How is the herbicide type divided?
Herbicides, also known as herbicides, are agents that allow weeds to die completely or selectively. It can be widely used to control harmful plants such as weeds, miscellaneous irrigation and miscellaneous trees in farmland, orchard, flower nursery, grassland and non-cultivated land, railway lines, rivers, reservoirs and warehouses.
What are the types of herbicides? Herbicides can be classified according to the mode of action, the site of application, and the source of the compound.
1. Classification according to the nature of action
(1) Selective herbicides: Herbicides have different degrees of resistance to different types of seedlings. This agent can kill weeds and is harmless to seedlings. Such as cover grass energy, trifluralin, chlorpyrifos, simazine, fruit and so on.
The selectivity of the herbicide is not absolute, but relative, that is, the choice of herbicide does not affect the crop at all, can kill the weeds, but the selectivity under certain objects, doses, time and conditions. The selectivity is determined by the selection factor, and the larger the coefficient, the safer it is.
(2) Herbicides: Herbicides are toxic to all plants, as long as they are in contact with the green part, regardless of seedlings and weeds, they will be killed or killed. It is mainly used before sowing, before emergence, after sowing, and on the main and auxiliary roads of the nursery. Such as glyphosate and so on.
The movement of the classification of herbicides in plants
(1) Contact-type herbicide: When the agent is in contact with weeds, only the part in contact with the agent is killed, and the local killing effect is exerted, and the plant body cannot be transmitted. It can only kill the aerial parts of weeds, and it is less effective for the underground parts of weeds or perennial deep-rooted weeds with underground stems. Such as herbicide ether, paraquat and so on.
(2) uptake and type herbicides: medicament is roots or leaves, or stems absorb the coleoptile conducted to the plants, the plants die. Such as glyphosate, chlorpyrifos and so on.
(3) Systemic absorption and contact killing herbicides: It has the functions of systemic conduction and contact killing, such as herbicide.
3, according to the chemical structure of the classification
(1) Inorganic compound herbicide: a compound composed of a natural mineral raw material and containing no carbon, such as potassium chlorate or copper sulfate.
(2) Organic compound herbicide: mainly synthesized from organic compounds such as benzene, alcohol, fatty acid and organic amine. Such as ethers - Gore, s-trinitrobenzene - chlorpyrifos, substituted urea - herbicide No. 1, phenoxyacetic acid - 2 methyl 4-chloro, pyridine - grass, can Alkyl anilines - trifluralin, amides - cables, organophosphorus - glyphosate, phenols - sodium pentachlorophenol.
4, according to the method of use
(1) Stem and leaf treatment agent: the herbicide solution is watered and sprayed evenly on the plant with fine mist droplets. The herbicide used in this spraying method is called stem and leaf treatment agent, such as grass, glyphosate, etc. .
(2) Soil treatment agent: the herbicide is evenly sprayed onto the soil to form a layer of a certain thickness. When the seedlings, seedlings and roots of the weed seeds are contacted and absorbed, the grass killing action is exerted. Herbicides, called soil treatment agents, such as simazine, chlorpyrifos, trifluralin, etc., can be applied by spraying, pouring, or toxic soil.
(3) Stem and leaf, soil treatment agent: can be used for stem and leaf treatment, but also for soil treatment, such as atrazine.
5. Classification by application time
(1) Pre-sow treatment agent: refers to the process of sealing the soil before planting, such as the consumption of trifluralin in cotton fields and the use of wild wheat in wheat fields, all of which are sprayed on the soil before cotton or wheat sowing, and Stir into the soil to a certain depth, so that the weed roots and shoots can be absorbed, and can reduce the evaporation and photolysis loss of the herbicide.
(2) Pre-emergence treatment agent after sowing: the soil treatment is carried out before emergence of the crop after sowing. This method is mainly used for weeds and young leaves to absorb 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 emergence of the weed. Some herbicides such as paraquat and glyphosate can be eliminated in the middle and late stages of weed growth. Herbicide is usually a herbicide that is absorbed by stems and leaves and can be transmitted to other parts of the plant.
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