Types and Application of herbicides after Maize Seedling

It is rainy in summer, and weeds are common in corn field. the main weeds are Magnolia mandshurica, barnyardgrass, Setaria angustifolia, Euphorbia angustifolia, Portulaca oleracea, amaranth, aconite and so on. Corn is most seriously harmed by weeds at seedling stage, and chemical control saves time and effort, but there are many herbicides in corn fields in the market, and farmers often do not know how to choose them. Many farmers mistakenly choose and use herbicides incorrectly, causing unnecessary damage to maize growth. Therefore, understanding the types and correct use of herbicides is the key to the control of summer corn weeds.

Types of post-seedling herbicides in corn

1. Single dose

① amide herbicides: at present, these products are the most important herbicides in corn field, which can be absorbed by weed buds. Soil closure treatment before weed germination can effectively control annual Gramineae weeds and some annual broad-leaf weeds. There are many kinds of herbicides, such as Acetochlor, alachlor, butachlor, Metolachlor, Metolachlor and so on.

② triazobenzene herbicides: can effectively control annual broad-leaf weeds and annual Gramineae weeds, mainly absorbed by weed roots, but also can be absorbed by weed stems and leaves. The representative varieties are atrazine, cyanazine, simazine, promethazine and so on, among which atrazine is widely used, which is safer to corn and has the highest activity, but atrazine should be mixed with Acetochlor to reduce the dosage and improve the herbicidal effect and safety to the following crops.

③ phenoxy carboxylic acid herbicides: mainly used to control broad-leaved weeds and aconite after maize seedlings. The representative varieties are 2-methyl-4-chloro-sodium salt and 2.4-murine D-butyl ester. Among them, 2-methyl-4-chloro-sodium salt is widely used to control Cyperus roxburghii in corn field, but it is easy to cause drug damage if it is not used properly.

④ sulfonylurea herbicides: nicosulfuron and sulfosulfuron can be used to control Gramineae weeds, Cyperaceae weeds and some broad-leaved weeds in corn fields, while thiazuron can be used to control annual broad-leaf weeds in corn fields.

⑤ other herbicides: paraquat and glyphosate are insecticidal herbicides, which can be sprayed after the corn is 40 cm high to effectively control a variety of weeds, and can also be used to control broad-leaf weeds in corn fields, such as Thalon, paraquat, bromobenzonitrile and bentazon.

2. Mixtures

1:1 mixture of ① Acetochlor and atrazine: the mixture of Acetochlor and atrazine suspension was first produced, which can be used to control annual Gramineae weeds and broad-leaved weeds before maize sprouting and after corn seedlings, and is safe for corn and subsequent crops. Similar products include butachlor + Acetochlor + atrazine, butachlor + atrazine, alachlor + Acetochlor + atrazine, Metolachlor + atrazine, Metolachlor + atrazine and so on.

2:3 mixture of ② Acetochlor and atrazine: this herbicide can be used to control annual Gramineae weeds and broad-leaved weeds in corn fields before sprouting and early after corn seedlings. it is safe for corn and may reduce the safety to wheat in especially dry years. The varieties with similar properties are chlorotoluron + Acetochlor + atrazine mixture, which can greatly improve the safety of subsequent wheat, but can not be used after corn seedlings.

The mixture of ③ and atrazine can effectively control annual Gramineae weeds and broad-leaf weeds in corn field. The herbicidal effect of applying weeding before maize sprouting is stable and less affected by soil moisture, but when Rain Water is larger, more leaching will reduce the weeding effect. In the growing period of maize, adverse environmental conditions such as high temperature and drought can induce maize drug damage.

④ nicosulfuron-atrazine mixture is an ideal herbicide mixture, which can not only effectively control many annual weeds, but also perennial Gramineae weeds and Cyperaceae weeds. It is easy to use and safe for maize and subsequent crops. However, it can not be mixed with organophosphorus insecticides before and after use, but can be mixed with pyrethroid pesticides.

The mixture of ⑤ Acetochlor, atrazine and paraquat has both sterilization and herbicidal effect, and its application in maize growing period can effectively control many kinds of weeds in corn field. There are many similar products, and there are herbicide mixtures that use glyphosate instead of paraquat.

Application of herbicides after Maize Seedling

In chemical weeding in corn field, selecting suitable herbicides, mastering the optimal application period, strictly according to the safe and effective dosage and adopting correct application methods are the key to ensure the control effect of chemical weeding and the safety to corn.

1. Correct selection of herbicides

The herbicide corresponding to the herbicide spectrum should be selected according to the herbicide spectrum when ① chooses the herbicide according to the weed population in the field.

② chooses herbicides according to field crops, so corn fields should choose special herbicides for corn fields.

③ chooses drugs according to the period of medication. Those used before seedling after sowing can not be used for post-seedling application, and soil treatment can not be used for stem and leaf treatment.

④ considers the safety of adjacent crops and the next crop.

2. Strict use of dose

The dosage of herbicides should strictly follow the standards stipulated in the instructions for use, and the dosage shall not be increased at will. If two or more herbicides are mixed, the dosage of each herbicide should be 1 / 2 of its conventional dosage. The amount of chemical solution per mu (after mixing the original solution with water), the amount of no straw returned to the field in soil treatment is not less than 30kg, that of straw returning to the field is not less than 45kg, that of stems and leaves is not less than 30kg per hour, and that of weeds is not less than 45kg when they are large.

3. Scientific mixed collocation

If a single herbicide is used, attention should be paid to calculating the dosage according to the safe and effective dose of the herbicide and the actual area of the corn field. When two or more herbicides are mixed at the same time, the herbicide spectrum must be different, but the suitable crops, periods and methods of use should be consistent and basically the same. When wettable powder is mixed with EC, the wettable powder should be dissolved in a small amount of water to make mother liquid, then EC should be added, semi-sprayer water should be installed first and then secondary diluted pesticide mother liquid should be added, and finally enough water should be added to shake well before spraying.