Eggplant dead seedlings have become a major obstacle in the production of eggplant, often resulting in a significant reduction in production or even no harvest, causing great economic losses to vegetable farmers. The main reasons for the death of eggplant are: unsuitable soil, improper management and fungal diseases.
Eggplant is deep in soil, rich in organic matter, and has good permeability. If it is planted in a 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. Seedlings of unearthed seedlings, embryonic stems and cotyledons browned and rotted, and 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. At low temperature and high humidity, a layer of white cotton-like hyphae often grows on the surface of the host disease and on the soil nearby. 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 cysts are not differentiated distinctly. 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, expanded 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, and the branch is at a right angle. The base of the branch has a shrinkage, and there is a diaphragm not far from the branch. There is sclerotium, the sclerotium has no certain shape, light brown to dark brown, loose texture and rough surface.
Second, the prevalence of diseases and the main determinants
1. Climate conditions. The microclimate conditions of low temperature and high humidity in the seedbed are important factors leading to the occurrence of diseases. The optimum 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, the disease is easily induced. When the temperature is too low, it is prone to collapse, the temperature is too high, the seedlings are long, and it is prone to blight; the air humidity is high, especially when the bed soil is humid, the seedlings are seriously ill. Because of the growth of pathogens, the germination and invasion of sclerotia require high humidity and certain moisture. When the bed humidity, unfavorable for seedling root growth, reduced resistance to disease, is conducive to the expansion and spread of diseases; adequate light, photosynthesis seedlings strong, robust growth, disease resistance. If insufficient light, seedling growth weak, it is easy to get sick.
2, the host growth period. Cotyledons seedlings have not been exhausted and the new solid roots, young stems during the sense of danger is not yet woody disease.
3, seedbed management. Seedbed low stuffiness, poor seedling root growth, the heavy disease. The ventilation and light transmission in the bed is poor, and the accumulation of toxic gases is high, and it is easy to induce diseases.
4. Soil properties. In the barren, heavy soil, the disease occurs more seriously, while the sandy loam with rich organic matter and good permeability is mild.
Third, prevention and treatment strategies. 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 seedbed is required to be easily irrigated, and the seat is sunny, which is convenient for controlling the temperature. Use decomposed fertilizer to create a good condition for eggplant growth. Strengthen management, pay attention to heat preservation, control humidity, timely ventilation and light transmission, and promote seedling growth. Implement a rotation and achieve a rotation of more than four years.
2. Treat the soil. Generally, it is 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 treatment. 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 It is 0.2% by weight of the seed. In addition, 25% metalaxyl WP can be mixed with 70% mancozeb wettable powder at 9:1, then immersed with water 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 removed 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.
Eggplant is deep in soil, rich in organic matter, and has good permeability. If it is planted in a 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. Seedlings of unearthed seedlings, embryonic stems and cotyledons browned and rotted, and 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. At low temperature and high humidity, a layer of white cotton-like hyphae often grows on the surface of the host disease and on the soil nearby. 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 cysts are not differentiated distinctly. 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, expanded 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, and the branch is at a right angle. The base of the branch has a shrinkage, and there is a diaphragm not far from the branch. There is sclerotium, the sclerotium has no certain shape, light brown to dark brown, loose texture and rough surface.
Second, the prevalence of diseases and the main determinants
1. Climate conditions. The microclimate conditions of low temperature and high humidity in the seedbed are important factors leading to the occurrence of diseases. The optimum 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, the disease is easily induced. When the temperature is too low, it is prone to collapse, the temperature is too high, the seedlings are long, and it is prone to blight; the air humidity is high, especially when the bed soil is humid, the seedlings are seriously ill. Because of the growth of pathogens, the germination and invasion of sclerotia require high humidity and certain moisture. When the bed humidity, unfavorable for seedling root growth, reduced resistance to disease, is conducive to the expansion and spread of diseases; adequate light, photosynthesis seedlings strong, robust growth, disease resistance. If insufficient light, seedling growth weak, it is easy to get sick.
2, the host growth period. Cotyledons seedlings have not been exhausted and the new solid roots, young stems during the sense of danger is not yet woody disease.
3, seedbed management. Seedbed low stuffiness, poor seedling root growth, the heavy disease. The ventilation and light transmission in the bed is poor, and the accumulation of toxic gases is high, and it is easy to induce diseases.
4. Soil properties. In the barren, heavy soil, the disease occurs more seriously, while the sandy loam with rich organic matter and good permeability is mild.
Third, prevention and treatment strategies. 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 seedbed is required to be easily irrigated, and the seat is sunny, which is convenient for controlling the temperature. Use decomposed fertilizer to create a good condition for eggplant growth. Strengthen management, pay attention to heat preservation, control humidity, timely ventilation and light transmission, and promote seedling growth. Implement a rotation and achieve a rotation of more than four years.
2. Treat the soil. Generally, it is 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 treatment. 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 It is 0.2% by weight of the seed. In addition, 25% metalaxyl WP can be mixed with 70% mancozeb wettable powder at 9:1, then immersed with water 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 removed 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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