Winter vegetable greenhouses to prevent "three evils"
In the winter season, vegetables in greenhouses are most prone to frost damage, fertilizer damage, and pests and diseases. For this “three harms,†prevention and control should be combined and comprehensive prevention and control should be carried out.
Frost damage prevention
Ice and snow disasters often occur in winter, causing various levels of damage to plastic greenhouses and other facilities. Under conditions of low temperature, high humidity, and low illumination in greenhouses, vegetables are not only prone to frost damage, but also have poor growth. They grow thin and weak, and are prone to infections. The main measures for prevention and control are: removing snow from the shed in time after snow to prevent the collapse of the shed; draining the sewer around the shed to reduce the humidity inside the shed; adding a small arch shed to the shed, covering the cold and heat insulation at multiple layers in the evening, and removing the cover during the day to increase Light; After the snow or after sunny days, it is necessary to properly shade or step by step to prevent plants from “flashing seedlings†due to sudden water loss; control watering to avoid lowering the ground temperature and increase air humidity; Victims of light vegetables may be sprayed with 2 to 3 0.2% potassium dihydrogen phosphate solutions as appropriate. For plants with yellowish nitrogen deficiency, two or three 0.3% urea solutions may be sprayed.
Prevention of fertilizer damage
Vegetables can be roughly divided into three kinds of fertilizer damage, the first is too much fertilizer or too close to the plant, the crop is burned with high concentrations of fertilizers, such as a large amount of urea so that the seeds or seedlings burned; the second is a certain Excessive application of nutrient elements leads to lack of other elements. For example, excessive application of potash fertilizer may lead to calcium deficiency and magnesium deficiency in crops. The third type is excessive application of nitrogen fertilizer under closed management conditions, and no ammonia or timely ventilation after application. Or nitrous acid gas poisoning. These three kinds of fertilizers should be controlled, but under the closed management conditions in winter, the prevention of ammonia and other harmful gases on crops should be the focus of burns. The first is scientific fertilization to prevent over-application of a large amount of fertilizer. After the basal fertilizer has to be applied, it must be covered with soil or fully mixed with the soil. For topdressing, it is advisable to cover the soil deeply and apply irrigation water promptly after application. Do not spread the fertilizer on the ground. The second is to balance the fertilization, potassium fertilizer should be appropriate, fractional or stratified application; do not zinc, iron and other trace element fertilizers and phosphate fertilizer directly blended, it is best mixed with decomposed organic fertilizer and humic acid fertilizer application. Third, over-application of nitrogen fertilizer will cause ammonia gas and nitrous acid gas to accumulate in the soil. Therefore, the nitrogen fertilizer should be applied in an appropriate amount and be combined with phosphorus, potassium and other fertilizers. After the application, the soil should be timely covered or the fertilizer and soil should be fully mixed so that the nitrogen fertilizer is applied to the crop. Absorb and use it fully. Fourth, the slow release of nutrients such as organic fertilizers and slow/controlled release fertilizers can reduce the production of harmful gases. In order to suppress nitrous acid gas, in addition to the rational application of nitrogen fertilizer, nitrification inhibitors can also be used in an appropriate amount. Fifth, in the event of toxic gas poisoning, we must promptly improve the ventilation conditions and escape harmful gases.
Pest Control
In winter, vegetable greenhouses are low-temperature, oligo-illuminated, and high-humidity. It is prone to diseases such as leaf mold, disease, gray mold, downy mildew, damping-off, and roundworm. In this regard, in addition to the use of chemical control, but also through the following measures for comprehensive prevention and control: First, we must choose suitable for the cultivation of the region's excellent disease-resistant varieties and no pests and diseases. Second, to improve the poor soil traits through different types of vegetable crop rotation, vegetable crop rotation and planting of shorter growing crops in the two seasons of vegetable leisure season. Third, we must disinfect the soil and seeds, grasp the appropriate planting density, and promptly remove diseased plants from the shed or remove diseased leaves. Fourth, we must do a good job in the greenhouse management of temperature, humidity, gas, water, ventilation and humidity in a timely manner to prevent rainwater leakage into the shed, the greenhouse must be covered with plastic film, in order to increase the temperature and reduce the greenhouse air humidity. 5. If there is a condition, use a dark plastic film to cover the ground completely, or use micro-irrigation fertilization techniques. This will not only improve the utilization of fertilizer and water, but also increase the ground temperature and reduce the air humidity, effectively preventing the occurrence of pests and diseases.
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