How can we make corn grow quickly after the weather turns cold in late spring?

It is rare for corn to be frozen, but I really met it this year, and it is plastic film corn, which is located in Luohai Palace, the highest village in Shanyang County, Shangluo City. At the beginning of May, the temperature plummeted, and not only corn, potatoes, Chinese toon and walnut trees were fatally hit. These corns are affected by the late spring cold in different areas, and the degree of disaster varies greatly. Some of them have almost no symptoms, some are just soft and black at the tip, some are very serious, and all the above-ground parts are withered and black. So how to take effective remedial measures? This needs to be handled separately according to the different situations of the disaster.

Maize freezing injury is a physiological disease and not contagious. Under normal circumstances, when the cold wave passes and the weather clears up, it is clear whether it is frozen or not. Only in this way can we judge and put forward the treatment plan according to the specific situation: 1. After the ground part is frozen, it will lose water, wilt, turn black and wilt, and even die, which is easy to identify. After sun exposure, the symptoms are particularly obvious. You should cut off the frozen part with scissors at the first time. There are two purposes, one is to avoid infection with pests and diseases, and the other is to prevent the normal development of new leaves from being affected. When it is cut off, part of it should be taken out of the plot and destroyed centrally.

2. Check the damage. Before the 5-leaf stage, the growing point of maize seedlings was in the underground part. If the damage is not particularly serious, it will grow and develop again, but the growth period will be delayed for a few days, but the management of water and fertilizer should be strengthened to reduce losses. If the growing point is damaged, the corn needs to be replanted.

3. Replanting method. If most corn plants in the whole plot are short of seedlings, the corn in this plot can't meet the transplanting needs, and the varieties in other plots may be different and can't be mixed, so as to avoid the situation that the grain number per plant of corn is reduced due to inconsistent propagation and pollination during the growing period. If only 1 ~ 2 seedlings are missing between two corn plants, it can be solved by leaving two seedlings to supplement the number of seedlings without transplanting. If the number of seedlings is more than 3, it is necessary to replenish the seedlings.

Replenishing seedlings can accelerate the growth rate by transplanting seedlings in small arch shed. If combined with soaking seeds to accelerate germination, the effect will be better. Transplanting can maintain the whole field growth period when it is basically close to the field growth period and there is one more leaf.

Tips: Replanted varieties must be the same.

4. intertillage and loosen the soil in time. The cold in late spring brings a lot of rain, and the soil is easy to harden. At the same time, weeds have not been affected by freezing injury and continue to grow vigorously. The procedures of intertillage and weeding are indispensable. At the same time, intertillage can not only increase the ground temperature, but also reduce the evaporation of soil moisture, which is beneficial to seedling protection.

5. Replenish soil nutrition in time. At the stage of three leaves and one heart, the seed nutrition has been absorbed, and the growth of corn seedlings depends entirely on soil nutrition. When corn needs to grow quickly again after being frozen, it must absorb more nutrients from the soil. At the same time, the tassel flower bud differentiation has begun in the three-leaf stage of maize, and a certain amount of phosphate fertilizer and potassium fertilizer are also needed. Therefore, when new leaves are born after freezing, 5 kg of urea and 5 kg of diammonium phosphate should be applied topdressing per mu of land, and potassium dihydrogen phosphate should be applied to the leaves to make the roots and leaves absorb enough nutrients, turn the leaves into dark green, improve photosynthetic efficiency and accelerate growth.

6. Pay attention to the harm of pests and diseases such as black cutworms. At this time of the year, corn covered with plastic film and black cutworm are very harmful in the alpine mountain area. What needs to be known is that the larvae of the black cutworm still lie on the corn leaves to feed, but the food intake is very small, which can't be seen without attention. Only a single layer of epidermis and mesophyll damage will be formed on the page, and holes will be formed later, and finally it will move to the base of the stem to feed on the corn stalk, causing the whole corn to fall to the ground. Therefore, in fact, while dealing with the rotten leaves caused by freezing injury, observe the occurrence of adults and larvae. If found, you can choose to spray beta-cypermethrin on the leaves in a sunny afternoon, without waiting until it becomes an older larva.

If older larvae are found, they can be directly killed by placing paulownia leaves and weeds in the corn field at night, or spraying pesticides under paulownia leaves for artificial trapping and killing. Pesticides such as trichlorfon and fried wheat bran can also be used to trap and kill.

According to past experience, freezing of maize seedlings in alpine mountain areas will aggravate the occurrence of maize seedling blight, which is characterized by few roots and yellow leaves on several leaves, mainly caused by cold and humidity. Therefore, if corn seedling blight symptoms appear, triadimefon and other drugs can be used for prevention and treatment.

7. It is uneconomical to replant maize if the seedling shortage rate in the field is above 60%. Simply replant for the second time. Due to the low effective accumulated temperature in alpine mountain areas, excessive sowing will cause abnormal maturity. If you switch to corn these days, you'd better choose a very early-maturing corn variety. You can find a county-level seed company to help allocate corn seeds in the name of the village Committee, sowing one day earlier and harvesting one day earlier. In order to germinate early and ensure Miao Zhuang, it is suggested that seeds should be dressed with zinc fertilizer, soaked to accelerate germination and sown. After sowing, water should be picked manually or diluted human excrement should be used to urinate corn to ensure a success.

Due to the limitation of climatic conditions, the growth period of maize in alpine mountain area is short and its growth and development are slow. The management of corn should be based on early sowing, early topdressing and early prevention and control of pests and diseases, and topdressing should end at the big bell mouth stage to avoid the phenomenon of greed for green and late ripening. Potassium dihydrogen phosphate can be sprayed twice in the later stage to promote early maturity.