Detailed Explanation of Common Pests and Diseases of Cucumber and Their Control Methods
Cucumber is widely cultivated throughout China and is now widely grown in temperate and tropical regions. It is one of the main greenhouse products and a common vegetable on the dining table. During cucumber cultivation, pests and diseases mostly occur as mixed infections. When controlling diseases, be sure to pay attention to the compounding of pesticides and the flexible control of dosage at different stages of disease occurrence. Now let us take a look at cucumber pest and disease control techniques!
Cucumber Disease Control
Cucumber diseases are mainly downy mildew, powdery mildew, anthracnose and gray mold. The main reason for their occurrence is that as the weather warms up and temperatures gradually rise, improper management creates a high-temperature and high-humidity environment. The cucumber disease control techniques are introduced as follows:
1. Downy Mildew
[Damage characteristics] Downy mildew is more serious in low-lying areas with poor ventilation and excessive watering. It mainly damages leaves, and occasionally stems and flower stalks. In the early stage of the disease, there are water-soaked angular lesions. The lesions do not perforate. When humidity is high, black mold may grow on the back of the lesions. In severe cases, because the lesions are numerous, expand quickly and merge with each other, the leaves scorch and die prematurely.
[Control methods] Ecological control: maintain good ventilation in the greenhouse and control the temperature inside, keeping it at about 25 degrees during the day and about 15 degrees at night. Chemical control: when the disease occurs, spray with 50% Juncheng diluted 2000 times with water. In severely affected plots, repeat the spray once every 3-5 days.
2. Powdery Mildew
[Damage characteristics] Powdery mildew damages all aboveground parts of the plant, but leaves and vines are mainly affected. In the early stage, small white nearly round powdery spots appear on both sides of the leaves, and later expand into large white powdery areas with indistinct edges. In severe cases, the entire leaf is covered with white powder. In the later stage, the white mold spots turn gray as the mycelium matures, and the diseased leaves turn yellow and withered, with small black dots.
[Control methods] Field management: choose disease-resistant varieties as much as possible, ensure light penetration, irrigate reasonably, reduce air humidity and apply sufficient organic fertilizer. Chemical control: in the early stage of the disease, spray with Tiannuo Granulefeng fungicidal type diluted 1000 times with water, once every 5-7 days, repeating 2-3 times.
3. Gray Mold
[Damage characteristics] Gray mold not only damages cucumber, but also damages green pepper, eggplant, kidney bean and others. Gray mold mainly damages cucumber leaves, fruits and flowers. The pathogen of gray mold invades from withered female flowers, grows a gray-brown mold layer, and then invades young cucumbers, causing the top to rot, soften and shrink. When large cucumbers are affected, the diseased part first turns yellow, until it rots and falls off.
[Control methods] Field management: use high ridge cultivation, reduce field humidity, irrigate reasonably, water in the evening, and ventilate properly to remove moisture, promoting healthy growth. Chemical control: in the early stage of the disease, spray with 50% Sumilex wettable powder 1500-2000 times or 50% Duomeiling wettable powder 800-1000 times.
4. Anthracnose
[Damage characteristics] Anthracnose mainly damages stems and leaves. Initially, small water-soaked spots appear. On affected leaves, the lesions are nearly round, reddish-brown, with a halo around them. When dry, the center of the lesion ruptures. On affected fruits, dark brown lesions appear, and the fruit is prone to bending and deformation.
[Control methods] Soil treatment: carry out crop rotation with non-cucurbit crops for more than 3 years. Disinfect the soil, choose disease-resistant varieties, rotate crops, remove diseased and residual plants, and increase application of phosphorus and potassium fertilizers. Chemical control: spray 1:2:100 Bordeaux mixture, or 65% mancozeb 500-800 times, 80% Anthracnose Fumei wettable powder 800 times, 70% mancozeb wettable powder 400 times, or use 45% chlorothalonil smoke agent at 250 grams per mu for fumigation. Use once every 7-10 days, for 3-4 consecutive times.
Cucumber Pest Control
Cucumber pests mainly include leafminer, whitefly and melon aphid. In the control process, strengthening field management should be the main measure. The cucumber pest control techniques are introduced as follows:
1. Leafminer
[Damage characteristics] After hatching, the larvae mine and feed on the leaf mesophyll, producing winding feeding marks. During the seedling stage, plants with 2-7 leaves are often affected. In severe cases, the mining marks are dense, causing leaves to turn yellow, scorch or fall off. The terminal end of the mine does not widen noticeably, which is a characteristic distinguishing this insect from Liriomyza lineata, Liriomyza sativae and Liriomyza trifolii.
[Biological control] Release parasitic wasps such as Eulophidae, Opius wasps and Diglyphus wasps. These three parasitic wasps have a relatively high parasitism rate on leafminers. Applying insect growth regulators can affect adult reproduction, egg hatching, larval molting and pupation.
[Chemical control]
① 5% fipronil suspension concentrate, 50-100 ml per mu; 40% Qixingbao emulsifiable concentrate 600-800 times. The control timing should be at the peak occurrence period, once every 5-7 days, for 2-3 consecutive treatments.
② Insect growth regulators: 5% Yitaibao 2000 times, 5% Cascade emulsifiable concentrate 2000 times. They have a sterilizing effect on adults of Agromyzidae, and after application the hatching rate of eggs laid by adults is low.
③ Use 50% phoxim emulsifiable concentrate 1000 times and spray at the peak occurrence period, once every 5-7 days, for 2-3 consecutive times. Stop applying 7 days before harvest.
2. Whitefly
[Damage characteristics] It secretes large amounts of honeydew, seriously contaminating leaves and fruits. Leaf symptoms: adults and larvae gather to cause damage and secrete large amounts of honeydew, seriously contaminating leaves and fruits and causing sooty mold.
[Biological control]
① Cultivate “pest-free seedlings”: before raising seedlings, fumigate the greenhouse to remove residual insects, clear weeds and residual plants, and add a layer of nylon gauze at the greenhouse vents to prevent external pest sources.
② Avoid mixed planting as much as possible: especially cucumber, tomato and kidney bean should not be mixed. Adjusting the production sequence is also an effective method, that is, arrange celery, sweet pepper and other vegetables less damaged by whitefly in the first crop, and then plant cucumber and tomato in the second crop.
③ Remove old leaves and burn them: older nymphs are mostly distributed on lower leaves. When pruning solanaceous fruits, appropriately remove some old leaves, bury them deeply or burn them to reduce the population.
④ Encarsia formosa: Encarsia formosa can successfully control whitefly in greenhouses. When adult whiteflies are below 0.5 per plant, release adult Encarsia formosa at 15 per plant every two weeks for a total of 3 times.
⑤ Yellow color has a strong attracting effect on adult whiteflies: set yellow boards in the greenhouse (1 m x 0.7 m fiberboard or cardboard, painted orange-yellow, then coated with a layer of sticky oil), using 32-34 boards per mu, with significant trapping and killing effect on adults. The yellow boards should be placed between rows at the same height as the plants. The sticky oil is generally No. 10 machine oil mixed evenly with a little butter, and recoated once every 7-10 days. Be careful to prevent oil droplets from falling on crops and causing burning damage.
[Chemical control]
① Use a knapsack motorized fogger or 3MF-3 knapsack multi-purpose plant protection machine to atomize 1% deltamethrin or 2.5% fenvalerate (sumicidin) oil into 0.5-5 μm droplets suspended in the air to kill adults.
② When the average number of adults is 2.7 and 6.6 per plant, spray 25% buprofezin (Pufeilu) wettable powder at 100 ppm and 200 ppm 1-2 times. When adults reach 19.5 per plant, spray a mixture of Pufeilu 100 ppm and bifenthrin (Tianwangxing) 5 ppm 2 times.
③ Spray 2.5% deltamethrin or 20% fenvalerate (Sumicidin) emulsifiable concentrate 2000 times, once every 6-7 days, for 3 consecutive treatments.
④ Methyl kresoxim-methyl acaricide (Miemandun) wettable powder 1500 times, bifenthrin 0.8-2 g per mu. One day after application, the control effect on adults is above 99.0%.
3. Melon Aphid
[Damage characteristics] Leaves curl, seedlings wilt, and may even die. Affected old leaves wither and fall prematurely, shortening the fruiting period and causing reduced yield.
[Biological control]
① Cultivate strong pest-free seedlings. Strictly use insect-proof nets from the seedling stage to cultivate pest-free seedlings.
② Use yellow boards to trap aphids. Taking advantage of aphids' attraction to yellow, use yellow boards to trap aphids.
③ Protect natural enemies. Such as Erigonidium graminicolum, Xysticus ephippiatus, Misumenops tricuspidatus, Coccinella septempunctata, Propylaea japonica, Scymnus hoffmanni, Chrysopa sinica, hoverflies, Nabis sinoferus, minute bugs, Aphidiidae wasps, Chrysopa formosa, Chrysopa septempunctata, Cecidomyiidae, Entomophthorales fungi and others.
[Chemical control]
① When aphid damage is found, use 0.65% shanzhaisu 100 ml, add 30-40 kg water and spray, or Shaoguanmycin 200 times plus 0.01% washing powder, or 2.5% derris extract emulsifiable concentrate 600-800 times, or spray tobacco water (tobacco to water = 1:30-1:40).
② 20% Sulefu oil 1000 times, or 40% Juma emulsifiable concentrate 2000 times, or 21% synergistic fenvalerate · malathion (Mieshabi) emulsifiable concentrate 4000 times, or 2.5% cyhalothrin (Kung Fu) emulsifiable concentrate 3000 times, or 2.5% bifenthrin emulsifiable concentrate 3000 times, or 10% imidacloprid wettable powder 2000 times, and spray again after 10-15 days.
To strictly control the above various pests, qualified insect-proof nets should be installed, and timely detection and timely control should be carried out to eliminate the insects at the stage of spot and patch occurrence. The preferred methods are physical and biological control. During outbreaks, necessary chemical control may be chosen.
Common Pests and Diseases of Cucumber and Their Control Methods
Cucumber is a common fruit vegetable, rich in vitamins, and deeply loved by people. Many pests and diseases appear during the growth of cucumber. Below, the editor briefly introduces the control methods for common cucumber pests and diseases.
(1) Cucumber Downy Mildew
1. Symptoms
This disease can occur throughout the entire growth period of cucumber and mainly damages leaves. At the initial stage, water-soaked light yellow small spots appear on the back of the leaves. As the disease develops, the lesions gradually expand and, restricted by leaf veins, form angular yellow spots. In severe cases, small lesions merge into large lesions. Under humid conditions, a gray-black mold layer grows on the back of the lesions. Diseased leaves develop from bottom to top, and in severe cases the whole plant's leaves wither and die.
2. Control methods
Increase application of phosphorus and potassium fertilizers to improve plant disease resistance. After fruiting, promptly remove lower old yellow leaves and spray 0.2% monopotassium phosphate, or spray a mixed solution of urea and sugar at 1:1:100, to increase the total sugar content of functional leaves and improve the physiological disease resistance of leaves. For chemical control, in the early stage of the disease, the following pesticides may be selected: (1) 25% metalaxyl wettable powder 800-**** times. (2) 90% Yishuangling wettable powder 500-600 times. (3) 75% chlorothalonil wettable powder 500-600 times. (4) 5% chlorothalonil or 5% Wanmeiling dust, 1 kg per mu, once every 7-10 days, for 3-5 consecutive treatments.
(2) Cucumber Powdery Mildew
1. Symptoms
This disease mainly damages leaves. In the early stage, white round powdery spots appear on the back and surface of leaves, and after expansion they form patches, with a layer of white powder growing and gradually turning gray-white. The leaves turn yellow and then wither and die, but do not fall off.
2. Control methods
Fumigation and disinfection in protected cultivation. Before planting, disinfect first with sulfur powder or chlorothalonil smoke agent. The method of fumigation with sulfur powder is to use 0.13 kg sulfur powder and 0.25 kg sawdust per 55 cubic meters. If using chlorothalonil smoke agent, use 250 grams per mu each time, place it in several spots, light it in the evening, keep it closed overnight, and open doors and windows for ventilation the next morning. You may choose 40% Fuxing emulsifiable concentrate 8000-**** times, or 25% triadimefon wettable powder 1500 times, or agricultural antibiotic 120 biological preparation 100 PPM, or 50% carbendazim wettable powder 600-800 times for spraying, alternating use, once every 7-10 days, for 2-3 consecutive treatments.
(3) Cucumber Bacterial Angular Leaf Spot
1. Cucumber cultivation technique symptoms
This disease mainly damages leaves, but sometimes also damages stems and fruits. When cotyledons are affected, initially there are water-soaked, round or oval sunken spots, producing pinhead-sized water-soaked spots, later turning light brown, restricted by leaf veins into a triangular shape. When humidity is high, white bacterial pus is produced on the spots on the back of the leaves, and after drying it becomes a layer of white transparent film. Later it becomes yellow-brown spots and dries up. In the later stage, the lesions are brittle and easily crack and perforate. On stems and fruits, the lesions are water-soaked, nearly round, later turning light gray. Cracks often appear in the middle of the lesions. Young cucumbers often rot and fall early after being affected.
2. Control methods
Seed disinfection: soak seeds in warm water at 55°C for 15 minutes, or soak in 50% amobam 500 times for 1 hour, or soak in 40% formaldehyde 150 times for 105 hours, then wash clean with water and germinate for later use. Chemical control: in the early stage of the disease, spray 50% Tian T 800 times, or 70% Keshade wettable powder 400 times, Xinzhiromycin 500 times, or 1:2:300-400 Bordeaux mixture, or 80% Ludebao wettable powder 500 times, once every 7-10 days, for 3-4 consecutive treatments.
For cucumber cultivation techniques, for detailed methods of using Salefu fertilizer during cucumber cultivation, please refer to the relevant instructions. It generally increases yield by more than 25% and can also effectively prevent the occurrence of various pests. It is the preferred fertilizer for pollution-free organic agriculture in greenhouses.
Common Pests and Diseases of Eggplant and Their Control Techniques
Eggplant originated earliest in India and was introduced to China in the 4th-5th century AD. The national eggplant cultivation area is about more than 3 million mu. Diseases mainly include eggplant Phytophthora rot, eggplant brown spot disease, damping-off and Rhizoctonia rot. Pests mainly include red spider mite and American leafminer. Now let us take a look at eggplant pest and disease control techniques!
Eggplant Phytophthora Rot
[Damage symptoms] Eggplant Phytophthora rot is also called “rotten eggplant” and “dropped egg”. Besides damaging eggplant, it also damages tomato, cucumber, potato and others. On eggplant, it mainly damages fruits, stems and leaves, and flowers can also be affected. On fruits, water-soaked round or oval brown small spots first appear, rapidly expand and become sunken, often causing the whole fruit to rot, and under humid conditions produce white loose cottony mold. The internal flesh turns black and rots, and it easily separates from the calyx. On young branches, water-soaked dark brown spots appear, which constrict and wither and die. When seedlings are infected, damping-off symptoms occur.
[Occurrence conditions] The pathogen mainly overwinters on diseased residues in the soil. The next year it can directly infect the stems or roots of seedlings, or splash onto fruits near the ground with rainwater and cause fruit disease. The sporangia on the lesions undergo secondary infection through wind and rain and watering. Generally in July-August, with continuous rain, stuffy hot weather, low-lying and poorly ventilated conditions, poor drainage and weak growth, the disease is severe.
[Control methods] ① Choose disease-resistant varieties: such as Beijing Jiuye Eggplant, Liuye Eggplant, Tianjin Damin, Liaoqie No. 3, Fengyan No. 1, Jinan Early Small Long Eggplant and others. ② Agricultural control: avoid continuous cropping with solanaceous crops. Choose sandy loam soil with high dry terrain and good drainage. Plant on high beds or small high ridges, or use wide ridges and close planting. Apply sufficient base fertilizer, promptly remove diseased and old leaves and handle them centrally. They must not be used for composting. After rain, harvest promptly and clean up diseased fruits in time. ③ Chemical control: spray once preventively before disease occurrence or before the rainy season. After disease occurrence, remove diseased fruits and leaves and spray once about every 7 days, for 2-3 consecutive sprays. Pesticides include 1:1:160 Bordeaux mixture, 50% thiophanate-methyl 1000 times, 50% captan 500 times. At the peak of the disease, spray 72% Dupont Curzate wettable powder 800-1000 times, or 58% metalaxyl mancozeb wettable powder 500 times, 64% Sandofan wettable powder 500 times.
Eggplant Brown Spot Disease (also called dry rot)
[Damage symptoms] When seedlings are affected, spindle-shaped water-soaked lesions often form at the stem base near the ground, later turning dark brown, sunken and shrunken. When conditions are suitable, the lesions expand around the stem and the seedlings damping-off. When leaves are affected, the bottom leaves become diseased first and gradually develop upward. At first, water-soaked brown spots appear, with a gray-white or light brown center, and many small black dots arranged in a ring in the center. When dry, the lesions easily crack; on rainy days they easily form perforations. When stems are affected, the lesions are irregular, sometimes water-soaked spindle-shaped, with dark brown edges and a gray-white center, bearing many small black dots. The lesions gradually become sunken and dry-rot, and connect into longer necrotic areas. Fruits are most severely affected. At the beginning of the disease, yellow-brown lesions appear on the fruit surface, slightly sunken, round or oval, expanding quickly. The fruit becomes semi-soft-rot. In the later stage, many small black dots are arranged in a ring, and finally the diseased fruit rots and falls off or shrinks on the branch into a mummified fruit.
[Occurrence conditions] Eggplant brown spot disease is a fungal disease, and this fungus only infects eggplant. The pathogen overwinters on diseased residues on the soil surface and can also overwinter on seeds. Seed-borne bacteria are the main cause of damping-off and Rhizoctonia rot in seedlings, and are also a route for long-distance spread of the pathogen. In the field, it mainly spreads through rainwater, insects and field operations. The suitable temperature for disease occurrence is 28-30°C, with relative humidity above 85%. In North China, July-August has high temperature and frequent rain, or high temperature and high humidity, and the disease is severe. Excessive planting density also easily causes disease. In addition, continuous cropping, poor drainage, heavy clay soil, excessive nitrogen fertilizer and too late planting of early spring eggplant also make the disease severe.
[Control methods] ① Seed treatment: soak seeds in 40% formalin 100 times for 15 minutes, then take them out and wash clean with water. You may also soak seeds in mercuric chloride water 1000 times for 10 minutes. ② Agricultural control: carry out crop rotation with vegetables of other families for 2-3 years. Disinfect the seedbed. Use Wudai mixture at 8-10 grams per square meter, or 50% carbendazim 10 grams plus fine soil 20 grams and mix evenly. Before sowing, scatter 1/3 on the bed surface, and after sowing cover with the remaining 2/3 medicated soil. Strengthen cultivation management, that is, N, P and K fertilizers should be used in combination, apply sufficient base fertilizer, and promptly remove diseased plants, diseased leaves and diseased fruits. ③ Chemical control: in the early stage of the disease, use 75% chlorothalonil wettable powder 600 times, 50% thiophanate-methyl 1000 times, 65% zineb 500 times, 70% mancozeb 500 times. Spray once every 7-10 days, for 2-3 consecutive sprays.
Damping-off
[Damage symptoms] Damping-off is also called “neck strangling” and mainly infects during the seedling stage. After seeds germinate and before emergence, disease can occur. Disease before emergence means rotten seeds or rotten sprouts. After emergence and before 2 true leaves, it mainly occurs at the stem base. The stem base of diseased seedlings near the ground shows water-soaked spots, then turns yellow and constricts into a line. When the cotyledons have not yet wilted, the seedlings fall over on the ground, that is, when the seedlings fall, the leaves are still fresh green, hence the name damping-off. When the environment is humid, an obvious layer of white cottony mycelium grows on the diseased seedlings and nearby soil surface.
[Occurrence conditions] The pathogen overwinters in the soil with diseased plant residues, or lives saprophytically in humus. The pathogen can survive in the soil for 2-3 years, and there are more pathogens in soil with high organic matter content. The pathogen spreads through rainwater or water flow in the soil. It reproduces relatively quickly at 15-20°C. Therefore, when raising seedlings in spring or winter, if there is rainy or snowy weather, or the greenhouse has poor insulation, poor ventilation and excessive watering, the seedbed temperature is often low and humidity high, and damping-off is severe.
[Control methods] ① Choose disease-resistant varieties: according to local consumption habits and temperature conditions, choose low-temperature-tolerant or early-maturing varieties, such as Jinan Small Long Eggplant, 94-1 Early Long Eggplant low-temperature-tolerant variety, Liaoqie No. 1 and Liaoqie No. 4 cold-tolerant varieties and others. ② Soil disinfection: 2-3 weeks before sowing, mix 5 grams of thiophanate-methyl with 50 times fine soil per square meter of seedbed and scatter it in the seedbed, or mix equal amounts of 65% zineb and 40% quintozene technical powder at 7-8 grams per square meter, or mix 50% carbendazim 8-10 grams with 15 kg fine soil to make medicated soil. Before sowing, first water thoroughly, and after the water seeps down, take 1/3 and scatter it on the bed surface, then cover the remaining 2/3 medicated soil over the seeds, about 1 cm thick, so that the seeds are sandwiched in the medicated soil. ③ Agricultural control: the seedbed should be chosen as a fertile plot with high dry terrain and good drainage. In the greenhouse, garden soil that has not grown solanaceous vegetables for many years should be selected as bed soil. Before sowing, strengthen ventilation and moisture removal in the seedling-raising site, and fully expose the bed soil to the sun. After emergence, water as little as possible to increase soil temperature, and promptly ventilate and let in light. Cover the shed with drip-free film to improve light conditions, facilitate photosynthesis and improve seedling disease resistance. You may also spray 800 times Lufeng 95 plant growth regulator to enhance seedling resistance.
[Chemical control] After seedlings become diseased, spray leaves with 75% chlorothalonil wettable powder 600 times, 64% Sandofan M8 wettable powder 500 times, 1000 times dexon solution, or 500 times thiram solution, or 800 times carbendazim solution. When the disease occurs, drench roots with 800-1000 times potassium permanganate solution, then wash the leaves.
Rhizoctonia Rot
[Damage symptoms] Rhizoctonia rot mostly occurs in the middle and late stages of seedling raising. After seedlings are infected, oval brown lesions appear at the stem base, then the stem becomes thin and constricted, and stems and leaves wilt and die. The aboveground part wilts during the day and recovers at night, and only withers after repeating several times. The diseased part has concentric rings or brown mold. When large seedlings or mature plants are affected, the stem base becomes ulcerous, and the aboveground part turns yellow, wilts and eventually dies.
[Occurrence conditions] Rhizoctonia rot is a fungal disease. The pathogen overwinters on diseased residues or humus in the soil and spreads through rainwater, flowing water, soil and fertilizer. The suitable temperature for pathogen development is 17-18°C, and high humidity favors disease occurrence. A warm and humid seedbed, poor ventilation and leggy seedlings all make disease occurrence likely.
[Control methods] Similar to the control methods for damping-off, with the focus on strengthening seedbed management and combining it with chemical control. ① Strengthen seedbed management: same method as for damping-off. ② Soil disinfection: use Wudai mixture for soil disinfection, which can control both Rhizoctonia rot and damping-off, with the same method as for damping-off. ③ Chemical control: spray 75% chlorothalonil wettable powder 600 times, or 64% Sandofan wettable powder 500 times, or 70% mancozeb wettable powder 500 times. During the seedling stage, spray once every 7-10 days, for 2-3 consecutive sprays.
Red Spider Mite
[Damage symptoms] They often gather on the back of leaves and suck sap with piercing-sucking mouthparts. Affected leaves first show small white spots, then fade green and turn yellow-white. In severe cases, the whole plant's leaves dry up and turn red as if burned, and the leaves fall off. When fruits are affected, the peel becomes rough, affecting quality.
[Occurrence pattern] It occurs 10-20 generations per year, and adults overwinter hidden in weeds and soil crevices. In the spring of the next year, they first reproduce on weeds or in overwintering sites, then transfer to eggplant or other vegetables to cause damage. They first damage lower old leaves, then spread upward. In North China, damage is severe from the end of May to early July. High temperature and drought easily lead to massive occurrence.
[Control methods] ① Clean the field: clean up weeds, dead branches and fallen leaves around the eggplant plot. After eggplant vines are pulled, clean up residual branches and fallen leaves to reduce insect sources. ② Chemical control: in the early stage of occurrence, use 20% dicofol 1000 times, 25% Miemandun wettable powder 1000-1500 times, 40% cyclopropyl dicofol wettable powder 1500-2000 times or 78% propargite emulsifiable concentrate 2000 times, spray once every 7 days, for 2-3 consecutive sprays, focusing on the back of leaves, and pesticides can be rotated.
American Leafminer
[Damage symptoms] Both adults and larvae can cause damage, with larvae mainly damaging leaves. Adults suck sap, and larvae tunnel into leaves, producing irregular snake-shaped white mines. The leaf surface is covered with mines, affecting photosynthesis, and in severe cases leaves fall off.
[Occurrence pattern] The American leafminer reproduces quickly and has a short generation interval. Generally, it reproduces 1 generation in 15-30 days in summer and 1 generation in 40-60 days in winter. It can occur year-round in protected cultivation. Larvae live inside leaves for 4-7 days, then older larvae bite through the epidermis and pupate outside the leaf or on the soil surface.
[Control methods] ① Agricultural control: strict quarantine to prevent the pest from spreading. Rotate, intercrop and relay crop with vegetables of other families. Promptly remove affected old leaves and withered yellow leaves and destroy them centrally. Eliminate them centrally in the early stage of occurrence. When a few affected leaves are found in the field, the larvae can be crushed leaf by leaf, then spray pesticides for control, with very good effects. Use fly-killing paper to trap adults. Because adults are attracted to yellow, yellow boards coated with machine oil can be used for trapping and killing. ② Chemical control: use 1.8% Avermectin emulsifiable concentrate 3000-4000 times, or 90% Wanling wettable powder 2500-3000 times, or 98% Batan technical powder 1500-2000 times, or 50% Yingqujing powder 2000 times for spraying. Spray once every 7-10 days, for 2-3 consecutive sprays. Note to alternate and rotate pesticides. For adult control, spray in the morning or evening; for larval control, it is best during the young larval stage, that is, when the length of most damaged mines is below 2 cm. In protected cultivation, dichlorvos can be used for fumigation.