When the wheat harvest comes , the summer corn planting and post-emergence elimination will be put on the agenda. Summer sowing maize seedlings are in high temperature and rainy seasons , and weeds in corn fields are common and diverse. According to the results of perennial weeds , there are 22 families, 38 genera and 43 species of weeds in corn fields . The main weeds include crabgrass, valerian, foxtail, goosegrass, amaranthus, purslane, iron leeks, and aconite. Wait. Experts suggest that the weeds in the corn seedlings are the most harmful , so the chemical control of weeds should be done in two critical periods before and after seeding.

What are the single agents of herbicides?

Amide herbicides is the most important of a corn field herbicides, weeds can sprout absorption, soil sealing treatment before the germination of weeds, effective control of annual grass weeds and some annual broadleaf weeds. There are many varieties of such herbicides , such as acetochlor, alachlor, butachlor, metolachlor, and propisochlor. Tests show that an effective dose in the same herbicidal activity of the comparison result is acetochlor> metolachlor> Propisochlor> butachlor> Alachlor; effective amounts in accordance with the quantization result of the comparison of the herbicidal activity is B metolachlor: metolachlor: butachlor: Propisochlor 1: 0.9: 0.8: 0.7; moisture greatly influence by such herbicides, the herbicidal effect is significantly reduced when the difference in moisture.

Trinitrobenzene herbicides can effectively control annual broadleaf weeds and annual grass weeds , mainly based on weed roots , and can also be absorbed by weed stems and leaves. Representative varieties are atrazine, cyanazine, simazine, Kusatsu flutter like, which use more atrazine, it is safe to corn, the highest activity; atrazine but should be mixed with acetochlor, in order to reduce the amount of , increase the herbicidal efficacy and safety of the following crops.

Phenoxycarboxylic acid herbicides mainly control broadleaf weeds and fragrant aconite after corn seedlings. Representative varieties are 2 methyl 4 -chloro sodium salt, 2,4-D butyl ester. Among them, 2 methyl 4 -chloro sodium salt is widely used in the corn field to control the fragrant aconite , but the use period is not easy to produce phytotoxicity.

The sulfonylurea herbicides nicosulfuron and sulfomesulfuron can be used in corn field to control grass weeds, sedge weeds and some broad-leaved weeds . Thia yellow can be used for corn field control for annual broadleaf Weeds.

Other herbicides paraquat and glyphosate are Herbicide may be directed spray after corn 40 cm high, more effective control of the weeds; Starane also be used, dicamba, bromoxynil, bentazon And other varieties to control broad-leaved weeds in corn fields.

What are the herbicide blends?

Acetochlor and atrazine 1 : 1 mixture The earliest production of this kind of herbicide mixture is Ea mixture ( acetamidine suspension ), which can be used for pre-emergence of corn after planting and early post-maize seedling control. grasses and broadleaf weeds, corn and succeeding crop safety. Similar products are butachlor + acetochlor + atrazine, butachlor + atrazine, alachlor + acetochlor + atrazine, metolachlor + atrazine, propisochlor + 莠津津, etc.

Acetochlor and atrazine 2 : 3 mixture This herbicide mixture can be used to control the annual grass weeds and broadleaf weeds in the corn field after the sowing of corn, and early in the corn seedlings , which is safe for corn; The year may reduce the safety of the post-war wheat. The similar performance varieties include chloromeron + acetochlor + atrazine , which greatly improved the safety of the glutinous wheat , but could not be used after the corn seedlings.

The combination of chlorpyrifos and atrazine can effectively control annual grass weeds and broadleaf weeds in corn fields. In the post-emergence application, the herbicidal effect is stable after the sowing , and the degree of the affected by the moisture is small . However , when the rain is large , the leaching will reduce the herbicidal effect. In the corn growth period , the corneal may be induced by adverse environmental conditions such as high temperature and drought. harm.

Nicosulfuron and atrazine are a kind of ideal herbicide mixture , which can not only effectively control a variety of annual weeds , but also control perennial grass weeds and sedge weeds , easy to apply , corn And crops are safe , but the price of this type of herbicide mixture is higher.

The combination of acetochlor, atrazine and paraquat has both killing and herbicidal effects . It can effectively control a variety of weeds in corn fields during corn growth. There are many similar products , and there are also herbicide mixtures that replace paraquat with glyphosate.

How much is the herbicide usually used?

Cornfield herbicidal sowing, using mixture B A 150-200 ml / acre; Early post-emergence (1-4 leaf stage of corn) herbicidal, Ebel 50% wettable powder can be 90 g / acre, or 38% Atrazine Suspension agent 75-100 ml / mu + 4% nicosulfuron suspending agent 75-100 ml / mu; corn growth mid-term weeding , can use 10% glyphosate water 200-300 ml / acre, 20% paraquat water agents 100-150 ml / acre, or 40% acetic herbicidal suspension 150 ml / mu + 20% paraquat 100-150 ml / seedling, directed spraying under windless conditions.

Selection of herbicides in different periods

Maize 3-5 leaf stage is an important period for weed control in corn fields . If weeds are not timely prevented , it will directly affect the growth and yield of corn. After the 5 leaf stage of corn pesticide prone to injury, such as when spraying when the temperature also prone to injury.

Corn plots for long-term application of herbicides such as acetic closed herbicide, at 3-5 leaf stage of corn, field of purple nutsedge, when occurring on a large valley cockle, you can use nicosulfuron or rimsulfuron such as stem and leaf postemergence The treatment agent is sprayed evenly. When the application is uneven or the dosage is large , the corn leaves have a small amount of yellow spots , which can be recovered in a short time , and generally does not affect the growth and yield of the corn.

For previously unrecognized chemical weed herbicide, poor moisture, less weed plots, may be 6-8 leaf stage of corn, plant height 50 cm after spraying both closed and herbicidal effects, not only to remove Weeds that have emerged in the field can be closed without grass. For example, nicosulfuron-methyl hydrazine can be used for directional spraying of water. When applying the medicine , choose windless weather . When directing the spray, be careful not to spray the liquid into the corn bell mouth , otherwise it may cause phytotoxicity. For the field where chemical weeding has not been carried out in the early stage , in the case of rainy days or irrigation , the field where a large amount of weeds in the field occurs , can also be sprayed with nicosulfuron-methyl hydrazine. For the field where the application of the closed herbicide in the early stage failed to prevent the fragrant aconite , the scented aconite was basically all emerged , and the fragrant aconite was in the seedling stage , which was a favorable period for control. The water can be sprayed with stems and leaves with sodium dimethyltetrachloride. When applying the medicine, it should be sprayed on the stems and leaves of the fragrant aconite, and try to avoid spraying on the corn. During the application period, the corn 5-6 leaf stage is better , not too early and too late , otherwise it is prone to phytotoxicity.

When the herbicide is sprayed, the temperature is too high ( more than 35 °C ), which is also apt to cause damage to corn. In the middle stage of corn growth , for the field where the previous stage of chemical weeding or application of pesticides is not good enough to control weeds , it can be after the corn 8 leaf stage, the corn plant height is over 60 cm, and the corn stem base is aging and purple. , directed by paraquat spraying water. Spraying should be selected in calm weather, be careful not to spray the liquid onto the corn stover when directional spraying, to avoid injury.

Source: Rural Volkswagen