various soil-borne and foliar pathogens, creating a synergistic effect when used in combination with *Trichoderma harzianum*.

[0047] In step 5, precise chemical control, the threshold for initiating chemical control can be appropriately lowered to achieve better results in facility-based seedling cultivation due to the relatively controllable transmission routes of pests and diseases. Chemical control should be initiated when the disease incidence rate exceeds 3% or the insect population density exceeds 20 insects per 100 plants. For pesticide selection, greater specificity is required: for damping-off, hymexazol wettable powder can be diluted 1:1500 for root drenching; for seedling blight, methyl thiophanate emulsifiable concentrate can be diluted 1:1000 for spraying; and for aphids, thiamethoxam suspension can be diluted 1:2000 for spraying. Strict control of concentration and dosage is essential to ensure seedling safety.

[0048] In step 6, seedling cultivation and management, the fertilization plan is adjusted accordingly due to the higher nutrient content of the substrate in facility-based seedling cultivation. For base fertilizer, use 1.5 to 2 kg of NPK compound fertilizer and 10 to 15 kg of well-rotted organic fertilizer per cubic meter of substrate. For topdressing, use water-soluble fertilizer applied through irrigation. The NPK fertilizer should be diluted 200 to 300 times and applied once or twice a week. The concentration of the chitosan oligosaccharide inducer is adjusted to 0.3% to 0.5% to suit the ecological environment of facility-based seedling cultivation.

[0049] By implementing the above technical solutions, the occurrence of diseases and pests in bitter gourd seedlings can be effectively controlled under facility-based seedling cultivation conditions, and robust bitter gourd seedlings can be cultivated, laying a good foundation for subsequent field cultivation.

[0050] Example 3 This embodiment provides a method for controlling diseases and pests in bitter gourd seedlings during the open-air small arched shed seedling raising stage, which is applicable to open-air seedling raising scenarios for early spring cultivation.

[0051] In step 1, the soil disinfection of the seedbed in the open-air small arched greenhouse seedling cultivation was carried out using solar energy combined with calcium cyanamide. After tilling the seedbed soil, calcium cyanamide was evenly spread on the soil surface at a rate of 80 to 100 grams per square meter of seedbed. Then, a transparent plastic film was laid and covered with the small arched greenhouse film. Solar energy was used to raise the soil temperature, and at the same time, calcium cyanamide reacted with water to produce hydrogen cyanide gas. The two worked synergistically to enhance the disinfection effect. After 10 to 15 days of treatment, the film was removed for ventilation for 5 to 7 days to allow residual chemicals in the soil to volatilize and dissipate. The calcium ions produced after the decomposition of calcium cyanamide can also regulate the soil pH and improve the soil structure. After the soil temperature dropped to a suitable level, the soil was inoculated with a compound inoculant of Bacillus subtilis and Bacillus megaterium at a rate of 15 to 20 grams per square meter of seedbed, with the ratio of the two bacteria in the compound inoculant being 1:1.

[0052] In step 2, the seed coating treatment, the seed coating agent formulation of this embodiment has been optimized and adjusted: 20 to 30 parts by weight of Bacillus subtilis powder, 10 to 15 parts by weight of chitosan, 8 to 12 parts by weight of neem extract, 3 to 5 parts by weight of tea saponin, 4 to 8 parts by weight of sodium alginate, and 3 to 6 parts by weight of polyvinyl alcohol. Tea saponin is a natural surfactant and insecticidal active substance, which, in synergy with neem extract, can enhance the repellency and killing effect on pests.

[0053] In step 3, environmental control during the seedling stage, the environmental control of the small arched greenhouse mainly relies on opening and closing the plastic film. During the day, when the temperature exceeds 30 degrees Celsius, promptly open the plastic film at both ends of the small arched greenhouse for ventilation and cooling to prevent scorching of the seedlings. After the temperature drops in the evening, promptly cover the film back to retain warmth. At night, cover the outside of the small arched greenhouse with straw mats or insulation blankets, with the insulation blankets being 2 to 3 centimeters thick. Water management adopts a method of frequent watering with small amounts of water, avoiding excessive watering that would lead to excessive humidity in the seedbed. Regarding light management, from emergence to the seedling stage, open the plastic film of the small arched greenhouse from 9:00 AM to 3:00 PM daily to increase light exposure, and cover the film back to retain warmth after 3:00 PM.

[0054] In step 4, biological control, the biological control strategy of this embodiment is enhanced. In addition to releasing predatory mites at the one-leaf-one-heart stage of seedlings, ladybugs are released at the two-leaf-one-heart stage to control aphids, at a rate of 20 to 30 ladybugs per square meter. Ladybugs effectively control aphid populations, complementing the control effect of predatory mites. Regarding the use of microbial agents, after spraying with *Trichoderma harzianum*, a second application of *Bacillus subtilis* agent is sprayed at an interval of 5 to 7 days. Alternating between the two agents enhances the control effect.

[0055] In step 5, precise chemical control, this embodiment focuses on controlling damping-off, seedling blight, and aphids, which are common in spring open-field seedling cultivation. Monitoring frequency is increased to twice daily, once in the morning and once in the afternoon. Diseased plants are immediately removed, and surrounding seedlings are sprayed for protection. After initiating chemical control, 64% cypermethrin wettable powder is sprayed at a dilution of 1:500 to control both damping-off and seedling blight; 10% imidacloprid wettable powder is sprayed at a dilution of 1:1500 to control aphids. The control effect is closely observed after application. If the effect is unsatisfactory, a second application is performed after 7 to 10 days, using a different pesticide.

[0056] In step 6, seedling cultivation and management, the focus of this embodiment is to enhance the seedlings' cold resistance and stress tolerance. After the seedlings reach the two-leaf stage, watering is appropriately controlled to harden them off, and the relative soil humidity is maintained at 60% to 65% to enhance their adaptability to drought stress. Chitosan oligosaccharide inducers are sprayed weekly at a concentration of 0.5% to 0.8% to enhance the seedlings' disease resistance. At the three-leaf stage, organic fertilizer and foliar fertilizer are applied once, using 100 to 150 grams of well-rotted chicken manure per square meter of seedbed, combined with a 0.2% to 0.3% potassium dihydrogen phosphate solution and a 0.1% boron fertilizer solution to promote flower bud differentiation and root development.

[0057] By implementing the above technical solutions, the challenges posed by the variable spring climate to pest and disease control can be effectively addressed under open-air small arched shed seedling cultivation conditions, resulting in the cultivation of robust bitter gourd seedlings and providing high-quality seedlings for early-maturing cultivation.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for controlling diseases and pests in bitter gourd seedlings, characterized in that, Includes the following steps: Step 1: Seedbed disinfection. Before sowing bitter gourd seeds, the seedbed soil is disinfected using a combination of physical heat disinfection and biological agents. Step 2: Seed coating. Bitter gourd seeds are coated with a seed coating agent containing probiotics and plant extracts to form a protective layer. Step 3: Seedling environment control. Temperature, humidity, and light conditions in the seedbed are adjusted to create an environment unfavorable to pests and diseases but conducive to healthy seedling growth. Step 4: Biological control. Natural enemy insects are released or microbial agents are sprayed at appropriate times during the seedling stage to establish a natural defense system. Step 5: Precision chemical control. When pest and disease trends are detected, low-toxicity, high-efficiency pesticides are selected for precise application, with strict control over dosage and application time. Step 6: Strong seedling cultivation and management. Rational water and fertilizer management and the use of plant immune inducers enhance the stress resistance and disease resistance of bitter gourd seedlings.

2. The method for controlling diseases and pests in bitter gourd seedlings according to claim 1, characterized in that, The soil disinfection treatment in step 1 includes: tilling the seedbed soil to a preset depth, then laying a transparent plastic film, using solar radiation to raise the soil temperature to a preset temperature and maintain it for a preset time, and then evenly spraying Bacillus subtilis wettable powder.

3. The method for controlling diseases and pests in bitter gourd seedlings according to claim 2, characterized in that, In step 2, the seed coating agent includes Bacillus subtilis powder, chitosan, neem extract, sodium alginate, and polyvinyl alcohol. The mass ratio of the seed coating agent to the seeds is a preset ratio. After coating, the seeds are air-dried until the moisture content is lower than the preset moisture content.

4. The method for controlling diseases and pests in bitter gourd seedlings according to claim 3, characterized in that, The environmental control parameters in step 3 are as follows: daytime temperature is controlled within a preset temperature range, nighttime temperature is controlled within a preset temperature range, soil relative humidity is maintained within a preset humidity range, air relative humidity is controlled within a preset humidity range, daily sunshine duration is a preset duration, and sunshine intensity is a preset intensity.

5. The method for controlling diseases and pests in bitter gourd seedlings according to claim 4, characterized in that, The biological control in step 4 includes: releasing predatory mites when the seedlings have one leaf and one heart; spraying Trichoderma harzianum wettable powder when the seedlings have two leaves and one heart, and then spraying again after a preset number of days.

6. The method for controlling diseases and pests in bitter gourd seedlings according to claim 5, characterized in that, The monitoring method for precise chemical control in step 5 is as follows: conduct field inspections every morning during the seedling stage and record the occurrence of diseases and pests; when the disease rate exceeds the preset threshold or the insect population density exceeds the preset density, chemical control is initiated; use carbendazim wettable powder or chlorothalonil wettable powder to control fungal diseases, and use imidacloprid wettable powder to control aphids, with the spraying time chosen to be after dusk.

7. The method for controlling diseases and pests in bitter gourd seedlings according to any one of claims 1 to 6, characterized in that, Step 6, the seedling cultivation and management, includes: spraying chitosan oligosaccharide inducer once a week; applying organic fertilizer once at the three-leaf stage of the seedlings, and irrigating with amino acid water-soluble fertilizer.

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