Corn, as one of the world's major food crops, has always been a concern for farmers in terms of chemical weed control in its fields. As a commonly used herbicide for post seedling stem and leaf treatment, Nicosulfuron has caused serious phytotoxicity in some areas due to improper application in recent years. Manifested as:
The corn heart leaves turn green and yellow, with irregular green spots appearing on the leaves. In severe cases, the leaves curl into a cylindrical shape, the leaf edges shrink, and the heart leaves take on a cow tail shape and cannot be pulled out normally. At the same time, the affected plants appear stunted, sometimes even forming clusters and secondary stems, seriously affecting the normal growth and yield of corn.
So, what are the reasons of the phytotoxicity caused by the nicosulfuron in corn fields? Here we will delve into this issue in depth.
Dosage and period of use:
Improper control of dosage: Excessive dosage or repeated spraying can lead to drug damage.
Choosing the wrong medication period: Using nicosulfuron before the 2-leaf stage or after the 6-leaf stage of corn can easily cause phytotoxicity. When using nicosulfuron, it should be used during the 3-5 leaf period to reduce the risk.
Application methods and weather factors:
Incorrect application method: if the non directional spray is carried out after the fifth leaf stage of maize, or mixed with organophosphorus pesticides, a large amount of liquid medicine will enter the heart and leaves of maize, which may also cause pesticide damage. In addition, if organophosphate pesticides are used within 7 days before and after medication, the sensitivity of corn to nicosulfuron will increase.
Insufficient uniformity of spray: uneven spray will also lead to drug damage.
Weather factors: After spraying, corn is susceptible to damage from nicosulfuron due to low temperatures and continuous rainy weather. Attention should be paid to weather and soil conditions when applying pesticides.
Crop and soil impacts:
Differences in crop types: Sweet corn, burst corn, seed corn, and the Denghai series are more sensitive to nicosulfuron.
Soil residue impact: Caution should be exercised when using METSULFURON METHYL, Chlorsulfuron and other long-acting herbicides on previous crops, or intercropping legumes in corn fields. Different crops have varying sensitivities to nicosulfuro, and residual herbicides in the soil can affect the effectiveness of its use.
Remedial measures after phytotoxicity:
If corn is mildly damaged by nicosulfuron, its growth will be temporarily inhibited, but no special treatment is needed. After a period of time, it can recover on its own without affecting yield. However, if the degree of phytotoxicit is severe, the following measures can be taken to remedy it.
Thoroughly water the corn roots to fully absorb water, thereby reducing the concentration of herbicides in the plant:
Spray 1-2% urea solution and 0.2-0.3% potassium dihydrogen phosphate solution on the leaves.
Spraying brassinolide, gibberellin, etc. on affected plants can help them recover their health as soon as possible.
Appropriately increase the depth and frequency of hoeing to improve soil aeration.
