Wheat herbicides are generally recommended to be removed before winter. Before winter, wheat growth is not good or weeds do not emerge much. When weather conditions are not good, it is generally better to perform chemical removal in spring.
Weed emergence in wheat fields generally has two peak periods, one is before winter and the other is spring. Generally, the peak period of weed emergence before winter is the main period. Among them, weed emergence accounts for most of the field weeds under better winter conditions about 70-80% of the total. The weather is dry before winter. When wheat is planted late, weed emergence in the field will drop sharply, and most of them will emerge in spring. In general, it has the following benefits in addition to winterization before spring:
1. Save medicine. Pre-winter weeds are generally small and have poor resistance to pesticides. Generally, when used at low doses, they have better control effects, so they usually have a significantly lower dose than in spring.
2. Save time. Before winter, not only weeds are small, wheat leaves are relatively small, plants are not high, and weeds are generally not effectively covered. Therefore, weeds can be accurately sprayed when applied to weeds, which is efficient, fast, and can save time. If closed Application is more efficient.
3. Good prevention effect. The weeds before winter are small and have poor resistance. In addition, it is convenient and uniform to apply weeds in the field. Generally, weeds are not affected by wheat cover. Therefore, as long as there is no abnormal climatic conditions after application, the control effect is usually Better. Antibiotic weeds are also significantly more effective when treated with medicaments than stems and leaves.
Although wheat pre-wintering has the advantages of saving medicine, time, and good effects, wheat pre-wintering should be performed when the following conditions are met, otherwise it should be postponed to the Spring Festival.
1. Wheat seedlings. When the herbicide is used after seedling, generally, the crop is sensitive to the pesticide and the growth should be normal at the same time, otherwise it will cause pesticide damage. Closed weeding of wheat should be used before sowing of wheat after seeding, and post-emergence should be carried out after the three-leaf stage of wheat. It is not suitable for high temperature growth, yellowing of plants or leaves, or heavy fields where diseases and insect pests occur.
2. Weeds. Weeds should be almost uniform before winter, and sprayed when the weeds are in the 2-3 leaf stage. When it is too small or too large, it will affect the prevention effect.
3. Meteorological conditions. Generally, the average daily temperature should be above 8 ℃, and the medicine should be used at noon in fine weather. There will be no strong wind and rain or snow in 1 week after the medicine. Otherwise, it will affect the prevention effect and even cause drug damage.
In short, if it is suitable for removal before winter, it should be carried out in time before winter, otherwise it is better to spray and control road chemicals according to the field weed species in time before jointing in spring.