There are many types of weeding in the market, and there is no clear classification for which the types of herbicides are removed. The reason why the herbicide type is not clear is because the herbicide classification basis is very different, as follows:
Which types of herbicides can be divided according to the following methods: according to the method of use, they are divided into stem and leaf treatment agents and soil sealing treatment agents; according to their mode of action, they are divided into two types: selective and natural; according to the conductivity in plants It is a contact herbicide and a conductive herbicide; it is classified into a sulfonamide herbicide and a malic acid herbicide according to chemical composition.
It can also be divided as follows:
According to the action mode of herbicides, it can be divided into systemic herbicides and contact herbicides.
1. Systemic herbicide
Some herbicides can be absorbed by the weed rhizomes and leaves separately or simultaneously, transported to various parts of the plant body through the transporting tissue, destroying its internal structure and physiological balance, thereby causing the plant to die. This method is called systemic. Herbicide with this characteristic is called systemic herbicide, such as 2, 4, 4, and glyphosate can be absorbed by the stems and leaves of plants, and then moved to various parts of the plant, including underground rhizomes, so glyphosate It can prevent annual weeds and prevent weeds.
2. Contact herbicides Some herbicides are sprayed onto plants and can only kill the part of the plant tissue that is in direct contact with the agent, but cannot be internally absorbed. A herbicide with this characteristic is called a contact herbicide. This type of herbicide can only kill the aerial parts of weeds, and has a poor effect on perennial weeds in the lower part of the weeds or underground reproductive organs, such as herbicide ether and sodium pentachlorophenol.
According to the nature of herbicides, it can be divided into herbicides and selective herbicides.
1. Herbicides Some herbicides, indiscriminately kill all kinds of weeds and crops, this herbicide is called a herbicide, such as sodium pentachlorophenol, gram, glyphosate and so on.
2, selective herbicide Some herbicides can kill some weeds, but not for other weeds, for some crops, but for other crops, this is selective, weeding with this characteristic The agent is called a selective herbicide. For example, 2 to 4 chlorine can only kill weeds such as ragweed, water leek, sedge, water sedge, etc., but it is ineffective against grass weeds such as valerian, double-spotted damselfly, safe for rice, suitable for rice fields. It is used in wheat fields and corn fields, but it has serious phytotoxicity to broad-leaved crops such as cotton, soybeans and vegetables. Another example is that the enemy can kill the weeds and protect the rice; the West Majin can kill a variety of annual weeds such as crabgrass and crickets, and it is safe for corn; and the grasses and wild swallows can kill wild oats. Safe for wheat, etc.
According to herbicide application, it can be divided into soil treatment agent and stem and leaf treatment agent.
1. Soil treatment agent: The herbicide is sprayed on the surface layer of the soil or the herbicide is mixed into the soil to a certain depth by mixing operation, and a herbicide sealing layer is established to kill the germinated weed. In addition to the use of physiological and biochemical selectivity to eliminate weeds, soil treatment of herbicides in many cases uses time difference or difference to selectively kill grass. Such as fluoxetine, herbicide ether, simazine, Afida and so on.
2. Stem and leaf treatment agent: the herbicide is diluted in a certain amount of water or other inert filler, the weed seedlings are sprayed, and the weeds are eliminated by the absorption and conduction of weed stems and leaves. Stem and leaf treatment mainly uses the physiological and biochemical selectivity of herbicides to achieve the purpose of killing grass and protecting seedlings.
According to the herbicide application time, it can be divided into pre-sow treatment agent, pre-emergence treatment agent and post-emergence treatment agent.
1. Pre-sow treatment agent: refers to the sealing treatment of the soil before the crop is planted. For example, the use of trifluralin in the cotton field and the wild wheat in the wheat field are all sprayed into the soil before the cotton or wheat sowing, and mixed. Enter a certain depth in the soil to absorb the weed roots and shoots, and prevent or reduce the volatilization and photolysis loss of the herbicide.
2. Pre-emergence treatment agent after sowing: the soil treatment is carried out before the emergence of the crop after the crop is planted. This method is mainly used for weeds and young leaves to absorb the herbicides that are transmitted to the growth point, and is safe for crop shoots.
3. Post-emergence treatment agent: refers to spraying the herbicide directly onto the weed plant after the weed emergence. Some herbicides such as paraquat and glyphosate can be eliminated in the middle and late stages of weed growth. Herbicide is generally a herbicide that is absorbed by stems and leaves and can be transmitted to other parts of the plant.
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