Whether the pesticide can be applied when the crop is flowering. Answering this question should be considered in many aspects. It is necessary to pay attention to the type, toxicity and residual level of pesticides, and pay attention to the concentration and dosage at the time of use. It is also necessary to pay attention to the timing of crops during flowering.
First, to prevent the application of highly toxic and high residual pesticides
In general, the flowering period of a crop is a critical period for the formation of fruit and grain. At this time, most of the substances absorbed by the vegetative organs such as stems and leaves of the crop are transported to the fruit or the ear, and a part of them will form a constituent material of the fruit or the kernel. Therefore, in the flowering period of crops, it is necessary to use high-efficiency, low-toxic and low-residue pesticides. Do not use highly toxic and highly residual pesticides to prevent excessive levels of pesticides in fruits and grains, and contaminate crop products. Food crops and melons and vegetables should be especially stressful to prevent the health of consumers.
Second, some pesticides have phytotoxicity to flowering crops
For example, cucumber, watermelon, eggplant and other crops are sensitive to the herbicide acetochlor (Wernes), especially in the flowering stage, the plants that grow vigorously, the young shoots can absorb the drugs, and it is easy to have symptoms of phytotoxicity. When taking the agent, pay special attention to the choice of spraying in a windless weather where the temperature is not too high. Do not let the drug touch these sensitive crops. Profenofos is a commonly used agent for controlling rice leaf roller in recent years. However, it must be used before the rice break period. If it is applied during flowering or filling, it will cause odor and difficult to enter.
In addition, profenofos is used in vegetables, and if the application period is not appropriate, it will also cause serious odors in vegetables, which is unbearable.
Third, the crop flowering period should be selected
Some crops are improperly applied during flowering, which can affect pollination or fertilization, and some can cause phytotoxicity. Therefore, we must master the appropriate time for the application of flowers. For example, the flowering time of late rice is mostly from 9:00 am to 2:00 pm, and the flowering amount is the most at 10-12 hours. When the rice is flowering, the husk is opened and the filament is rapidly elongated. The pollen is topped outside the hull. If the drug is applied at this time, the liquid (or powder) can easily enter the flower, kill or kill the pollen and the ovary. At the same time, the drugs entering the flower will also wash down the pollen, which seriously affects the pollination and firmness, resulting in an increase in the rate of imperfections. Therefore, the flowering period should be carried out after 3 pm after pollination and the hull has closed.
Cotton generally blooms in the morning. If it is sprayed or sprayed in the morning, the osmotic pressure of the stigma of the flower will be reduced, and the pollen will be broken, causing the ovary not to be inseminated and fall off. Therefore, when cotton is applied during flowering, it should be after 4 pm, soybeans usually bloom at 6 o'clock in the morning, 8-10 o'clock is the flowering period, and there is very little flowering in the afternoon. Windy days flower early, cloudy flowering delay, stamen anthers have been cracked before flower opening, corolla 15-20 minutes after pollen germination, and wilting after about 2 days. According to the test, the application of the drug at 6 o'clock in the morning when the dew is large, generally reduces the yield by about 10%, and the glutinous granules increase. Therefore, the application of soybean should be selected after 3-4 pm. Crops such as wheat and broad beans should not be applied during the flowering period and should be carried out before or after flowering.
Fourth, to prevent high or high dose medication
When the crop is flowering, the newly extracted ear or flower tissue is young and the drug resistance is weak. At this time, the concentration of the drug and the amount of the drug should be mastered more than usual, so as to avoid phytotoxicity.
In addition, if there is no rain or dry air during the flowering period, less or no powder pesticide should be applied, and pesticides such as emulsion pesticides or wettable powders should be sprayed or poured, and the amount of water should be appropriately increased when formulating pesticides. This can effectively prevent flowering phytotoxicity.
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