A Detailed Guide to the Latest Application Methods of Cornfield Herbicides

Application methods for cornfield herbicides. The main weeds in cornfields include crabgrass, redroot pigweed, yellow foxtail, chloris, lovegrass, black nightshade, barnyardgrass, amaranth, small chenopodium, glaucous goosefoot, purslane, livid amaranth, Russian thistle, summer cypress, thorny amaranth, green foxtail, panicled amaranth, amaranth, goosefoot, green amaranth, goosegrass, feather cockscomb, prickly chenopodium, copperleaf, velvetleaf, wild watermelon seedling, axillary-flowered amaranth and other weeds; perennial weeds include bindweed, reed, and purple nutsedge. Now let us take a look together at the application methods for cornfield herbicides!

Pre-emergence herbicides applied after sowing

1. 40% Acetochlor-Atrazine Suspension Concentrate (Acetochlor-Atrazine Mixture)

40% Acetochlor-Atrazine Suspension Concentrate is a special-effect herbicide dedicated to cornfields. It has excellent control effects on annual grass weeds in cornfields such as crabgrass, green foxtail, barnyardgrass, goosegrass, moleplant, lovegrass, and bluegrass, as well as annual broadleaf weeds such as goosefoot, smartweed, amaranth, black nightshade, cocklebur, false daisy, purslane, copperleaf, chickweed, knotgrass, summer cypress, thistle, small fleabane, and Asiatic dayflower, and also has a noticeable inhibitory effect on sedge weeds.

40% Acetochlor-Atrazine Suspension Concentrate not only has a broad herbicidal spectrum, but also has high weed-killing activity and a long duration of use, and is very safe for corn and subsequent crops such as wheat. From after corn sowing and before emergence to before the 3-leaf stage of weeds after corn emergence, use 40% Acetochlor-Atrazine Suspension Emulsion per fen: 2250-3000 g for summer corn in North China, 2250-3750 g for spring corn in North China, and 4500-6000 g for spring corn in Northeast China, adding about 750 L of water, and spray evenly. The field persistence period is 50-60 days. One application can ensure that corn is free from weed damage throughout the entire growth period.

The herbicidal effect of Acetochlor-Atrazine Suspension Emulsion is closely related to soil moisture. When moisture is relatively high, the efficacy is good; when the soil is dry, the efficacy is low. Usually, before application, it is necessary to irrigate once, either lightly or heavily, or there should be rainfall. The timing of application must be strictly controlled. It is best to apply before weeds emerge to ensure the efficacy is fully exerted. If applying after emergence, it is also best before the 3-leaf stage of weeds. After the 4-leaf stage, if the weeds are too old before application, the efficacy will decrease because weed resistance increases. On sandy loam soils with low organic matter content, the application rate of this agent should be appropriately reduced.

2. Acetochlor-Baoshou Tank Mix

Acetochlor-Baoshou Tank Mix is a ready-to-mix root tank mix made from acetochlor and Baoshou. It can be used in cornfields and corn-soybean intercropping fields to effectively control annual grass weeds and annual and some perennial broadleaf weeds. The field persistence period is 30-60 days, and it is very safe for crops such as corn, soybean, and subsequent wheat. Apply before crop sowing or after sowing and before emergence. In spring cornfields in Northeast China, use 3000 mL of 50% acetochlor plus 26.7 g of 75% Baoshou per fen. In summer corn (or intercropped soybean) fields, use 1500 mL of 50% acetochlor plus 19.95 g of 75% Baoshou per fen, add 450-750 L of water, and spray evenly. When mixing the agent, first dissolve Baoshou in a small cup with a small amount of warm water to make a stock solution, pour it into a mixing tank already containing half the water, then add acetochlor, then add the other half of the water and stir well. Applying with a fan-shaped nozzle gives the best effect.

3. 50% Hebao Emulsifiable Concentrate

50% Hebao Emulsifiable Concentrate is a new type of herbicide with high efficiency, broad spectrum, and safety. It can effectively control many annual grass weeds and broadleaf weeds. It is most effective against crabgrass, barnyardgrass, goosegrass, green foxtail, large lovegrass, moleplant, chloris, dock-leaved smartweed, small chenopodium, glaucous goosefoot, redroot pigweed, thorny amaranth, livid amaranth, purslane, copperleaf, false daisy, and black nightshade, and also has a noticeable inhibitory effect on some perennial weeds and sedge weeds.

50% Hebao Emulsifiable Concentrate can be used both for soil-closing treatment after sowing and before emergence, and for stem treatment before the 3-leaf stage of weeds after corn emergence. Use 1.2-1.5 L of 50% Hebao Emulsifiable Concentrate per fen, add 750 L of water, and spray evenly, which can effectively control many weeds. Soil moisture is closely related to efficacy; when moisture is suitable and soil moisture conditions are good, efficacy is high. This agent is sensitive to weed seedlings, and the best effect is obtained when applied after corn sowing and before emergence or in the early post-emergence stage.

4. 50% Du'a Mixture

After corn sowing and before emergence, use 2-35 kg of 50% Du'a Mixture per hectare, add 750 L of water, and spray evenly on the soil surface. It has relatively good control effects on annual grass weeds and annual broadleaf weeds such as crabgrass, goosegrass, green foxtail, lovegrass, goosefoot, livid amaranth, redroot pigweed, knotgrass, false daisy, cocklebur, purslane, black nightshade, and ground cotton.

5. Atrazine

Atrazine is a triazine selective pre-emergence and post-emergence herbicide. It can be used to control annual monocotyledonous and dicotyledonous weeds such as crabgrass, green foxtail, lovegrass, goosegrass, shepherd's purse, false daisy, cocklebur, purslane, black nightshade, ground ivy, field thistle, and weeds of the Scrophulariaceae and Fabaceae families, and also has a certain inhibitory effect on some deep-rooted weeds.

After corn sowing and before emergence, use 2.25-2.7 kg of 38% atrazine suspension per fen. During the corn seedling stage, before the 3-leaf stage of weeds, use 2-2.25 kg of 38% atrazine per fen, add 750 L of water, and spray evenly.

Atrazine has good efficacy and good selectivity for corn, and is very safe, but its field residual effect period lasts as long as 120-160 days. If used improperly, it can easily cause phytotoxicity to subsequent crops. The dosage must be strictly controlled, the amount must not be increased at will, and application must be even, avoiding repeated spraying and missed spraying. Atrazine can be mixed at reduced rates with acetochlor, Duer, Lasso, and cyanazine, which not only broadens the herbicidal spectrum but also reduces soil residues, making it safe for subsequent wheat.

6. Acetochlor

Acetochlor is an amide selective pre-emergence herbicide. It has a special effect on annual grass weeds such as goosegrass, crabgrass, barnyardgrass, green foxtail, lovegrass, moleplant, bluegrass, and wild millet, and also has relatively good control effects on broadleaf weeds such as goosefoot, smartweed, amaranth, and purslane. After corn absorbs acetochlor, it can quickly degrade into non-toxic substances, so it is safe for corn. After corn sowing and before emergence, use 2.25-3.75 kg of 50% acetochlor emulsifiable concentrate per fen in Northeast China. In North China and areas to the south, use 1.2-2.5 kg of 50% acetochlor emulsifiable concentrate per hectare, add 750 L of water, and spray evenly on the soil surface. For plastic-film mulched fields, reduce the amount by about 1/3.

In areas with fertile soil and high organic matter content, the dosage should be increased. In areas with poor soil and low organic matter content, the dosage should be appropriately reduced. High soil moisture is conducive to the absorption of the herbicide by weed seeds, and the efficacy is better. Soil drought affects the exertion of efficacy. Therefore, before application it is best to irrigate or have rainfall so that the soil has good moisture conditions.

7. Duer (Metolachlor)

Duer is a selective pre-emergence soil treatment herbicide. Its effect on controlling grass weeds is better than on broadleaf weeds. After corn sowing and before emergence, use 1.2-1.8 kg of 72% Duer emulsifiable concentrate per hectare, add 750 L of water, and spray evenly. Use the lower rate on sandy soil and the higher rate on clay soil. If the soil surface is dry, shallow incorporation into the soil is best.

8. Lasso (Alachlor)

Lasso is an amide selective pre-emergence herbicide. This agent has high herbicidal activity, and its persistence period in soil is 4-8 weeks. It can effectively control annual grass weeds and some annual dicotyledonous weeds. After corn sowing and before emergence, use 3-4.5 kg of 48% Lasso emulsifiable concentrate per hectare, add 750 L of water, and spray evenly. If rainfall or irrigation occurs within 1 week after application, it is beneficial to the exertion of efficacy. Under dry conditions, shallow soil incorporation should be carried out after application, with an incorporation depth of 2-4 cm, which can improve the weed control effect.

9. Hennessy

Hennessy is an amide selective pre-emergence herbicide. Hennessy has a special effect on annual grass weeds such as barnyardgrass, green foxtail, moleplant, bluegrass, and shortawn foxtail, as well as on bitter cress, and also has a certain control effect on smartweed, goosefoot, amaranth, Asiatic dayflower, black nightshade, purslane, and yellow nutsedge. It should be applied before weeds emerge; once weeds have sprouted and grown larger, they cannot be killed. After corn sowing and before emergence, use 0.9-1.2 L of 90% Hennessy emulsifiable concentrate per hectare in North China, 1.5-1.8 L in Northeast China, 0.6-0.9 L in the Yangtze River basin and South China, and 450-675 mL for plastic-film mulched corn, add 600-900 L of water, and spray the soil surface. After application, a certain amount of soil moisture is needed to fully exert the efficacy. In arid areas or areas with low rainfall, pre-sowing soil treatment can be adopted, and after application, shallow incorporation into the soil of 2-3 cm can be carried out, followed by sowing after incorporation.

10. Mixing of Herbicides

Different varieties of herbicides have different herbicidal spectra. Although some herbicide varieties have relatively broad herbicidal spectra, their herbicidal spectra are still limited due to restrictions on crop safety. Furthermore, some herbicides, because of high water solubility or too long field persistence, excessive dosage, or uneven application, can easily cause residual toxicity to the current crop or subsequent crops. Therefore, in production, two herbicides with different herbicidal spectra and complementary advantages are mixed after appropriate rate reduction. This not only broadens the herbicidal spectrum and significantly improves the weed control effect, but also avoids the possibility of phytotoxicity to the current crop and residual toxicity to subsequent crops.