Premature-ripening vegetables susceptible to disease and prevention

First, freeze-chilled peppers and eggplants are suitable for daytime temperatures above 25°C and nighttime temperatures above 15°C. The daytime temperature of tomatoes should be above 20°C and not less than 8°C during the night. When cold air arrives, thermal insulation should be strengthened, or artificial warming measures should be taken to prevent cryogenic damage caused by low temperatures.
2. After germination, the cotyledon and embryo stems are rotted, resulting in rotten species. After the cotyledons were unfolded, the base of the diseased seedlings developed water-spotted lesions, which then turned yellow-brown and curled up into a line, that is, tripped. The fallen seedlings cannot stand upright. The other appearances of seedlings are the same as those of healthy seedlings.
Control methods 1. The selection of seedbeds should be as far as possible on the ground of unripe oysters. Do not build old seedbeds. To build a bed in an old seedbed, it is necessary to replace the soil with less germs or to disinfect the soil. Fertilizer must be cooked. 2. The seedling raising technology utilizes modern seedling raising techniques, such as electric hotbed technology and artificially controlled temperature seedling raising techniques, to maintain the suitable temperature of the seedbed. 3. Bed soil disinfection Formalin disinfection: 2-3 weeks before sowing, the bed soil is loosened, 50 ml of formalin per square meter of nursery bed, and 18-36 kilograms of water (depending on the soil moisture ), evenly poured on the seedbed. Then covered with plastic film on the bed soil. After 3-5 days, remove the cover and loosen the soil. After about two weeks, the liquid is fully evaporated and then sown. Disinfection of pentachloronitrobenzene, etc.: mix 70% of quintozene with 50% of thiram and mix equally, 8 to 10 grams per square meter (4 to 5 grams for each drug), plus Dry fine soil 20-30 kg and mix well. Before sowing, one-third of the medicine soil is spread on the bed surface first as a bedding, then the seeds are sowed on the bedding, and the remaining two-thirds of the medicine soil is evenly covered on the seeds as cover soil. After covering the soil, the surface of the soil should be sprinkled with water to keep the soil moist, and the soil should not be too dry so as to avoid phytotoxicity. Carbendazim or thiophanate disinfectant: Use 50% carbendazim or 50% thiophanate, 8-10 grams per square meter, using the same method as above. Enemy Pine powder disinfection: with 70% enemy powder, 500 grams per mu, and then add 20-25 kg of dry soil before use. 4. Seed Treatment Seeds soaked with warm water 48°C-49°C for 10-15 minutes. Or use 50% of Fairchild WP, ​​or 65% zein zinc wettable powder. The dosage is 0.3% of seed weight. 5. Seedbed management seedbed temperature should be appropriate to reduce the damage of low temperature. Appropriately increase the number of soil loosening and promote root growth. Control the appropriate humidity. In the initial stage of emergence, levigate the soil 1 to 2 times on the surface of the bed in order to protect the site and make up for cracks in the ground. When the humidity of the seedbed is too high, the number of ventilations should be increased when the temperature is high, the humidity of the seedbeds should be eliminated, and the humidity of the seedbeds should be reduced. When the nursery's drought must be watered, it should be done in the morning. Immediately after the watering, the plastic film is tightly sealed to raise the temperature of the seed bed. When the temperature is high at noon, the air is ventilated. The amount of water used was the degree of soil moisture in the rhizosphere of the seedlings. Take all measures to improve the light conditions of the seedbed. Lift the insulation covering timely to prolong the time of light exposure. After seedling emergence and time seedlings, seedlings should be divided in time to prevent seedlings being too dense, affecting ventilation and light transmission, resulting in excessive humidity and causing seedlings to grow weak. When the watering or seedbed humidity is too high, dry ash on the seedbed can be sprinkled several times. Dry ash has the functions of absorbing moisture, reducing moisture and increasing light absorption, increasing the temperature of the ground, and inhibiting the growth of bacteria. The diseased seedlings were found to be removed in a timely manner and carried deep outside the field or burned. One ten-thousandth of a solution of natural algae--Shandongfeng 481 is sprayed once to increase the resistance to disease. 6. After the prevention and treatment of pesticides, the following agents are available: 75% chlorothalonil wettable powder 600 times; 64% antivirus WP 500 times; 70% mancozeb wettable powder 500 times; 70% enemies Ke Songyuan 1000 times liquid. Choose one of the above-mentioned agents, or use them alternately, once every 7-10 days, and spray them 2-3 times.
Third, blight occurred in the middle and late stages of nursery. The elliptical dark brown spots on the base of the seedlings of the affected seedlings developed. The early diseased seedlings wilted during the day and recovered at night. After the lesion gradually sag. After the development of lesions around the stem one week later contracture occurs, the roots gradually dry and wilting until dead. The control method is the same as damping-off disease.
Fourth, the roots of young roots do not produce new roots, the root of the skin is yellow and brown, and finally rot. The growth of the aerial parts was inhibited, and the leaf color was pale or yellow, no new leaves were produced, and the wilting-like appearance was mostly observed around noon during the day. Seedlings are easy to pull up.
Prevention and control methods The disease is a physiological disease, without spraying control, other agricultural measures with damping-off.
5. The wind seedlings that have not been ventilated for a long time are exposed to the environment with high air humidity. The transpiration is not very strong. If they are suddenly hit by strong winds, the transpiration suddenly increases and the water absorption and transpiration of the root system are damaged. The balance between the two often results in the dehydration of tender leaves and the lack of timely supplementation. If the wilting time is too long, the leaves will not recover, and eventually it will die in green. This phenomenon is called "air drying."
Preventive measures: When the seedbed is ventilated, it must be small to large. Do not be too rushed to make the seedlings have an adaptation process. When encountering strong winds, be careful not to allow the wind to blow away the cover.
6. The wilt sunshine seedlings are exposed to low light conditions of 10 000 lux for a long period of time. If they suddenly become exposed to strong light conditions at 20 000 lux, wilting can easily occur. The symptoms are: the tip of the leaf is curled upwards, and over time, the leaves are green and dry.
Preventive measures: Let the seedlings from the low-light conditions to the light conditions should be gradual, not too sudden, the use of partial shade measures; morning, afternoon, see the light, noon coverage, so that the seedlings have a process of adaptation.

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