Herbicides require higher use techniques than insecticides and fungicides; misuse of pesticides and fungicides may only affect the control effect. The misuse of herbicides will not only affect the weeding effect, but may also occur. It only kills the crop and the weeds are safe and sound. Therefore, it is necessary to correctly select the type of herbicide, the strict use amount, the period of use and the method of use.
(1) Strictly distinguish the type of herbicide: A herbicide has its strictly defined crop types. When used, it must be strictly distinguished, and the scope of use cannot be blindly expanded. For example, 2,4-D-butyl ester is only suitable for wheat fields; it is sensitive to dicotyledonous crops such as cotton, peanuts, soybeans, spinach, and tomatoes. Very small amounts of 2,4-D-butyl ester can cause serious phytotoxicity in cotton. For example, acetochlor is suitable for broad-leaved crops such as corn, peanuts, cotton, and soybeans, but it is susceptible to phytotoxicity to wheat.
(2) The use of strict herbicides: The selectivity of herbicides is the selectivity within a certain dosage range. Therefore, even selective herbicides may cause phytotoxicity to crops beyond the specified dosage range. . For example, 2,4-D-butyl ester has certain selectivity to wheat, but when the dosage is too large, it will also kill wheat or severely deform wheat plants, affecting yield. In addition, the amount of herbicides is also affected by factors such as crop type, soil texture, and climatic conditions.
(3) The period of use of strict herbicides: Different types of herbicides are used in different periods. Pre-emergence herbicides can only be absorbed by the radicle, coleoptera or hypocotyl of weeds, killing weeds. After the grass is used after emergence, there is generally no herbicidal effect or the herbicidal effect is very low. Post-emergence herbicides are also safe and effective for use in weeds or crops at a certain stage of growth. For example, the grass grass can be used in the 3 to 5 leaf stage of weeds, and the control effect on grass weeds is usually 90 to 100%, but the effect is lower after the 5 leaf stage.
(4) How to use strict herbicides: The methods of using herbicides include stem and leaf treatment, soil treatment and herbicidal method. At present, the most commonly used methods are stem and leaf treatment during the growth period and soil treatment before sowing. Stem and leaf treatment during the growth period is a method of spraying herbicides on weed stems and leaves at a certain growth stage after crop emergence. In this way, the herbicide is not only exposed to weeds, but also to crops, so herbicides are required to have a higher selectivity or directed spray for safe application. The post-emergence soil treatment after sowing is a method of spraying the herbicide on the soil surface before the crop is planted. Most soil treatment agents are used in this way. Stem and leaf treatment herbicides usually fall into the soil and are quickly deactivated or decomposed by microorganisms to lose herbicidal activity, while soil treatment herbicides are generally ineffective against weeds after emergence. Therefore, herbicides are different and the method of use is different.
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