1. Tillage operation is blocked: If there are a large number of Rhizoma Bletillae, Descurainia sophia and Echinacea purpurea in the wheat field, there are more barnyard grass, Hedyotis diffusa and amaranth in the rice field, and the crops are prone to lodging, which will affect the 1000-grain weight and reduce the yield. After rice and wheat lodging, the harvester can't harvest. In soybean and corn fields, when the amount of hemp is large and the grass damage is serious, the harvester is easily blocked by grass and fails. In addition, if the grass is mixed too much during harvesting, it is not easy to dry, and it is easy to be moldy and cause losses.
2. Competing for fertilizer, light, water and space with crops: weeds have developed roots, and the stems on the creeping ground can also take root, with strong absorption capacity, fast seedling growth and high photosynthetic efficiency. Photosynthetic products are quickly transmitted and distributed to new leaves, and the vegetative growth is rapidly transferred to reproductive growth, which has the special property of disturbing crops, and its ability to capture water, nutrients and sunlight is much greater than that of crops. It has excellent growth characteristics and outstanding environmental adaptability.
3. Reduce crop yield and quality: After toxic wheat is mixed with wheat, the ground flour is toxic to people. If people eat it, it will cause dizziness, coma, nausea, vomiting, diarrhea, convulsions and even death. When livestock eat feed containing a certain amount of toxic wheat, it will also cause poisoning or death. Adding barnyard grass to rice will reduce rice quality and rice yield. Weeds in orchards can also affect the color and quality of fruits.
4. Breeding of pests and diseases (intermediate host): For example, as a virus transmission host, some weeds are infected by insects, and then the virus on weeds is transmitted to crops by insects, which becomes one of the important sources of infection of virus diseases; Cotton aphids overwinter on weeds such as seaweed and shepherd's purse; Barnyard grass is the intermediate host of rice planthopper and leafhopper.
5, affecting human and animal health: flour containing more than 4% poisonous wheat causes poisoning or even death; When livestock eat feed containing a certain amount of toxic wheat, it will also cause poisoning or death. Therefore, wheat poison is listed as the national quarantine object. Domestic animals eating feed containing wild oat seeds often cause inflammation of oral cavity, esophagus and gastric mucosa; The pollen of ragweed can make sensitive person allergic.
6. Impact on water conservancy facilities and river navigation: slow down the flow rate of rivers and canals, silting up, providing conditions for rats to nest and inhabit, thus damaging dams. At the same time, the river full of weeds will have a certain impact on the flood discharge capacity of the river. Generally speaking, the amount of water passed in a certain period of time is related to the section of the river. The larger the section, the greater the amount of water passed. If there are too many weeds and rubbish, the cross section will become smaller. At the same time, it will also affect the flow velocity of water and reduce the flood discharge capacity of rivers.