Three Benefits of Selecting a Residual Herbicide to Control Weeds at Pre-emergence


Controlling early season weeds at pre-emergence is beneficial for minimizing yield-robbing competition.

After planting, there is one sight every grower dreads to see—weeds. It can be especially troubling when young weeds are visible before the crop even has emerged. These early season weeds pose one of the greatest threats to corn plants. If left unmanaged, they will compete with corn for sunlight, water and nutrients, often resulting in reduced yields and lower profits. However, as dreadful as weeds can be, there are strategies you can take to mitigate their effects. In fact, before you even see a weed, you can take steps to ensure that corn plants grow without unnecessary competition and yield losses. 

One of the most promising ways to eliminate early season weed competition is by applying a pre-emergence herbicide with strong residual control. 

Three benefits of selecting a pre-emergence herbicide with residual

Pre-emergence, residual herbicides take out weeds before the crop emerges from the ground. While important, this is only one part of the picture.

“Of course, the initial control of emerged weeds is very important. But in order to keep those weeds at bay throughout the season, you really need a herbicide that not only controls weeds, but provides powerful residual too. This gives you a strong foundation for a solid integrated weed management program,” said Frank Rittemann, selective corn herbicides product manager at Bayer. “The benefits of pre-emergence herbicide applications can be felt not only early in the season, but also later in the season and in future growing seasons as well.”

1.  Minimizes weed-related yield losses  

Early season weeds pose the greatest threat to yield. Managing weeds with a pre-emergence herbicide takes out tough weeds before they can compete with corn. Competition often results in improper development, with the corn plants growing taller rather that developing a solid root system that will allow for maximum grain fill. Availability of ample resources allows corn plants to develop fully and properly. Therefore, less competition from weeds minimizes the risk of reduced yields.i

2. Builds a foundation for weed control later in the season

Applying a residual herbicide at pre-emergence timing can build the foundation for season-long weed control. Most residual herbicides remain active in the soil for a few weeks, so this extends the window for a postemergence application. When early season weeds are controlled by a pre-emergence herbicide with residual, there is less pressure on the postemergence herbicide application to take out all weeds that might have emerged since the beginning of the season.ii

3. Mitigates the development of herbicide resistance

As part of a two-pass system, a pre-emergence herbicide application can also mitigate the development of herbicide resistant weeds. It is recommended to incorporate multiple and different effective sites of action into the tankmix. With this approach, weeds are targeted in multiple ways for early season weed control. When weeds are successfully managed at pre-emergence, the risk of developing herbicide resistance is reduced considerably.iii

Bayer solutions for pre-emergence weed control

Rittemann recommends Corvus® for superior control of weeds at pre-emergence. “Corvus has multiple sites of action to take out weeds that have already come up out of the ground,” said Rittemann. “This helps growers begin with clean, weed-free fields to give corn plants a good start without competition.”

Corvus provides extended early season weed control due to its long-lasting residual and unique feature of reactivation. With as little as a half inch of rain, Corvus reactivates to take out additional weeds that may have emerged even after extended dry periods.

©2019 Bayer Group. Always read and follow label instructions. Bayer, the Bayer Cross and Corvus are registered trademarks of Bayer Group. Corvus is a Restricted Use Pesticide. Corvus is not registered in all states. For additional product information please call toll-free 1-866-99-BAYER (1-866-992-2937) or visit our website at Bayer CropScience LP, 800 North Lindbergh Blvd, St. Louis, MO 63167.

Work Cited

i Texas Farm Bureau. “Corn benefits from pre-emergent herbicides.” Texas Agriculture Daily, 2015.

ii Jhala, A., & Kruger, G. “Why Residual Herbicides are Important tools in Battling Hard-to-Control Weeds.” Nebraska CropWatch, 2015.

iii GROW. “Diversifying herbicide modes of action.” Getting Rid of Weeds through Integrated Weed Management, 2018.

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