Why do the leaves of corn seedlings turn yellow? How to wilt after fertilizing?

Corn tastes sweet, can do all kinds of dishes, such as corn, corn juice, etc., it is also the main raw material of industrial alcohol and liquor, so China's north and south will plant a large number of corn seedlings. So why are corn leaves yellow? What to do after fertilizer wilting?

The yellow leaves of corn seedlings are caused by the following reasons:

1. Sowing too deep. Sowing too shallow is not easy to emerge, too deep will appear weak seedlings, seedlings yellow, sowing depth should be controlled at 3-5 cm.

2. Thinning and fixing seedlings are not timely. After corn emergence, seedlings should be thinned when corn leaves are 3-4, and seedlings should be fixed when corn leaves are 6-7, so as to avoid crowding seedlings, competing for fertilizer, water and glory, and forming weak seedlings, sick seedlings and yellow seedlings.

3. Insufficient watering. The maize is watered insufficiently before or after sowing, and the seeds do not get enough water, which affects the normal germination and emergence, and the emergence time is too long to cause weak seedlings and yellow seedlings.

4. Water damage seedlings. Water damage seedlings corn seedlings often coincide with rainy season, poor drainage of low-lying land or wheat harvest rolling water, resulting in yellow seedlings.

5. Disease. If the seedling stage encounters long-term low temperature and rainy weather, it will cause the occurrence and epidemic of maize seedling blight. Seedling blight disease mostly begins at the second and third leaf stage, the leaves of the diseased seedlings are yellow and dry, the edges are scorched, and the leaves gradually turn yellow and dry from bottom to top; the root hairs are less, the root system turns brown and develops poorly, resulting in yellow seedlings and weak seedlings.

6. Pests. The main pests in maize seedling stage are cotton bollworm, armyworm, aphid, thrips, Swedish stem fly, cutworm, and sunflower mealybug. The sunflower mealybug concentrates in the stem base, root and leaf sheath near the ground surface of maize seedling as nymph and female adult to absorb sap, causing the leaf sheath of damaged maize to turn yellow and dry first.

7. Herbicide hazards. Improper use of herbicides, random increase in herbicide dosage; blind mixing with other pesticides; excessive drug concentration; sprayer interaction; fake and inferior herbicides on the impact of subsequent crops, will cause yellow corn seedlings.

8. Deficiency. Maize is a zinc-sensitive crop, zinc deficiency will appear white flower seedlings, looks like corn seedlings yellow.

Second, the corn seedlings wilting is caused by ammonia smoke from urea decomposition.

Because the corn seedlings are still small, the leaves are young and close to the ground, and the urea application amount is large, and it is applied to the soil surface. In the high temperature season, only a small amount of surface water is poured, which cannot leach granular urea into the soil depth, and only a large amount of urea can be dissolved in the surface. Calcareous soil belongs to alkaline soil. Dissolved urea molecules decompose rapidly at high temperature to produce a large amount of ammonia and carbon dioxide, resulting in fumigation.

In this case, conditional plots are watered first and then cultivated. It can dilute nitrogen fertilizer and aerate to promote root growth. For plots without irrigation conditions, measures of cultivating soil after deep cultivation should be taken immediately to keep nitrogen and reduce ammonia volatilization, and remove soil moisture to promote root penetration. Case tips: urea is a high concentration of nitrogen fertilizer, do topdressing, a suitable amount of application. Calcareous soil is alkaline and should be covered with urea and ammonium nitrogen fertilizer.