Causes and countermeasures of phytotoxicity of farmland chemical herbicides
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The phytotoxicity refers to the process of chemical weeding in the farmland. Due to the action of herbicides, the crops grow abnormally, the stems and leaves are twisted, clumped, the plants are dwarfed, the flowers are not real, and even the dead yield is reduced. There are four types: one is to produce phytotoxicity to cockroach crops; the other is to produce phytotoxicity to sensitive crops; the third is to produce phytotoxicity to squat crops; the fourth is "secondary phytotoxicity".
The main reasons for the elimination of phytotoxicity in farmland:
1, the drug is not right, the herbicide has a strong specificity, its control object has a certain range, once used wrongly will produce the main phytotoxicity. For example, 2,4-D butyl ester is mainly used as a herbicide for controlling broad-leaved weeds in wheat fields. If it is used in cotton, melon, etc., it will cause phytotoxicity.
2, the medication time is not appropriate. The pot life of herbicides is very strict, and some herbicides can only be used before or after planting. After the seedlings are used, the main phytotoxicity will be produced. For example, wheat field herbicides used to control weeds in spring must be used before the jointing of winter wheat after greening. After the jointing of wheat, it will cause phytotoxicity.
3, free to increase the amount of medication. The amount of herbicide used is stipulated, and any increase in the amount of the drug may also cause phytotoxicity.
4. The environment is not suitable. The use of herbicides is subject to certain environmental conditions. If the herbicide is used in sandy land, it is easy to produce the main phytotoxicity. Especially for herbicides with high water solubility and high mobility, the crops have poor resistance to stress when the temperature is too high or low. At this time, the herbicides are also easy to cause phytotoxicity. Different crop varieties have different sensitivity to herbicides, and the sensitivity is strong. The variety is also easy to produce the main phytotoxicity.
5. Lack of understanding of the herbicide medicinal properties. If the herbicide herbicide, licorice or gram, is mistakenly used as a selective herbicide, it will also cause phytotoxicity when sprayed onto the crop.
6. Use a single herbicide with a long residual period for many years. For example, when the summer corn field is removed, the annual use of atrazine is too large, or the spray is not uniform, and there will be a phenomenon of dead wheat in the lower crop.
7, the drug is not clean. Sprayers that have used herbicides, without thorough cleaning, and spray insecticides or other chemicals, often cause "secondary phytotoxicity" in sensitive crops.
8. The herbicide is of poor quality. Herbicide is also of poor quality and contains substances or impurities that are irritating to some crops.
Effective measures to avoid phytotoxicity:
1. Prepare for pre-spraying. 1.1 First, according to the type of crop and the object of control, purchase the herbicide, and according to the instructions on the label, find out the name of the medicament, the dosage form, the content of the active ingredient and the amount of use.
1.2 Do a good job in the maintenance of the medical equipment, make a trial run, carry out a simulated water spray test, calculate the spray width, the walking speed and the area of ​​a sprayer (one bucket) of water to be sprayed.
1.3 Accurately measure the land area, calculate the dose according to the measured area, and prevent the drug from being too large or insufficient.
2, strict control of the appropriate period of medication. For example, in the spring wheat field, it should be carried out after the wheat is greened and before the jointing, and the herbicide can no longer be used after the jointing.
3, strictly control the amount of medication. In particular, some high-efficiency herbicides must be strictly controlled to prevent phytotoxicity.
4, farmland in addition to the operation area to stay away from sensitive crop fields (at least 100 meters or more) to avoid the herbicide drifting to sensitive crops on the main phytotoxicity.
5. Choose the appropriate environmental conditions for medication. Do not ban medication on windy days and hot noon. Sand should be appropriately reduced or not used.
6, do a good job of drug dilution. It is best to use the second dilution method to use the herbicide, that is, first dilute and stir the original medicinal small amount of water, and then add the sufficient amount of water according to the dilution factor, and the spray is uniform and thoughtful.
7. The medication should be thoroughly cleaned. Spray equipment sprayed with herbicides should be thoroughly cleaned thoroughly. Before spraying insecticides or fungicides, use water to test spray. If there is no phytotoxicity, use it again. Herbicides and pesticides should not be mixed.
8. Pay attention to the reasonable use of herbicides, because the same long-acting herbicides have a cumulative effect in successive years, which is easy to cause the resistance of weeds to produce drug damage or affect the crops.
9, to be familiar with the herbicide's medicinal properties. When using the herbicide herbicide, wear a protective cover on the sprayer nozzle and directional spray to avoid spraying the liquid onto the crop and causing phytotoxicity.
10. Do a good job in pharmaceutical testing. Before promoting the use of new herbicides, field trials should be carried out to test the herbicidal effects of herbicides and the safety of crops to prevent phytotoxicity.