Prevention measures and comprehensive management to avoid onion whitening, short and fine air

1. Select excellent varieties of Changbai onion, such as Zhangqiu onion, grain onion (whip onion), etc.

2. Choose a plot with deep soil layer, fertile soil and good drainage, and deeply plow and rake, generally dig more than 30 cm deep, dig 20~30 cm deep, 15~30 cm wide, and 70~80 cm wide ridges for cultivating soil. Furrowing fertilization before planting, applying farm manure 1000~5000 kg per mu, and then deeply loosening furrows to combine manure and soil.

3. Planting between mango seed and summer heat should be early rather than late. If planting is too late, the formation period of onion white is short, the onion white is short, thin and the yield is low. At the same time, the seedlings are easy to grow, and the weather after planting is hot and difficult to slow down.

4. When planting onions, plant them deeply and bury them shallowly so that they can cultivate soil in stages later. General plant spacing 1 cm, buried soil 8 cm or so, not to bury the onion seedling heart leaves as the standard. Before planting, onion seedlings should be selected, and seedlings with stem diameter of about 1 cm, 3~4 leaves, 30~40 cm high and no diseases and insect pests should be selected.

5. Strengthen cultivation management. After planting to the beginning of autumn is the period of slow seedling over summer. In the semi-dormant state, it is necessary to strengthen intertillage to preserve soil moisture and promote root development. It is better not to irrigate the soil if it is not dry. From the beginning of autumn to the end of white dew, the plants enter the full leaf period. From late August to late September, fertilizer and water management shall be strengthened. 15kg urea shall be applied per mu. After top dressing, soil shall be buried, cultivated and irrigated in time. After white dew, it shall enter the growth period of scallion white. The fertilizer shall be mainly quick-acting nitrogen fertilizer. Watering shall be frequently irrigated and re-irrigated. The soil shall be kept moist frequently to meet the needs of scallion white growth.

6. Cultivate soil in combination with intertillage. Before the rainy season comes, ridge furrows should be cultivated slightly to prevent the roots from rotting due to ponding in planting furrows. Cultivate soil once every 10~15 days after the beginning of autumn. Cultivate soil is an effective measure to increase the length of scallion. Cultivate 3~4 times in total. The first time to shallow culture, in order to improve the ground temperature, the next two times more soil, especially the last time to try to high culture, do not exceed the heart leaf.

7. When the leaves stop growing, the harvest period is 15~20 days before the soil freezes, generally from frost to early winter harvest.