First of all, high temperature and high humidity are the main reasons for the formation of high seedlings. From late April to early May, many places were in a continuous rainy stage for a long time. The temperature is low for a long time, the light is insufficient, the cotton seedlings are thin, and some cotton fields drip too much. During this period, the humidity in the cotton field was high, and the current temperature jumped to 28 degrees. High temperature and high humidity are easy to form tall seedlings.

② Some cotton farmers are afraid that their seedlings won't grow up. Because of growth factors, they spray hormones such as gibberellin or compound sodium nitrate to raise seedlings quickly.

Second, the harm of high cotton seedlings:

① High temperature and sufficient water accelerate the absorption of nutrients, and the physiological activities of plants are unbalanced, with less nitrogen and more carbon, which promotes the growth of nutrients and makes the stems and leaves flourish. However, the high water content in the surface soil affects the deep growth of the main roots, and the shallow lateral roots of the main roots are few, and the weather resistance decreases after the next day, which is easy to cause cotton plants to lodging in a large area. This makes management more difficult.

(2) The tall seedlings produced at the time of emergence are difficult to form strong seedlings because of the high nutrient consumption, which leads to insufficient fruiting branches and delayed maturity of beautiful seedlings; After the formation of high seedlings, the cotton plant height is high, the leaves are plump and the nutrients grow vigorously. After the formation of high seedlings, the cotton plant height is high, the leaves are fat, the nutrition grows vigorously, and the field is easy to shade, which is not suitable for field management.

Three. Khmer seedling solution

(1) Carry out chemical control in time to control the stable growth of seedlings.

1. Generally, two drip irrigation seedlings or hybrid cotton fields are controlled at cotton seedling stage. The second stage is cotyledon stage. The chemical control at this stage is mainly to promote roots, reduce seedlings and even raise seedlings. Generally, before cotton seedlings grow into real leaves, the suitable spraying period is four or five days after cotton seedlings emerge.

2. During this period, pesticides such as imidacloprid, acetamiprid or thiamethoxam should be sprayed, and it is suggested that the dosage of carbendazim should be reduced to one gram per mu. The second chemical control was carried out in two true leaf stages. It is suggested to use carbendazim 0.5g ... The chemical control in this period is mainly to promote flower bud differentiation to promote early budding.

(2) Grasp the sunny day and plough deeply.

Deeply cultivate loose soil, create conditions of temperature, light, water and air suitable for cotton plant development, so that a large amount of water in the soil will evaporate, cut off some roots, and force the growth of stems and leaves to slow down.

③ Spraying fertilizer to promote the stable growth of seedlings.

High seedling is actually a kind of weak seedling, and it is very important to promote the growth of seedlings in this period. One hundred grams of potassium dihydrogen phosphate and fifty grams of urea can be sprayed in the middle of the plow, and brassinolide and other regulators for stable growth can be supplemented.

④ Strengthen the investigation and control of thrips gossypii.

The rapid rise of temperature will also heat up the wind, leading to the rapid reproduction of cotton thrips. To do a good job in the prevention and control of cotton thrips, seedlings are often more prone to pests, and prevention and control of cotton thrips is also an important technology to promote early maturity. We should have the idea of preventing insects first and then preventing grass.