Can you spray corn after herbicide doesn't work? How did that happen? How do I fix this?

After the general emergence of corn, farmers can weed it, but due to the variety of corn varieties, and the efficacy of herbicides are different, so it is inevitable that the herbicides are not obvious after weeding, so can the herbicides be sprayed again if the herbicides are not effective after corn seedlings?

The reasons that affect the efficacy of the drug:

1. Influence of weeds. When the grass age is small, the drug resistance is poor and the efficacy is good; when the grass age is older, the drug resistance increases and the efficacy is poor. In the case of drought, the weeds do not germinate, and the unearthed weeds look small, but the grass age is too old, especially the wettable powder products, the adsorption is poor, the spray solution dries quickly, the powder falls off, and the effect is not good.

2. Usage. Water consumption, spray uniformity, leaking spray, re-spraying and adding surfactant all have obvious effects on the efficacy.

3. Soil conditions. It has a great impact on closed herbicides, especially in the plots where soil treatment agents are applied, the content of organic matter is high, and the solution is easy to be absorbed by the soil, so it is necessary to increase the dosage. The sandy land with low content of organic matter is easy to leakage and leaching, the formation of drug film is not good, and the herbicidal effect is poor.

4. Temperature. The efficacy and damage of herbicides have a lot to do with air temperature. Such as nicotinyl sulfuron, methyl sulfonate, etc. in the case of low temperature, the efficacy is slow or poor. On the other hand, it is easy to cause drug damage under the condition of high temperature. Therefore, the application of pesticide before and after evening is relatively safe for crops.

5. Weather conditions. The efficacy is often not good under drought conditions; when applied after rain, the effect of high soil moisture is better; in windy weather, the liquid drifts, the efficacy is not good, and drift is easy to cause drug damage to other crops, and so on.

6. Soil moisture. The moisture content is good, the medicine liquid is absorbed by the soil less, is advantageous to the weed absorption, the medicine effect is good. Under the condition of drought, the effective components of herbicides are absorbed and fixed by soil, so they are not easy to be absorbed by weeds and the efficacy is not good.

Solution:

1. Soil sealant

When the soil moisture is good after irrigation or rain, apply the medicine according to the instructions, do not increase or decrease at will, spray evenly on the soil surface, form a drug film, and improve the weeding effect.

2. Post-seedling treatment agent

When the weeds are applied after irrigation or rain as far as possible, the weeds are in a state of growth, and the stomata are open, which is conducive to the absorption of the drug solution; and the plant growth is exuberant, and the drug solution is transmitted quickly in the body.

The efficacy is good, and the weeding effect is good. Drought must increase water consumption, water consumption per mu is not less than 30kg, uniform spray, wet through the stems and leaves of weeds, help absorption and transmission.

It is best to use medicine in the 2-5 leaf stage of weeds, when the grass age is younger and the weeding effect is better. Surfactants such as organosilicon auxiliaries can be added to the solution to increase the extended moisture of the leaves, promote the absorption of the solution and improve the herbicidal effect.

In addition, the improper use of corn post-seedling herbicides not only does not remove weeds thoroughly, but also may cause certain drug damage. So after the first spray has no effect, spray it again at intervals of 2-3 days. More importantly, the use of herbicides after corn seedlings must be appropriate to avoid drug damage. Specific operation methods, please look down!

Seven points for attention in the use of herbicides

1. Spraying time

As it takes 2-6 hours to absorb the herbicide after spraying corn seedlings, whether the efficacy is good (that is, whether the weeding effect is ideal) is closely related to air temperature and air humidity in these 2-6 hours.

Spraying in the morning, noon or afternoon when the temperature is high and the weather is dry, because the temperature is high, the light is strong, and the liquid volatilizes quickly, the liquid will evaporate soon after spraying, so that the amount of herbicide entering the weed body is limited and the absorption is obviously inadequate. thus affecting the weeding effect; at the same time, spraying in high temperature and drought, corn seedlings are also prone to drug damage.

The best spraying time is after 6 o'clock in the evening, because at this time, the temperature is lower, the humidity is higher, the liquid stays on the weed leaf for a long time, and the weeds can fully absorb the herbicide components to ensure the weed control effect. the use of medicine in the evening can also significantly improve the safety of corn seedlings and is not easy to cause drug damage.

2. Spraying method

Mu dosage of water 15-30 kg, see grass spray, spray carefully, no grass to go, save medicine and time-saving effect.

3. Look at the size of the grass

When spraying herbicides after corn seedlings, many farmers have a misunderstanding that the smaller the weed, the less resistant the grass is, the easier it is to kill the grass.

In fact, it is not, because the grass is too small to apply medicine area, the weeding effect is not ideal. The best grass age is from 2 leaves and 1 heart to 4 leaves and 1 heart, when the weeds have a certain drug area, the weed resistance is not big, and the weeding effect is significant.

4. Corn seedling size

The best spraying time of herbicides after maize seedlings is the 2-5 leaf stage of maize, when the resistance of maize is high and it is not easy to cause drug damage.

The whole field can be sprayed before 5 leaves, and after 6 leaves, the sprinkler should be lowered and sprayed with corn to prevent the liquid from causing drug damage (mainly nicosulfuron without safety agent, if it is safe, nicosulfuron can also be sprayed all over the field.) .

5. Maize varieties

At present, most of the post-seedling herbicides of corn are nicosulfuron, and some corn varieties are sensitive to this composition and are prone to drug damage, so the corn fields planting sweet corn, waxy corn and Denghai series can not be sprayed to prevent drug damage. For new corn varieties, please try them first and then popularize them.

6. Mixed use of pesticides

It is forbidden to spray organophosphorus insecticides 7 days before and after spraying herbicides, otherwise it is easy to cause drug damage. But can be mixed with pyrethroids and carbamate insecticides, spray should pay attention to avoid heart leaves as far as possible, anti-drug liquid perfusion.

Swedish flies and thrips have occurred seriously in some corn fields this year. Imidacloprid or acetamiprid can be used to control these two kinds of small pests, but do not mix them with post-seedling herbicides, although imidacloprid or acetamiprid are not organophosphorus. Because spray heart leaves are needed to control two kinds of small pests, if mixed spray heart leaves are easy to cause damage, you can spray herbicides separately: spray seedlings in front and spray herbicides separately. Followed by imidacloprid or acetamiprid spray leaves.

7. The resistance of weeds themselves

In recent years, the resistance of weeds has been strengthened, in order to prevent excessive evaporation of water in the body, weeds do not grow so stout, but grow gray and short, and the actual age of the grass is not small (that is, the so-called "little old man").

Most of these weeds are covered with small white hairs to reduce the evaporation of water. When spraying pesticides in this way, the liquid is topped by these small villi on the surface of the stems and leaves of the weeds, and the weeds themselves absorb very little, which naturally affects the exertion of the efficacy, so no matter what medicine is applied in high temperature and drought, the amount of liquid sprayed should be increased so as not to affect the exertion of the efficacy. Please do not cherish the water or medicine when applying the medicine.

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