Many types of herbicides, although the same herbicide, but their effectiveness is different, must be strictly distinguished, there are many herbicides classification, as according to the different mode of action, the herbicide can be divided into systemic herbicide and Contact herbicides, according to different methods of pest control, can be divided into extinct herbicides and selective herbicides, etc., let's take a look at the small series below.
First, according to the mode of action can be divided into
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 herbicide
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.
Second, according to the method of pest control can be divided into
1. Extinction herbicide (ie non-selective herbicide): refers to herbicides that can kill all crops and weeds in a selective manner, such as paraquat, glyphosate, etc. under normal dosage.
2. Selective herbicides: herbicides that only kill weeds without harming crops, or even killing one or a certain type of weeds, such as propanil, acetochlor, butachlor, and napu.
Third, according to the application of drugs can be divided into
1. Soil treatment agent
That is, the herbicide is sprayed on the surface of the soil or the herbicide is mixed into the soil to a certain depth by a soil mixing operation, and a herbicide sealing layer is established to kill the germinated weeds. 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
That is, 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 the stems and leaves of the weeds. Stem and leaf treatment mainly uses the physiological and biochemical selectivity of herbicides to achieve the purpose of killing grass and protecting seedlings.
Fourth, according to the time of application can be divided into
1, pre-shipment treatment agent
Refers to the closure of the soil before planting, such as the use of trifluralin in cotton fields and the use of wild wheat in wheat fields. The herbicides are sprayed into the soil before sowing in cotton or wheat, and mixed into the soil to a certain depth so that It is absorbed by weed roots and shoots, and can prevent or reduce the volatilization and photolysis loss of herbicides.
2. Pre-emergence treatment agent after sowing
That is, the soil is treated before the emergence of the crop, and the 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-treatment agent
Refers to spraying the herbicide directly onto the weed plants after the weeds emerge. 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.
5. According to the scope of application, it can be divided into
1, full application
That is, uniform and uniform spraying of the whole field, including weeds and crops. This applies to the case where highly selective herbicides and weeds are weeded in crops that are common throughout the field and are dense.
2, strip application
The liquid medicine can be placed in a continuous limited range, and a fan-shaped nozzle can be used, for example, a planting belt of about 5 cm in a crop is sprayed to eliminate inter-plant weeds on the crop belt, and the field weeds other than the seed belt are used. Interplanting crops or artificially assisted cultivating. Strip spray can save one-half to two-thirds or more of the dose, but requires more sprayer attachments and reduces the amount of work by about 15%.
The above is the classification of herbicides. To learn more about pesticides , please pay attention to pesticides.
3, point application
It can be used to treat a limited area, such as grass or as a partial re-spray after crop treatment, or to spray the core distribution of weeds (such as perennial weeds such as fragrant aconite). This method is highly targeted and economical.
4, directional spray
Control the spray direction of the liquid, apply it to weeds or the ground, and try not to touch the crop as much as possible. This is a protective spray for post-emergence crop treatment with some of its biocide or contact herbicides.
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