What unfavorable weather conditions should be avoided when applying pesticides?
What do the letters on a pesticide label mean? Here is an introduction: (1) pH: indicates acidity and alkalinity. When the pH value equals 7, it is neutral; above 7, it is alkaline, and the larger the number, the stronger the alkalinity. Below 7, it is acidic, and the smaller the number, the stronger the acidity; (2) PPm: parts per million concentration. That is, the number of pesticide parts contained in 1 million parts of liquid or powder; ...
What kind of weather is unsuitable for applying pesticides? Here is an introduction.The control effect of pesticides is often affected by weather. Under climatic conditions such as strong wind, rain, high temperature and high humidity, using pesticides will affect the normal performance of the pesticide's efficacy. Therefore, pesticides should not be applied under the above weather conditions. The reasons are as follows:
(1) Do not apply pesticides in strong wind. This is because windy weather easily makes the sprayed powder or spray droplets drift with the wind, so they cannot quickly fall and evenly attach to the surface of the crops to be protected; at the same time, the pesticide drifting onto nearby sensitive crops can easily cause phytotoxicity, drifting onto the applicator's body can easily cause poisoning, and drifting into the air and water sources can easily cause environmental pollution. Even if part of the pesticide reaches the surface of the crops to be protected, because the crop plants sway and rub against each other under the influence of strong wind, it will also cause the loss of the pesticide.
(2) Do not apply pesticides on cloudy days, when rain is imminent, or on rainy days. This is because rainwater can directly wash away the pesticide, causing loss, which not only affects the control effect but also causes pollution of rivers and waters, leading to the poisoning and death of fish, shrimp and other aquatic organisms. Different pesticide varieties and formulations have different abilities to resist rain washing. Generally, systemic pesticides can be absorbed into the plant body, so they are less affected by rain; especially seed-dressing pesticides are even less affected by rain. Among formulations, powders and wettable powders are the least resistant to rain washing and are easily lost, while emulsifiable concentrate pesticides, because they form an oil film on the crops, have a certain resistance to rain washing, but there is also a certain limit.
(3) Do not apply pesticides in high-temperature weather. High temperature will promote the decomposition of pesticides and accelerate the volatilization of the pesticide, thereby shortening the pesticide's residual effect period and reducing the control effect. At the same time, because crops have vigorous metabolism in hot weather, the leaf stomata open more and wider, and the pesticide can easily enter the plant body, causing phytotoxicity. Therefore, at high temperatures, even if pesticides must be applied as a last resort, the pesticide concentration should be appropriately reduced, and application should as far as possible not be done at noon, so as to avoid phytotoxicity and applicator poisoning accidents.
(4) Do not apply pesticides in high-humidity weather. If the air humidity is high, with heavy fog or a lot of dew, it is easy to cause chemical decomposition of the pesticide, making the pesticide ineffective or causing crop phytotoxicity. However, when microbial pesticides are used under high-temperature conditions, they can better exert their efficacy.
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