A Detailed Guide to Key Points of Weed Control in Cornfields and How to Choose Herbicides

In recent years, the use of herbicides in cornfields has become increasingly common, yet many farmers have found that of herbicides bought at the same time, one field shows very good results while another field shows very poor results. What is the reason for this? In fact, apart from differences in the quality of the herbicide products themselves, this phenomenon is mainly affected by many other external factors. Below, we explain the key points of weed control in cornfields.

1. Choose herbicides suitable for use in corn

Each herbicide is required for different crops and is highly selective. Apart from herbicides specifically for cornfields, other herbicides cannot be used indiscriminately in cornfields; one should not assume that any herbicide can be used in a cornfield. Generally, any herbicide being used for the first time must be treated with caution, otherwise it may cause serious consequences.

2. Grasp the appropriate application period

The weed-killing effect of a herbicide is related to the period of use; it should be used at the time when the weed-killing effect is best and it is safest for corn. For example, the herbicide acetochlor acts mainly on the coleoptile and young roots of weeds, so this herbicide works ideally when used before weeds emerge, and has no obvious killing effect on large weeds.

3. Before applying the herbicide, understand the crops planted nearby

Some herbicides can kill weeds and are harmless to corn, so they can be used safely in cornfields, but they are very harmful to some crops and vegetables. For example, 2,4-D butyl ester can be applied to corn, sorghum and foxtail millet at the 4-5 leaf stage after emergence. However, cotton and soybean are sensitive to this herbicide, so its use should be cautious where cotton is planted in neighbouring fields, especially when the terrain is lower than the cornfield or the field is downwind; in such cases it must not be used, so as to avoid harming the neighbouring field.

4. Effects on subsequent crops

Some herbicides have a very long residual effect, and improper application may harm sensitive subsequent crops. For example, atrazine is an excellent herbicide for cornfields, but its residual effect is very long and it is very sensitive to legume crops, so when using it, the arrangement and planting time of the following crop must be taken into consideration.

5. Observe the sky, the soil and the crops

For example, do not apply before heavy rain, so as to avoid the herbicide being washed away or concentrated by rainwater, which would reduce the efficacy or cause phytotoxicity. When the soil is too dry, the effect will also be reduced. At the seedling stage, when weeds are small, systemic herbicides should be chosen as the main option. After the corn reaches the large trumpet stage, when weeds are larger, contact-killing herbicides should be selected instead.

6. Strictly master the concentration and method of use

Because there are many types of herbicides that can be used in cornfields, and different herbicides require different application concentrations, the concentration and dosage must be mastered before use. If the concentration is too low and the amount used too small, it may fail to control weeds, while if the concentration is too high and the dosage too large, it will often harm the corn. Generally speaking, commercial products will give a certain concentration and dosage range. In plots with high soil organic matter content and low soil moisture content, the upper limit of the safe concentration should be used; conversely, the lower limit should be used. When using herbicides, pay special attention to spraying evenly and not missing any area; for post-emergence application, do not spray onto the corn, so as to avoid harming it.