Strategies for Controlling Late-Season Weed Escapes in Corn and Soybeans

As your corn and soybean crops enter July, August and September, keep a close eye on weed escapes. Troublesome weeds such as Palmer amaranth, horseweed and kochia are notorious for releasing seeds that survive through the winter and cut into future yields.

Here’s a quick corn and soybean weed control guide to help you manage late-season weed escapes.

Weed control in soybean and corn: How weed escapes wreak havoc

A single Palmer amaranth plant can produce as many as 500,000 seeds, many of which can remain viable in soil up to five years.¹ Remarkably, common lambsquarters can be viable for 40 years.² Velvetleaf seed, meanwhile, can last 60 years.³

If weeds were left to grow uncontrolled, U.S. and Canadian corn and soybean yields could be reduced by approximately 50%. That would translate into $43 billion in annual economic losses to corn and soybean crops.⁴

Locations and causes of end-of-season weed escapes

Weed escapes frequently occur around field edges, in wheel tracks, in planting skips or in field areas with underdeveloped crop canopy. These escapes are typically:

• Weeds that are not controlled by pre or post herbicides. Root causes can include improper application or poor application timing.
• Weeds that emerge late in the season after herbicide applications and when residual control is fading.
• Herbicide-resistant weeds that are not controlled by your herbicide program.
  

Improper application and environmental conditions can also work together to impair corn and soybean weed control, as when soil-applied herbicides are not properly activated with adequate rainfall.⁵

Weed seeds can also hitch a ride from field to field on harvest equipment, causing economic impact from added weed pressure in future seasons.⁶

What makes weed escapes hard to manage?

An occasional weed escape in an otherwise clean field will likely have a negligible effect on this year’s corn and soybean yields. What you want to avoid is a trickle-down effect in which many seeds grow out of control.

The level of pain your weeds inflict depends on several factors, including:

• Which weed species you face (e.g., weeds such as marestail, waterhemp, and Palmer amaranth can require an aggressive mid-season control strategy)
• Reasons for the escape (e.g., herbicide resistance, which could indicate bigger challenges and the need for a more robust weed-management plan)
• The presence of other in-field pests, such as soybean cyst nematode, which can overwinter in winter annual weeds and make it even harder for your soybean crop to compete and thrive
  

Weed escapes eat into your corn and soybean productivity by producing viable seeds that exponentially increase the weed seed bank and devour water and nutrients.

They also eat into your bottom line: Weed seeds can contaminate trucks you haul to the elevator, resulting in dockages.⁷

Strategies for weed control in soybean crop and corn fields

Although it isn’t always realistic to do so, you should ideally pull weeds before they set and drop seeds. Mowing can be another helpful pre-harvest activity, though it should be done before seed set to be effective. Remember: This won’t curb weed seeds that have already dropped to the ground.

Remove distinct patches of weeds and keep records of their location for future scouting and management in future crops.

Products from the BASF herbicide portfolio can also help you keep weeds in check.

Experts are available to help you learn how to manage late-season weed escapes before they become next year’s headache. Reach out to your nearby extension office agent or a company professional like your regional BASF representative.

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Endnotes

1. “Managing Weed Escapes.” University of Maryland Extension,https://extension.umd.edu/resource/managing-weed-escapes/. Accessed 9 Mar. 2026.
2. Michigan State University Extension. “Common Lambsquarters.” Michigan State University Extension, n.d.,https://www.canr.msu.edu/weeds/extension/common-lambsquarters. Accessed 19 March 2026.
3. Washington State Noxious Weed Control Board. “Velvetleaf.” Washington State Noxious Weed Control Board, n.d.,https://www.nwcb.wa.gov/weeds/velvetleaf. Accessed 19 March 2026.
4. Kansas State University. “Left Uncontrolled, Weeds Would Cost Billions in Economic Losses Every Year.” ScienceDaily, 11 Feb. 2025, www.sciencedaily.com/releases/2016/05/160516130720.htm. Accessed 9 Mar. 2026.
5. Lingenfelter, Dwight. “Early Season Residual Herbicide Issues: Corn and Soybean.” Penn State Extension, The Pennsylvania State University, 7 May 2024, extension.psu.edu/early-season-residual-herbicide-issues-corn-and-soybean. Accessed 9 Mar. 2026.
6. Hunter, Mike. “Weed seed movement and equipment clean out.” College of Agriculture and Life Sciences, cals.cornell.edu/weed-science/ecological-management/weed-seed-movement-and-equipment-clean-out. Accessed 9 Mar. 2026.
7. Naeve, Seth, et al. “Got Weeds in Your Beans? You’re Not Alone - Take II.” Minnesota Crop News, University of Minnesota Extension, 12 Sept. 2022, blog-crop-news.extension.umn.edu/2022/09/got-weeds-in-your-beans-youre-not-alone.html. Accessed 9 Mar. 2026.