First, the correct choice of herbicides. Each herbicide has a certain herbicidal spectrum, which is non-productive and selective. For example, Gramoxone can kill all the green plants, and wild barley only controls wild oats. Yunonong can kill almost all weeds and crops except corn. Another example is tribenuron-methyl, thrips in control of broad-leaved weeds and gramineous weeds in wheat fields, and it is also safe for wheat. If used in rapeseeds, beans, etc., it will kill crops. Another example is the use of canola, peanuts, soybeans and other broad-leaved crops. If it is used in wheat fields, it will produce phytotoxicity. Therefore, we must first select effective herbicides based on the crop species and the main varieties of weeds. Second, herbicides should be selected according to the farming system. Such as superstars, dimethyl tetrachlorine, humican, etc., can be used in a variety of planting systems weeding, but chlorsulfuron, metsulfuron, etc., can only be used in the wheat field under the rice-wheat rotation system, if the post-corner is corn, soybean And so on, there will be different symptoms of phytotoxicity. In addition, we must pay attention to mixing and alternation herbicides. Because the same kind of herbicides are used for many years continuously, the susceptible weeds are gradually reduced, and the resistance to weeds is increased. Therefore, herbicides must be mixed and used alternately each year to achieve long-term control of weeds.
Second, choose the best time for spraying. According to the nature of the herbicide, the time of weed occurrence, weeds and the growth period of the crop, the appropriate period of application is selected. There are many types of herbicides, including herbicides for stem and leaf treatment, herbicides for soil treatment, contact herbicides, and herbicides for eradication. Some of them are suitable for pre-emergence weed control and others are suitable for weed control of stems and leaves. Soil treatment herbicides are applied directly to the soil surface to kill just-grown weeds. If dole, acetochlor, etc., should be used before the weeds are unearthed after the sowing of the crops. When the weeds are applied after the emergence of the weeds, not only the effect is poor, but also some of them will injure the crops. Stem and leaf herbicides at the seedling stage should be used at the sensitive stage of weeds (before the second leaf stage) and when the crops have strong drug resistance (after two leaves and one heart). For example, in the field of wheat seedlings, weed herbicides are used in most grassy weeds in the period from the first leaf to the second leaf stage, and broadleaf weeds are used before the second leaf stage. For example, when paddy fields are dominated by valerian and cattle blankets, weeding should be applied 4 to 6 days after weeding (weeds germination stage); if the focus is on controlling weeds like Tianzi Cai, Tian Ziping, etc. 15 days (basic weed out) is appropriate.
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