In nature, there are thousands of varieties of annual and perennial weeds.These ubiquitous "annoyed" make a tough competition to the crop plants, robbing them of moisture, light and nutrients from the soil.Such a common method as weeding, are not always effective against weeds as perennial species germinate quickly in the soil of the remaining parts of the rhizomes.It was then, and come to the aid of herbicides to control weeds.
herbicides
Herbicides - are special chemicals intended to control the amount of
or prevent the growth of weeds.In addition, using the herbicidal compositions is possible to reduce or even eliminate manual or mechanized cultivation, thereby reducing moisture loss and prevents soil erosion.Herbicides are divided into two categories - non-selective (continuous action) and selective (selective).
herbicides to control weeds nonselective
solid herbicidal compositions are used in the absence of action on the field
(garden) of cultivated plants, as they destroy all existing vegetation, penetrating into the leaf surface.Typically, non-selective means are used until the first sprouts after harvest or when the field settles vapor.However, recent developments make it possible to use some types of herbicides in this category as the sample to genetically modified varieties
and hybrids of crops (such as soybeans, sugar beets, potatoes and so on.), Since they have a gene for resistance to these funds.The action of non-selective herbicides can be done in two ways - contact and systemic.If the contact action of the drug is influenced directly on the treated surface.They start working very quickly and are not washed off by rain.In the systemic action of the active substance, moving the plant to the point of its growth, causing their extinction.Such funds are absorbed more slowly into the plant, but is very effective in killing perennial weeds with a powerful and extensive root system.
herbicides to control weeds
selective herbicidal agents selective use for specific crops without damaging them, but only to suppress weeds, growing the culture in the same field.These agents include various chemical classes and possess different mechanisms of action.To eliminate the phytotoxicity of the drug culture, in certain instances, the antidotes.Herbicides to control weeds possess biochemical selectivity, based on the ability of the plants to destroy their toxic compounds into non-toxic.Morphological selectivity is based on differences in the external structure of crop plants, namely in the form and arrangement of the leaves, as well as characteristics of their surfaces (hairiness, waxy film and so on.) - All of which prevents the penetration of herbicides.
Topographic selectivity is characterized by fixation of herbicide in the upper layer of soil by absorbing its colloidal particles (clay, humus), so that the toxic effect of the drug does not reach the roots of the crop and weeds growing in the upper soil layer, are destroyed.The most effective currently selective herbicides for controlling weeds.The price of these preparations depends on their composition and mode of action.
