Which herbicide is the best for closing grass in corn field?

Commonly used locally: single dose of atrazine, acetochlor, dole and lasso (alachlor), or compound: 40% atrazine gel suspension +72% dole EC.

I. Types of corn herbicides

(1), atrazine is also called atrazine: at high temperature, alkali and inorganic acid can hydrolyze it into hydroxyl derivatives, and it has no weeding activity. The allowable residue in corn is 0.02× 10-6. Commercial preparations include 50% wettable powder and 40% colloidal suspension.

Atrazine is a selective systemic herbicide, which is used before seedling and after seedling.

It can control annual gramineous weeds and broad-leaved weeds on corn, and also inhibit some perennial weeds to some extent.

Corn should be used before sowing: in areas with soil organic matter content of L ~ 2, 40 colloidal suspension175 ~ 200ml should be used per mu; In areas where the organic matter content is 3 ~ 5 and there are many weeds, the lower limit of 200 ~ 250ml of 40 colloidal suspension per mu should be applied to sandy soil and the upper limit to clay. After sowing 1 ~ 3 days, add 30kg water to spray soil.

Post-treatment of corn seedlings: it can be carried out at the 4-leaf stage. The requirements are basically the same as those of pre-seedling treatment.

Herbicide is sensitive to beans and peach trees, so we should pay close attention to it when using it.

(2), 2,4-butyl ester: the pure product is a colorless oily liquid with strong volatility and decomposes when it meets alkali. The preparation is 72 EC. The herbicide is a systemic selective herbicide, which is mainly used to control dicotyledonous weeds and some malignant weeds in Gramineae crop fields.

Apply pesticide at 4-5 leaf stage after maize emergence, add 45-90g of15-75 dry gram of water per mu, and spray weeds on the leaves. Spraying drugs 3-5 days after sowing is suitable for pre-seedling treatment, and the treatment of stems and leaves should not exceed 5-leaf stage. The dosage is 50-100g per mu, and L5-75kg of water is added. Generally, the effective period is 3 ~ 6 weeks, and it is effective for monocotyledonous and dicotyledonous weeds. It is harmful to cotton, soybean and other crops, so there should be a certain isolation area when using it.

(3) Alachlor, also known as lasso, is hydrolyzed under the condition of strong acid and alkali. The allowable residue of corn is 0.05 10. It has a strong stimulating effect on eyes and skin. Commercial commodities include 43 and 48 EC and 10 and 15 granules.

Alachlor is a selective herbicide used before seedling, which can control annual gramineous weeds and some broad-leaved weeds.

43 EC 175 ~ 300g per mu after sowing in corn field, before emergence or after sowing, and before weeds germinate, and 50 ~ 60kg of water is evenly sprayed on the topsoil (2 ~ 4cm shallow mixed soil in arid area).

If it spills into eyes and skin, wash it with clear water immediately and seek medical attention as soon as possible. If you take it by mistake, you should immediately send it to the hospital for emergency treatment, vomiting or gastric lavage with 5 sodium bicarbonate solution.

(4) Acetochlor: Both acetochlor and alachlor are acid amine herbicides, which have slight irritation to eyes and skin. The preparation has 43 and 50 emulsifiable concentrates.

Acetochlor is a selective herbicide in dry land and before germination, and its efficacy in soil can last for more than 8 weeks. The whole growth period can be controlled by one application, and weeds will not be harmed. It can control annual gramineous weeds, but it is ineffective for perennial weeds. The main absorption site of acetochlor by weeds is the bud sheath, which must be applied before weeds are unearthed. Use 50-70g of 50 EC per mu, 30-60g of south dry land with high soil moisture, and 40-60kg of water in northeast dry land 130g, and spray before sowing.

Cucumber, rice, spinach, wheat, leek, millet, sorghum and other crops are sensitive to acetochlor and should not be used.

(5) Paraquat (Gramoxone): Paraquat is a quick-acting contact-killing herbicide, which can be used for no-tillage weeding of corn or weed control (directional weeding) in the later stage. Before maize emergence, spray 265 ~ 400 ml of 15 water agent and 20 ~ 30 kg of water per mu.

Do not let livestock enter the spraying area 24 hours after spraying. People who are poisoned by mistake should immediately induce vomiting and be sent to hospital for treatment.

Because of the passivity of inactivated herbicide when it meets soil, it is necessary to use clear water when preparing liquid medicine and shake it well to improve the control effect in an all-round way.

There are many herbicides in corn soil, such as acetochlor, acetochlor, dichlorvos and atrazine.

2. Herbicides not suitable for corn:

1, quizalofop-ethyl

Corn is sensitive to quizalofop-p-ethyl. If it is applied incorrectly or in adjacent plots, it will cause phytotoxicity, and the fog drops will float to the corn plants.

Can't be used in corn fields. When applying quizalofop-p-ethyl in adjacent plots, it is necessary to leave enough distance to set up isolation belts, and pay attention to the wind direction and wind force when applying drugs to prevent the liquid from floating to the corn field. Once the application is serious, it should be replanted in time.

2. Chlorsulfuron-methyl (soybean sulfuron-methyl)

Chlorsulfuron-methyl is used in previous crops or the local dosage is too high. Chlorosulfuron residues in soil will cause phytotoxicity to the following maize.

Chlorosulfuron is not suitable for corn field, especially before seedling stage. Excessive or uneven application of chlorimuron-methyl in the previous soybean field is not suitable for planting corn in the next soybean field.

3. Nicosulfuron

Corn is resistant to nicosulfuron, and normal application will not cause phytotoxicity, but only excessive application or local application will cause phytotoxicity symptoms. The use of organophosphorus pesticides and nicosulfuron may cause phytotoxicity.

Avoid excessive application and ensure uniform application. There is generally no need to take measures to produce phytotoxicity. Corn seeds coated with naphthalenedicarboxylic anhydride can reduce the phytotoxicity caused by the interaction between nicosulfuron and organophosphorus pesticides.

4. Glyphosate (Review)

Corn is sensitive to glyphosate, which will cause phytotoxicity if it is not applied properly or the liquid medicine falls on corn plants.

Avoid medication errors and liquid medicine falling into corn fields. Due to the slow development of phytotoxicity, it takes dozens of days to observe the lethal vaccine. Therefore, measures should be taken as soon as possible according to the possible situation of drug abuse. If the application rate per hectare exceeds 600g, consideration should be given to destroying the seeds.

5, dimethoxyguanidine (catch net)

Corn is sensitive to dimethoxystrobin. If it is applied incorrectly or in adjacent plots, it will cause phytotoxicity, and fog will drop on corn plants.

Metformin cannot be used in corn fields. Sufficient isolation zones should be reserved for pesticide application in adjacent plots, and attention should be paid to the wind direction and wind force when pesticide application is carried out to prevent the liquid from floating to the corn field. Once the wrong application is serious, it should be replanted or destroyed in time.

Herbicides in corn fields mainly include the following categories:

1, metolachlor, atrazine: products include Yudiqing, Yuhuan, etc.

2. Acetochlor and atrazine: products include neoacetochlor and atrazine;

3. Acetochlor, alachlor and atrazine: The main products are yucaojing, yucaote and so on.

4. Butachlor and atrazine: The main products are Yu Wei and Yu Youyou.

5, nicosulfuron+atrazine: and so on.

Judging from the current herbicide formula in corn field, metolachlor and atrazine are ideal products for the future herbicide upgrading in corn field. In this regard, farmers should choose herbicides with different formulations according to different geographical environments and weed species, and be sure to explain the soil type and weed species of the herbicide plot you use to the business unit when purchasing, so as to choose the right herbicide products at the right time and improve the weeding effect.

(4) Matters needing attention in field application:

1. Because the herbicide is passivated when it meets soil, clear water must be used when preparing the liquid medicine, and it should be fully shaken when dispensing, so as to comprehensively improve the control effect;

2. No matter what kind of corn field, the soil water content is good, the soil surface water content should be above 75, and the spraying time should be before 9 am and after 5 pm.

With the continuous popularization and application of modern agricultural science and technology and the large-scale transfer of agricultural labor force, chemical herbicides are more and more accepted by farmers and widely used in agricultural production. In recent years, herbicides in China have developed rapidly, especially corn herbicides, which have a wide variety and high technical requirements. Improper use will not only fail to achieve weeding effect, but also cause phytotoxicity to corn. Therefore, it is very important to select suitable herbicide varieties and master the application technology to improve the agricultural production level. This paper introduces several kinds of common corn herbicides and their application techniques for farmers' reference. 1 .alachlor. Alias lasso, also known as grass is not green, 48% emulsifiable concentrate. Alachlor is a selective herbicide used before seedling, which can control/kloc-0 annual gramineous weeds and some broad-leaved weeds. After application, it is absorbed by weed buds, so that the buds are killed and not unearthed. Use corn after sowing and before emergence, and the dosage per mu is175-300ml. Alachlor is safe for soybean, so it is also suitable for chemical weeding in corn-soybean intercropping. Second, acetochlor. 50% EC is the largest 1 herbicide in China at present. It can control 1 year gramineous weeds, but the control effect on dicotyledonous weeds is poor. The action site of acetochlor on weeds is bud sheath and young root. Therefore, the application effect of this herbicide before the emergence of weeds is ideal, and it is generally used before the emergence of corn after sowing, and the dosage per mu is 150-200ml. The herbicide is safe for soybeans and peanuts, and is also suitable for intercropping corn with soybeans and peanuts. Third, butachlor. Use 50% and 60% emulsifiable concentrate before maize emergence after sowing, with 50% butachlor150-180ml and 60% butachlor125-150ml per mu. Butachlor is safe to soybean and peanut, so it is also suitable for corn intercropping with soybean and peanut, and its weeding characteristics are very similar to acetochlor. Fourth, atrazine. Acetochlor is a mixture of acetochlor and atrazine, which is used after sowing and before emergence of corn, and the dosage per mu is 200-300ml. Atrazine is sensitive to soybean and peanut, so it can not be used in intercropping fields of corn, soybean and peanut, but only in corn monoculture fields. Five, atrazine. 40% colloidal suspension, also known as atrazine, is a common broad-spectrum herbicide in corn field. The herbicide is a selective systemic herbicide before and after seedling, which can control 1 annual gramineous weeds and broadleaf weeds. Use corn 1-3 days after sowing (shallow ploughing is needed in dry weather), and the dosage per mu is 200-300ml. When used in the four-leaf stage of maize, the requirements are basically the same as before seedling treatment. Because atrazine remains in the soil for a long time, it is easy to remain in the soil, which is harmful to the following crops. Therefore, it is generally sprayed with stems and leaves when there are 3-5 leaves of corn and 2-3 weeds to reduce soil residue. Atrazine is sensitive to beans, so the arrangement of the next crop should be considered when using it to avoid phytotoxicity to sensitive crops. Sixth, Toure. Commonly known as metolachlor, 72% EC, dosage per mu 100- 150ml. Tol is safe for the next crop, and the application technology is the same as acetochlor. Seven, paraquat. The quick-acting contact herbicide has a strong destructive effect on the green tissues of monocotyledonous and dicotyledonous plants, so it can't be carried out and can only damage the receiving parts. Pesticides will be adsorbed and passivated after contact with soil, and corn can be planted in a short time after application. Paraquat is often used for weeding no-tillage corn and controlling weeds in the later stage. Use 265-400 ml of paraquat 15% water agent per mu, which is often used to kill the grown grass before or after sowing, and can also be sprayed directionally between rows after corn seedlings grow up, with no residual effect. When using the above herbicides, we should not only know the application target and application period, but also consider the weather conditions. Do not use herbicides before heavy rain, so as to avoid the loss or accumulation of herbicides caused by rain erosion, reduce the efficacy or produce phytotoxicity. At the same time, strictly controlling the concentration and dosage of labor, too low concentration and too little dosage, can not achieve the ideal weeding effect; If the concentration is too high and the dosage is too large, it will hurt corn. Generally speaking, the upper limit of safe concentration should be adopted for plots with high soil organic matter content and low soil water content; On the contrary, the lower limit should be used, and the liquid medicine, concentration and dosage should not be expanded at will, so as not to cause undue losses.