Weeds are plants whose growth seriously interferes with crops. Weeds breed easily. These plants belong to poisonous herbs, they are on all continents, but there is no benefit from them.
Not all weeds were originally such. So, for example, if sunflower, which does not belong to weeds, showers its seeds, then some of them will sprout in the spring and will clog the crops of cultivated plants. Most often these are winter crops that are sown in this place after sunflower.
Weed plants, the species amount of which has already exceeded several thousand, cause serious harm to the agricultural sector, and this harm is diverse. They absorb a huge amount of water from the soil, their roots poison the soil with emitted harmful substances. Consuming a lot of water, they are characterized by rapid growth, respectively, crop plants are deprived of light , while the yield is reduced. Sometimes crops even die.
Serious losses during harvesting are caused by clumps of weeds such as field bindweed or highlander bindweed. Under their weight, crops are lodged, which means that their harvesting will be difficult - and part of the crop will remain in the fields.
Harvesting machines suffer from weeds (artisans, sow thistles, etc.) , their parts become clogged with grass, which leads to reduced productivity. At the same time, weeds are able to reduce the quality of the harvested crop. This is due to increased humidity of the seed and grain when the juicy parts of weeds get into the harvested crop.
One cannot fail to mention one more misfortune. Sometimes seeds of poisonous weeds fall into the grain, and then this leads to poisoning of domestic animals, and sometimes humans. Weed plants can reduce yield and nutrition, and sometimes even completely displace forage grass varieties from farmland. Weeds leading to siltation of irrigation canals, in addition, reduce their throughput. And in the hot season they become the source of fires. Especially dangerous is the abundance of weeds in the so-called exclusion zone of oil pipelines or gas pipelines.
Classification of weeds is carried out according to several criteria: place of growth, characteristics of reproduction, distribution and renewal.
According to the characteristics of reproduction, there are three biological groups: perennial and 2 groups of young plants (seed and vegetative). The group of seed infants includes plants that multiply, spread and renew with the help of a seed, fetus or seed germ. They are both annual and biennial.
Annual weeds are divided into subgroups. In the subgroup of early spring crops, which are the main pests for early spring crops, quinoa, oatmeal, hemp. The subgroup of late spring, which clogs millet and actively interferes with the development of late spring, includes weeds, the names of which are bristles, shiritsa, etc. The subgroup of winter weed plants tolerates winter well, bearing fruit in a year.This group of plants causes the main damage to winter crops. The wintering group includes a shepherd’s bag and a field yakut.
Two-year-old weeds live for two years: in the first year of life, vegetative organs from the seed appear, and the plant bears fruit and dies in the second year of life.
A separate group is made up of parasitic weeds, which include dodder, broomrape, late dentate or large rattles. Dodger is attached to the stalk of alfalfa, clover or another plant, the broomrape is fed from the roots of tomatoes, alfalfa or tobacco, and the last two weeds are semi-parasites.