The wheat varieties that show yellowing symptoms are particularly sensitive to potassium deficiency. Although many wheat varieties exhibit yellowing, the most widespread and severe cases are observed in only a few specific types, which may be genetically more vulnerable to low potassium levels. Early sowing has also contributed to this issue. In areas where yellowing wheat appears dead, most of these fields were sown just before or after the Cold Dew (a traditional Chinese solar term), about 15 days earlier than usual. Due to the early planting and sufficient rainfall, the plants became leggy, leading to yellowing and eventual death. However, wheat replanted on the same plot showed no signs of legginess or yellowing.
Soil potassium levels have been severely depleted over the years due to long-term lack of organic manure or potash application, or very limited use of potassium fertilizers. Continuous high yields in summer and autumn have further exhausted the soil’s nutrient reserves, especially potassium. The soil has reached a critical point where it can no longer supply enough potassium, and timely replenishment was not carried out.
Another contributing factor is the partial application of nitrogen fertilizer. This practice has caused a serious imbalance between nitrogen and potassium levels. Due to the high cost of potash this year, combined with other factors, farmers have reduced their use of potassium fertilizer—either intentionally or unintentionally—from the start of the autumn crop fertilization. Some farmers have even increased nitrogen fertilizer application to compensate for the lack of potassium, resulting in excessive nitrogen and insufficient potassium, which has led to widespread yellowing and withering of wheat crops.
According to field surveys, as long as there is no partial application of nitrogen fertilizer, and if quality potassium or compound fertilizers are used, regardless of the sowing date or variety, very few yellowing symptoms are observed.
**Control Methods:**
Foliar spraying of potassium fertilizer is recommended. For yellowing wheat and seedlings showing early symptoms, spray a 0.3% solution of potassium dihydrogen phosphate on the leaves. Apply this every 5 to 7 days, and repeat 2 to 3 times if necessary.
Topdressing with potassium fertilizer is also effective. If the wheat is still viable, apply 8–10 kg of high-quality potassium fertilizer per mu (approximately 667 square meters). A key warning is that many farmers mistakenly believe yellowing is due to nitrogen deficiency and plan to apply urea after snowfall. This will only worsen the problem.
For fields that are beyond recovery, apply 8–10 kg of quality potassium fertilizer per acre, then reseed with strong spring varieties at a rate of 15–20 kg per acre. Wheat planted around the Winter Solstice was sown in mid-to-late January 2009. With proper management, these fields can still yield up to 250 kilograms per mu in the following season.
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