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Early Weed Prevention

Effective weed control early in the crop planting season can make the difference between making or losing money.

Aaron Hager is an associate weed science professor at the University of Illinois. He recommends planting into a clean field with no existing weed vegetation. This is accomplished with a burn-down herbicide application, mechanical tillage, or a combination of both. After planting, a post-emergence herbicide should be applied before weeds become taller than three-to-four-inches.

"And the simple reason is that the longer the weeds are allowed to compete with the crop, the greater the likelihood that that interference, or that competition, could potentially reduce the crop yield potential at the end of the growing season," he says. "So, in other words, it’s hard to be too early when you’re trying to remove weeds that are growing within an existing crop stand."

There is no blanket herbicide or recommendation for all situations, so Hager says it’s whatever works for your fields. You should know what weed species are there and what’s labeled for use in that particular crop.

"And certainly with the widespread evolution of herbicide resistance, we need to really have an understanding of whether or not that one species, or the multiple species in that field remain sensitive or susceptible to that herbicide," says Hager. "So in other words, we really have to know not only what the weeds are, but whether or not that they’re still effectively controlled with the products that we’re going to actually select to use in that field."

Routinely scout your fields and remove weeds that re-infest after the initial herbicide application. They can also become very competitive and should be controlled while they’re small.

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