The death of eggplant has become a major obstacle in the production of eggplant, often resulting in a significant reduction in yield or even an unacceptable harvest. This has caused great economic losses to vegetable growers. The main causes of dead eggplant are: inappropriate soil, improper management, and fungal diseases.
The eggplant has a deep layer of soil, is rich in organic matter, and has a good sandy loam. If it is planted in a clay with a high viscosity, it can easily induce rot. Eggplants have large leaves and strong transpiration. They require large amounts of water, but they are afraid of cockroaches. Therefore, management can not make eggplants lack of water, nor can watering be too large, causing water accumulation in the fields. Otherwise, it is easy to cause hypoxia in the roots, and the product of anaerobic respiration can cause poisoning in the roots and cause rot.
First, the disease
1, tripping disease. Eggplant seedlings can be damaged before or after unearthing. Unripe seedlings develop, embryonic stems and cotyledons become brown, and seedlings die. After the emergence of the seedlings, the base of the stem was initially water-stained. Afterwards, the diseased part became yellow-brown and shrank to a shallow shape. The disease develops rapidly, often before the cotyledon has wilted, and the seedlings are folded and affixed to the ground. However, the seedlings are still blue-green, so they are called cataplexy. At low temperatures and high humidity, a white cotton flocculent mycelium grows on the body surface of the host's disease and adjacent soil. In the seedbed, when the beginning of the seedlings, only a few seedlings were found. After a few days, the seedlings spread to the surrounding area and eventually caused the seedlings to stumble.
pathogen. It is Pythium trichoderma in the genus Pythium. Mycelium developed, many branches, colorless and no diaphragm. The differentiation of cysts is not obvious, and the sporangia are terminal or apical, forming an enlarged tubular, and some have fissure-like branches. The zoospore is a double flagellum and kidney-shaped. After swimming for a short time in the water, it turns into a circular resting spore. After germination, the germinating tube invades the parasite.
2, blight. More in the bed temperature higher seedbed or nursery later in the disease. At the early stage of disease, the elliptic dark brown spots were found at the base of the seedlings. Early diseased seedlings wilted during the day and recovered sooner or later. Afterwards, the diseased part gradually sag, spread around the stem for a week, and shrank and dried up. Finally, the plant died. Because diseased plants mostly stand dead and die, it is called blight.
Pathogen: Rhizoctonia solani of the genus Deuteromycotina. The mycelium was colorless in the early stages and gradually turned pale brown at the later stage. The branches showed a right angle. The bases of the mycelium were shrunk, and there was a septum not far from the branches. Sclerotia, sclerotia without a certain shape, light brown to dark brown, fluffy texture, rough appearance.
Second, the disease of the popular conditions and the main determinants
1, climatic conditions. The small meteorological conditions of the seedbed at low temperature and high humidity are important factors leading to the occurrence of diseases. The suitable temperature for eggplant growth is 22 to 23°C. The optimum seedling temperature is 20-30°C. Within this temperature range, the seedlings grow well and have strong disease resistance. On the contrary, high or low temperatures are easy to induce disease. If the temperature is too low, it will be prone to damping-off, excessive warming, long seedlings, and prone to blight; air humidity is high, especially when bed and soil humidity is high, and the seedlings are seriously ill. Because of the growth of germs, germination and invasion of sclerotia all require higher humidity and a certain amount of moisture. When the humidity is high on the bed, the growth of the roots of the seedling is unfavorable and the resistance to disease is reduced, which is conducive to the spread and spread of the disease. With adequate illumination, the seedlings are lush with vigorous growth, strong in disease resistance. If the light is insufficient, the growth of seedlings is thin and thin, it is easy to get sick.
2, host growth period. The nutrients in the cotyledon of seedlings have been depleted and the new roots are not yet tough, and the young stems are in danger of becoming susceptible during the period of no lignification.
3, seedbed management. The low humidity in the seedbed and poor root growth of the seedlings are more serious. Bad ventilation and light in the bed, more toxic gas volume, but also easy to induce disease.
4, soil properties. In the poor, viscous soil, the occurrence of disease is heavy, while the sandy loam with rich organic matter and good permeability is less likely to occur.
Third, the prevention and control strategy. The main cultivation and management, supplemented by chemical control.
1, agricultural control. Carefully select the bed site and build the bed scientifically. The request for seedbed irrigation is convenient, and the seat is sunny and easy to control the temperature. Using rotten fertilizers, a good condition was developed to facilitate eggplant growth. Strengthen management, pay attention to insulation, control humidity, timely ventilation and light, and enhance seedling growth. Fulfill rotation and achieve rotation for more than 4 years.
2, solve the mud. Usually 2 to 3 weeks before planting, the soil is first raked, 450 ml of formalin per square meter, 20-30 kg of water, poured on the bed, and then covered with plastic film for 4 to 5 days; Remove the film, loosen the bed soil, allow the liquid to fully evaporate before planting.
3, where conditions can be used to nurse seedlings.
4, the seed solution. Warm soaking: soaking in warm water at 55°C for 15 minutes; dressing seed or soaking seed; 40% seed dressing or seed dressing WP, 80% chlordane wettable powder, dosage for seed dressing For the seed weight 0.2%. In addition, the use of 25% metalaxyl WP and 70% mancozeb WP to 9:1 mixed, then immersed in water 1500 times soaked, dried after sowing.
5, pharmaceutical control. If a small number of diseased seedlings have been found on the seedbed, they should be promptly eliminated and sprayed to protect the disease from spreading. The agent can be sprayed with 75% chlorothalonil wettable powder 1000 times or 70% mancozeb wettable powder 600 times.
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