When is corn post-emergence herbicide effective and safe
The suitable time to apply herbicide is after 6 o’clock in the evening. Due to the low temperature and high humidity at this time, the liquid will stay on the weed leaves for a long time, and the weeds can fully absorb the herbicide ingredients. It is beneficial to improve the weeding effect, and at the same time, the safety of corn seedlings can be improved, and phytotoxicity is not easy to occur.
When to apply herbicides after corn seedlings
1.Because the post-emergence herbicide is sprayed, it takes 2-6 hours for the absorption process. In these 2-6 hours, whether the effect of the herbicide is ideal is generally closely related to the temperature and air humidity. Spray in the morning, or at noon and in the afternoon when the weather is dry.
2. Due to the high temperature, strong light, and fast volatilization of the liquid medicine, the liquid medicine will evaporate shortly after spraying, so that the amount of herbicide entering the weeds is limited, which will lead to insufficient absorption, thus affecting the herbicidal effect. When spraying during high temperature and drought, corn seedlings are also prone to phytotoxicity.
3. The suitable time for spraying is after 6 o’clock in the evening, because at this time, the temperature is low, the humidity is high, the liquid stays on the weed leaves for a long time, and the weeds can fully absorb the herbicide ingredients. , is conducive to ensuring the weeding effect, and the evening medication can also improve the safety of corn seedlings, and it is not easy to cause phytotoxicity.
4. Since most of the post-emergence herbicides in corn are nicosulfuron-methyl, some corn varieties are sensitive to this component and are prone to phytotoxicity, so it is not suitable for corn fields planting sweet corn, waxy corn, Denghai series and other varieties to be sprayed , to avoid phytotoxicity, for new varieties of corn, it is necessary to test and then promote.
2. How to use post-emergence herbicides in corn
1. Look at the size of the grass
(1) When spraying herbicides after corn seedlings, many farmers think that the smaller the weeds, the smaller the resistance and the easier it is to kill the grass, but this is not the case.
(2 Because the grass is too small, there is no medicine area, and the weeding effect is not ideal. The best grass age is 2 leaves and 1 heart to 4 leaves and 1 heart. At this time, the weeds have a certain application area. Weed resistance is not large, so the weeding effect is better.
2. Corn varieties
Because most post-emergence herbicides in corn are nicosulfuron-methyl, some corn varieties are sensitive to this component and are prone to phytotoxicity, so it is impossible to spray corn fields where sweet corn, waxy corn, Denghai series and other varieties are grown. To produce phytotoxicity, new corn varieties need to be tested before promotion.
3. The problem of mixing pesticides
rganophosphorus insecticides should not be sprayed for 7 days before and after spraying the seedlings, otherwise it is easy to cause phytotoxicity, but it can be mixed with pyrethroid insecticides. The medicine fills the heart.
4. The resistance of the weed itself
In recent years, the ability of weeds to resist stress has been improved. In order to avoid excessive evaporation of water in the body, weeds grow not so strong and sturdy, but grow gray and short, and the actual grass age is not small. Weeds are mostly covered with small white fluff all over the body to reduce the evaporation of water.