How to prevent and control yellowing of wheat seedlings before winter? The key lies in treating according to the condition of the seedlings

After barley and @#@245@#@ are sown and emerge, due to the influence of adverse conditions and cultivation management, varying degrees of yellowing often occur before winter. There are many reasons for wheat seedlings turning yellow before winter, such as drought, insect pests, nitrogen deficiency and potassium deficiency, etc. The remedy should be applied according to the different causes, so as to promote the yellowing wheat seedlings to transform into strong overwintering seedlings.

Drought-induced yellowing: in a dry winter year, with long periods of clear weather and no rain, soil hardening, and insufficient water, root extension is difficult, which often leads to yellowing of wheat seedling leaves, slow growth, and delayed tillering stage. For wheat seedlings yellowing due to water shortage and drought, timely watering for drought relief should be carried out. For drought relief, the method of rapid irrigation and rapid drainage can be adopted. After the drought is alleviated, an appropriate amount of quick-acting fertilizer can be applied with irrigation in combination with intertillage, or a 2% potassium dihydrogen phosphate solution can be sprayed to prompt the wheat seedlings to quickly shift into winter growth and strong tillering.

Insect pest-induced yellowing: pests such as wheat aphids or red spiders can also cause wheat leaves to turn yellow. After discovering pests, timely control should be carried out. Generally, per 667 sq m, a 1500-fold to 2000-fold solution of 40% omethoate, or a 1000-fold solution of 4.5% beta-cypermethrin emulsifiable concentrate, or a 1000-fold solution of 10% imidacloprid wettable powder, or a 1500-fold solution of 3% acetamiprid can be sprayed for control.

Nitrogen deficiency-induced yellowing: some wheat seedlings show symptoms such as uniform discoloration and yellowing of the whole plant, older leaves more affected than new leaves, narrow leaves and a reduction in new leaves. This is caused by nitrogen deficiency. It is especially severe in fields with too many and excessively vigorous seedlings, insufficient organic fertilizer in the base fertilizer, and relatively little seedling fertilizer and tillering fertilizer. For this, the main measure should be supplementary application of quick-acting nitrogen fertilizer. Generally, per 667 sq m, 1000 kg of human excrement and urine plus 10 kg of ammonium bicarbonate can be diluted with water and applied; if the soil is too wet, this can be changed to broadcasting 20 kg of ammonium bicarbonate. Broadcasting ammonium bicarbonate must be done after the morning dew has dried to prevent seedling burn and improve fertilizer use efficiency.

Potassium deficiency-induced yellowing: for wheat seedlings in some sandy soils, if symptoms appear that start first from the leaf tips, then extend downward along the leaf margins, with a clear boundary between the yellow patches and the normal parts, forming mosaic-type chlorotic spots, and the yellow leaves often become soft and later lie flat on the ground, this is caused by potassium deficiency. For this, in the initial stage, generally per 667 sq m, 150 kg to 200 kg of plant ash can be broadcast. For more severe yellowing, per 667 sq m, 10 kg to 15 kg of potassium chloride can be broadcast after the dew has dried or applied with water. For potassium-deficient wheat seedlings, while taking the above measures, a 2% potassium dihydrogen phosphate solution can also be sprayed on the leaves.