Wheat seedling stage refers to the period from seedling emergence to jointing stage, during which wheat seedling stage, tillering stage before winter, tillering stage before winter, tillering stage before winter, tillering stage before winter, tillering stage before winter, tillering stage before winter, tillering stage before spring, seedling stage during spring, tillering stage during spring.
In production, improper cultivation, fertilization and field management measures often lead to yellow seedlings in the field and affect the normal growth of wheat, which should be avoided.
1. Poor land preparation quality
The results showed that the seedlings in the field grew unevenly, the weak seedlings had poor root development, few tillers and weak growth.The main reason is that the former stubble stubble long, crushing degree bad, affect the quality of land preparation.
Countermeasures: before land preparation, the straw of previous crops should be crushed, and the length of crushed straw should not exceed 5 cm. The places with more straw should be spread out in time and buried after deep turning. Then, the soil should be prepared by rotary tillage and raking.
2. Lack of moderate repression
After the former stubble straw returned to the field, the cultivated layer soil is too fluffy, which has poor soil moisture conservation and frost prevention ability, and affects the wheat seedlings to take root, easy to form "suspension seedlings" and "suspension seedlings", which reduces the wheat seedlings' drought resistance and cold resistance ability, and aggravates the occurrence of weak yellow seedlings.
Pay attention to the timely suppression after the sowing of wheat, and determine the time and intensity of the repression according to the soil condition and other factors in the field.
3. Field water
After the sowing of wheat, if there is continuous rainy weather and water accumulation in the field for a long time, the root system of wheat seedlings will not grow well and the absorption and transport of nutrients will be affected.
Pay attention to the ditch moisture, ensure that waterlogging can drain, stain can fall.When the soil moisture is suitable, tillage in wheat row can loosen soil, enhance soil air permeability, improve ground temperature, promote soil microbial activity and enhance root absorption capacity.
Combined with tillage and loose soil, a certain amount of nitrogen fertilizer was applied to promote slow seedling.
4. Underground pest hazards
Corn, soybean and other crops crop crop underground pests often occur more serious, mainly grubs, acicula, mole cricket 3 kinds, in the winter before or after the spring temperature rise, autumn damage caused by lack of wheat seedlings and broken ridges, spring damage caused by seedlings withered heart, so that the plant died in advance.
After entering winter, the weather turns cold and the underground pest harm is reduced.For the control of underground pests, seed dressing and soil treatment can be adopted before sowing, and root irrigation or toxic soil application can be applied after sowing, with the application of sulphothion.
5. Seedling disease
There are many diseases that cause yellow leaves in seedling stage of wheat.
6. Take-all disease
It is a typical root disease. The seedling stage is damaged, the primary root and the root part become black and brown, the upper leaves of the surviving seedlings become pale, the leaves at the base turn yellow, the plants grow short, and the diseased plants are easy to be pulled off from the root part.
7. Sheath blight
In the seedling stage, the underground stem was mainly damaged, and the transport of nutrients and water was impeded, resulting in yellow wheat leaves, which then gradually developed upward.
To prevent and control wheat seedling diseases, the key is to treat the seeds with agents before sowing. The commonly used drugs include 25 g/l pyronitrile suspension seed coat agent, 4.8% phenyl ether pyronitrile suspension seed coat agent, 12.5% silamethamine suspension agent, etc.
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