After the wheat is harvested, it is the season of corn planting. If you want the corn to rise well, it is very important to do the post-emergence weeding work. After applying the corn seedlings, the herbicide needs to master the correct method, otherwise it will not achieve the effect, and may also cause The phytotoxicity, let's follow the Xiaobian to understand it.
1, spraying time
After the corn seedling herbicide spray, it takes 2 to 6 hours of absorption process. During these 2 to 6 hours, the effect of the drug is good (that is, whether the herbicidal effect is ideal) is closely related to temperature and air humidity.
Spraying in high temperature, dry morning, noon or afternoon, due to strong light, the liquid evaporates quickly, the amount of herbicide entering the weed body is obviously insufficient, which seriously affects the herbicidal effect, and the corn seedling is also prone to phytotoxicity.
The optimal spraying time of the herbicide after corn seedlings is after 6 o'clock in the evening, because the temperature is lower after application, the humidity is larger, the liquid stays on the weed leaves longer, and the weeds can fully absorb. The herbicide ingredient ensures the herbicidal effect, and the evening use can also significantly improve the safety of the corn seedlings, and is less prone to phytotoxicity.
2, spraying method
The amount of medicine used is 15 to 30 kilograms of water. See the grass spray, spray carefully, no grass will go, save the medicine and save time.
3, look at the grass size
When spraying herbicides on corn seedlings, many farmers think that the smaller the weeds, the smaller the resistance, the easier it is to be killed. Actually, it is not the case. Because the grass is too small and there is no medicine area, the weeding effect is not ideal. The best grass age is 2 leaves 1 heart to 4 leaves 1 heart period. At this time, the weeds have a certain area of ​​medicine, the resistance is not large, and the weeding effect is obvious.
4, see the size of the seedlings
The best spraying time for corn post-emergence herbicides is 2 to 5 leaf stage of corn. At this time, the resistance of corn is high and it is not easy to cause phytotoxicity. 5 leaves before the whole field spray, after 6 leaves spray to lower the nozzle against the corn tree spray, to prevent the drug solution caused by the drug (mainly without the safety agent of nicosulfuron, if it is safe nicotinic acid The sulfonate boutique can also be sprayed in the whole field).
5, corn varieties
At present, most of the corn post-emergence herbicides are nicosulfuron-methyl. Some corn varieties are sensitive to this ingredient and are prone to phytotoxicity. Therefore, corn fields such as sweet corn, waxy corn and Denghai series cannot be sprayed. Preventing phytotoxicity. For new corn varieties, please test and promote.
6, pesticide mixed
It is strictly forbidden to spray organophosphorus pesticides within 7 days before and after spraying of herbicides, otherwise it is prone to phytotoxicity. However, it can be mixed with pyrethroids and carbamate insecticides. When spraying, pay attention to avoiding happy leaves and anti-drug solution.
This year, some corn fields have serious occurrences of Swedish flies and thrips. These two small pests can be sprayed with imidacloprid or acetamiprid, but they should not be sprayed with post-emergence herbicides. Although imidacloprid or acetamiprid is not an organophosphorus, it is necessary to spray the heart leaves because of the control of two small pests. If mixed with the heart leaf, it is easy to cause phytotoxicity. It can be sprayed separately: the herbicide is sprayed on the front side, followed by imidacloprid. Or acetamiprid squirting heart leaves.
7, weeds themselves resistance
In recent years, the resistance of weeds has been continuously strengthened. In order to prevent excessive evaporation of water in the body, weeds grow not so watery and thick, but grow gray and short, and the actual grass age is not small (so-called " Little old man").
Most of these weeds are covered with white small fluff to reduce the evaporation of water. When the pesticide is sprayed, the liquid is topped on the surface of the weed stems and leaves, and the weeds themselves absorb little, which naturally affects the efficacy of the drug. Therefore, no matter what kind of medicine is applied during high temperature and drought, the amount of liquid medicine to be sprayed should be increased to not affect the exertion of the drug effect.
More pesticide knowledge, please pay attention to China Pesticide Network
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