Apply a pre-emergent weed herbicide to your planting area in early spring and late fall. Pre-emergent herbicide prevents weed seeds from germinating. While a pre-emergent herbicide does not control existing weeds, it does prevent the spread of weeds. Because there are two types of weeds, summer- and winter-growing weeds, two applications of pre-emergent herbicide is required.
By fertilizing in the early spring or before your corn is ready to compete with weeds, you encourage weeds to grow and spread. Therefore, you should wait until your corn is two feet high to fertilize it. Use a liquid fertilizer that is high in nitrogen.
Pour boiling water on weeds during the hottest part of the day. Boiling water will not only dehydrate weeds, but it will also make pulling them out of the ground easier. It is better to remove as many of the weeds as you can to reduce the amount of herbicide you have to use.
Dig a hole a few inches away from the weeds to lift underneath their root systems. Leaving weed roots will only temporarily slow down weeds. Remove the entire root systems and throw them away or burn them.
Apply a broadleaf herbicide like Dual II Magnum. Broadleaf fertilizers kill weeds and impeding grass without causing harm to your corn plants. Follow the directions accordingly.