In early spring, the weather is changeable and the temperature is high and low, and the low temperature will cause seedlings such as cowpeas, watermelons and tomatoes that have been cultivated in the shed to suffer from various degrees of frost damage. After the cold air passed, as the weather cleared, the temperature in the shed suddenly rose, resulting in crop shoots and wilting. The preventive measures for abnormal seedlings that often occur in early spring are described below: First, frozen seedlings The main reason is that the seedbed temperature is too low. Control methods: 1. Improve the means of raising seedlings, artificial temperature control seedlings, such as electric hotbeds. 2. Warming and freezing, before the arrival of the cold, strengthen the night insulation, such as stamping a thick straw curtain, erecting a small arch shed, etc., if necessary, can be heated stove and so on. 3. Appropriate control of watering, reasonable increase of phosphate fertilizer, improve the cold resistance of seedlings. 4. The sprayed nutrient solution was sprayed on the frozen seedlings, and the formula of the nutrient solution was: 30 ml of sprayed poem, 0.3 g of rooting powder, and 15 kg of water. Second, the root seedlings are mainly caused by high humidity and low temperature. Control measures: 1. Select a well-perforated soil as seedbed and try to increase the temperature. 2. The electric wire was used to raise seedlings so that the temperature of the seedbed was kept at 20°C and 25°C during the day and 15°C at night. 3. Control watering. 4. In the event of rooting, timely ventilation and dehumidification, spraying fine soil and ash to absorb moisture. Third, leggy seedlings are mainly caused by large amount of sowing and caused by high temperature and high humidity after emergence. Control measures: 1. Strictly control the seeding rate. 2. When the seedlings grow in crowded conditions, the seedlings will be seedlings. 3. Try to increase the amount of light, even on a cloudy day, so that the seedlings can see the light. 4. Controlling watering, foliar spray 0.2% spray plus 0.2% 3% potassium dihydrogen phosphate mixed solution, to promote seedlings turn strong. Four, wilt seedlings It was mainly caused by the unraveling of continuous rain and fine weather. Preventive measures: In the event of a sudden turn of rain after continuous rain, it is necessary to gradually see the seedlings. Do not immediately uncover all the coverings. Remove them in batches and gradually increase the light. If some seedlings are found to be wilting after being exposed for a long time, they must be covered immediately. After the seedlings return to normal, they should be re-opened and the water should not be watered. Fifth, wearing a cap seedling This seedling is caused by the seedbed over dry, overlying soil. Control measures: 1. Bottom water should be sufficient. 2. The thickness of the cover soil is uniform and appropriate, such as the thickness of pepper, eggplant 1 cm, cucumber 1.5 cm. 3. Before emergence, the seedbed covers the mulch to keep the soil moist. 4. When the seedlings are worn, the water can be sprayed first. After the moisture of the seed shell is absorbed, brush the seed shell gently with a brush. Six, aging seedlings Mainly due to the age of seedlings and seedlings caused by excessively long time. Preventive measures: 1. Strictly control the age of seedlings, when the seedlings are not allowed to be cold for a long time and prolonged drought, it is best to use methods that do not control water. 2. For aged seedlings, spray a mixture of 300500 times potassium dihydrogen phosphate per square meter of seedbed to stimulate seedling growth. Shanghai J.Shine Co.,Ltd , https://www.jshinechem.com