Corn dead seedlings, red seedlings, purple seedlings? The reason has been found! Be sure to pay attention this year!

There are many reasons for the emergence of dead seedlings, red seedlings and purple seedlings in corn. How to distinguish them?

First, the corn dead seedlings

Reasons for dead seedlings:

1, the use of pesticides or herbicides, more than a certain concentration, can form abnormal color leaf spots, such as white spots or brown spots. The shoots and roots are curled or thickened, the growth of the plants is inhibited, the leaves are shortened or the grains are exposed. Excessive application of dichlorvos, trichlorfon, phoxim, kungfu, 2,4-D, etc. may cause phytotoxicity. Applying or drifting 2,4-D, the leaves can be curled into onion leaves, the lower stems and leaves are clustered together, and the aerial roots are not in contact with the soil; excessive application of phoxim can cause partial or mostly whitening of the leaves. Eventually the leaves are dry and frosty.

2, when the fertilizer is too much soluble nitrogen, potassium and other chemical fertilizers close to the seed, it will inhibit the seed germination or death after the emergence, the residual seedling dwarf makes the leaves yellow or dead.

3, high temperature and drought corn seedlings have a long period of lack of rain, resulting in atmospheric and soil drought, can not meet the needs of corn growth and development in the absence of water in the soil is likely to cause dead seedlings. The corn seedlings are dry, and the upper leaves of the young plants are rolled up and dark. In severe cases, the edge or tip of the blade turns yellow, and then the tip or leaf edge of the lower blade is dry. The seedlings dried up and died on loose sand.

4, the remaining herbicides in the upper mites herbicides in the wheat field herbicide application late in the early spring due to low temperature, some farmers in the wheat field chemical weeding time postponed until April 10, due to the grass age, correspondingly increased the superstar, fensulfuron The amount of use is 0.5--1 times larger than the conventional dosage, which increases the pesticide residue in the soil. Most of the summer corn sowing date is from June 5 to 10. The use period of superstars and bensulfuron-methyl is a safe period after 60 days of sowing of the next crop, so that the application of the upper sputum and the squatting period of some farmers did not reach a safe period, resulting in phytotoxicity of corn.

5, seedling blight summer maize infection seedling blight leaf sheath turned brown tearing, the leaves yellow, the edges are dead focus, the heart leaves curl, easy to fold, the leaves gradually dry from bottom to top; no secondary roots die Seedlings, a small number of secondary roots form weak seedlings.

Prevention:

1. Choose drought-resistant and disease-resistant varieties.

2, using formula fertilization technology, timely and appropriate amount of application, not excessive.

3. When using herbicides, strictly select the variety and master the dosage to avoid excessive concentration and should not be sprayed directly on the bell mouth.

4. Do not use sensitive insecticides such as trichlorfon and dichlorvos in corn fields. Strictly control the dosage when applying phoxim to control underground pests.

5. After drought or phytotoxicity, it is necessary to timely water and strengthen management.

6, with urea, potassium dihydrogen phosphate aqueous solution and superphosphate, grass ash filter leachate spray, can cool down and humidify, while providing the leaves with the necessary moisture and nutrients.

7, found seedling blight, can choose one of the following pesticides on the stem base spray: 50% carbendazim 600 times, 20% triadimefon 1000 times, carbendazim 3000 times, even spray 2 times.

Second, corn red seedlings, purple seedlings

In recent years, with the development of China's agricultural economy, the planting area of ​​corn, one of the three main staple foods in China, is also constantly increasing. In the growing period of corn, there is often such a situation that corn is in 3~ The purple-red plants appeared in the four-leaf stage, and some did not fade when they reached the 7-8 leaves of corn. This phenomenon is called corn red seedling.

The problem of "red seedlings" in a short period of time is not big. If the "red seedlings" are too long, the production will be seriously reduced. Red seedlings can cause short plants, low chlorophyll content, and decreased root activity.

Etiology analysis:

In recent years, with the large-scale promotion of compact corn varieties, dense planting, high temperature, weed coexistence, and continuous cropping for many years have resulted in various soil-borne diseases and defects in corn. In addition to red leaf seedlings, common diseases in maize seedlings include yellow leaf seedlings, albino seedlings, dead leaf seedlings, purple leaf seedlings, yellow-green seedlings, corn dwarf mosaic seedlings, maize rough-reducing disease seedlings, and total-etching disease seedlings. Sheath blight and so on. The corn plant is a purple-red corn plant called "red seedling".

This phenomenon usually occurs from the 3rd leaf stage to the 4th leaf stage of corn, and some do not fade when it grows to 7 leaves to 8 leaves. Some of them are only red or purple in the leaves, and in severe cases, the entire sheath and stem are purple-red.

There are many reasons for the occurrence of "red seedlings", mainly due to the following.

First, the plant is deficient in phosphorus.

Phosphorus deficiency in the soil can not meet the growth needs of maize seedlings, root growth and development are hindered, and seedlings grow slowly. As the phosphorus content in the seedlings gradually decreases, the leaves turn from dark green to red or purple.

Second, the water in the field.

Poor drainage in the field, large soil moisture, affecting the respiratory and metabolic effects of the root system, the growth of the root system is blocked, resulting in malnutrition and redness and purple.

Third, underground pest damage.

The roots of the seedlings are bitten by underground pests (such as golden worms), and the water absorption and absorption capacity are weakened, resulting in weakening of the seedlings and formation of red seedlings.

Fourth, low temperature can also cause corn seedlings to become red.

In the northeast region or Huanghuaihai spring sowing corn, corn planting earlier, in the early spring due to "cold spring" cold damage, will cause corn seedlings redness. In this case, as the temperature increases, the red seedling phenomenon will gradually ease and disappear later.

5. Phytotoxicity and pests can also cause corn seedlings to become red.

The phytotoxicity, insect pests, etc. caused the sugar metabolism in the corn seedlings to be blocked, and a large amount of anthocyanins were produced, forming a purple-red seedling. If a large area occurs, it is necessary to consult with the experts of the local agricultural department in time to find out the cause and then remedy it in a targeted manner.

Six other reasons.

The soil is too sticky, soaked too deep or shallow, and improperly fertilized to cause "burning seedlings", improper handling of pesticides, introduction of seedling poisoning, etc. will lead to "red seedlings."

Prevention:

1. For early application of phosphate fertilizer, it is mainly based on quick-acting phosphate fertilizer, which can apply 10~15 kg of calcium phosphate per acre, and can also be combined with insecticide spraying 1% of superphosphate leaching solution.

2. Leveling the land, excavating the drainage ditch, so that the rain stops and the water is dry, and the field does not accumulate water.

3. Do a good job in the prevention and control of underground pests, use coated seeds, and if necessary, use Bayer to take the second coat.

4. For shallow or early seedlings, it is necessary to water them at the right time, and cultivate the loose soil to protect the seedlings.

5. If red seedlings have appeared in the field, spray the 300-500 times solution of potassium dihydrogen phosphate plus strontium for 2 to 3 times, spray once every 3 days; adjust the growth balance nutrition.

It should be specially reminded that potassium dihydrogen phosphate must use genuine products. At present, there are many very cheap "potassium dihydrogen phosphate" on the market, which is actually "magnesium sulfate". Farmers must be careful when purchasing.