How to use corn post-emergence herbicides?

For corn post-emergence herbicides , corn growers are used every year, but every year there will be corn phytotoxicity, no effect after the end of the problem, sometimes there will be herbicide after the corn seedlings, the weeds are not dead, corn It’s dead, it’s a headache for farmers.

Today, I will talk about the safest time when the corn seedling herbicide is safest, how to play the best, the best spraying time, the spraying method, what are the precautions in the use process? With a series of questions, let's come together Learn:

Best spraying time for corn seedling herbicide

Since the corn seedling herbicide requires 2-6 hours of absorption after spraying, in the 2-6 hours, the effect of the drug is good (that is, the herbicidal effect is ideal) and the temperature and air humidity are closely related.

Spraying in the morning, noon or afternoon when the temperature is high and the weather is dry, because the temperature is high, the light is strong, the liquid evaporates quickly, and after a spraying, the liquid will evaporate, so that the amount of the herbicide entering the weed body is limited, and the absorption is limited. The amount is obviously insufficient, which affects the herbicidal effect; at the same time, when spraying at high temperature and drought, corn seedlings are also prone to phytotoxicity.

The best spraying time is after 6 o'clock in the evening, because the spraying at this time, the temperature is lower after application, the humidity is larger, the liquid stays on the weed leaves for a longer period of time, and the weed can fully absorb the herbicide. The ingredients ensure the herbicidal effect, and the evening medication can also significantly improve the safety of the corn seedlings, and it is not easy to cause phytotoxicity.

Several leaves of corn seedlings can be sprayed with corn seedlings and herbicides

3 to 5 leaves of corn, 2 to 4 leaves of weeds are the best, especially the combination of Yu Nong Le and 2,4-D butyl ester can not be applied after the 5 leaf stage of corn.

The weeds in the field are basically out, and most weeds are sprayed at the 2~4 leaf stage. The application period was too late, the weed resistance was enhanced, and the herbicidal effect was affected. When spraying, the temperature is required to be 15 to 25 ° C, the relative humidity of the air is 65% or more, and the wind speed is 4 m / sec or less. Select spray equipment and nozzles as required and apply according to the spray operation specifications.

How to use corn seedlings after herbicide

Let me tell you a method that is summed up in the actual fight-making process. Under the premise of sufficient dose, the more water the better (of course not the unlimited water addition, relatively speaking), for example, the purchase of herbicides, the recommendation is 1 bottle of 1 barrel of water, 1 mu of land, that is, about 15 kg of water, sprayed in an acre of land, but if you are 20-25 kg of water, the same spray in an acre of land, the effect is better than 15 kg of water Better.

In the vulgar point, a bottle of 1 barrel of water and 1 mu of land becomes 1 bottle of 2 barrels of water and 1 mu of land. Interested friends can try it, but note that the spray volume must be uniform, and must not be more than one piece. .

Look at the grass size

When spraying herbicides after spraying corn seedlings, many farmers have a misunderstanding. The smaller the weeds, the smaller the resistance, and the easier the grass is to kill. Actually, it is not the case. Because the grass is too small, there is no medicine area, and the weeding effect is not ideal. The best grass age is 2 leaves 1 heart to 4 leaves 1 heart period. At this time, the weeds have a certain area of ​​medicine, the weed resistance is not large, and the weeding effect is remarkable.

Corn variety

Since most of the corn seedling herbicides are currently nicosulfuron-methyl, some corn varieties are sensitive to this ingredient and are prone to phytotoxicity. Therefore, corn fields such as sweet corn, waxy corn and Denghai series cannot be sprayed to prevent drugs. Harmful. For new corn varieties, please test and promote.

Pesticide mixed problem

It is strictly forbidden to spray organic phosphorus insecticides 7 days before and after spraying the herbicides, otherwise it is prone to phytotoxicity. However, it can be mixed with pyrethroid insecticides. When spraying, pay attention to avoiding happy leaves and anti-drug solution.

This year, some corn fields have serious occurrences of Swedish flies and thrips. The two small pests can be sprayed with imidacloprid or acetamiprid, but they should not be sprayed with post-emergence herbicides, although imidacloprid or acetamiprid is not organic. Phosphorus.

Because the control of two small pests requires the heart spray, if mixed with the heart leaf, it is easy to cause phytotoxicity. It can be sprayed separately: the herbicide is sprayed on the front side, followed by the spray of the heart leaf with imidacloprid or acetamiprid.

Weed itself's resistance

In recent years, the weed resistance of weeds has been strengthened. In order to prevent excessive evaporation of water in the body, weeds grow not so watery and thick, but grow gray and short, and the actual grass age is not small (so-called "Little old man"). Most of these weeds are covered with white small fluff to reduce the evaporation of water.

When spraying pesticides in this way, the liquid is topped on the surface of the weed stems and leaves, and the weeds themselves absorb very little, which naturally affects the exertion of the drug effect. Therefore, no matter what medicine is applied during high temperature and drought, it should be added. The amount of liquid sprayed by the large spray does not affect the exertion of the drug effect. Please do not cherish the water when applying pesticides to farmers.

Maize seedling herbicide use precautions

1. Perform constant spray according to the prescribed dosage. Do not increase the dosage.

2, using the "second dilution method", first formulated into a mother liquid, and then evenly sprayed on the water.

3, the general use of corn post-emergence herbicide should be in the corn after visible leaves 2 leaves to visible leaves before 5 leaves. If the drug is used in the 5-7 leaf stage, it should be used between the corn rows to prevent the liquid from being sprayed into the heart leaf.

4. Some corn post-emergence herbicides are sensitive to sweet corn, seeding, and inbred lines. Do not use them. It should be used in strict accordance with the herbicide label instructions.

5. Corn treated with organophosphorus is sensitive to post-emergence herbicides. The interval between the two drugs is at least 7 days.

6, using a motorized sprayer to apply drugs, do not increase the amount of drugs without authorization, prohibit repeated spray.

7. Before using the herbicide, pay attention to cleaning the sprayer sprayed with organophosphorus pesticides.

8, after 4 o'clock in the afternoon, the effect of medication is good, continuous high temperature (temperature over 35 °C) to avoid medication.

It rained after the corn had finished the herbicide. Did it use heavy spray the next day?

First of all, we do not recommend the second post-emergence herbicide.

So some farmers are afraid that the grass will not die, and want to play the second time, what should I do?

1. It rains immediately after the medicine is finished.

2, heavy rain or heavy rain, the time is very long.

3, broadleaf grass 3-5 days, 5-7 days after the sharp-leaved grass, there is no poisoning phenomenon, corn also grows normally.

If you meet the above 3 points, you can re-spray once.

in contrast:

1. It is not big under the rain, and the time is short.

2. It rained after spraying the herbicide for 6 hours.

3. Weeds have been poisoned.

If the above 3 points are met, it is not recommended to re-spray to avoid phytotoxicity.

Some friends will say that I don't meet the above conditions, but when I play the second time, I don't hit the corn, I only play weeds, and I can spray it. Can it?

A: That is definitely ok!!

The mixture of medicines should be scientific. Before mixing the medicines, we must first understand the physical and chemical properties, action characteristics and biological activities of the medicines, and then pass the field application test, and finally can be used in large areas, and must not be abused. The consequences could be disastrous.

So, can corn herbicides be mixed with pesticides, and what kind of pesticides can be mixed with? What is the effect of mixing? With a series of questions, let us know the following:

Why do many people doubt this question? It is nothing more than wanting to be lazy, lazy and worrying about it! Can we first learn the following:

Principle of pesticide mixing

1. There is no adverse chemical reaction (such as hydrolysis, alkaline hydrolysis, acid hydrolysis or redox reaction) between the mixed varieties to ensure normal efficacy or synergism, and does not affect the physical properties of the agent (such as emulsification and suspension rate reduction). Wait).

For example, most organophosphorus pesticides cannot be mixed with Bordeaux mixture, stone sulphur mixture, etc.; powders cannot be mixed with wettable powders and soluble powders.

2. After mixing different varieties, the crops should not be phytotoxic. For example, when the organophosphorus pesticide is mixed with the enemy, the rice will cause phytotoxicity, and the Bordeaux mixture is mixed with the stone sulphur mixture, which is easy to cause phytotoxicity to the crop.

3. After the pesticide is mixed, it will not increase the toxicity and ensure the safety of humans and animals.

4, mixed use should be reasonable. Including the reasonable mix between the species, such as the control of weeds in the soybean field, the use of catching the net, covering the grass can be prevented, and then using the two mix, although feasible from the stability of the drug, but the mix is ​​unreasonable, both It does not increase efficiency, and does not expand the scope of prevention and control.

The mixture of pesticides is to save labor and time, and to improve economic benefits. If the mixture is made into a mixture, the additional cost is not allowed.

5, pay attention to the antagonism between pesticide varieties, to ensure the effect of mixed use, such as the combination of bentazon and catching and catching due to antagonism to reduce the control of grass weeds.

Can corn herbicides be mixed with pesticides?

For crops, there are pre-emergence (or pre-emergence) treatment, mainly refers to the crop before planting (or before transplanting), or before the crop is planted, the soil spray treatment is closed to kill the unseeded weeds.

Such herbicides in corn fields include amides of acetochlor, refined metolachlor, triazines, atrazine, etc., which can control a variety of annual grasses and some small-leaf broad-leaved weeds in the field. If it is in the three provinces of Northeast China, it will also use a mixture of herbicides such as 2,4-d butyl ester to increase the herbicidal spectrum or increase the efficacy.

If there is no application or soil sealing effect in this period, you can choose to use the post-emergence herbicide to control the stem and leaf spray of the emerged weeds, including the sulfonylurea-type nicosulfuron (Nippon Ishihara), etc. All right.


Be sure to strictly follow the technical points and precautions of the label and instruction manual of the herbicide pesticide to avoid causing phytotoxic accidents.


It is best not to mix, the focus of the two drugs is not the same, one to fight grass, one to fight corn. In addition, the pesticide may contain organic phosphorus, which is easy to be mixed with corn post-emergence products, so it is not recommended to mix.

Analysis of the reasons why corn herbicides and pesticides are not mixed:

1. I don’t know what ingredients are herbicides and pesticides. In the case of corn herbicides, the herbicide containing nicosulfuron and the pesticide containing organic phosphorus will be mixed, and there will be phytotoxicity. Organophosphorus pesticides should not be used within 7 days after corn herbicides.

2, throw away the physiology does not say, corn herbicide is mainly sprayed on the grass, let the grass absorb the liquid, and then kill the weeds, while the insecticide is hit on the corn leaves, let the corn leaves absorb the liquid, To achieve the purpose of pest control and pest control. If mixed, do you say that it is mainly on corn or on weeds?

(Article source: pesticide assistant)

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