Now many farmers and friends are planting summer corn, many people will encounter the top core leaf "twisted into a cow's tail" or "rolled into a twisted braid" curl deformity problem during the corn seedling stage, which is commonly known as the corn seedling "screw core leaf can not be spread" problem in the mouth of our farmer friends. Of course, as long as the corn seedlings appear to have the problem of twisting, rolling and deforming the new leaves, such corn must not grow well, and if it is not remedied in time, it will directly reduce the yield to the later stage of corn.
In the actual corn planting management process, many experts generally introduce to farmers and friends that the problem of curling the core of corn heart leaves is caused by small pests such as thrips, and it is necessary to quickly spray insecticides such as thiamethoxam for prevention and remediation. It is true that thrips are one of the most common causes of heart twisting core leaves in corn at the seedling stage, but the agricultural technology basket should be particularly emphasized here: the causes of corn seedlings twisting heart leaves in addition to thrips infestation, there are many other causes, such as high temperature and drought, medicinal pests (such as chimney sulfonylfuron, sulfonylron and other herbicides such as other insecticides, fungicides, etc.), insect pests (such as thrips, borers, Swedish stalk flies, etc.) diseases (such as the occurrence of bacterial top rot, smut disease, etc.), Serious deficiency of hormones (such as serious lack of calcium fertilizer), rainstorm seedlings (heart leaves are buried), etc., and different reasons caused by corn twisting heart leaf symptoms are different, after the occurrence of symptoms more need to flexibly use different means and methods to solve the victim corn seedlings, otherwise, you see the corn core blindly to fight insecticide to control thrips pests, but if the core of corn seedlings is not caused by thrips infestation, you spend more money, white medicine does not say, the key is that it can not remedy the effect of prevention and control, ah, Not to mention the in case of drug damage problems after the drug!
In order to help you better understand the problem of screwing and rolling leaves on corn seedlings, today's agricultural technology small back basket will give you a comprehensive summary of various common causes, symptoms and specific prevention and control methods, we may wish to read it carefully, compare the problem of twisting the core leaves of your corn seedlings in the end what kind of causes are caused, in the end which method is the most appropriate remedy.
First, the problem of screwing corn seedlings caused by insect pests
Thrips infestation is the most common cause of "core twisting" of the heart leaf at the corn seedling stage, and corn thrips are 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 to suck the sap in the young leaves of corn and damage the growth point of corn heart leaves, and the time of pest destruction is long, which will cause the heart leaves, young leaves, growth points at the top of the corn to degenerate green and yellow, twist the core curl leaves or rot the heart leaves.
For the corn thrips this small pest, this pest individual is very small, and during the day like to hide in the place where there is no sunlight, if you do not pay attention to careful observation, in the daytime when the sun is stronger, you can not find the trace of pests, so corn seedlings in the heart leaf twisting symptoms, first peel off the curly heart leaf to see if there is a small thrips bug inside.
The occurrence of this pest of thrips is not very much related to temperature, mainly related to the humidity of the soil air in the field, and the environment with high temperature, less precipitation and high humidity is conducive to the outbreak of thrips infestation. Generally speaking, in the year or region with more precipitation, on the soil moist plot, the incidence of thrips is relatively low, the number of insect pests is relatively small, the degree of insect infestation is relatively light, if it is in the year or plot with arid climate, less precipitation, and soil water shortage, the incidence of thrips on corn is higher, the number of insects is more, and the degree of insect infestation is more severe.
In addition, the occurrence of maize thrips infestation also has a lot to do with the quality of field management. In general, corn fields with too much nitrogen fertilizer such as urea (saples are tender, and thrips like to suck sap), corn fields with more weeds in the field and surroundings (thrips will parasitize a large number of weeds to spread insect pests into corn fields), corn fields with too sparse planting density (sparse plots are well lighted and ventilated, and the soil in the field will be relatively dry), such corn fields are also prone to more serious thrips infestation and cause corn seedlings to twist and roll leaves.
In judging the symptoms of thrips infestation, if the reverse side of the leaf of the corn seedling has silver-white nibbling lines and insect droppings, and there are long stripes of insect spots (green and yellow dots) on the front of the corresponding leaves, then it is the thrips insect infestation that is inseparable from the eight or nine!
If it is determined that the corn core problem caused by thrips, we need to hurry up the drug for prevention and control, and pay attention to the following points when spraying: (1) Do not choose thrips to the drug has developed resistance to imidacloprid, acetamiprid (poor insecticidal effect), it is recommended to choose thiamethiazide, pyrazone, enaderidine, ethyl polybactericide, high efficiency cypermethrin and other such drugs (insecticidal effect is good) ;(2) Because thrips have a daytime and nocturnal insectity, it is recommended not to go to the medicine in the daytime. Instead, choose the time period when thrips are more active to spray, for example, in the early morning or evening, these two time periods are the best for insecticidal effect. (3) When spraying to prevent and control thrips, it is necessary to focus on spraying the heart leaves and leaf backs of a large number of concentrated hidden thrips. (3) For corn grown in protected areas, if it is not suitable for spraying, you can use the characteristics of thrips pests to have a tendency to blue, and hang more blue sticky oil plates in the field for physical booby traps.
If you want to prevent or reduce the thrips infestation on corn seedlings, the agricultural technology basket recommends that you do the following: (1) in the case of drought in the corn seedling stage and soil lack of water, you should water in time to increase soil moisture, so as to inhibit and reduce the occurrence of thrips infestation; (2) before corn sowing or after seedling emergence, comprehensively do a good job of corn seedling soil closure weeding (herbicide within 3-5 days after corn sowing) or post-seedling weeding management (corn seedlings grow to 3-5 leaf stage to play herbicide), In order to destroy the place where thrips live and reproduce, cut off the source of thrips transmission from weeds to corn seedlings; (3) at the corn seedling stage, it is necessary to apply as little and strictly control nitrogen fertilizers such as urea at the seedling stage, and appropriately apply more phosphorus and potassium fertilizers to enhance the robustness and insect resistance of corn seedlings. (4) It is recommended to spray medicine as early as possible in the 3-5 leaf stage of maize seedling stage for prevention and treatment.
For corn seedlings that have already had heart leaf core problems due to thrips infestation, the curl leaves should be picked out from the middle immediately after discovery, so that the affected heart leaves can return to normal growth as soon as possible.
In addition to the thrips this pest will lead to corn screw problem, Swedish flies, black bugs, corn borer and other pests will also cause corn seedlings to twist the core of the leaf problem, we farmer friends should also pay attention to the type of insect pest timely spray prevention and treatment, the best way to prevent insect pests is to carry out secondary drug coating treatment of corn seeds before sowing, the method of treatment is naturally to find insect pests after timely spraying!
Second, the problem of screwing the core of corn heart leaves caused by diseases
In addition to the causes of insect pests, diseases are also very easy to cause corn to have the problem of twisting the core and rolling leaves, and we should also pay attention to timely detection and treatment.
In general, the types of diseases that are easy to cause problems such as leaf twisting and leaf curling in corn seedlings are mainly the following: (1) corn madness (the problem of leaf twisting, rolling and shrinking after the jointing of corn seedlings) ;(2) corn bacterial top rot disease (when serious, causing corn heart leaf rot and adhesion is a typical symptom, generally in mid-July high temperature and rainy and humid climate conditions occur the most, other periods may also occur) ;(3) corn smut disease (generally after the corn ear is drawn before showing symptoms, Leaf curl deformity is a manifestation of this disease symptom) (4) cornoma powdery mildew (this disease may occur at any time after the corn seedling, as long as the disease infects the corn seedlings, leaf sheaths, heart leaves, etc. will cause the corn leaves to fail to unfold normally).
For corn due to diseases such as screw core, leaf curl, leaf failure, etc., we all have two main methods of prevention and control, one is to use fungicide drugs for seed mixing or disinfection and sterilization treatment of the land before sowing, and the other is to select drugs 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 use methods of agricultural technology small back basket is not introduced to everyone in this one, to the pesticide company you say what diseases you need to control, they will naturally recommend you the correct sterilization control drugs.
Third, the problem of twisting the core of the corn heart leaf caused by the drug damage
Whether it is an insecticide, a fungicide, or a herbicide, as long as your drug is improperly used (such as spraying during high temperature periods) or the dosage is too large and the concentration is too high, it is easy to cause drug damage to corn, which in turn causes corn seedlings to curl leaves, twist cores, leaf curls and other problems.
In terms of herbicide damage, after the emergence of corn seedlings, the herbicide treated in the soil is closed, or the herbicide after spraying the seedling before 3 leaves or 5 leaves of the corn, or the herbicide sprayed on the heart leaf of the corn when the corn seedling is weeded after the seedling, or the organophosphorus herbicide is sprayed within 7 days after the herbicide such as chimney sulfuron is sprayed in the corn field, or the amount of medication is too large and the concentration is too high when the drug is sprayed, which will cause the corn seedlings to appear core, curl leaves, leaf wrinkles and other symptoms due to the occurrence of herbicide damage. The leaves of corn seedlings that occur in drug damage often have irregular green macula (plaques).
Therefore, to prevent the occurrence of herbicides in the corn seedling stage, it is necessary to grasp the best time to spray herbicides in the corn field, in general: (1) the corn seedlings before the weeding in the corn seedlings 3-7 days after the corn sowing, the corn seedlings are strictly prohibited after spraying; (2) the corn seedlings after the weeding in the corn seedlings grow to 3-5 leaf stage and weeds 2-4 leaf stage spray herbicide is the most appropriate, corn seedlings before 3 leaves or after 5 leaves are strictly prohibited in spraying herbicides. (3) When playing herbicides, it is strongly recommended that you spray the herbicides alone, spray them at high temperatures at noon, and try not to spray the herbicides and other fungicides, insecticides, and foliar fertilizers together, otherwise it is easy to cause drug damage to corn seedlings.
For the corn seedlings that have occurred the herbicide drug damage, the agricultural technology basket also provides a remedy to alleviate the drug damage, the drug damage is relatively mild, it is recommended to cooperate with field watering, apply urea nitrogen fertilizer continuously sprayed 2-3 times brassinolide + amino acid foliar fertilizer + potassium dihydrogen phosphate; but for the degree of drug damage, the heart leaf is seriously twisted or curled corn seedlings, in addition to the above methods, it is recommended that you timely twist, roll, shrink, wrinkled leaves from the middle of the manual peeling, So that the damaged leaves can gradually return to normal growth as soon as possible.
The types of herbicides that are commonly prone to cause medicinal harm to corn are: (1) herbicides that are closed in the soil before corn seedlings - flolefin, dimethylpentan, methylpyroxalamine, acetochloramine, isopropyl methylchloramine, ethoxyfluorother, etc. (2) Herbicides for the stem and leaf of corn seedlings - chimney sulfon, sulfonylfuron, thiophenesulfuron, 2,4-D, chlorofluoropyroxyacetic acid, dichloropyridine acid and herbicides remaining when weeding wheat fields. In addition, after using a sprayer to spray herbicides such as glyphosate, fine quinoquine, flupiramide, and enohedin, if you continue to spray foliar fertilizer with a sprayer that is not clean and has drug residues, if you spray the residual liquid on the heart leaves of corn, it will also cause the heart leaves of corn to appear without pulling leaves, dead leaves, twisting leaves, rolling leaves, etc.
In terms of insecticides and fungicides, the most common is improper drug mixing (the types of drug compounding can not exceed three, and the secondary dilution method must be taken when dispensing the liquid), followed by the use of insecticides, insecticides and other drugs in the corn field when the amount of pesticides, insecticides and other drugs is too large or the concentration is too high or the amount of water is insufficient, and then it is sprayed when the soil is dry or at noon when the drug is damaged, if the corn has a drug damage, there will often be the problem of drug burning leaves, dead leaves, no leaves, no leaves.
In addition to the above several drug pests, the agricultural technology basket also recommends that everyone pay attention to a kind of drug harm problem, that is, the seed coating agent drug damage when the corn is coated with secondary drugs. This situation is generally because the use of seed coating agent is too large, or the finished corn seed has been coated with a certain drug before leaving the factory, and later we all use this same seed coating agent for secondary coating, which is easy to lead to corn seeds due to excessive amount of coating agent and the problem of corn seedling stage deformity (such as twisting leaves, rolling leaves, difficult to draw leaves, not spreading leaves, etc.). In this agricultural technology basket reminds everyone: If we plan to coat the corn seeds twice, we must ask what kinds of drugs you bought before leaving the factory when buying corn seeds, and how much they are coated, so as to prevent the drug damage caused by the excessive amount of coating agent or repeated use of coating agents during the secondary coating.
Fourth, the problem of corn heart leaf twisting caused by high temperature and drought
Corn from sowing to the seedling stage, many areas are in high temperature and drought weather conditions, if the weather before and after the corn sowing is hot and hot, natural precipitation is small, the soil drought and water shortage is serious, but our farmer friends have not watered and humidified in time to make up for the moisture, then the corn in the growth process will be because the soil is too dry roots can not absorb enough water and fertilizer nutrients and the problem of heart leaf curling.
High temperature drought caused by corn heart leaf twisting problem is better to judge, the general symptoms are drought-stricken corn seedling heart leaves or top leaves curled into a barrel of symptoms, for high temperature drought caused by corn leaf twisting problem is also easier to solve, generally as long as timely watering to increase soil moisture or the next rain condition becomes better, the corn core curl problem will soon be alleviated and returned to normal.
Fifth, the problem of twisting the corn heart leaf caused by extreme bad weather
Bad weather such as storms, flood disasters and late frost damage (for spring corn), hail, etc., will also cause corn to have symptoms such as heart leaf twisting, rolling, wrinkles, damage, etc. after bad weather, such as storms and floods, which will cause corn seedlings to fall and the upper leaves and heart leaves are buried in the soil and water, if we do not timely lodging and buried in the sandy soil, the corn leaves will be inhibited due to growth and leaf stretching or twisting problems; for example, for example In the early spring planting of corn has low temperature frost damage or suffered from hail frost damage, etc., at this time some of the leaves on the corn seedling plant will freeze to death or frostbite, which affects the normal extraction and stretching 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 becomes better or artificially peel off the heart leaves, and the affected corn seedlings will slowly return to normal growth.
Sixth, the problem of twisting the corn heart leaf caused by genetic mutations
When we sow corn, we can not guarantee the purity of each corn seed gene, and a small number of corn in the growth process will also be affected by natural environmental conditions and genetic mutations, for such corn will also appear twisting leaves, leaf curls, deformities and leaf discoloration, deformation and other issues, for such individual corn seedlings due to genetic mutations, we just need to find it at any time to pull it out at any time.
In addition to the above 6 reasons, corn calcium deficiency is also easy to cause corn to appear similar to the symptoms of thrips infestation, resulting in corn seedlings with too soft leaves, new leaves and heart leaf stretching problems, we should also pay attention to the following.
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