1, corn blocking herbicide
Closed herbicide for corn mainly refers to spraying closed soil before sowing (or transplanting) or before emergence of crops after sowing to kill weeds that have not yet emerged. Such herbicides in corn fields include acetochlor amide, metolachlor, triazene and so on. It can control many annual gramineous weeds and some small-grained broad-leaved weeds in the field.
2. Herbicide after maize seedling
The herbicide is sprayed for 2~5 leaves after maize seedling, at this time, maize has strong resistance and is not easy to be harmed.
It can be sprayed all over the field before the fifth leaf and after the sixth leaf. It is necessary to lower the nozzle and spray around the corn seeds to prevent the drug damage caused by liquid medicine perfusion.
Due to drought and low temperature, corn grows slowly and weeds appear irregularly in northern spring corn fields. When the weeds are in full bloom, the corn has passed the five-leaf stage. Some pesticides have poor efficacy, so it is easy to cause phytotoxicity if nicosulfuron is used again. It is easy to cause phytotoxicity if applied too early or too late.
If no pesticides are applied during this period or the soil sealing effect is not good, you can choose to use post-emergence herbicides to spray the stems and leaves of weeds that have emerged, and the control effect is still good.
In addition, we should know that pre-emergence herbicides have been on the market for a long time, and post-emergence herbicides will not be available until several years later.
3. Pre-emergence herbicide:
The main components are "acetochlor and atrazine (atrazine)", and there are also products of atrazine compounded with alachlor, butachlor and metolachlor.
Advantages: the soil is closed, and there is basically no phytotoxicity to corn.
Disadvantages: It is greatly influenced by the climate, especially in the case of drought, which often affects the weeding effect.
In particular, the wheat harvested by machine is too high, the straw coverage rate is high, and the amount of farmers' liquid medicine is insufficient, which directly affects the effect.
4. Post-emergence herbicide:
The main components are nicosulfuron, mesotrione, oxadiazon and oxadiazon (domestic patented products), as well as these four kinds of mixed atrazine products and ternary compound products (all products are sold by manufacturers, but the main weeding effects are nicosulfuron, mesotrione, oxadiazon and oxadiazon).
It is worth noting that nicosulfuron is easy to cause phytotoxicity to corn seedlings. Even if some manufacturers introduce so-called safety agents, don't believe it.
Advantages: Compared with pre-emergence herbicides, it uses less water and is less affected by climate.
Disadvantages: Improper use can easily cause phytotoxicity (especially the first two are easy to cause phytotoxicity, while the latter two are relatively safe but costly).
5. Matters needing attention in using corn herbicide
(1) Carry out constant spraying according to the prescribed dose, and do not increase the dose at will.
(2) Adopt the "secondary dilution method", first prepare the mother liquor, and then spray water evenly.
(3) Generally speaking, the suitable period of applying pesticide after maize seedling should be from 2 visible leaves to 5 visible leaves.
If at 5
The medicine should be used between rows of corn at the stage of 0 ~7 leaves to avoid spraying the liquid medicine into the heart leaves.
(4) Some post-emergence herbicides are sensitive to sweet corn, farming and inbred lines, so don't use them.
The herbicide should be used in strict accordance with the label instructions.
(5) Strictly control the application period.
Soil sealing treatment should be carried out within 3 days after corn sowing; The treatment of stems and leaves after seedling should be in the 3-5 leaf stage of corn, and the effect of early application is poor (annual weeds are unearthed irregularly)
(6) After sealing the soil, people and animals are not allowed to enter the ground within one week, so as not to damage the medicine film and reduce the control effect.
(7) Corn seedlings treated with organophosphorus pesticides are sensitive to herbicides.
The interval between two doses is at least 7 days.
(8) When using a motorized sprayer, the dosage shall not be increased without authorization, and repeated spraying is prohibited.
(9) Pay attention to cleaning the sprayer sprayed with organophosphorus pesticides before using herbicides.
The above content is about whether corn herbicides are planted before or after seedling, and what are the herbicides after seedling? I hope these contents can help you. Want to know more about corn planting management technology, you can pay attention to the official account nh 1988.tv of Bianxiao WeChat, and more fresh information is waiting for your discovery!