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2. The sedge, straw, wheat stubble and big grass left in the wheat field. Now the harvest of the wheat field is harvested by a large harvester. The height of the wheat stubble is 25-30 cm. The wheat straw and wheat bran are scattered to the field. The farmers do not kill the cockroach, do not concentrate, and do not pull it out. They use mechanical sowing to spray the medicine. Less on the surface of the soil and weeds, it does not play a role in closing the ground and killing weeds. The grass is left in the wheat field, and the current corn herbicide has little effect on it. 3. envirnmental factor. Summer maize sowing period is mostly in mid-June, at this time, high temperature, drought, less rain, and abnormal climate change. After spraying the herbicide, the liquid evaporates and is fast, and it is difficult to form a closed film on the surface of the soil; high temperature and drought also hinder the drug effect in the weed body to transport and conduct; sometimes it suddenly rains after spraying, so that the drug effect is lost with the rain.
4. Spraying is late and the dosage is small. The currently used corn herbicides have the best effect on spraying before the 5-leaf stage of weeds. However, some farmers sprayed the drugs in time, the weeds grew, the drug resistance increased, and the best period of prevention and control was missed. In order to save labor and labor, some farmers add a small amount of water when disposing the liquid. Generally, only about 15 kg per mu is used. After spraying, the ground shape is not a film, which does not achieve the expected control effect.
5. Failed to use the medicine correctly. (1) When the suspending agent herbicide is not sufficiently shaken, it is used. (2) Instead of using the inverted spray method, the forward type is used, so that the ground that has just been closed with the liquid is trampled by the foot, and the foot continues to grow. (3) The spraying is uneven, and there is a phenomenon of leakage spray and heavy spray. (4) The spraying time is wrong. Spraying around noon, the liquid evaporates quickly, which reduces the efficacy. (5) Spraying on a windy day, some pesticides fall outside the corn field, and the effective dose is reduced, which affects the effect of weeding.
Main factors affecting the effectiveness of herbicides
1. Improper selection of herbicides. Since most farmers do not know enough about the chemical composition of herbicides and the types of weeds, they cannot be used on the types of grasses.
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