The cause of phytotoxicity of herbicides

The main causes of herbicide phytotoxicity:

First, excessive medication

Each herbicide has the best dosage to be applied, and the dosage and concentration per unit area are increased arbitrarily.

Second, misuse of herbicides

Each herbicide has a certain range of applications, and it is easy to produce phytotoxicity when it is applied outside the registration range. If the wheat herbicide chloromeron is used in rice fields, it will cause the rice seedlings to die.

Third, improper medication period

Each herbicide has an optimum application period, and it is not suitable to use the medicine to make the herbicide match the sensitive period of the crop and cause phytotoxicity. For example, the application of chlorpyrifos and butachlor in the germination stage of rice seeds can easily cause seedlings to sprout, and the leaves are dark green and yellow. In severe cases, the seedlings die.

Fourth, improper application methods

Do not apply according to the herbicide application instructions, causing the occurrence of phytotoxicity. For example, when applying oatmeal, the depth of soil mixing is the same as that of wheat, which causes phytotoxicity in wheat: soil-blocking herbicide is used for stem and leaf treatment to cause crop damage.

V. Improper application interval

When two drugs are applied to the same crop, the application interval is too short to cause phytotoxicity. Shortly after the application of the enemy, the use of organophosphorus or carbamate insecticides to detoxify the rice against the enemies and cause phytotoxicity: nicosulfuron and organophosphate insecticides are used in a short period of time, causing corn Drug damage, etc.

6. Improper operation of farming

After using the soil treatment agent, the soil layer should not be destroyed, otherwise it may cause phytotoxicity. For example, after the application of chlorpyrifos in the paddy field, the grass is quickly plucked or fertilized, so that the agent is exposed to the roots of the rice to cause phytotoxicity.

7. Improper operation of the application device

In the field operation, there is a lack of precise adjustment of the spraying device, the nozzle flow is uneven and repeated spraying, which causes phytotoxicity to the crop. It is not cleaned after spraying the herbicide, and it is easy to cause phytotoxicity when used again.

Eight, improper application of mixed

Herbicide can also cause phytotoxicity if it is mixed with another herbicide or insecticide. If Kekele and Napeng are mixed, it will increase the phytotoxicity of Kekuole on soybeans: Baocheng and organophosphate insecticides can be mixed, which is easy to cause corn phytotoxicity: Bean sulfonate and high-efficiency grass can be mixed.

Nine, drug volatilization and droplet drift

The applied herbicide liquid and powder migrate to the adjacent field, causing phytotoxicity to sensitive crops. For example, 2,4-D butyl ester is used for spraying and weeding corn and wheat field stems and leaves, and the droplets drift with wind to nearby sensitive broad-leaved crops and fruit trees to produce phytotoxicity: paraquat or glyphosate for field hoeing, roadside weeding When the mist drifts to the crops in the field, it causes phytotoxicity. In the case of high temperature and high wind speed, the herbicide droplets can drift 2,500 meters. Volatile herbicides not only have drift problems, but also the chemicals are constantly volatilized for a period of time after application, and continue to cause phytotoxicity to surrounding sensitive crops.

X. Meteorological factors

Abnormal temperature can easily lead to herbicide phytotoxicity, especially when the temperature changes drastically, it is more likely to cause phytotoxicity: low atmospheric humidity will accelerate the absorption of herbicides by crops, and it is easy to produce phytotoxicity: paraquat quickly shows drugs under strong light. Harm: After the emergence of the tomato, it is sprayed with secazine, and the light is strong after application, and the plant is susceptible to phytotoxicity.

XI, soil impact

Soil texture, organic matter content, humidity, salinity, pH value, etc. are closely related to herbicide phytotoxicity. For example, sandy soil, sandy loam soil and soil with organic matter content less than 2% are prone to phytotoxicity; rainy, soil water accumulation or rice field water layer is more susceptible to phytotoxicity than salt: Alkali land is easy to produce phytotoxicity: heavy rain causes herbicide leaching to occur easily Drug damage, etc.

Twelve, herbicide quality

Herbicides contain impurities or fake pesticides that are harmful to crops, and are susceptible to phytotoxicity after application. If alachlor is mixed with alachlor, the inhibition of rice will be greatly increased: if the benzosulfuron contains impurities such as metsulfuron, it will cause phytotoxicity to wheat and crops. Some herbicides that are improperly stored and cause deterioration or failure not only affect the efficacy, but also cause phytotoxicity.

Thirteen, crop varieties

Different varieties of the same crop have different resistance to herbicides. Such as sweet corn, popcorn, Denghai series, Zhangyu 19, Zhongdan, Pioneer series, individual [from varieties and other sensitive to nicosulfuron, easy to produce phytotoxicity: Shannon 15 soybean sensitive to soybean sulfonate: cabbage rapeseed It has poor resistance to mustard-type rapeseed.

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