Causes and countermeasures of medicinal damage caused by wheat herbicides
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1 Analysis of the causes of phytotoxicity
1.1 The type and type of herbicide are not properly selected, causing crop damage.
1.2
Herbicide drift causes damage to non-target crops. This problem is most prominent in the wheat field closed herbicides in the wheat field. In the early stage of wheat jointing, the herbicide is concentrated in the farmland, causing the suspended concentration of the herbicide active ingredient in the air to be too large, or the application liquid to drift with the wind to cause other non-targets. Sensitive crops are affected.
1.3
Subsoil crops caused by herbicide residues. For example, wheat fields and rice fields use residual herbicides (metsulfuron-methyl, chlorsulfuron) to cause damage to post-crops crops such as corn and peanuts. Farmers often do not know enough about this, and it is difficult to take timely and effective methods to remedy them.
1.4
Herbicide causes damage to target crops due to improper use. If the dosage is too large, it can cause phytotoxicity to crops when the crop is applied during the sensitive period and the herbicide is improperly mixed.
1.5 The phytotoxicity caused by the mixing of spray equipment.
2 Countermeasures
2.1
According to the type of crops and weeds, the herbicide varieties and dosage forms are correctly selected. Different herbicide varieties have different action characteristics, the types of weeds that can be controlled, and the safety of different crops. In addition, weeds in different crop fields have different distribution and community composition. Therefore, when selecting herbicide types and dosage forms, scientific and reasonable selection must be made according to the types of crops and weeds.
2.2 Strictly according to the dosage, period of use and method of use prescribed by the product.
2.2.1
Reasonable dosage is the key to safe medication. Due to the long-term formation habits, most of the pesticides used by farmers will use larger doses. It is believed that only when the dosage is larger than the label requirements, the efficacy is guaranteed. This may not be a serious consequence for safer herbicides. For products with poor safety, it is easy to cause phytotoxicity. Therefore, in order to ensure safety, it is recommended that farmers use the dosage according to the product strictly. Do not increase the dosage for any product.
2.2.2 The appropriate period of medication is a prerequisite for safe medication. When it is not applied, the herbicide is compatible with the sensitive period of the crop, which is easy to cause phytotoxicity, such as 2 4 -
D is prone to phytotoxicity before spraying and after the jointing of wheat 2 to the flowering stage, causing wheat ears and leaves to curl and affecting heading.
Therefore, farmers who are prone to phytotoxicity must be applied according to the marked use period.
2.2.3
The correct method of application is the guarantee of safe medication. Improper use, and sometimes phytotoxicity. If the herbicide is mixed with other chemicals, it is easy to occur (the urea herbicide is mixed with the phosphate insecticide, which seriously damages the cotton seedling, which is the case).
2.3 According to the environmental conditions at the time of application, choose the best time to take the medicine.
2.3.1
temperature. Most herbicides have an optimal temperature range for exerting efficacy. Above or below the optimum temperature, the herbicides are not effective, but some herbicides can cause phytotoxicity at a certain temperature, such as using 2
For 4-D products, high temperatures should be avoided to avoid toxic effects on surrounding sensitive crops.
2.3.2
illumination. The high light intensity is beneficial to the weed absorption and conduction of herbicides, and can enhance the herbicidal effect, but for the volatile and photolyzed herbicide varieties, it is prone to phytotoxicity. For example, trifluralin is volatile under light, and even photolysis fails. If it is used in a greenhouse, the droplets that are volatilized to the top of the greenhouse will cause damage.
2.3.3
Soil conditions. Fields with accumulated water should avoid the use of soil-treated herbicides, such as “acetochlor†and “sulfuronâ€. In the case of better soil moisture, the effect is stable, but soil water produces phytotoxicity. . Some rugged fields are prone to plague after using soil treatment agents.
2.3.4
In addition, the wind will affect the spraying quality of the herbicide. If the liquid is drifted to sensitive crops, it will cause phytotoxicity. Therefore, the use of herbicides should generally be selected in the absence of wind, sufficient light, temperature of 20 ° C ~ 35 ° C, soil moisture is good.
2.4 Scientific application of pharmacy
2.4.1
The use of highly volatile pharmaceutical agents. Some herbicides are highly volatile and can easily cause phytotoxicity to nearby sensitive crops. If there are cruciferous vegetables, cotton and other crops near the wheat field, avoid using 2
4 - D herbicides, etc. When using such products, the types of crops in the surrounding fields should be investigated to avoid the occurrence of phytotoxicity.
2.4.2
Unsuitable for mixing. Most herbicides can be mixed to increase the spectrum of herbicides and enhance the efficacy. However, some herbicides may aggravate the phytotoxicity. For example, if the soybeans are emerged, they should avoid "enegrafen" and "trifluorocarbamate". Ether (weed burning) is mixed.
2.4.3
Long residual agent. Different herbicide varieties have different durations of use, and attention must be paid to the effects on the crops after harvest. For example, the soybean field that needs to be planted with beets, potatoes, melons, sorghum and other crops should avoid the use of "flumursulfuron"; after the cultivation of corn fields such as wheat and cucumber, the use of "Atrazine" should be avoided.
In addition, the quality of the herbicide itself is also an important factor affecting safety. At present, the pesticide market is not standardized enough. There are many varieties of herbicides, and there are counterfeit and shoddy products. When selecting herbicides, farmers must pay attention to the products of reputable enterprises and merchants. Spray equipment should be used exclusively.
In short, "scientific and rational use of drugs to avoid the occurrence of phytotoxicity" has practical significance. The administrative departments at all levels of agriculture should do a good job in supervision and technical service, improve the overall quality of farmers, and popularize the use of herbicides.