Chemical weeding has become an important means of controlling weeds in wheat fields. However, herbicides have high requirements for the use of technology, especially winter wheat. The herbicides are used from mid-November to March of the following year. This period is at a low temperature, and the weeding in the wheat field is long due to the long period of use and temperature. For some reasons, such as the strong selectivity of herbicides, it is easy to cause phytotoxicity when it is not noticed. Then, when is the use of herbicides safe and efficient? The author makes a comprehensive summary of the precautions and the restricted area of ​​wheat field herbicides. For your reference before using herbicides!
1. Master the best time for weeding
About 40 days after the sowing of wheat (in the middle and late November), the herbicide is the safest. At this time, the wheat is worth 4 or 4 leaves, and the herbicide is more resistant and safer. In addition, the field is mixed at this time. The grass has been released, and the grass age is small, the drug resistance is poor, and the weeding is safe and efficient.
2, master the weeding temperature
Herbicides are generally marked with 5 ° C or 10 ° C can be used, then the temperature mentioned here does not refer to the temperature at the time of use, but refers to the lowest temperature of the day, that is, the lowest temperature can be used above 5 ° C, and use It is best not to drop the temperature below two days before and after the herbicide. In high winds, there is generally no need for medicine to avoid drift, reduce the efficacy, and possibly damage surrounding crops.
3. The second dilution method is used for dispensing
Before applying the drug, dilute the drug into a mother liquid with a small amount of water. When the medicine is used, first add the prepared mother liquid in the medicine barrel, then make up the remaining amount of water needed to mix and spray. In the market where Xiaobian visited, many dealers have realized the importance of the second dilution method. When selling drugs, they can prompt farmers to use drugs in this way. Most of the herbicides in the wheat field are mainly powders. Sometimes, depending on the weed conditions in the field, it is necessary to mix and use a variety of liquids. If the second dilution method is not used, it is directly mixed, which is easy to cause sedimentation, the liquid is not uniform, and the amount of the drug is light. Grass can not be effectively prevented, and places with heavy doses are prone to phytotoxicity. The second dilution method is undoubtedly the best way to evenly mix the liquid, avoiding the liquid blocking the nozzle and the herbicidal effect is better.
4. Correctly treat the yellowing phenomenon of herbicides
After some herbicides are used, wheat will have a short yellowing of the tip of the leaves. This is a normal seedling phenomenon, which is generally self-recovering when the wheat is green. This phenomenon generally does not cause wheat to reduce production, but instead controls Function, so you don't have to worry too much about this phenomenon.
Weeding in the wheat field should not enter these 8 major misunderstandings
1, before the 4 leaves of wheat and after the jointing, do not fight herbicides
Most of the wheat field herbicides are used after 4 leaves, and the drug is stopped at the jointing stage of wheat. Before the 4-leaf stage, the wheat is delicate, the detoxification ability and immunity are low, and it is easy to produce phytotoxicity. After the jointing stage, the wheat enters the booting stage, which is also the most fragile and critical period in life. At this time, the herbicide is very easy to produce phytotoxicity, especially It is 2 methyl 4-chloro, 2,4-titration ester, which sometimes causes the wheat to be unable to be extracted, or deformed, which seriously affects the final yield, except that the flufenic acid herbicide can be used in half after the jointing, other Herbicide is best not to try!
2, the average daily temperature is less than 8 degrees without herbicide
Except for individual herbicides (diflufenacil, which is less resistant to low temperature), the general herbicides are not ideal in low temperature weather and are prone to phytotoxicity. Therefore, it is best to use the medicine at the lowest temperature of 8 degrees above the day. The higher the temperature, the better the weeding effect. Because the weeds absorb the light and grow vigorously, the pores are open, and the water and liquid are easily absorbed (the temperature is low). Good weeding effect.
3. No herbicides in dry weather
In addition to looking at the temperature, the herbicide should also grasp the humidity of the soil. In the case of severe drought, it is necessary to grasp the timing of watering the wheat field and timely apply the medicine to ensure the efficacy of the herbicide. Most herbicides exert their effects. It requires a certain amount of soil moisture, and the soil moisture is most beneficial to the efficacy of herbicides when it is 40%-60%.
4, wheat seedlings weak, no roots when the herbicide is not used
Generally, winter wheat fields will be returned to the field, and the land will be loose. If the weather is in an abnormal year (such as warm winter drought), the roots of wheat may be too loose due to the soil to be deep, or some roots are bare. This kind of wheat is easy. Causes frostbite and water shortage, which is sensitive and fragile. If the herbicide is hit at this time, it will cause certain damage to wheat.
5, no herbicides when wheat disease occurs
In recent years, wheat sheath blight, root rot, total rot disease and other species-borne or soil-borne diseases frequently occur, and the disease resistance of wheat is extremely low. Once phytotoxicity occurs, it is not easy to recover, so the land with serious disease of wheat is generally not It is recommended to use herbicides to treat diseases and strong seedlings first.
6. Do not use herbicides before and after heavy rain and cold air.
The use of herbicides before and after heavy rain and before the arrival of cold air affects the herbicidal effect on the one hand, and is highly susceptible to phytotoxicity on the other hand. It is forbidden to use herbicides in bad weather such as frost, rain, snow, hail, cold current, etc. These are bad weather, especially in the 7 days before the cold spring, the herbicides cannot be used, and the winter medicine should pay more attention to the weather forecast.
7. Organic phosphorus and carbamate pesticides are not used for herbicides 7 days before and after use.
As we all know, the cornfield played organophosphorus or carbamate pesticides for an interval of 7 days to the use of herbicides, pesticides and wheat field played needs at least such an interval 3-5 days, to use the herbicide, Otherwise, it is easy to cause yellowing of wheat leaves, because organophosphorus pesticides reduce the ability of wheat to degrade herbicides, and the use of herbicides can easily lead to phytotoxicity.
8, can not be re-sprayed or leaked
The herbicide must be evenly sprayed. If the spray is sprayed or sprayed less, the weeds are not treated uniformly and the control effect is not good. Secondly, remember not to re-spray, which will cause the wheat to yellow and easily cause herbicide damage.
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