The best time to use wheat herbicides is in the seedling period before the beginning of the year and the greening period after the year. Pre-emergence and post-emergence herbicide for sorghum field

In the previous period of time, some areas where planting was early can already be used for herbicide, and those areas where planting is late can wait.

However, when the following situation occurs in wheat, do not use herbicides and wait until the situation is resolved before using it.

This situation is the common phenomenon of weak seedlings, yellow seedlings and rotten roots.

Yellowing of wheat indicates that its growth is unhealthy. It is not only affected by its own physiological factors, but also by external adverse environmental conditions or pests and diseases, which causes wheat to fail to grow normally, showing yellow leaves, weak growth, poor root production, and poor resistance to stress. The weak yellowing of general wheat seedlings in production is caused by the following effects:

1. Insufficient base fertilizer causes yellowing.

Generally, premature sowing, insufficient base fertilizer or low nitrogen content in base fertilizer will cause yellowing of wheat and poor growth.

In addition, insufficient phosphate fertilizer will also affect root growth and tillering, resulting in yellow leaf tips and dark green leaves.

2. Shallow tillage

After the last crop of crop straw is returned to the field, although it can improve the fertility of the soil, if the amount of returning the field is too large or not carefully adjusted, it may cause the cultivated layer to become shallow.

In this kind of living environment, the root system of wheat cannot be deepened, and the nutrient supply cannot keep up. Yellowing is unavoidable.

Therefore, I suggest that when you encounter this situation in the future, you must suppress it after sowing to avoid hollows in the soil.

3. Caused by the effects of too deep sowing.

If the wheat is sown too deeply, the root system does not grow well, and the germination and emergence consume too much nutrients, which will lead to weak growth and yellow plants.

4. The impact of returning straw to the field.

The amount of straw returned to the field is large, uneven distribution, or too shallow plowing, or improper suppression, poor heat preservation and moisture preservation performance, easy to cause the wheat root system to hang in the air, or it is difficult for wheat to take root in the soil, insufficient nutrient and water supply, which causes yellowing .

In addition, if the appropriate amount of nitrogen fertilizer is not applied, the effect of the straw decomposing and absorbing too much nitrogen fertilizer will also cause the leaves to yellow.

5. The impact of pesticide residues in the field of last season crops.

Especially in corn fields with medicaments such as nicosulfuron or atrazine, if the dosage is too large or the accumulation is large throughout the year, the wheat will turn yellow and the growth will not be good.

6. The impact of pests and diseases.

Wheat aphids and wheat spiders can cause yellowing if they suck leaf juice. Wheat root rot, sheath blight, leaf blight or total erosion can also cause yellowing.

Underground pests such as gold pinworms or grubs can also cause yellowing of the root system. In turn, it affects normal water and fertilizer drainage, weakens its growth, and causes yellowing.

7. Rainy weather and high humidity in the field, as well as the influence of low temperature and insufficient light, will also affect the growth of the root system and cause yellowing of the leaves.

The post-emergence herbicides of wheat are generally based on the ability of the wheat itself to decompose or resist herbicides to ensure that the normal production of wheat is not affected and the weed plants die when the herbicide is sprayed for weeding.

However, if the wheat grows abnormally, its decomposition or resistance or resistance to chemicals will decrease, especially when it grows weak, or is affected by pests, or the root system is not good, or the temperature is not affected, it will be further reduced The ability to decompose drugs, drug resistance or drug resistance decreased more.

If herbicides are sprayed at this time, it is easy to cause phytotoxicity, which will aggravate the yellowing of the leaves, and cause the plants to die or not grow in severe cases. In particular, wheat is not sensitive to herbicides, and it is better than normal use of herbicides for wheat. The risk of harm increases exponentially.

If yellowing is caused by the effects of herbicide residues, after spraying the herbicides, yellowing and even death will be accelerated, which will also have a serious impact on the later production.

Therefore, in order to ensure the yield of wheat, it is necessary to analyze the causes of yellowing in time after the wheat turns yellow, and take symptomatic treatment measures to quickly upgrade and transform the seedling condition, so that it is appropriate to spray herbicides according to the actual situation after returning to normal. .

There are technical problems in the use of herbicides in wheat fields. Among them, "eight don't, two must" in the process of using wheat herbicides are hard to learn.

One no: do not use herbicides before and after the 4 leaves of wheat

Before the four-leaf stage, wheat is relatively delicate, with low detoxification ability and immunity, and is prone to phytotoxicity.

After the jointing stage, the wheat enters the booting stage and is very fragile. At this time, the use of herbicides is very easy to produce phytotoxicity, especially 2-methyl-4 chloride, which sometimes causes the wheat ears to fail to extract or deform, which seriously affects the final yield.

Two: Don't use wheat herbicide when the temperature is below 6 degrees

Herbicides are not effective in low temperature weather. It is best to use the herbicide at a daily average temperature of 6 degrees or more. The effect of weeding is good from 10 am to 3 pm.

Because weeds absorb light and grow vigorously, their stomata are open, and they can easily absorb water and liquid medicine (the opposite is the case when the temperature is low), and a good weeding effect can be achieved.

Three don't: don't use wheat herbicide in dry soil

When the soil is relatively dry, it is necessary to seize the opportunity of watering the wheat field and apply the pesticide in time to ensure the effectiveness of the herbicide.

The effect of most herbicides requires a certain amount of soil moisture. Soil moisture content of 40%-60% is most conducive to the effect of herbicides.

Four Don't: Don't use wheat herbicide in bad weather

The use of herbicides before and after heavy rains and before the arrival of cold air affects the weeding effect on the one hand, and can easily cause phytotoxicity on the other hand. These are all severe weather, especially the herbicides cannot be used for 7 days before the cold spring. Weather forecast.

Five Don't: Don't re-spray or miss wheat herbicide

Weeds must be sprayed evenly when using herbicides. If the weeds are not evenly received in areas where the spray is missed or less sprayed, the control effect will not be good. Remember not to respray. Wheat is prone to yellowing, which can easily cause herbicide damage.

Sixth do not: do not mix wheat herbicides with other herbicides, pesticides, and foliar fertilizers to avoid phytotoxicity.

Seven no: do not use wheat herbicide for 7 days before and after the use of organophosphorus and carbamate pesticides

It takes at least 3-5 days before the herbicides are used in wheat fields after they have been sprayed with such pesticides. Otherwise, it is easy to cause wheat to turn yellow and burn leaves, because organophosphorus pesticides reduce the ability of wheat to degrade herbicides. The use of herbicides can easily cause phytotoxicity.

Eight don't: Don't increase or decrease the dosage of wheat herbicides at will

Follow the instructions of the wheat herbicides, reducing the amount of the herbicide will not achieve the purpose of weeding, and increasing the amount of the herb will easily cause phytotoxicity.

One must: the use of wheat herbicides must use the secondary dilution method

When using herbicides, you must pay attention to the secondary dilution. Some farmers' friends just pour the herbicides into the sprayer without any hassle, just find a branch and stir it. This method of dispensing medicine is very unscientific.

Before applying the medicine, dilute the medicine with a small amount of water to form a mother liquor. When using the medicine, add the prepared mother liquor into the medicine bucket, and then make up the required remaining water and mix well before spraying.

According to market feedback, many distributors are now aware of the importance of the double dilution method and can promptly remind farmers to use this method when selling medicine.

Second, it is necessary to maintain the medicine equipment in time before spraying, to prevent running, blowing, dripping, and leakage during spraying, and to achieve uniform spraying.

After application, the equipment should be cleaned promptly and thoroughly to avoid phytotoxicity to other crops.