The suitable time for using wheat herbicides is during the seedling stage before the year, and during the post year greening period. During this period of time before the new year, some areas that were sown early could already be treated with herbicides, while areas that were sown later could wait a little longer.
However, when the following situations occur in wheat, do not apply herbicides. Wait until the situation is resolved before using it again.
Yellowing of wheat indicates unhealthy growth, which is influenced by both physiological factors and external adverse environmental conditions or pests and diseases, resulting in abnormal growth of wheat. This manifests as yellowing of leaves, weak growth, poor root production, and poor stress resistance. The weak yellowing of wheat seedlings in production is generally caused by the following factors:
1. Insufficient base fertilizer causes yellowing.
Premature sowing, insufficient basal fertilizer, or low nitrogen content in basal fertilizer can cause wheat to turn yellow and grow poorly.
In addition, insufficient phosphorus fertilizer can also affect root growth and tillering, leading to yellowing of leaf tips and dark green color of leaves.
2. Shallow cultivation layer
After the previous crop straw is returned to the field, although it can improve soil fertility, if the amount of return is too large or not carefully turned over, it may cause the plow layer to become shallower.
In this living environment, the root system of wheat cannot penetrate deeply, and nutrient supply cannot keep up, resulting in yellowing that cannot be avoided. So it is recommended that in the future, when encountering such situations, everyone must suppress them after sowing to avoid hollow soil.
3. Caused by excessive sowing depth.
Sowing wheat too deeply can lead to poor root growth, coupled with excessive nutrient consumption during germination and emergence, resulting in weak growth and yellowing of plants.
4. The impact of returning straw to the field.
The amount of straw returned to the field is large, unevenly distributed, or plowed too shallow, or not compacted properly, resulting in poor insulation and moisture retention performance, which can easily cause the wheat root system to hang in the air or make it difficult for the wheat to root in the soil, resulting in insufficient nutrient and water supply, and ultimately causing yellowing. In addition, insufficient application of nitrogen fertilizer and excessive absorption of nitrogen fertilizer by straw decomposition can also cause yellowing of leaves.
5. The impact of residual pesticides on crops in the previous season.
Especially for corn, the use of herbicides such as nicosulfuron or atrazine in fields can cause wheat to turn yellow and grow poorly if the dosage is too high or accumulated over the years.
6. Effects of pests and diseases.
Wheat aphids and spiders can cause yellowing when ingesting leaf sap, as well as wheat root rot, sheath blight, leaf blight, or take all disease. Underground pests such as golden needles or grubs can also cause yellowing of the root system. This further affects normal water and fertilizer diversion, weakens growth, and causes yellowing.
7. Rainy and cloudy weather, high humidity in the fields, and insufficient low temperature and light can also affect root growth, leading to yellowing of leaves.
The post emergence herbicides for wheat are generally based on the wheat's ability to decompose or resist herbicides, in order to ensure that the normal production of wheat is not affected and the weed plants die when spraying herbicides.
But if the growth of wheat is abnormal, its ability to decompose or resist pesticides or drug resistance will decrease, especially when the growth is weak, or it is affected by diseases and pests, or the root system is not good, or the temperature is uncomfortable, it will further reduce the ability to decompose pesticides, and the resistance or drug resistance will decrease more.
If herbicides are sprayed at this time, it is easy to cause pesticide damage, which can worsen leaf yellowing, and in severe cases, cause plant withering or not growing. Especially when wheat is not sensitive to herbicides, the risk of herbicide damage is doubled compared to normal use of herbicides in wheat.
If residual herbicides cause yellowing, spraying herbicides will accelerate yellowing and even withering, which will inevitably have a serious impact on later yield.
Therefore, in order to increase wheat yield, it is necessary to analyze the causes of yellowing in wheat in a timely manner and take targeted treatment measures to quickly upgrade and transform its seedling condition, in order to restore normal conditions and then spray herbicides according to the actual situation for chemical removal.
There are technical issues with the use of herbicides in wheat fields, among which the "eight musts" and "two musts" in the process of using wheat herbicides are heart wrenching and worth learning.
Do not use herbicides before and after the 4th leaf of wheat
Before the 4-leaf stage, wheat is relatively tender, with low detoxification and immunity, and is prone to drug damage.
After the jointing stage, wheat enters the booting stage and is very fragile. At this time, the use of herbicides can easily cause pesticide damage, especially 2,4 chloride, which can sometimes cause the wheat ears to fail to extract or deform, seriously affecting the final yield.
Second, do not use wheat herbicides if the temperature is below 6 degrees Celsius
Herbicides are not effective in low temperature weather, and it is best to use them at a daily average temperature of 6 degrees Celsius or above. The weeding effect is good from around 10am to 3pm.
Because weeds absorb light and grow vigorously, their stomata open, making them easy to absorb water and chemicals (the opposite is true for low temperatures), they can achieve good weed control effects.
Three Don'ts: Do not use wheat herbicides due to soil drought
When the soil is relatively dry, it is important to seize the opportunity to water the wheat field, apply pesticides in a timely manner, and maximize the effectiveness of herbicides.
The effectiveness of most herbicides requires a certain amount of soil moisture, and soil moisture between 40% -60% is beneficial for the effectiveness of herbicides.
Four Don'ts: Do not use wheat herbicides in adverse weather conditions
The use of herbicides before and after heavy rain, as well as before the arrival of cold air, not only affects the effectiveness of weed control, but also easily causes pesticide damage. These are all considered adverse weather conditions, especially the 7-day period before the onset of late spring cold. When using herbicides in winter, it is important to pay more attention to weather forecasts.
Five Don'ts: Do not spray or miss the spraying of wheat herbicides
When using herbicide, it must be evenly spray. If weeds are not evenly treated in areas where spraying is omitted or less, the control effect must be poor. Remember not to re spray. Wheat is prone to yellowing, which is likely to cause herbicide damage.
Six Don'ts: Wheat herbicides should not be mixed with other herbicides, pesticides, or foliar fertilizers at will to avoid drug damage reactions.
Seven Don'ts: Do not apply wheat herbicides for 7 days before and after the use of organophosphorus and carbamate pesticides
Wheat fields that have been treated with such insecticides also need to wait at least 3-5 days before using herbicides, otherwise it is easy to cause wheat yellowing and leaf burning. Organic phosphorus pesticides reduce the ability of wheat to degrade herbicides, and subsequent use of herbicides can easily lead to pesticide damage.
Eight Don'ts: Do not arbitrarily increase or decrease the dosage of wheat herbicides
Following the instructions for using wheat herbicides, reducing the dosage does not achieve the goal of weeding, while increasing the dosage can easily cause pesticide damage.
One must: The use of wheat herbicides must use the secondary dilution method
When using herbicides, pay attention to secondary dilution. Some farmers try to save time by pouring herbicides directly into the spray, and just find a branch to stir. This method of mixing medicine is very unscientific.
Before applying the medicine, dilute the medicine with a small amount of water to form the mother liquid. When applying the medicine, add the prepared mother liquid into the medicine barrel, and then make up the remaining water needed to mix well before spray.
Market feedback shows that many dealers have realized the importance of the secondary dilution method, and can promptly remind farmers to use this method when selling medicine.
Secondly, it is necessary to maintain and upkeep the medical equipment in a timely manner before spraying, in order to prevent the phenomenon of running, emitting, dripping, and leaking during the spraying process, and achieve uniform spraying.
The pesticide equipment after application should be cleaned in a timely manner to avoid causing pesticide damage to other crops.