After corn is hit by late spring cold, how can we quickly resume growth?
It is rare for corn to get frozen, but I really encountered it this year, and it was mulched corn in Conch Palace, the highest village in Shanyang County, Shangluo City. The temperature suddenly dropped in early May, not only corn, but also potato, toon, walnut trees, etc. were fatally affected. Due to different regions, these corns were affected by the late spring cold, and the degree of damage varied greatly. Some had almost no symptoms, some only softened and turned black at the leaf tips, and some were very serious, with all the above-ground parts wilting and turning black. So how to carry out effective remedial measures? This needs to be dealt with separately according to different disaster situations. Corn freeze damage is a physiological disease and is not contagious. Under normal circumstances, after the cold wave passes and the weather clears up, it is clear at a glance whether you have been frozen or not. Only then can you make a judgment and propose a treatment plan based on the specific situation:
1. The above-ground part will appear water-soaked after being frozen. Loss of water, wilting, blackening and wilting, and even death are easy to identify. Symptoms are particularly obvious after exposure to the sun. The frozen part should be cut off with scissors as soon as possible. There are two purposes, one is to avoid infection by pests and diseases, and the second is to prevent the normal expansion of new leaves from being affected. When cutting, the parts should be taken out of the plot and destroyed centrally.
2. Check the damage. Before the 5-leaf stage, the growth point of corn seedlings is in the underground part. If the damage is not particularly serious, it will grow and develop again. It will only delay the growth period for a few days. However, water and fertilizer management needs to be strengthened to reduce losses. If the growing point is damaged, the corn plant will need to be replanted.
3. Methods of patching up seedlings. If most of the corn plants in the entire plot lack seedlings, the local corn plot cannot meet the transplanting needs, and the varieties in other plots may be different and cannot be mixed to avoid inconsistent growth periods, poor reproduction and poor pollination, and a reduction in the number of corn kernels per plant. situation occurs. If there are only 1 to 2 seedlings missing between two corn plants, this can be solved by leaving double seedlings to replenish the number of seedlings without transplanting. If the number of missing seedlings exceeds 3, it will be necessary to replace the seedlings.
Repairing seedlings can accelerate the growth rate by transplanting seedlings in small sheds. If combined with soaking seeds to accelerate germination, the effect will be better. When it is basically close to the field growth period and there is one more leaf, transplanting will be done. It can maintain the entire field growth period.
Warm reminder: The varieties of seedlings must be the same.
4. Timely cultivating and loosening the soil. This late spring cold brought a lot of rain, and the soil was easy to harden. At the same time, the weeds were not affected by the freezing damage and continued to grow vigorously. The procedures of cultivating the soil and removing weeds were indispensable. At the same time, cultivating and loosening the soil can not only increase the ground temperature, but also reduce the evaporation of soil water, which is beneficial to the preservation of seedlings.
5. Replenish soil nutrients in a timely manner. When corn reaches the three-leaf and one-heart stage, all the seed nutrients have been absorbed, and the growth of corn seedlings depends entirely on soil nutrients. If corn is frozen and needs to grow again quickly, it must absorb more nutrients from the soil. At the same time, the three-leaf stage of corn has begun to differentiate tassel flower buds, and a certain amount of phosphorus and potassium fertilizers are also needed. Therefore, when a new leaf emerges after being frozen, 5 kilograms of urea and 5 kilograms of diammonium phosphate are needed per acre of land. At the same time, potassium dihydrogen phosphate is used for foliar spraying to encourage the roots and leaves to absorb sufficient nutrients. , the leaves become dark green, improve photosynthetic efficiency and accelerate growth.
6. Pay attention to the dangers of diseases and insect pests such as cutworms. At this time of year, cutworms cause serious damage to mulched corn in alpine mountainous areas. What needs to be known is that the young cutworm larvae still lie on the corn leaves to feed. However, the amount of food is very small and cannot be seen if you are not careful. It will only damage the single layer of epidermis and mesophyll of the page, and then form holes later. Finally, Then they move to the base of the stem to feed on the corn stalks, causing the entire corn plant to fall to the ground. Therefore, while dealing with leaf rot caused by frost damage, observe the occurrence of adults and larvae. If found, you can choose to spray foliar control with high-efficiency cypermethrin in the afternoon on a sunny day. There is no need to wait until it turns into older larvae.
If older larvae are found, they can be artificially trapped by placing Paulownia leaves and weed piles in the cornfield in the evening, or you can spray pesticides under the Paulownia leaves to directly kill the young cutworm larvae. You can also use trichlorfon and other pesticides mixed with fried wheat bran to trap.
According to past experience, freezing of corn seedlings in alpine mountainous areas will also aggravate the occurrence of corn seedling blight. The specific manifestations include less root system and yellow leaves on several leaves. The main reason is caused by cold and damp conditions. Therefore, if symptoms of seedling blight appear, you can use triadimefon and other chemicals for control.
7. If the corn seedling deficiency rate in a field is above 60%, it is not cost-effective to replenish the seedlings. Simply replant a second time. Because the effective accumulated temperature in alpine mountainous areas is low, sowing too late will cause the problem of normal maturation. If you want to replant corn in the past few days, it is best to choose extremely early-maturing corn varieties. You can ask the county-level seed company for help in the name of the village committee to allocate corn seeds, so that you can sow one day earlier and harvest one day earlier. In order to ensure the early emergence of seedlings and ensure the robustness of the seedlings, it is recommended to use zinc fertilizer for seed dressing and seed soaking to promote germination and sowing. After sowing, water is collected manually or corn is dotted with diluted human feces to ensure first-time success.
Corn in alpine mountainous areas is restricted by climatic conditions, has a short growth period, and slow growth and development. Corn management is based on early sowing, early top dressing, and early prevention and control of pests and diseases. Top dressing ends at the trumpet stage to avoid greed. Late puberty occurs. Potassium dihydrogen phosphate can be sprayed twice in the later period to promote early maturity.