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Eggplant is deep in soil, rich in organic matter, and sandy loam with good permeability. If it is planted in sticky soil, it is easy to induce rotten roots. The leaves of eggplant are large, the transpiration is strong, and the water demand is large, but it is afraid of cockroaches. Therefore, it is impossible to make the eggplant lack of water in management, and it cannot be watered too much, resulting in water accumulation in the field. Otherwise, it is easy to cause hypoxia in the roots, and the products of anaerobic respiration will cause root poisoning and cause rotten roots.
First, the disease
1, stumbled over. Eggplant seedlings can be damaged before or after excavation. The unearthed seedlings developed, the embryo stems and cotyledons became brown and smashed, and the seedlings died. After the seedlings were unearthed, the base of the stem was initially water-stained, and the diseased part became yellowish brown and shrank into a shallow shape. The disease develops very quickly, often before the cotyledons have not withered, the seedlings fold down and stick to the ground, but the seedlings are still blue-green, so it is called tripping. In the case of low temperature and high humidity, a layer of white cotton-like hyphae often grows on the surface of the host disease and its adjacent soil. In the seedbed, only the individual seedlings were seen at the beginning, and a few days later, the center spread and spread around, and finally caused the seedlings to stumble.
pathogen. It is a Pythium pyogenes in the genus Pythium. The mycelium is developed, multi-branched, colorless and without membrane. The differentiation of the cysts is not obvious. The sporangia are terminal or pointed, forming a tubular shape with some lobed branches. The zoospores have double flagella and kidney shape. After a short swim in the water, they become circular resting spores, which then germinate into germ cells to invade the parasite.
2, the blight. Mostly in the bed temperature or bed nursery in the middle of the bed. At the beginning of the disease, elliptical dark brown lesions are produced at the base of the seedlings. The early diseased seedlings wilted during the day and recovered sooner or later. Later, the diseased part gradually sag, spread around the stem for a week, and overflowed and dried up, and finally the plants died. Because the diseased plants are mostly erect and die, they are called blight.
Pathogen: Rhizoctonia solani, a genus of the genus Aspergillus. The mycelium is colorless in the early stage, gradually becomes pale brown in the later stage, the branch is at a right angle, the base of the branch is overflowing, and there is a diaphragm not far from the branch. There is a sclerotium, the sclerotium has no certain shape, light brown to dark brown, the texture is fluffy, and the appearance is rough.
Second, the popularity of eggplant seedlings died of diseases and conditions of the main determinants of
1. Climate conditions. The small meteorological conditions of low temperature and high humidity in the seedbed are important factors leading to the occurrence of diseases. The suitable temperature for eggplant growth is 22-23 °C. At the seedling stage, the temperature is 20-30 °C. In this temperature range, the seedlings grow well and have strong disease resistance. On the contrary, if the temperature is too high or too low, it is easy to induce disease. If the temperature is too low, it is prone to collapse, the temperature is too high, the seedlings are long, and the blight is prone to occur; the air humidity is high, especially when the bed soil is humid, the seedlings are seriously affected. Because of the growth of pathogens, the germination and invasion of sclerotia require high humidity and certain moisture. When the humidity in the bed is high, the root growth of the seedlings is unfavorable, and the disease resistance is reduced, which is conducive to the expansion and spread of the disease; the light is sufficient, the photosynthesis of the seedlings is flourishing, the growth is strong, and the disease resistance is strong. If the light is insufficient and the seedlings grow thin, it is easy to get sick.
2. Host growth period. The nutrients in the cotyledons of the seedlings have been exhausted and the new roots have not yet been tough. The young stems are not dangerous during the lignification period.
3. Seedbed management. The low temperature and humidity in the seedbed and the poor growth of the roots of the seedlings are serious. The ventilation and light transmission in the bed is poor, and there are many toxic gas volumes, which are also easy to induce diseases.
4, the nature of the soil. In the barren, sticky soil, the disease occurs more seriously, while the sandy loam with abundant organic matter and good permeability is mild.
Third, the prevention and control strategy of eggplant dead seedlings. It is mainly based on cultivation management, supplemented by chemical control.
1. Agricultural control. Carefully choose the bed site and scientifically build the bed. The bedding is easy to irrigate, and the seat is sunny, which is convenient for controlling the temperature. Using a fermented fertilizer, invent a good condition that is conducive to the growth of eggplant. Strengthen management, pay attention to heat preservation, control humidity, timely ventilation and light, and promote seedling growth. Fulfill the rotation and achieve a rotation of more than 4 years.
2. Solve the soil. Usually carried out 2-3 weeks before sowing, the bed soil is first loosened, 450 ml of formalin per square meter, 20-30 kg of water, poured on the bed surface, and then covered with plastic film for 4-5 days; Remove the film, loosen the bed soil, and let the liquid fully evaporate before seeding.
3. Where there are conditions, nutrition and nursery can be carried out.
4. Seed solution. Soaking in warm soup: soaking in warm water at 55 °C for 15 minutes; seed dressing or soaking; 40% seed dressing or seeding WP can be used for seed dressing, 80% of dexamethasone wettable powder, dosage 0.2% by weight of the seed. In addition, 25% metalaxyl WP can be mixed with 70% mancozeb WP at a ratio of 9:1, then immersed in water for 1500 times, and can be sown after air drying.
5, chemical control. If a small amount of diseased seedlings have been found on the seedbed, it should be eliminated in time and sprayed to prevent the spread of the disease. The medicament can be sprayed with 75% chlorothalonil WP 1000 times or 70% mancozeb WP 600 times.
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