When is the best and safest time to apply post-emergence herbicide to corn seedlings?

AbstractThe suitable time to apply herbicide is after 6 PM in the evening. Because the temperature is lower and the humidity is higher at this time, the liquid will remain on the weed leaves for a longer period, allowing the weeds to fully absorb the herbicide components, which helps improve the weeding effect and also improves the safety of corn seedlings, making herbicide damage less likely.

1. When to apply post-emergence herbicide to corn seedlings

1. Because after post-emergence herbicide for corn seedlings is sprayed, it needs an absorption process of 2-6 hours. During these 2-6 hours, whether the herbicidal effect is ideal is generally closely related to temperature and air humidity. In the morning, or at noon and in the afternoon, when the temperature is high and the weather is dry, spray the herbicide.

2. Because the temperature is high, the light is strong, and the liquid evaporates quickly, the liquid will evaporate shortly after spraying, limiting the amount of herbicide that enters the weeds and leading to insufficient absorption, which affects the weeding effect. At the same time, when spraying under high temperature and drought, corn seedlings are also prone to herbicide damage.

3. The suitable time to spray is after 6 PM in the evening, because when spraying at this time, the temperature is lower and the humidity is higher, and the liquid remains on the weed leaves for a longer period. The weeds can fully absorb the herbicide components, which helps ensure the weeding effect. Evening application can also improve the safety of corn seedlings, making herbicide damage less likely.

4. Because most post-emergence herbicides for corn seedlings now contain nicosulfuron, and some corn varieties are sensitive to this component and prone to herbicide damage, corn fields planted with varieties such as sweet corn, waxy corn, and Denghai series should not be sprayed, to avoid herbicide damage. For new corn varieties, they need to be tested before promotion.

2. How to use post-emergence herbicide for corn seedlings

1. Look at the size of the weeds

(1) When spraying post-emergence herbicide for corn seedlings, many farmers believe that the smaller the weeds, the lower their resistance, and the easier the weeds are to kill, but this is not actually the case.

(2) Because if the weeds are too small, there is no surface area for the herbicide to adhere to, and the weeding effect is not ideal. The better weed age is from the 2-leaf 1-heart stage to the 4-leaf 1-heart stage. At this time, the weeds have a certain surface area for the herbicide to adhere to, and the resistance of the weeds is not great, so the weeding effect is better.

2. Corn variety

Because most post-emergence herbicides for corn seedlings now contain nicosulfuron, and some corn varieties are sensitive to this component and prone to herbicide damage, corn fields planted with varieties such as sweet corn, waxy corn, and Denghai series cannot be sprayed, to avoid herbicide damage. For new corn varieties, they need to be tested before promotion.

3. Pesticide mixing issues

Within 7 days before and after spraying post-emergence herbicide, do not spray organophosphorus insecticides, otherwise herbicide damage is likely to occur. However, it can be mixed and sprayed with pyrethroid insecticides. When spraying, be careful to avoid the heart leaves as much as possible, to avoid the liquid pouring into the heart.

4. The resistance of the weeds themselves

In recent years, the stress resistance of weeds themselves has increased somewhat. To avoid excessive evaporation of water from within, weeds do not grow so tender and robust, but instead grow grayish-white and short. Their actual weed age is not small. These weeds are mostly covered all over with small white hairs to reduce water evaporation.