To water and topdress timely. As the temperature rises, the onion begins to grow and the leaf area will expand rapidly. At this time, the focus of management is to promote the vigorous growth of the leaves and lay the foundation for bulb expansion. For this reason, watering and topdressing should be timely. It is recommended that water is applied every 10 days or so. Combined with watering, 25-30 kg of potassium sulfate-type compound fertilizer is rushed per acre. It is carried out when the plant grows to 8-9 functional leaves. Cultivated squatting seedlings.
After squatting, the onion enters the bulb expansion stage. During this period, the temperature rises, the plant growth speed increases, and water evaporation begins to increase. At this time, watering should be carried out. Generally, watering is carried out once every 5 to 7 days, and nitrogen, phosphorus and potassium are applied at the same time to fertilize 10 to 15 kg. When the bulbs are near maturity, the physiological functions of the leaves and roots begin to decline. Watering should be gradually reduced. Stop watering 7 to 8 days before harvest to reduce the water content in the bulbs and improve storage stability.
Attention should be paid to preventing and curing diseases in advance. Diseases that are prone to onions are mainly anthracnose, soft rot, and gray mold. In order to reduce and prevent the occurrence of diseases, in addition to strengthening daily management, it should also be combined with chemical prevention and control to spray medicine in advance to prevent it.
When anthracnose occurs on the leaves, fusiform to irregular spots appear on the leaves, grayish brown to brown, with many small black spots. The enlarged lesions cause the upper leaves to die. When the temperature is around 20 ° C, the disease is severe under high humidity conditions. The drug can be sprayed with 75% daconin wettable powder 600 times liquid, 10% Shigao water dispersible granules 1500 times liquid or 70% methyl tobbutin 500 times liquid + fish protein 600 times liquid spray, spray every 7-10 days 1 time, continuous spraying 2-3 times.
Soft rot can occur during onion bulb expansion and storage. The main symptoms are softening of the base of the leaf sheath and lodging of the outer leaves. In the early stage of the onset, it can be sprayed with agricultural streptomycin or neophytemycin 4000 times solution + pulidon fish protein 600 times solution, once every 5 to 7 days, and then twice.
In the growing season, gray mold often occurs from the bulb neck and leaf sheath. In a humid environment, a gray mold layer is grown. The control can be sprayed with 40% Shijiale suspension agent 1000 times liquid, 40% Shijiale 1200 times liquid, or 600-1000 times liquid spray of farmers orchard (mioxamine), spraying once every 7-10 days, and spraying 2-3 times.
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