"A few days after the spring corn seedlings emerged, there were a lot of small weeds in the field, can you go to apply herbicides?"
This is the question asked by a farmer to the little helper, his family planted spring corn this year, the corn sown on April 11, it has been 10 days now, and the corn seedlings in the field are still good. However, with the emergence of corn seedlings, more weeds come out, and I heard others say that the smaller the weeds, the better the control effect of spraying herbicides, so I am ready to apply herbicides now.
However, they are worried that if they are sprayed too early, the corn seedlings will not be harmed. If you don't fight now, wait for the corn to grow for a few days, weeds are also growing, and then the corn is safe, and the weeds are difficult to control again?
On this issue, the little helper receives a similar inquiry every year, that is, the use time of corn herbicide, too early or too late, is not conducive to weed control and corn safety.
Effects of premature use of corn herbicides
If the corn herbicide is used too early, the weeds in the field are often at the stage when the corn seedlings are very small, and they are also at the stage where they have just germinated or just begun to spread their leaves. At this time, weeds have limited leaf area and weak herbicide absorption. Therefore, if the herbicide is sprayed too early, the solution may not be able to fully contact the leaves of the weed, resulting in insufficient amount of the solution absorbed by the weed.
In addition, with the premature use of herbicides, some weeds have not yet emerged, and corn post-emergence herbicides are often contact killing, and only when the herbicide solution is sprayed on the weed leaves can it play a herbicidal effect (unlike closed herbicides). Therefore, after spraying herbicides, it has little effect on the weeds that have not yet emerged, and it seems to be prevented, and after a period of time, there are still many weeds in the field.
Another point, the early use of herbicides may cause pesticide damage to corn seedlings, corn seedlings are more sensitive to herbicides in the early stage of growth, especially before the 3-leaf stage of corn seedlings, corn seedlings have weak detoxification ability, spraying herbicides at this time, the liquid medicine is easily absorbed by corn seedlings, and then has a pesticide damage effect on it. In the case of yellowing, drying, and severe leaf decay, the seedlings will die directly, and they may need to be replanted.
Effects of late use of corn herbicides
The late use of corn herbicides will affect the normal growth of corn, when the corn plant enters the jointing stage, its leaf area and root development have reached a certain extent, at this time, the herbicide is used, and the liquid is sprayed on the corn leaves more, resulting in corn pesticide damage. The leaves show symptoms such as dryness, curling and yellowing, which affects the photosynthesis and nutrient absorption of maize, hinders the growth of maize, and reduces the yield.
In addition, applying herbicides too late can also reduce the effectiveness of herbicides. As weeds grow, their roots and leaves become more developed and their resistance to herbicides increases. Especially after 8 leaves of corn, weeds are almost 5-6 leaves (or even more), and then use herbicides, the weeding effect will be greatly reduced.
Another point is that the late application of herbicides will also increase the cost of cultivation for some farmers. Due to the poor weeding effect, some farmers may use herbicides many times, which not only increases the purchase cost of pesticides, but also increases the labor cost and time cost.
The best time to use a corn herbicide
In general, when corn grows to 3-5 leaves, it is the best time to spray corn herbicides, and the weeds at this time are basically 2-4 leaves.
On the one hand, corn itself has strong resistance, even after absorbing a certain herbicide solution, it will ensure that the growth of corn itself is not affected through its own detoxification ability.
On the other hand, at this time, the weeds themselves are relatively weak in resistance, and the weeds that should emerge in the field have also emerged, which can not only control weeds well, but also have the effect of clean and thorough dead weeds.
Precautions when using corn herbicides
First, two best use periods are determined: the first is to use closed herbicides to form a layer of medicinal soil on the soil surface after sowing and before emergence, and weeds absorb herbicides and are killed when they germinate. The second is the one mentioned above, in the 3-5 leaf stage of corn seedlings and the 2-4 leaf stage of weeds, choose post-seedling stem and leaf herbicides for spraying.
Second, when dispensing, it is recommended to "double dilut", that is, first mix a small amount of water with the medicine evenly in a small barrel, then pour it into a large barrel, and then add the remaining water, stir evenly and spray. It is not recommended to pour the medicine directly into the vat to avoid uneven distribution of the liquid medicine.
Third, use according to the instructions and recommended dosage of herbicides, and do not increase the dosage without authorization, so as not to cause pesticide damage. At the same time, be careful not to allow the corn leaves to shade the weeds, making sure that the herbicide can fully reach and act on the weeds.
Seeing this, I believe you have a certain understanding of the use of corn herbicides, and ask everyone, when did you apply herbicides in previous years?