Vegetable disease and pest control
Vegetable disease and pest control
Rural Practical Technology Training Materials
How to correctly use various bactericides
The application techniques for fungicides are more demanding than those for insecticides, making them more difficult to master. Therefore, when using fungicides, it is essential to adhere to the following principles to achieve optimal results.
1. It's essential to know the main diseases that crops may be susceptible to. This is crucial for targeted treatment. Because different types of fungicides have different properties, characteristics, and modes of action, there is no " cure-all . "
2. Understand the properties of fungicides. Based on their effectiveness in controlling diseases, fungicides can be broadly classified into three categories:
Protective fungicides: These fungicides can protect the uninfected parts of the plant from infection. They are effective only if the plant is sprayed before the disease comes into contact with the crop or before the disease occurs. Examples include copper-based fungicides (Bordeaux mixture), sulfur-based fungicides (lime sulfur), mancozeb, and zineb.
Eradicative fungicides: These agents can directly kill pathogens before they invade and treat already infected application sites. They often have a disinfecting effect and are rarely applied directly to crops. For example, formalin can be used to disinfect infected seeds, and when applied correctly, triadimefon can eradicate wheat stripe rust and powdery mildew.
Therapeutic fungicides, also known as systemic fungicides: These fungicides are absorbed and translocated by the plant, preventing the development of pathogens in various parts of the plant. Examples include carbendazim, thiophanate-methyl, and kasugamycin.
3. Different types of pesticides have different application methods.
① Systematic protection during the seedling stage: This includes seed soaking in pesticide solution, seed fumigation in pesticide solution, seed dressing with pesticides (dry or wet), seed coating agents, and seedling dipping in pesticide solution, etc. Commonly used pesticides include seed dressing agents such as thiram and mancozeb. Seedlings include seeds, tubers, rhizomes, bulbs, cuttings, seedlings, saplings, and other organs used for propagation.
② Soil treatment with chemicals. This involves overall or partial protection, such as direct application of chemicals to the seedbed soil. Examples of chemicals used include pentachloronitrobenzene and chloropicrin. Soil treatment can be done using the following methods: irrigation (using water-soluble solutions, at a rate of [per square meter]).
③ Foliar spraying; Foliar spraying comes in various formulations, such as powder, micro powder, wettable powder, emulsifiable concentrate, suspension concentrate, aqueous solution, and fumigant.
Traditional Chinese Medicine Methods for Pollution-Free Control of Vegetable Diseases and Pests
In recent years, with the increase in the multiple cropping index of vegetables, the occurrence of pests and diseases has become increasingly serious. Vegetable farmers generally report that prevention and control are difficult, especially pollution-free prevention and control. To help farmers effectively prevent and control various pests and diseases in vegetables, we introduce several simple and easy-to-implement pollution-free methods for the prevention and control of vegetable pests and diseases without chemical pesticides for your reference.
1. Wood Ash Method: The ash left after burning fallen leaves, straw, rice husks, fruit vines, rice straw, firewood, weeds, etc., contains a large amount of calcium oxide and potassium carbonate, and is alkaline. Applying 20-30 kg of wood ash in furrows or holes around the roots of vegetables has an excellent control effect on pests of onions, garlic, leeks, and melons, such as seed flies and onion fly maggots. In the morning when there is dew, sprinkling wood ash on the soil surface and leaves around melon vines can effectively kill pests such as cucumber beetles. For each acre of vegetable field , use 15-20 kg of wood ash , soak it in 50-75 kg of water, filter it after 24 hours, and spray the filtrate. This can control pests such as aphids and thrips, with an effectiveness of over 95 %. Wood ash is also a good fertilizer, which can improve the resistance of vegetables and has a significant yield-increasing effect.
2. Brown sugar solution method: Put 300g of brown sugar into 500 mL of water, and after it is completely dissolved, add 10g of yeast. Stir once a day . After about 20 days, an alternating white film will appear on the surface. At this time, add rice vinegar and white wine, each diluted in 50 kg of water , and spray it on the diseased cucumbers. Spray once every 7 days to effectively control cucumber gray mold and bacterial angular leaf spot. 3 . 4. ** Urine-Washing Agent Method:** Mix 500g of urea and 200g of laundry detergent with 100kg
of water to prepare a " urine-washing agent . " Spray after the laundry detergent is completely dissolved. This method not only effectively controls aphids on vegetables but also promotes foliar fertilization and growth. However, the " urine-washing agent " should be prepared and used immediately to prevent the urea from evaporating and becoming ineffective.
5. ** Pig Bile Solution Method:** Add an appropriate amount of baking soda or laundry detergent to 10% pig bile solution and spray directly onto vegetable plants infested with aphids and cabbage caterpillars. This effectively kills the pests. The diluted liquid can remain effective for 10-12 days .
6. **Lime Method:** During the rainy season, leafy vegetables growing in low-lying areas with high soil moisture are susceptible to snail damage, and general pesticide control is often ineffective. On sunny or cloudy days when the dew has dried and the air humidity is low, sprinkle sieved, fine lime powder around the vegetable plants or on the soil surface between the rows. When snails crawl over it, the lime on their bodies will dry out their soft bodies and cause them to die. However, this method is ineffective on rainy days.
6. Flour Paste Method: Take 250 g of flour, add 2 kg of water to moisten it, put it in a basin or bucket, then add 8 kg of boiling water and stir thoroughly. After cooling, spray it directly onto the back of the vegetable leaves damaged by spider mites. After about 10 minutes, the spider mites will be stuck in the paste and die. The best time to spray is after 2 pm .
7. Insect Method: Harvest 100 g of dead cabbage caterpillars from the field , crush them, add 200 g of water and soak for 24 hours . After filtering, take the clear liquid, dilute it with 50 kg of water, add 50 g of laundry detergent and stir thoroughly. Spray it on the vegetables damaged by cabbage caterpillars. It has a significant control effect.
8. Rabbit, sheep, or cow manure water method: Take 1 kg of fresh rabbit, sheep, or cow manure , place it in a bucket or vat, seal it, and ferment for 10-20 days . Stir thoroughly and filter before use. Spray the filtrate, using 25 kg per acre of vegetable field . This can control powdery mildew in melons. Alternatively, on sunny or cloudy days after the dew has dried, apply the solution to the root zone of dried chili peppers, eggplants, tomatoes, cabbages, green beans, and other vegetables to effectively repel cutworms, beetles, and other underground pests, with an overall effectiveness rate of over 85 %.
9. Potassium permanganate method: Apply an 800- fold dilution of potassium permanganate to the roots of solanaceous vegetables after they have established themselves. This can prevent wilt and damping-off diseases. If wilt has already occurred and seedlings are wilting, immediately apply a 400- fold dilution to the roots, with an effectiveness rate of over 80 %. However, it is important to note that potassium permanganate solution must be prepared with clean, uncontaminated water, and should be used immediately after preparation. It should not be left to stand for a long time, and certainly not used overnight, otherwise its efficacy will be reduced or even rendered ineffective.
Pollution-free control technology for pests in protected vegetables
Winter-warm greenhouses and other protected cultivation facilities create suitable microclimates for the growth and development of greenhouse vegetables, but they also provide a favorable environment for the emergence, reproduction, and damage of vegetable pests. Since the 1980s, with the rapid development of protected vegetable production, the types, numbers, and severity of pests have increased significantly and become increasingly rampant. Furthermore, due to a long-standing lack of scientific guidance in pest control and excessive reliance on chemical pesticides, pests have developed resistance, increasing the difficulty of effective control. This has also, to some extent, killed natural enemies of insects, disrupted the ecological balance, increased pesticide residues in vegetable products, reduced quality, and seriously affected export earnings and market access, causing huge economic losses to vegetable farmers. Therefore, environmentally friendly pest control is urgently needed.
Common pests affecting protected vegetables include greenhouse whiteflies, American serpentine leafminers, aphids, broad mites, cabbage mites, cotton bollworms, diamondback moths, and leek maggots.
1. Greenhouse Whiteflies
: Whiteflies have a wide host range, mainly damaging fruit and vegetable crops. Adults and nymphs congregate on the undersides of leaves, sucking sap and robbing nutrients. Affected leaves turn yellow and lose their green color, the plant weakens and wilts, and may even die completely. They also attract mold through honeydew secretion, contaminating vegetables and reducing their commercial value. Control measures in production are as follows: 1.1 Cultivating
" Insect - Free Seedlings " : During seedling cultivation, ensure " no greening , " meaning thoroughly remove weeds and plant debris from the greenhouse to reduce intermediate hosts. Separate the seedling room from the production greenhouse. Before seedling cultivation, thoroughly disinfect the greenhouse in the seedling room. Use 400-450 grams of 22 % dichlorvos fumigant per acre of greenhouse to eliminate any remaining insects. Install nylon mesh insect netting at ventilation openings to prevent the invasion of external insect sources. 1.2 Rational Crop Layout: Avoid planting cucumbers in and around the greenhouse. Intercropping tomatoes and beans helps prevent the creation of a favorable living environment for whiteflies. It is recommended to plant celery, mustard greens, and garlic sprouts—crops that whiteflies dislike and are relatively cold-resistant—as the first crop in greenhouses during autumn and winter, making it difficult for whiteflies to overwinter safely. 1.3 Physical control : Utilizing the whiteflies' strong attraction to yellow, in the early stages of infestation, yellow sticky traps ( 1 meter x 0.2 meters ) coated with No. 10 machine oil are hung between the rows of plants in the greenhouse, at the same height as the plants. The traps are reapplied every 7-10 days, with 32 traps per acre. This method is effective. 1.4 Biological control : Whiteflies have a waxy body and strong resistance to pesticides; using chemical agents alone is unlikely to achieve ideal control. In areas with suitable conditions, natural enemies such as Encarsia formosa, Lacewingia sinensis, and Verticillium can be artificially released into the greenhouse. These measures have been successful both domestically and internationally, with good results . 5. Chemical Control: Spraying should be carried out at the initial stage of infestation, preferably in the morning, spraying the upper surface of the leaves first and then the undersides. 25% imidacloprid wettable powder at a dilution of 1000-1500 times , or 10 % fenvalerate EC at 5-20 ml /667 square meters, or 40.7 % chlorpyrifos EC at a dilution of 800 times, or 25 % chlorpyrifos wettable powder at a dilution of 500 times, can be used to spray and control adults or larvae with good results. Alternatively , 0.5 kg of 22 % dichlorvos smoke agent per acre can be used. In the evening, the greenhouse should be sealed, and the smoke agents should be evenly distributed at 4-5 points and lit one by one. Doors and windows should be closed tightly, and operations can resume as usual the next morning. 2. The American serpentine leafminer damages almost all vegetables, including melons, beans, solanaceous vegetables, and leafy vegetables, causing severe damage and significant losses. The larvae bore into leaves and petioles, forming irregular, serpentine white tunnels. This causes the affected leaves to lose their photosynthetic capacity, deplete nutrients, and eventually wither and fall off. Adult females can also pierce leaves to feed and lay eggs. Control measures include: 2.1 Strict quarantine to prevent spread. 2.2 Agricultural control : Clean the field, thoroughly remove infested plants and leaves, and bury them deeply; rotate crops with onions and garlic. 2.3 Physical control: Use yellow sticky traps or yellow insect-attracting paper to lure adult larvae; replace the traps promptly after they become full; install insect-proof screens on greenhouse doors and windows to prevent leaf miners from entering and causing damage. 2.4 Chemical control: Use 1.1 % abamectin EC at a dilution of 3000 times, or 1 ... 1% Green Wave No. 2 at 1000x dilution, or 40% Green Vegetable Protect EC at 1000x dilution, 20 % Confluence soluble compound at 2000x dilution, 48 % Lorsban EC at 800x dilution, 75 % Qianke WP at 600x dilution, 20 % Green Defu microemulsion at 1000x dilution , 5 % Carbohydrate EC at 2000x dilution, spray alternately, once every 6 days, for 5 consecutive treatments . For adult control, apply pesticides in the morning; for larval control, spray during the 1st-2nd instar. Alternatively, use dichlorvos fumigant, see the method for greenhouse whiteflies. 3. Broad mites, also known as white spider mites or tender leaf mites , have a wide host range and varied diet, and can damage most cultivated vegetables in protected environments. Adults and nymphs concentrate on tender parts to suck sap, depleting nutrients, leading to plant deformities and slow growth, affecting yield. 1. Eliminate pest sources: Promptly remove weeds around greenhouses, and promptly remove and burn dead branches and fallen leaves after vegetable harvest. Pay attention to pest control in seedling houses and production greenhouses during winter to eliminate overwintering pest sources. 3.2 Cultivate pest -free seedlings: Apply pesticides to seedlings 1-2 times before transplanting. 3.3 Chemical control: Broad mites have a short life cycle and strong reproductive capacity, so early control is crucial. Strengthen pest monitoring and apply pesticides as soon as possible after infestation. Focus spraying on tender shoots, the backs of tender leaves, and young fruits. Use 1.8% abamectin EC at 2000-3000 times dilution, or 20 % miticide EC at 1000 times dilution, 0.2% abamectin (matrine) Aqueous solution at 300-400 times dilution, or 5 % nissorun EC at 2000 times dilution, or 73 % dicofol EC at 3000 times dilution, and 40 ... 4. Red spider mites , also known as cabbage mites , include various species. They damage cucumbers, beans , and solanaceous vegetables in greenhouses . Adults and larvae feed on sap on the underside of leaves and spin webs. Control methods are the same as for broad mites, but tebufenozide is the most effective for controlling red spider mites. 5. Cotton bollworms and tobacco budworms in protected cultivation mainly damage autumn-grown tomatoes, while tobacco budworms mainly damage sweet peppers. Both larvae bore into buds, flowers, and fruits, and also feed on tender stems, leaves, and buds, causing flower and fruit drop, fruit rot, and reduced yield. Control should focus on agricultural measures, promote biological control, and use pesticides rationally to eliminate larvae before they reach the fruit. 5.1 Combine pest and egg control with field management. Remove tender branches and leaves with eggs from the greenhouse for disposal and promptly remove infested fruits. Remove lower old leaves in a timely manner to improve ventilation and light penetration. 5.2 Biological control: During the peak egg hatching period, spray with Bacillus thuringiensis preparations such as Bt or HD - 1 , or cotton bollworm prismatic polyhedrosis virus. The dosage is 10 billion/g live Bacillus thuringiensis at a dilution of 200-250 times, or 1 billion/g cotton bollworm prismatic polyhedrosis virus wettable powder at 800-1200g per 60 square meters . 5.3 Chemical control: Focus on applying pesticides during the peak egg hatching period until the peak of the second instar larvae, before they enter the fruit. 2 % [ specific pesticide name missing ] can be selected . Spray alternately with 5 % baicalein EC at a dilution of 2000-3000 times, or 5% fenvalerate EC at a dilution of 1000-2000 times , or 5 % fenvalerate EC at a dilution of 1000-1500 times, or 3 % mobilon EC at a dilution of 1000 times , or 15% acetamiprid SC at a dilution of 2000 times, or 5% flufenoxuron (carbendazim) EC at a dilution of 1500 times. 6. Leek maggots and root maggots: Leek maggots mainly damage leeks and leek sprouts in protected cultivation. The larvae burrow into the underground parts, causing the above-ground leaves to become weak, yellow, wilted, and die; in severe cases, entire clumps of seedlings may die. The larvae bore into the rhizomes and pseudostems, causing rot and sometimes destroying the greenhouse. Root maggots damage seeds sown in seedbeds, causing malformed and rotten seedlings that fail to emerge; they can also damage the host's rhizomes, causing rot and death. 6.1 Agricultural Control: Do not apply uncomposted manure or cake fertilizer, and avoid exposing fertilizer to the soil surface. Do not apply diluted manure to leeks. When planting garlic, carefully select garlic seeds and peel off the skin. Soak and germinate melons and beans before sowing, and water thoroughly to promote early emergence. 6.2 Seed Treatment: Treat seeds with 40 % diazinon powder at a rate of 0.3%-0.5% of the seed weight . Before sowing , apply 50 grams of diazinon powder or a 1000-fold dilution of 80 % dichlorvos emulsifiable concentrate per acre via furrow application or mix with base fertilizer. 6.3 Adult Control: Apply pesticides during the initial peak of adult emergence, between 9 and 11 am , when adults are most active. Spray with 50 % phoxim EC at 800 times dilution, or 2.5% deltamethrin EC at 3000 times dilution, or trichlorfon crystals at 1000 times dilution , or 40 % cypermethrin EC at 3000 times dilution. Note that the last application should be no less than 10 days before harvest. 6.4 Control of larvae: Use 50 % phoxim EC at 800 times dilution, or 48 % chlorpyrifos EC at 150-200 grams per mu (acre) diluted in 1000 kg of water for root irrigation. Irrigate each clump of chives with about 200 ml of the solution. Alternatively, irrigate the roots with 1.1 % matrine powder at 1500-2000 times dilution. You can also use 2-3 kg of matrine per mu , mixed with 15 kg of fine soil , and spread along the clumps . Water 3 days later. After the first cut, mix 2 kg of matrine with fine soil and spread it on the stubble, then hoe it again . Water 3 days later. 6.5 Control of leek maggot infestation in greenhouses: Select healthy leek roots to prevent leek maggots from being introduced into the greenhouse. If maggot infestation occurs, use a non-systemic pesticide such as 90 % trichlorfon at 1000x dilution, 50 % phoxim at 1000x dilution, or 1.1 % matrine powder at 2000x dilution for root irrigation. Note that the last application of pesticide should be no less than 10 days after leek harvest . 7. Aphids: The main aphids in protected cultivation are melon aphids, radish aphids, and cabbage aphids. Melon aphids mainly damage cucurbits and cruciferous vegetables; the other three mainly damage cruciferous plants, with peach aphids also damaging other cruciferous vegetables and spinach. All aphids, in their adult and nymphal stages, congregate on the undersides of leaves and tender stems and tips to suck sap and secrete honeydew, and can also transmit viral diseases. Control measures are as follows: 7.1 After harvest, promptly dispose of damaged branches and leaves, remove weeds, thin out infested seedlings, and remove them from the greenhouse for disposal. 7.2 Yellow sticky traps: Refer to the control methods for greenhouse whiteflies. 7.3 Silver - gray film for aphid repellency: Cover the ground with silver-gray film, using 5 kg per acre , using the same method as transparent film.
Hang 10-15 cm wide strips of silver film around the greenhouse , using 1.5 kg per acre . 7.4 Chemical control: When aphids occur, use 50 % aphid repellent at 2000-3000 times dilution (poor effect on melon aphids), or 10 % imidacloprid wettable powder at 1000-1500 times dilution, or 0.5% veratrine (Guardian Bird) alcohol solution at 800 times dilution, or 3 % mobilon (Suocimi) emulsifiable concentrate at 1000 times dilution for spraying. 7.5 Fumigation: Before covering the greenhouse in the evening, fumigate with 22 % dichlorvos smoke agent, using the same method as for greenhouse whitefly control. 8. Underground pests include grubs, mole crickets, and wireworms. Drenching the roots with 90% trichlorfon or 50% phoxim at a dilution of 800 times will yield ideal results.
Integrated pest and disease control techniques for pollution-free bell peppers
With the adjustment of agricultural structure, the planting area of bell peppers has been expanding year by year, and the occurrence and damage of diseases and pests have also been increasing year by year. Diseases such as damping-off, anthracnose, viral diseases, late blight, gray mold, powdery mildew, scab, aphids, bollworms, beet armyworms, and whiteflies directly affect the yield and quality of bell peppers. To ensure high yield and quality of bell peppers, the following are the pollution-free prevention and control techniques for different growth stages of bell peppers .
1. Prevention and control before sowing to sowing period
1.1 Adjust the planting structure and implement reasonable crop rotation. Avoid continuous cropping with cucurbits and solanaceous vegetables. Rotation with cruciferous vegetables such as cabbage and Chinese cabbage; and lily family vegetables such as scallions and garlic for more than three years is recommended.
1.2 Select disease-resistant varieties. Examples of pepper varieties include Haijiao No. 2 , Zhongjiao No. 4 , Zhongjiao No. 5 , Zhongjiao No. 6 , Zhongjiao No. 7 , Zhongjiao No. 8 , Tianjiao No. 3 , Tianjiao No. 4 , Tianjiao No. 6 , Zhijiao No. 1, Peijiao No. 9, Fengjiao No. 1, Dujiao No. 1, Jinjiao No. 8 , Lisheng Jiechun, Champion Big Green Pepper, and Zaoshu No.
1. 1.3 Seedbed disinfection. A 1 : 100 solution of 50 % carbendazim can be applied as a toxic soil mixture (1.2 kg/m²), or 10 g/m² of 75 % thiophanate-methyl mixed with a small amount of soil can be applied. Alternatively, 1 g of Greenhen No. 1 diluted 300 times with water can be sprayed evenly into the seedbed before or after sowing. Or, 1 g of Greenhen No. 1 can be mixed with 15-20 kg of sieved fine soil to make toxic soil; 1/3 of this toxic soil can be applied to the seedbed, and the remaining 2/3 can be used to cover the seeds after sowing. 1.4 Seed treatment. For every kilogram of seeds, treat with 1-1.5 grams of Greenhen No. 1 and 3-4 grams of 50% thiram wettable powder or 8-10 grams of Greenhen No. 3 , and sow immediately after treatment. 1.5 Seed soaking: Soak seeds in 10 % trisodium phosphate solution for 30 minutes, or in 100 times formalin for 30 minutes, or in 50 % carbendazim solution at 500 times dilution for 2 hours. 2. From sowing to transplanting: 2.1 Use 75 % thiophanate- methyl solution at 600-800 times dilution or 75 % propiconazole solution at 1000 times dilution to control damping-off; spray the seedbed with 5-7.5 ml/m² of 72.2 % propamocarb hydrochloride solution to control wilt disease, and also treat early blight, anthracnose, etc. 2.2 During the seedbed stage, spray two bags of Jianshi pepper spray or 500-800 times diluted Kebingling solution or 4m diluted Virus A wettable powder per 667 square meters to prevent viral diseases. Spray once every 7 days, for a total of 3 sprays , all of which can achieve good results. 3. From transplanting to fruiting stage, use 50 % aphid repellent or 5g /(mu) of 10 % imidacloprid diluted in 40kg of water to control aphids, which also controls cotton bollworms; alternately use 400ml /(mu) of Dt emulsion , or 50-60ml /(mu) of 2 billion PIB /ml cotton bollworm nucleopolyhedrovirus suspension to control cotton bollworms, which also controls tobacco budworms and aphids. Before and at the early stage of Fusarium wilt, drench the roots with a 3000- fold dilution of Greenhen No. 1 , or a 600- fold dilution of Greenhen No. 2 , or a 1500-2000 - fold dilution of Greenhen No. 8 , or a 500- fold dilution of Green Pepper An No. 2. Repeat every 7-10 days for 2-3 consecutive times . This also treats other diseases. For viral diseases, use a 1000-1500- fold dilution of Plant Disease Control Agent, or a 600 - fold dilution of Virus A , or a 300-400 ml/(acre) spray of 2 % Zhongnanmycin ; the effect is significant. 4. Fruiting period 4 . 1. Disease control: Spray pesticides in the field at the early stage of disease on 75 % thiophanate-methyl at 600-800 times dilution, or 40 % carbendazim at 400-600 times dilution, or anthracnose mancozeb at 600 times dilution to control anthracnose, powdery mildew, blight, etc.; use 72 % agricultural streptomycin at 20 g/(acre), or 25 % chlorothalonil wettable powder to control bacterial scab; use 72 % propamocarb hydrochloride aqueous solution, or 30 % cymoxanil hydrochloride aqueous solution at 800 times dilution. For example, use 70 % mancozeb wettable powder at a dilution of 500 times to control wilt and gray mold; use 20 % Virus A or 1.5% Plant Disease Control wettable powder at a dilution of 500 times to control viral diseases; use 72 % chlorothalonil wettable powder at a dilution of 600-800 times, or 77 % copper oxychloride wettable powder at a dilution of 500 times to control late blight, downy mildew, and downy rot; in protected cultivation, use
5% cymoxanil dust, or 5% cymoxanil dust, or 5% chlorothalonil dust at a rate of 1 kg/(acre) to spray and control various diseases. 4.2 Pest control: ① Spraying during the early larval stages : use 0.9 % abamectin at a dilution of 3000 times to control broad mites; use 10 % cymoxanil wettable powder at a dilution of 1000 times to control aphids; use 2.5% cypermethrin EC, or 10% imidacloprid EC, or 4 ... ① **Physical Control:** Use 5% high-efficiency cypermethrin EC at a dilution of 1500 times to control aphids, cotton bollworms, tobacco budworms, beet armyworms, and American serpentine leafminers. Spray 10 times every 5-7 days , for a total of 3 sprays . ② **Physical Control:** In protected areas, use yellow sticky traps or yellow sticky traps to attract and kill whiteflies, tobacco whiteflies, aphids, and American serpentine leafminers, which are attracted to yellow. Alternatively, cover the ground with silver-gray mulch to repel aphids. ③ ** Biological Control:** Actively protect and utilize natural enemies. When adult whiteflies are found, release Encarsia formosa. Use biological agents such as 1.8 % chlorpyrifos soluble liquid, 2% nitrofurazone (Ningnanmycin), 72 % agricultural streptomycin sulfate soluble powder, or 5% carbaryl EC to control pests and diseases.
Occurrence and control of gray mold in greenhouse tomatoes
With the continuous development of winter greenhouse vegetable production, the cultivation area of tomatoes has gradually expanded in recent years, becoming one of the main vegetable varieties. The yield per 667 square meters typically exceeds 10,000 jin (5,000 kg), generating significant economic and social benefits. However, off-season cultivation creates ideal conditions for gray mold in tomatoes, characterized by low temperature, high humidity, and weak light. Coupled with years of continuous cropping, the pathogen has accumulated and caused significant damage, making gray mold a major disease of greenhouse tomatoes, with an incidence rate of 30 %–50 % , severely impacting product quality. Field practice using integrated pest management has yielded excellent control results.
1. Symptoms and Conditions for Disease Development:
This pathogen can damage flowers, fruits, leaves, and stems, but it primarily affects the fruit. The disease typically begins to affect leaves from the leaf tip, with lesions expanding inward in a " V " shape. Initially, the lesions are water-soaked, light brown, and have alternating light and dark concentric rings. Later, the lesions turn pale green, a gray mold layer develops on the surface, and the leaves wither and die. When fruit is affected, it primarily damages unripe fruit, first infecting the remaining flowers and receptacles, then spreading to the fruit surface or pedicel, causing the skin to turn grayish-white and soft rot. A dense gray mold layer grows on the affected area, and the lesions are generally about 5
cm in diameter ; in some cases, half the fruit may be affected, causing the fruit to fall off. Tomato gray mold is a fungal disease caused by *Botrytis cinerea*. It begins to appear when the temperature in the greenhouse reaches 15 °C and the relative humidity is above 80 %. The disease becomes highly prevalent when the temperature is between 25°C and 25 °C and the relative humidity is above 95 %. Therefore, greenhouse-grown tomatoes exposed to low temperatures and high humidity,
poor ventilation, overcrowding, and vigorous early growth of branches and leaves are highly susceptible to gray mold. 1. Prevention and Control:
Farmers have long relied on single-drug applications to control tomato gray mold, leading to resistance to fungicides like iprodione and propiconazole, thus failing to achieve the desired control. Only integrated pest management can effectively control gray mold. 2.1
Selecting Disease-Resistant Varieties: Suitable tomato varieties for cultivation in the Jinzhou area include: 402 , Baoguan, Jiafen 15 , Liaoza No. 1
and No. 2 , Maofen 802 , etc. 2.2 Seed Disinfection: Soak seeds in 50-55 ℃ warm water for 10-15 minutes , stirring constantly to ensure even heating. Then, when the water cools to 28-30 ℃ , place them in a constant temperature environment of 25-28 ℃ to germinate. 3. Ridge planting with mulch: Ridge planting helps loosen the soil, promotes tomato root development, and avoids root rot and seedling death caused by excessive watering. Mulching helps maintain or increase soil temperature and can prevent adverse ecological environments such as increased humidity and condensation on the film surface caused by soil moisture evaporation. 2.4 After watering under the film for 24 hours, the relative humidity in the greenhouse is only 82 % -85 %. If the furrows are filled with water, the relative humidity in the greenhouse reaches 95 % -100 % after 24 hours, which is not only very favorable for the occurrence of gray mold, but also extremely favorable for other moisture-loving diseases. 2.5 Ecological control : During the flowering and fruiting period, the daytime temperature in the greenhouse should be controlled at 22-28 ℃ , and the nighttime temperature at 10-12 ℃ . When the relative humidity is below 80% , it takes about 15 days for spores to be produced, and the spore germination rate is 0% . If the relative humidity is above 95 %, gray mold can produce a large number of spores in 3-4 days. The spore germination rate reached 100% within 48 hours . This demonstrates the significant effect of humidity reduction and disease prevention. 2.6 Chemical Control : It is crucial to seize the optimal control period for pre-harvest gray mold, as withered flowers provide a natural breeding ground for the gray mold fungus, leading to fruit rot. Therefore, this opportunity should be seized, combined with the above-mentioned control measures, and then using highly effective, low-toxicity pesticides for control. The first application should be during the flowering period of the first fruit cluster, combined with spraying flowers with an anti-drop agent. Add 0.1 % of a gray mold control agent such as iprodione to the pesticide solution and spray directly onto the female flowers. This prevents flower and fruit drop and controls gray mold. The second application should be during the fruit set and enlargement period after flowering. To avoid increasing humidity in the greenhouse, a gray mold fumigant should be used. At the first sign of disease, close the greenhouse in the evening, placing 50 grams (one small packet) per 10 linear meters , placing the packets from the outside in, and then igniting them from the inside out . Ventilation can be carried out after 1 hour. Apply once every 15 days. If gray mold is found during day and night ventilation, spray with a 600- fold dilution of 65 % carbendazim once every 7 days, for 2-3 consecutive applications to achieve the desired control effect.
Non-pesticide control techniques for vegetable diseases and pests
In recent years, through repeated practice, the author has developed a set of pesticide-free techniques for controlling vegetable pests and diseases. This not only reduces pesticide pollution and lowers costs, but also facilitates the production of pollution-free vegetables and the development of vegetable export trade. The techniques are introduced below. I. Physical Measures for Pest and Disease Control 1. Seed Sun-drying, Warm Water Soaking, and Salt Water Soaking Before sowing, choose a sunny day to sun-dry vegetable seeds for 2-3 days . Sunlight can kill pathogens attached to the seed surface, reducing disease incidence .
Soaking seeds of cucurbits and solanaceous vegetables in 55 ℃ warm water for 10-15 minutes , and seeds of legumes and cruciferous vegetables in 40-50 ℃ warm water for 10-15 minutes , can disinfect and sterilize the seeds, preventing seedling diseases. Soaking legume seeds in 10 % salt water for 10 minutes can remove and kill sclerotinia rot pathogens and nematode eggs mixed in with the seeds, preventing sclerotinia rot and nematode diseases. 2. Solar-powered high-temperature sterilization is commonly used in vegetable greenhouses through high-temperature fumigation. During the summer and autumn off-season, the greenhouse is covered with plastic film and sealed for 5-7 days on sunny days , raising the internal temperature to 60-70 ℃ . This effectively kills pathogens and pests inside the greenhouse and on the soil surface. 3. Pest control and trapping: Use waste fiberboard to create 1m x 0.2m strips, paint them yellow, and then coat them with a layer of sticky oil (a mixture of No. 10 machine oil and a little butter). Place 25-30 strips per 667 square meters , between rows, at the same height as the plants. When whiteflies cover the strips, reapply the sticky oil promptly. 4. High-temperature composting kills pathogens and pests : Vegetable base fertilizer is mainly organic fertilizer, but farmyard organic fertilizer often contains plant pathogens and pests. One to two months before application , the fertilizer should be moistened with water, piled up, and tightly covered with plastic film to allow for full fermentation and decomposition. During the fermentation period, the temperature inside the pile can reach around 70 °C , effectively killing pests and diseases. Furthermore, applying the decomposed fertilizer into the greenhouse will not cause root burn or toxic gas hazards to vegetables. II . Cultivation Measures for Pest and Disease Control 1. Crop Rotation and Garden Cleaning Implementing a crop rotation of 2-4 years or more for various vegetables has a significant effect on reducing and mitigating pests and diseases, and also significantly increases yield. Remove all diseased plant debris and fruit from the greenhouse and destroy or bury them deeply to reduce the disease population. Especially after the previous crop is removed, thoroughly cleaning the garden and combining this with high-temperature greenhouse fumigation can effectively prevent certain pests and diseases in the next crop. 2. Increase the application of organic fertilizer and formula fertilization: On the basis of increasing the application of organic fertilizer, formula fertilization should be carried out according to the appropriate ratio of nitrogen, phosphorus and potassium nutrients required by various vegetables. This can not only improve the soil nutrition status and promote the healthy growth of vegetable crops, but also enhance the disease resistance of vegetables, increase yield and improve quality, and reduce the number and amount of pesticides applied. 3. Implement ridge planting and mulching: Greenhouse vegetables should be planted on ridges and covered with mulch. This facilitates irrigation in the furrows under the film, reduces soil evaporation, lowers the air humidity in the greenhouse, inhibits the occurrence and development of vegetable diseases, and prevents the spread of soil-borne pathogens, thereby reducing the occurrence of diseases. III. Ecological Environment Control of Vegetable Diseases and Pests: Ecological control method utilizes the different environmental requirements of vegetable and pathogen growth and development. By creating ecological environment conditions that are conducive to vegetable growth and development but unfavorable to the occurrence and development of diseases and pests, the occurrence of diseases and pests can be reduced or mitigated. For example, downy mildew, gray mold and powdery mildew do not occur or develop slowly under conditions above 32 ℃ and relative humidity below 80 %. The optimal photosynthetic temperature for warm-loving vegetables is 18-28 ℃ , with 70 % -80 % of photosynthesis occurring between 8 AM and 12 PM . Therefore, ecologically, it's advisable to uncover the straw mats earlier in the morning to extend the light exposure time, ensuring adequate ventilation to maintain a greenhouse temperature below 28 ℃ and humidity below 80 %. Close the greenhouse in the afternoon to briefly raise the temperature to 33 ℃ , using the high temperature to inhibit pathogen development. Then, ventilate to remove moisture. After dehumidifying under the afternoon's high temperature, the air humidity inside the greenhouse will be relatively low at night, reducing condensation and thus inhibiting pathogen spread. Regarding watering greenhouse vegetables during the cold winter and spring seasons, the following "three no-watering, three-watering, and three-control" principles can be adopted: no watering on rainy days, water on sunny days; no watering in the afternoon, water in the morning; no watering directly under the film, water under the film; control watering during the seedling stage; control watering during consecutive cloudy days; control watering during low temperatures. This effectively inhibits the occurrence and spread of warm-loving, high-humidity, and low-temperature tolerant pathogens such as Phytophthora blight. IV. Vegetable Pest Control Methods 1. Cucumber Vine: Crush 1 kg of fresh cucumber vines with a little water, filter out the residue, and spray the filtered juice with 3-5 times the amount of water. This method is over 90 % effective in controlling cabbage caterpillars and cabbage moths . 2. Bitter Gourd Leaves : Pick fresh, juicy bitter gourd leaves, crush them with a small amount of water, and extract the liquid. Add 1 kg of lime water to each kg of the liquid, mix well, and then use the mixture to irrigate the roots of seedlings. This method is highly effective in controlling cutworms. 3. Loofah: Crush fresh loofah, add 20 times the amount of water, stir well, and spray the filtered liquid. This method is over 95 % effective in controlling cabbage caterpillars, spider mites, aphids, and cabbage moths . 4. Pumpkin Leaves: Crush pumpkin leaves with a small amount of water and extract the liquid. Dilute the liquid with 3 times the amount of water ( 2 parts original liquid) , add a small amount of soap solution, stir well, and spray. This method is over 90 % effective in controlling aphids .
Common Nutritional and Physiological Diseases of Greenhouse Tomatoes and Their Control
Insufficient or excessive nutrients in vegetables not only fail to promote normal growth and development but can also lead to various physiological diseases.
I. Blossom-
end rot in tomatoes mainly manifests as a sunken, blackened tip on the fruit, which gradually expands until the fruit rots after the pathogen invades. The main cause of this physiological disease is soil drought and calcium deficiency in the fruit area. Because calcium is not easily mobile within plants, roots cannot absorb calcium from the soil when it is dry, or the soil may be high in nitrogen, leading to vigorous vegetative growth and preventing the fruit from obtaining calcium in time. This disease is more prevalent during hot and dry weather. Cultivation should ensure the soil is not too dry, nitrogen fertilizer should not be excessive, and more organic fertilizer should be applied, while also supplementing the calcium deficiency in the soil.
II. Deformed tomatoes
mainly occur on the first fruit cluster, and occasionally on individual fruits on the second cluster. This primarily results in various deformed, multi-carpel fruits.
The causes of this phenomenon are: low temperatures during the seedling stage, excessive nitrogen fertilizer, high soil moisture, and excessive vegetative growth, leading to abnormal ovary development. Therefore, during the seedling stage, the daytime temperature should be maintained at 20 ℃ , and the nighttime temperature should be controlled below 10 ℃ . Applying less nitrogen fertilizer and avoiding excessive irrigation can help prevent deformed fruit.
Third, white-veined tomatoes
are those where the vascular bundles in the flesh become necrotic, turning dark or white. Black-veined tomatoes often occur due to weak light, excessive vegetative growth, overcrowding, excessive nitrogen fertilizer application, and abnormal metabolism during fruit development. White-veined tomatoes are caused by potassium deficiency and excessive absorption of ammoniacal nitrogen. In practice, attention should be paid to soil drainage in greenhouses and polytunnels. Temperatures should not be too high when light is insufficient. Good ventilation should be maintained during the day. Excessive nitrogen fertilizer application should be avoided, and reasonable planting density should be maintained. Appropriate amounts of potassium and boron should be applied, preferably nitrate nitrogen fertilizer, but the amount should not be excessive.
Fourth, poor fruit coloring is another issue. Tomatoes that are not red but yellowish-brown when ripe are considered to have poor fruit coloring. This is caused by weak light, low temperature, excessive nitrogen fertilizer application, and low activity of chlorophyll-degrading enzymes in the fruit. The solutions are to avoid overly dense planting, reduce nitrogen fertilizer application to prevent excessive vegetative growth, and avoid excessively low temperatures. Fifth, netted fruit: A netted pattern appears on the surface of the tomato fruit, extending to the flesh. This type of fruit matures slowly, mainly due to dry soil, poor root absorption of phosphorus and potassium fertilizers, or difficulty in their movement within the plant, leading to metabolic disorders. Therefore, proper irrigation is necessary to prevent soil drought. Sixth, excessive nitrogen fertilizer: Excessive nitrogen fertilizer inhibits the growth of tomato plants, resulting in shorter, stiff, and dark green leaves. In severe cases, leaves lose turgor pressure, leaf margins dry, and sunken, water-soaked spots appear. In practice, nitrogen fertilizer application should be stopped, and proper irrigation can mitigate the damage. Seventh, physiological harm of manganese : Excessive manganese in tomato plants causes slight vegetative growth, inhibits growth, results in small top and middle leaves, and chlorosis in the interveinal tissue of small leaves. Many necrotic veins appear on older leaves, and later, the midrib and veins die, causing older leaves to fall off first. In practice, a diluted manganese sulfate solution can be added to 1 part per 50 kg of water . Apply 6 grams of zinc as a foliar spray every 7-10 days . VIII. Physiological Harm of Zinc: When tomato plants experience excessive zinc, they become stunted, exhibit excessive vegetative growth, and young leaves become extremely small with chlorotic veins and a purplish underside. Older leaves bend downwards excessively, eventually turning yellow and falling off. A diluted zinc sulfate solution should be applied promptly; dissolve 4.4 grams of zinc sulfate in 50 kg of water and then spray the leaves.