Nowadays, many farmers are planting summer corn. Many people will encounter the curling deformity problem of the top core leaves "twisted into a ox tail" or "rolled into a braid" shape during the corn seedling period, which is commonly known as the problem of corn seedlings "twisted into a cork leaf that cannot be expanded". Of course, as long as new leaves of corn seedlings appear, such corn will definitely not grow well. If remedial and relieve them in time, it will directly reduce the yield in the later stage of the corn.
In the actual corn planting management process, many experts generally introduced to farmers that the problem of crimping the core of corn heart leaves is caused by small pests such as thrips , and pesticides such as thiamethoxam need to be sprayed immediately for prevention and remediation. It is true that thrips are one of the most common causes of heart-wrenching and core-rolling leaves in corn during the seedling stage. However, the agricultural technology backpack here is here to emphasize to you: In addition to thrips pests, there are many other reasons, such as high temperature and drought, drug damage (such as nicosulfuron , sulfrenching and and other herbicides or other insecticides, fungicides, etc.), pests (such as thrips, borers, Swedish stalk flies, etc.) diseases (such as bacterial top rot, Smut disease, etc.), severe deficiency of nutrients (such as severe calcium fertilizer deficiency), heavy rain seedlings (heart leaves are buried), etc., and the symptoms of corn cassette leaves caused by different reasons are different. After symptoms occur, different methods need to be used to flexibly solve the victim corn seedlings. Otherwise, when you see the cork twisting core, you will blindly use insecticides to prevent and control thrips pests. However, if the cork twisting core of the corn seedling is not caused by thrips pests, you will not only spend more money or in vain to take medicine, the key is that it will not have the effect of remedy and prevention, let alone if the medicine damage occurs after injection!
In order to help everyone better understand the problem of twisting and rolling the core on corn seedlings, today the Agricultural Technology Backpack will give you a comprehensive summary of various common causes, symptoms and specific prevention and treatment methods. You may wish to read it carefully and compare the problem of twisting and rolling the core on your corn seedlings, and which method is the most suitable to remedy it.
1. Corn seedling core twisting problems caused by pests
Thrips pests are the most common cause of "screw core" of the heart leaves during corn seedling period. It is most likely to occur from mid-June to mid-July. Because thrips pests have the characteristics of becoming tender and sweet, they like to hide in the heart leaves of corn and suck the juice in the tender leaves of corn and damage the growth points of corn heart leaves. If the pests are destroyed for a long time, it will cause problems such as greening, yellowing, twisting and rolling leaves or rotting heart leaves on the top of the corn.
For small pests such as corn thrips, this type of pest is very small, and likes to hide in places without sunlight during the day. If you do not pay attention to carefully observe, you will not find any traces of the pest when the sun is strong during the day. Therefore, after the corn seedlings have symptoms of heart leaf twisting, they must first peel off the curly heart leaf to see if there are very small thrips insects inside.
The occurrence of thrips, a pest, is not very related to temperature, and is mainly directly related to the humidity of the soil air in the field. An environment with high temperature, less precipitation and high humidity is conducive to the outbreak of thrips pests. Generally speaking, in years or areas with more precipitation, and on moist soil plots, the incidence of pests of thrips is relatively low, the number of pests is relatively small, and the degree of pests is relatively light. If it is in years or plots with drought climate, less precipitation, and soil lack of water, the incidence of thrips on corn is relatively high, the number of pests is relatively large, and the degree of pests is relatively heavy.
In addition, the occurrence of corn thrips pests is also closely related to the quality of field management.Generally speaking, corn fields with excessive use of urea , such as nitrogen fertilizer, , (spermia is tender and juicy, thrips like to suck juice), corn fields with more weeds in the fields and surrounding areas (thrips will parasitize in a large number of weeds and spread pests into the corn fields), corn fields with too sparse planting density (sparse with sparse seedlings are well lit and ventilated, and the soil in the field will be relatively drought). Such corn fields are also prone to more serious thrips pests, causing the cord and leaf rolling during the corn seedling stage.
In the judgment of symptoms of thrips pests, if there are silver-white eating patterns and insect feces on the back of the leaves of corn seedlings, and there are long insect spots that turn green and yellow (green and yellow spots) on the front of the corresponding leaves, then the thrips pests are most likely to be turned away!
If it is determined that the corn core twisting problem caused by thrips, we need to spray medicine quickly for prevention and control. Pay attention to the following points when spraying: ① Do not choose imidacloprid , acetaminami , which has been resistant to drugs to drugs (poor insecticide effect). It is recommended to choose thiamethoxam, pyramidone , enedicycline , ethyl polyfungicin, high-efficiency cyanthrin and other drugs (good insecticide effect); ② Because thrips have the insecticidal properties of daytime and night, try not to spray medicine in broad daylight, but choose thrips to spray medicine in time when they are more active, for example, in the early morning or evening, insecticide is the best effect. ③ When spraying medicine to prevent and treat thrips, focus on spraying and spraying the heart leaves and backs of the leaves that are hidden in large quantities. ③ For corn grown in protected areas, if it is not suitable for pesticide, thrips pests can be used to have a tendency towards blue and hang more blue sticky oil plates in the fields for physical lure.
If you want to prevent or reduce the thrips pests on corn seedlings, the agricultural technology small backpack recommends that you do the following: ① In the case of drought and soil lack of water during the corn seedling period, watering should be timely increased to increase soil moisture to inhibit and reduce the occurrence of thrips pests; ② Before or after corn seedlings, fully implement closed weeding for corn seedlings before seedlings (apply herbicide within 3-5 days after corn seedlings) or post-seeding weeding management (apply herbicides to the 3-5 leaf stage) to destroy the places where thrips live and reproduce and cut off the source of thrips spread from weeds to corn seedlings; ③ During the corn seedling period, try to apply less and strictly control nitrogen fertilizers such as urea, and apply more phosphorus and potassium fertilizers appropriately to enhance the robustness and insect resistance of corn seedlings. ④ It is recommended to prevent and treat early spraying during the 3-5 leaf stage of corn seedling stage.
For corn seedlings that have had heart leaf core twisting problems due to thrips pests, the rolled leaves should be immediately picked and opened from the middle after discovery so that the victim heart leaves can resume normal growth as soon as possible.
In addition to the problem of cord twisting of corn, Swedish fly , black bugs, corn borer and other pests can also cause cord twisting of cord seedlings . We farmers should also pay attention to timely spraying medicine according to the type of pest. The best way to prevent pests is to use secondary drug coating on the corn species before sowing. The treatment method is naturally to use timely spraying medicine after discovering the pest!
2. Corn heart leaf core twisting problem caused by diseases
In addition to pest causes, diseases are also very likely to cause corn core twisting and rolling problem. We should also pay attention to timely detection and treatment.
Generally speaking, the types of diseases that are prone to cause corn seedlings to cause leaf twisting and leaf rolling deformity, mainly include the following types of : ① Corn crazy top disease (the leaves are twisted, rolled and shrinked after corn seedlings are jointed); ② Corn bacterial top rot (in severe cases, the rot and adhesion of corn heart leaves is a typical symptom, which is generally the most common in high temperature, rainy and humid climate conditions in mid-July, and may also occur in other periods); ③ Corn black sputum (usually the symptoms are only shown after corn earing, and the curling deformity of leaves is a manifestation of this disease) ④ Corn tumor black powder disease (this disease may occur at any time after corn seedlings. As long as the disease invades the leaves, leaf sheaths, heart leaves, etc. of the corn will cause the corn leaves to not be able to spread normally).
For corn core twisting, rolling leaves, and unstretching due to diseases, we have two main methods to prevent and treat. One is to use fungicide drugs to mix seeds before sowing or spraying and disinfecting the land. The other is to select medicines and spray medicines in time according to the type of disease.
In order to shorten the length of the article and save everyone's reading time, the specific drugs and methods of use will not be introduced to you in this article. When you go to the pesticide company, what diseases do you need to prevent and control, they will naturally recommend you the correct sterilization and control drugs.
3. Corn heart leaf core twisting problems caused by drug damage
Whether it is an insecticide, fungicide, or herbicide, as long as you use the medicine improperly (such as high-temperature time period) or excessive dosage and too high concentration, it is easy to cause drug damage to the corn, which in turn causes problems such as leaf rolling, core twisting, and leaf curvature of the corn seedlings.
In terms of herbicide damage, uses herbicides for soil sealing treatment after corn emerges, or sprays the herbicides after 3 leaves or 5 leaves of corn, or sprays the herbicide on the heart leaves of the corn when weeding after corn seedlings, or sprays organic phosphorus herbicides within 7 days after spraying the corn field, or uses too much medicine and too high concentration during the injection. These will cause the corn seedlings to suffer from the damage caused by herbicide damage, and irregular greening yellow spots (medicine spots) often appear on the leaves of corn seedlings that suffer from herbicide damage.
Therefore, to prevent the herbicide damage in the corn seedling stage, you should master the best time to spray herbicide in the corn field. Generally speaking, ① Spray the weeding before corn seedlings 3-7 days after corn seedlings, and it is strictly forbidden to spray herbicide after corn seedlings emerges; ② The most suitable spray herbicide after corn seedlings grows to the 3-5 leaf stage and the 2-4 leaf stage of weeding. It is strictly forbidden to spray herbicide before corn seedlings 3-7 days after corn seedlings. ③ When applying herbicides, it is strongly recommended that you spray the herbicide alone and apply medicine at severe high temperatures at noon. Try not to spray herbicides with other fungicides, insecticides, and foliar fertilizers together, otherwise it is easy to cause the corn seedlings to suffer from medicine.
For corn seedlings that have had herbicide damage, the agricultural technology backpack also provides you with a method to remedy and alleviate the damage. If the damage is relatively mild, it is recommended to use the field watering and apply urea nitrogen fertilizer to spray brassinolide + amino acid foliar fertilizer + potassium dihydrogen phosphate 2-3 times in a row. However, for corn seedlings with severe damage and severe core twisting or curling of the heart leaves, in addition to the above methods, it is recommended that you manually pick and peel off the twisted, rolled, shrinked, and wrinkled leaves from the middle in time so that the victim leaves can gradually resume normal growth as soon as possible.
The common herbicides that are prone to cause medicinal damage to corn are mainly: ① Herbicides for soil sealing herbicides before corn seedlings - Flerolyl , Dimethyl chloropyrimidine , Acetyl chloropyrimidine , Acetyl chloropyrimidine , Acetyl chloropyrimidine , Acetyl chloropyrimidine , chloropyrimidine , chloropyrimidine , chloropyrimidine , chloropyrimidine , bensulfurone , etc. ② Herbicides for stem and leaf herbicides after corn seedlings - nicosulfurone, sulforon, thiophenesulfurone, 2,4-D, chloropyrimidine , chloropyrimidine , chloropyrimidine , chloropyrimidine , bensulfurone , and herbicides such as methanesulfurone , chloropyrimidine , chloropyrimidine , bensulfurone , chloropyrimidine , bensulfurone , etc.In addition, after spraying herbicides such as glyphosate , quinolin , quinolin , enehelin , enehelin , if the sprayer that is not clean and has drug residues continues to spray leaf fertilizer, if the residual medicine liquid is sprayed on the heart leaves of the corn, it will also cause the corn's heart leaves to not pump, dead leaves, twist leaves, and roll leaves.
In terms of insecticides and fungicides, the most common thing about is improper combination of drugs (there are no more than three types of drugs for compounding, and the secondary dilution method must be adopted when dispensing the liquid). Secondly, when spraying insecticides, insecticides and other drugs in the corn field, the dosage is too large or the concentration is too high or the amount of water is insufficient. Secondly, when spraying the soil in drought or high temperature at noon, the medicine will often cause the problem of burning leaves, dry leaves, not pumping leaves, and not spreading leaves.
In addition to the above-mentioned drug damage, agricultural technology small backpack also recommends that you pay attention to a drug damage problem, that is, the seed coating agent during secondary drug coating of corn. This situation is generally because the seed mixing coating agent is used too much, or the finished corn seedlings have been coated with a certain drug before leaving the factory. Later, we all used this same seed coating agent for secondary coating. This can easily lead to corn seed due to excessive coating agent use, resulting in corn seed deformity (such as twisting leaves, rolling leaves, difficulty in drawing leaves, not spreading leaves, etc.). Here is a small agricultural technology backpack reminding everyone: If we plan to secondary coating of corn seeds, we must ask clearly what kinds of medicines you used before leaving the factory when purchasing corn seeds, and how much amount of coatings you have used to coat them, so as to prevent the corn seeds from being damaged due to excessive amounts of coating agents or reusing the coating agent during secondary coating.
4. Corn heart leaf twisting problems caused by high temperature drought
When corn is sown to seedling stage, many areas are in high temperature and drought weather conditions. If the weather is hot before and after corn sowing, there is little natural precipitation, and the soil is drought and water shortage is severe, but have we farmers watered and increased wet to make up for the moisture, then the root system will have a curling heart leaf problem due to the soil being too dry and the root system cannot absorb enough water, fertilizer and nutrients.
The problem of twisting and rolling of corn heart leaves caused by high temperature drought is easy to judge. Generally, the symptoms are the symptoms of the heart leaves or top leaves of corn seedlings curling into a cylinder due to drought. The problem of twisting and rolling of corn leaves caused by high temperature drought is also easy to solve. Generally, as long as watering timely increases soil moisture or the next rainy moisture becomes better, the problem of twisting and rolling of corn will be quickly alleviated and returned to normal.
5. Corn heart leaf twisting problem caused by extreme bad weather
Bad weather such as storms, floods, and night frost damage (for spring corn ), hail, etc., will also cause symptoms such as heart leaf twisting, rolling, wrinkling, and damage after bad weather. For example, after storms and floods, the upper leaves and heart leaves will be buried in the cement soil due to lodging. If we do not pull out the leaves of the lodged and buried from the sand and soil silt in time, the leaves of the corn will be suppressed due to growth. The leaves may not stretch smoothly or twist them; for example, corn planted in early spring has suffered from low temperature frost damage or hail frost damage, etc. At this time, some leaves on the corn seedlings will be frozen or frost-damaged, which will affect the normal ejaculation and expansion of the corn heart leaves and growth points. In this case, we need to cut off the dead leaves that hinder the growth of the heart leaves in time after the weather gets better or peel off the heart leaves manually, and the victimized corn seedlings will slowly return to normal growth.
6. Corn heart leaf twisting problem caused by gene mutations
When we sow corn, we cannot guarantee the purity of each corn species gene. Moreover, a few corn will also undergo gene mutations during the growth process. For such corn, there will also be problems such as twisting, rolling, deforming, leaf discoloration and deformation. For such corn seedlings that are individually mutationed due to gene mutations, we just need to remove them at any time.
In addition to the above 6 reasons, calcium deficiency in corn can easily cause symptoms similar to thrips pests, which leads to corn seedlings with too soft leaves and poor stretching of new leaves and heart leaves. We should also pay attention to the following.
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