When Is the Best Time to Apply Corn Herbicide?

Corn fields are relatively prone to weeds, and if weeds appear they may affect the normal growth of corn. Farmers choose to spray corn herbicide to control weeds. So when is the best time to apply corn herbicide?

1. When is the best time to apply corn herbicide

The suitable period means strictly following the period specified in the instructions, choosing to apply the herbicide during the growth stage when weeds are most sensitive to the herbicide and corn has the strongest tolerance to it, so as to improve the control effect and ensure the safety of the seedlings. For those suitable for pre-sowing soil treatment, they should be used before sowing; for those suitable for use after sowing but before emergence, they should be used after sowing but before emergence; for those suitable for stem and leaf treatment, the crop's sensitive period should be avoided. Choosing the right time means avoiding high temperature, high humidity, strong wind, or cooling weather, to prevent phytotoxicity or reduced efficacy. Generally, it is safer to choose clear, windless weather and apply the herbicide after 5 p.m. Corn is most sensitive to herbicides during the bud stage and before the 1-4 leaf stage, and is prone to phytotoxicity. When applying herbicides during these growth stages, attention should be paid to the concentration of the preparation.

2. Types of corn herbicide

1. Amide herbicides: This type of product is currently the most important type of herbicide for corn fields. It can be absorbed by weed buds and used for soil-closing treatment before weeds germinate, effectively controlling annual grass weeds and some annual broadleaf weeds. There are many varieties of this type of herbicide, such as acetochlor, alachlor, butachlor, metolachlor, and propisochlor.

2. Triazine herbicides: They can effectively control annual broadleaf weeds and annual grass weeds, mainly absorbed by weed roots, and can also be absorbed in small amounts by weed stems and leaves. Representative varieties include atrazine, cyanazine, simazine, and prometryn, among which atrazine is used more, is relatively safe for corn, and has the highest activity; however, atrazine should be mixed with acetochlor and others to reduce the dosage, improve the weeding effect, and increase safety for subsequent crops.

3. Phenoxycarboxylic acid herbicides: Mainly used after corn emergence to control broadleaf weeds and purple nutsedge. Representative varieties include MCPA-sodium salt and 2,4-D butyl ester. Among them, MCPA-sodium salt is widely used in corn fields to control purple nutsedge, but improper timing of use can easily cause phytotoxicity.

4. Sulfonylurea herbicides: Nicosulfuron and rimsulfuron can be used in corn fields to control grass weeds, Cyperaceae weeds, and some broadleaf weeds; thifensulfuron can be used in corn fields to control annual broadleaf weeds.

5. Other herbicides: Paraquat and glyphosate are non-selective herbicides and can be used for directed spraying after corn reaches 40 cm in height, effectively controlling many kinds of weeds; fluroxypyr, dicamba, bromoxynil, bentazone, and other varieties can also be used to control broadleaf weeds in corn fields.

Corn herbicide should be matched to the target, and decided according to the actual usage situation, otherwise phytotoxicity may occur.