Optimum time and temperature for spraying herbicide on wheat.
1. The optimum temperature for weeding wheat with herbicide is10-20 C, which has good effect and should not be applied at low temperature.
2. Generally, herbicides are sprayed before the emergence of wheat and at the time of 3 leaves 1 heart, and appropriate herbicides are selected according to weed species.
3. When applying pesticide, the daily average temperature shall not be lower than 5℃, which is usually carried out in the period of high temperature, and the pesticide is applied in the afternoon when the temperature drops in spring.
4. The effect of using herbicides in spring is not as good as that in winter, and there will be pesticide residues, which may affect the emergence and growth of the next crop.
5. According to the weather forecast, the spraying effect is good in sunny days. It is forbidden to spray in windy weather, and it is not advisable to water immediately after spraying.
A few days after spraying wheat herbicide, it took effect:
1. The effective time of herbicide depends on the kind of herbicide, whether it rains after spraying, spraying time and environment.
2, paraquat, about 2-3 hours, the weeds began to change color. Glyphosate usually takes effect in 5-7 days, the weeds turn yellow, and the weeds will slowly die in about half a month.
After spraying Baicaotan for 2 hours, the absorption and assimilation of carbon dioxide in the process of photosynthesis of weeds were inhibited. 1 1 hour all stopped, the leaves withered and turned yellow, and finally died.
3. After spraying the herbicide, if it rains immediately, the herbicide will be diluted by the rain, resulting in reduced efficacy or even failure.
4. The effective time of herbicides is related to environmental factors. For example, herbicides such as prometham and glyphosate have high activity and good weeding effect in high temperature and sunny days, but poor weeding effect in cloudy days and low temperature.