Prevention and control of yellowing of wheat seedlings before winter due to seedling treatment

After sowing and emergence of barley and barley, different degrees of yellowing often occur before winter due to the influence of bad conditions and cultivation management. There are many reasons for the yellowing of wheat seedlings before winter, such as drought, insect pests, nitrogen deficiency and potassium deficiency, which should be caused by different causes to promote the transformation from yellow wheat seedlings to strong winter seedlings.

Drought yellowing such as winter dry years, long sunny without rain, soil hardening, lack of moisture, root extension difficulties, often lead to wheat seedling leaves yellowing, slow growth and delayed tillering stage. Wheat seedlings that are dry and yellowing due to lack of water should be watered in time to resist drought. The method of urgent irrigation and drainage can be adopted to fight drought. After the drought is alleviated, combined with ploughing, an appropriate amount of quick-acting fertilizer can be applied, or 2% potassium dihydrogen phosphate solution can be sprayed to promote the wheat seedlings to be transferred to winter tillers as soon as possible.

Insect pests such as wheat aphids or red spiders can also cause yellowing of wheat leaves. After the pests are found, they should be controlled in time. Generally, 40% omethoate 1500-2000 times, or 4.5% cypermethrin EC 1000 times, or 10% imidacloprid wettable powder 1000 times, or 3% acetamiprid 1500 times, can be used for spray control.

Some wheat seedlings with nitrogen deficiency and yellowing showed the symptoms of uniform discoloration and yellowing of the whole plant, heavier old leaves than new leaves, narrow leaves and fewer new leaves, which was caused by nitrogen deficiency. It is especially serious in the fields where there are too many seedlings and insufficient organic fertilizer in base fertilizer, and relatively few seedling fertilizer and tillering fertilizer. In general, 1000 kg of human feces and urine can be used to add 10 kg of ammonium bicarbonate to water, and if the soil is too wet, it can be changed to 20 kg of ammonium bicarbonate. The application of ammonium bicarbonate must be carried out after the dew is dry in the morning to prevent burning seedlings and improve fertilizer efficiency.

Potassium deficiency yellowing wheat seedlings in some sandy soil, such as starting from the leaf tip, and then extending downward along the leaf edge, the boundary between the macula and the normal part is obvious, becoming mosaic yellowing spots, yellow leaves are often softened, and the symptoms of sticking to the ground in the later stage are caused by potassium deficiency. In this regard, in the initial period, 150 kg ~ 200 kg of plant ash can be used for every 667 square meters. If the yellowing is more serious, 10 kg ~ 15 kg of potassium chloride can be used to sprinkle or add water to dry dew every 667 square meters. While taking the above measures for potassium deficient wheat seedlings, 2% potassium dihydrogen phosphate can also be used for foliar spraying.