Weeds don’t take the season off just because you’ve put up the combine and harvest is over. Especially in warmer climates, the window of time between the end of harvest and the first frost is a prime opportunity for winter annual weeds to get ahead of you.
If these weeds aren’t dealt with appropriately, they’ll gladly deposit a few million new weed seeds in your seedbank and cause trouble for next year’s growing season. More seeds in the seedbank means more competition for your next crop and more time, money and chemistry needed to get ahead of them.
Post-harvest weed control isn’t just about cleanup. This is a crucial time to protect yield potential, reduce herbicide dependence and save on input costs long term.
In this article, we’ll break down your post-harvest weed control options and show how each option can help you set the stage for a cleaner, more manageable planting season.
Using tillage for post-harvest weed control
Post-harvest tillage can be an effective way to prevent newly emerging weeds from gaining a foothold. A shallow pass of just 1" to 2" deep is usually enough to uproot weed seedlings and expose roots to air or frost. It’s also shallow enough to preserve soil structure and minimize erosion.1
When your field has a lot of corn stubble and residue, it is difficult to do a shallow tillage pass as you would just drag all the stubble along. For tillage to act as effect weed control in fields with heavy corn stubble, it would require deeper tillage that would help to chop and bury stubble and weed root balls.
However, going deeper isn’t always better. Aggressive tillage can actually backfire by dragging buried weed seeds to the surface, where they can eventually germinate. Instead of reducing your weed pressure, you may be setting up a flush of new weeds to fight later.
Strategic post-harvest tillage can reduce the need for herbicides, save time during spring applications and make early-season weed control more manageable. Additionally, knowing what weed species are present in your fields is key, as different species respond differently to post-harvest tillage.
Fall burndown herbicides
If you’re dealing with perennial weeds, then fall burndown herbicides may be an effective tactic for your fields. For example, perennial weeds such as Canada thistle, quackgrass, or dandelion can be effectively controlled by a well timed fall application of glysphosate alone or tank mixed herbicide. In fact, fall is the most effective time as the herbicide moves down into the roots and rhizomes in the fall when the weed is moving sugars downward for winter survival. For annual weeds, spraying an herbicide with a long residual for fall burndown can not only eliminate emerging or actively growing weeds, it can also prevent late weed flushes, reducing the overall number of applications you’ll need for post-harvest weed control.2
Taking out weeds in the fall reduces the population pressure before planting, and that means fewer spring passes, less early competition, and potentially fewer herbicide inputs overall. You also spread out your workload and avoid the springtime spray bottleneck when everyone is trying to cover acres quickly. Fall burndown herbicides are especially effective against troublesome winter annual species that like to overwinter and explode in the spring if left unchecked.
Mowing for post-harvest weed control
It’s easy to assume that your combine is doing enough damage to suppress weeds, but some species are more resilient than they appear. Palmer amaranth, for example, can recover quickly from combine damage and still produce seed.3
If you find that your fields are surrounded by areas with high weed pressure, it may be a good idea to mow field edges, fence rows, and waterways.
By targeting field margins right after weeds flower but before they go to seed, you reduce the likelihood that weeds will mature and deposit seeds that can be carried into your cultivated land by wind, wildlife, or equipment.
This approach is often faster and more practical than managing these areas with tillage or herbicide applications, especially when soil conditions are less than ideal or when weeds have become too mature for chemical control to be fully effective. Additionally, mowing can limit herbicide-resistant weeds from establishing a foothold along field borders.
You don’t have to go overkill when it comes to post-harvest weed control. It’s about being smart with your tools and strategies. Whether you choose post-harvest tillage, herbicide applications, mowing, or a combination, tackling weeds now gives you more control, more flexibility, and a cleaner start next season.
Experts are available to help you make your post-harvest weed control decisions. Reach out to a nearby extension office agent, or a seed company professional like your regional BASF representative.
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Endnotes
- Everman, Wesley. “Weed Management.” North Carolina Soybean Production Guide, North Carolina State Extension, https://content.ces.ncsu.edu/north-carolina-soybean-production-guide/soybean-weed-management.
- “Double‑Crop Soybean Weed Management.” C.O.R.N. Newsletter, Ohio State University Extension Agronomy Team, 2022, https://agcrops.osu.edu/newsletter/corn-newsletter/2022-20/double-crop-soybean-weed-management.
- Russell, David. “Post‑Harvest Weed Control: Don’t Quit Yet.” Alabama Cooperative Extension System, 19 Aug. 2019, https://www.aces.edu/blog/topics/crop-production/post-harvest-weed-control-dont-quit-yet/.
