Weed Control in Corn: Best Practices, Herbicides and Timing Tips

As the battle against herbicide-resistant weeds grows more complex and the economic pressures on corn production mount, it’s important to leverage advanced and integrated approaches to weed management. A strong plan for weed control that includes cultural practices, appropriate herbicide selection and proactive crop competition strategies will help you stay in the game and produce optimal yields.

With the upcoming growing season on the horizon, now is an ideal time to develop a comprehensive weed management plan for your corn. Making smart choices about inputs and methods will improve weed control in your fields. It will also help you avoid problems caused by over-reliance on single-herbicide modes of action (including the proliferation of virulent herbicide-resistant weeds such as Palmer amaranth, waterhemp, giant ragweed and marestail).

Why early weed control in corn is key

If weeds get a jump-start on your corn crop, the damage to your yields can be irreversible. Evidence shows that uncontrolled weeds that reach just six inches high can translate to losses of seven bushels per acre. And if they grow to a foot high, you can lose up to 31 bushels per acre.¹
This kind of reality check shows the importance of building a multifaceted plan to address weed control in corn fields.

Select corn hybrids carefully

The first step you can take to combat weeds in corn is to plant the right hybrids and determine the optimal population, ensuring your approach is custom tailored to your local climate and field conditions. For a hybrid to qualify to be grown on your farm, it should:

• Be adapted to your unique location
• Be vigorous as demonstrated in year-over-year trials
• Boast early canopy closure to crowd out weeds, especially herbicide-resistant ones

Typical 30” row spacings and consistent plant-population densities between 30,000 and 34,000 plants per acre work well to produce abundant shade that limits sunlight’s ability to supercharge weed growth beneath the canopy.²

Planting timing for optimal weed control in corn

Second, always try to plant into soils that are at least 50 F, which can accelerate corn germination. The faster your corn can establish a uniform stand, the faster you’ve got an edge over weeds.
By contrast, delayed planting in no-till corn gives weeds more time to thrive in the absence of competition. Delayed planting in conventional till corn will help to control early emerging weeds such as giant ragweed and common lambsquarters.

Before hitting the field, make sure your equipment is up to the challenge. Whether you’re using tillage or not, make sure planters are equipped to establish good seed-to-soil contact. Especially in a minimum till or no-till environment, make sure your planter is equipped to break through crop residue left on the soil surface so it can get the seeds in the ground.

Once the crop is up, explore a combination of tillage passes. A rotary hoe can travel through the field and kill weed seedlings while corn is small, while a row cultivator is better suited for corn once it reaches five or six inches high because it minimizes pruning of corn roots.³

Manage nutrients wisely

Third, implement a diversified nutrient management strategy to help your crop set up well and navigate its early phase of life. Often, this looks like beginning with band-applied starter fertilizers at planting. A good rule of thumb is to apply starter nitrogen at under 30 lb. per acre.⁴ The goal of this fertilizer application is to give your corn a quick boost early on and allow it to subsequently out-compete weeds.

Then, evaluate whether your crop needs a split application of nitrogen. Over-application can increase your cost of production, cut farm income and increase the odds of nutrient runoff into waterways, so choose carefully. By providing your corn crop with the right nutrition, you optimize its growth so it can beat the weeds. Additionally, your crop can establish a solid canopy that prevents sunlight from hitting the soil, further suppressing weeds. If you do opt for a split application, you can effectively balance the nitrogen your corn needs with nitrogen already available in the soil. This matters because if your crop is in an active vegetative growth stage and lacks proper N, you’ll invariably hurt yield. Liquid nitrogen products can be especially effective and have been documented to provide 19% greater nitrogen use efficiency compared to granular products.⁵

Time herbicide application correctly to provide weed control in corn

Fourth, consider a combination of pre-emergence and post-emergence herbicide to suppress weeds during planting, germination and emergence.
Pre-emergence herbicides act as an insurance policy, keeping weeds at bay while corn is establishing in your fields. Then, you can apply a post-emergence herbicide once the crop is up to knock down small weeds and preserve yield. When possible, avoid getting the planter ahead of the sprayer; planting ahead of pre-emergence applications can create greater-than-necessary weed pressure early on.

What’s the risk if you fail to control weeds within the right window? Delaying weed removal can cost you 2% in yield loss per every leaf stage of delay, on average.⁶

To avoid that outcome, your local BASF representative can walk you through their portfolio of herbicides for timely weed control in corn, including:

Surtain™

Use as a pre-emergence on barnyardgrass, crabgrass, foxtails, pigweed and waterhemp. It can also be used for post-emergence application up to V2 corn.

Verdict®

Apply as a pre-emergence herbicide for HPPD resistance in waterhemp, ragweed and lambsquarters.

Zidua® SC

Use for pre-emergence application to kill grasses, pigweed and waterhemp

Status®

This post-emergence herbicide works to combat HPPD-resistant waterhemp, Palmer amaranth and morning glory up to V8 corn.

Experts are available to help you make decisions for weed control in corn during the upcoming growing season. Reach out to your retailer, a nearby extension office agent, or a company professional like your regional BASF representative.

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Endnotes

1. Rupp, Erin. “Protecting Crop Yields Starts with Early-Season Weed Control.” Michigan State University Extension, 22 Apr. 2024, https://www.canr.msu.edu/news/protecting-crop-yields-starts-with-early-season-weed-control. Accessed 24 June 2025.
2. University of California Agriculture and Natural Resources. “Integrated Weed Management.” UC IPM: Pest Management Guidelines for Corn, https://ipm.ucanr.edu/agriculture/corn/integrated-weed-management/#gsc.tab=0. Accessed 24 June 2025.
3. Cornell University College of Agriculture and Life Sciences. “Weed Management Methods.” Field Crops: Corn, https://cals.cornell.edu/field-crops/corn/weed-control-corn/weed-management-methods. Accessed 24 June 2025.
4. University of Minnesota Extension. “Using Banded Fertilizer for Corn Production.” University of Minnesota Extension, https://extension.umn.edu/crop-specific-needs/using-banded-fertilizer-corn-production#using-pop-up-fertilizer-1082612. Accessed 24 June 2025.
5. Motasim, Ahmmed Md, et al. “Split Application of Liquid Urea as a Tool to Nitrogen Loss Minimization and NUE Improvement of Corn: A Review.” Chilean Journal of Agricultural Research, vol. 82, no. 4, Dec. 2022, https://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392022000400645. Accessed 24 June 2025.
6. Knezevic, Stevan Z., and Alex R. Martin. “Timing Weed Control in Corn to Get the Most Effect.” CropWatch, University of Nebraska–Lincoln, 8 June 2007, https://cropwatch.unl.edu/timing-weed-control-corn-get-most-effect/. Accessed 24 June 2025.