What should be paid attention to in chemical weeding?

What should be paid attention to in chemical weeding? Please introduce chemical herbicides with strong selectivity and specificity. The technical requirements of its use are more stringent than pesticides and fungicides, and improper use often causes drug damage. In order to give full play to the role of herbicides in agricultural production, attention should be paid to the following seven points. (1) the correct selection of pesticides is to choose the herbicides corresponding to the herbicide spectrum if the weeds in the field are mainly used. The second is to select herbicides according to field crops. Third, according to the drug use period, the drugs before sowing can not be used for post-seedling application, and those suitable for soil treatment can not be used for stem and leaf treatment. (2) the strict dosage of herbicides shall strictly follow the standards stipulated in the instructions for use, and shall not be increased at will. If 2 or more herbicides are mixed, the dosage of each herbicide shall be 1 × 3-1 × 2 of the normal dosage of the herbicide. The dosage of herbicide covered with plastic film should be 3 beat 4-2 beat 3 of the conventional dosage. The amount of liquid used in every 667m2 (after the original solution to water), the amount of soil treatment is generally about 3kg, and that of stems and leaves is generally not less than 40kg. (3) Scientific dispensing is the scientific mixing of herbicides, and when two or more herbicides are used to kill many kinds of weeds at the same time, the herbicides mixed must have different herbicide spectra, but the applicable crops, applicable periods and methods of use must kiss each other. The second is to prepare the liquid scientifically, first dissolve the wettable herbicide in a small amount of water, make the mother liquid, then install the semi-sprayer water, then pour the mother liquid into the sprayer, and finally add enough water to shake well before spraying. If the wettable powder is mixed with the EC, the wettable powder should be made into the mother liquid first, then the EC should be poured into the emulsion and applied with enough water according to the above method. (4) the appropriate period of drug use shall be strictly in accordance with the instructions for the use of herbicides during the specified period. If it is suitable for pre-sowing treatment, the soil should be treated before sowing, and if it is suitable for post-sowing and pre-bud, it should be applied before bud after sowing. For the herbicides treated with stems and leaves, on the basis of finding out the growth period of crops, the sensitive period must be avoided and applied in the 2-4 leaf stage of weeds in order to achieve the purpose of effective weeding and preventing drug damage. (5) when spraying herbicides, try to avoid high temperature, high humidity or windy weather, so as to prevent drug damage or reduce the efficacy. It is generally advisable to choose sunny and windless weather of 20 ℃-30 ℃. The high temperature season should be carried out before 10:00 or after 4 p.m. (6) the scientific operation of spraying herbicides should be done carefully and scientifically, so as to ensure that the walking speed is uniform and appropriate, the working pressure of the sprayer is stable and moderate, the field round-trip stubble is accurate, no leakage spray is not repeated, and the sprinkler head is kept low as far as possible. When useful, you should first spray the thunder, and then spray the thunder, the orifice direction should be consistent with the wind direction, and the walking direction should be perpendicular to the wind direction. Leave a protective belt at a certain distance when there are other sensitive crops around the application field. When dealing with stems and leaves, try to make the liquid wet the stems and leaves, but do not make the liquid fall to the ground. In short, the application should be uniform and consistent. (7) sprayers and other appliances for cleaning utensils that are sprayed with herbicides must be washed thoroughly with alkaline water before they can be used in other crop fields to prevent drug damage. Click to get more herbicide application techniques