The best time to use pesticides
(1) The best time to use pesticides
In the process of crop planting, pesticides are applied when pests and diseases occur. What time is the most effective? Xiaobian has done some research, for reference only: the best time to fight different crops in different seasons is different, for example, for cucumbers in greenhouses, in general, in the summer and autumn high temperature season The best time for pesticide application should be selected at around 9 am and after 4 pm on sunny days. At around 9:00 am, the general dew is dry, the temperature is not too high, and it is the most vigorous time for pests and diseases. At this time, the effect of the drug is good; after 4 pm, the light is getting weaker, the temperature is getting lower, and the night pests are getting out. (Powder, hummer) began to be active, spraying at this time, also has a higher sterilization and pest control effect. Practice has proved that spraying pesticides in summer, whether for food crops, vegetable crops, cash crops, or fruit trees, should be the best time between 8:00 am and 5:00 pm. What is the reason for this?
This is because: around 9 am, the general dew is dry, the temperature is not too high, it is the sunrise, pests feeding, activity, mating the most vigorous time, so the medication at this time, will not be washed or diluted by the dew Reduce the efficacy of the drug, and will not affect the efficacy of the drug due to high temperature. On the contrary, the use of drugs at this time will increase the chances of pests feeding and taking medicine, effectively improving the lethality of pesticides. At about 5 o'clock in the afternoon, the sun is already westward. It is the "Japanese medicine Xishan evening". At this time, the light is getting weaker, and the night-time pests are active (feeding, mating, etc.). Higher killing effect.
Also note that it is not advisable to spray pesticides at noon. Therefore, the temperature is high, the sun is strong, and some pests are afraid of glare and hide in the backlight, or even stop the activity. In addition, the drug decomposes rapidly at high temperatures, so the efficacy is reduced. At the same time, the general drug solution is evaporated at noon, which is easy to cause poisoning of humans and animals.
In the winter and spring low temperature season, the pesticide application time is preferably from 2:30 to 3:30 pm. Because of the low temperature in the shed during the winter and spring seasons, the photosynthesis gradually enters the peak period after the morning leaves dew. If the spraying in the morning is bound to affect the temperature increase and reduce the photosynthetic efficiency, it is not suitable for medication in the morning. Do not spray at noon on sunny days. Because the temperature in the shed is high when spraying at noon, the high temperature tends to promote the decomposition of the drug and the volatilization of the active ingredient of the drug. In addition, in hot weather, the vitality of the crops will become strong, and the stomata on the leaves will be open and large. If the medicament is sprayed at this time, the medicament will easily invade the crop body, and the chance of being harmed by the medicine is greatly increased. In addition, when spraying at noon, the chemical activity of the agent will also become stronger, and the toxicity of the pesticide will also become larger, which is highly prone to poisoning incidents of the application personnel.
(two) efficacy
(1) Reasons for pesticides: The chemical composition, physical and chemical properties, mechanism of action, dosage and processing properties of pesticides directly or indirectly affect the efficacy. For example, chlorpyrifos is effective against many lepidopteran pests, but not for mites; the effect of controlling lepidopteran pests with 20 ml and 40 ml per acre is quite different. According to the control object, the type of crop and the period of use, choose the appropriate pesticide variety, dosage form and dosage.
(2) Reasons for prevention and treatment: There are differences in living habits of different pests and diseases. Even if the same disease or pest, the response to different pesticides or similar pesticides is different due to different developmental stages, it is often manifested as the difference in control effects. For example, the grass can be effective against most grass weeds and is not effective against broadleaf weeds; monocrotophos has a good effect on the first and second instar larvae of cotton bollworm, but it is less effective for larvae after 3 years old.
(3) Environmental reasons: environmental factors such as temperature, humidity, rain, light, wind and soil properties directly affect the physiological activities of pests and diseases and the performance of pesticides, and the results will affect the efficacy of pesticides. For example, the herbicides acetochlor, trifluralin, laso, and dur are used at the same dosage. The herbicidal effect is poor during drought, and the herbicidal effect is high under suitable soil moisture conditions. The effect on sand land is significantly higher than that in It is used in the ground where the organic matter content is high. The phoxim is easy to decompose and is ineffective. Therefore, before using pesticides, it is necessary to master its performance characteristics, biological characteristics of the control object; in the application process, make full use of all favorable factors to control adverse factors, in order to achieve the best control effect.
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