Prepare Your Corn for Every Punch to Secure a Winning Season

Just like you, weeds, pests and diseases are waiting anxiously to see what conditions next season brings. No matter the weather, one or more will be ready to battle your corn crop. Having a strategy that prepares your crop to face any opponent in any condition will tip the odds of a winning harvest in your favor.

Dominate Early-Season Weeds

Your corn crop’s first challenger is early-season weed pressure. Make sure your weed management strategy includes a timely application of a residual preemergence herbicide with an overlapping postemergence residual and multiple effective sites of action.

“Early-season weed control is about effective control,  which is necessary for high-yielding corn crops,” says Travis Gustafson, Syngenta agronomist in Nebraska. He explains that if corn emerges next to a weed, it will orient its leaves to avoid the competition. This leads the corn to instead compete with its neighboring corn plants as it grows.

“Additionally, in a weed-free field, corn will shade the row faster, gather more sunlight throughout the growing season, and ultimately be a healthier, more productive plant,” he says.

An effective preemergence residual herbicide also provides a longer window for young corn plants to establish healthy root systems free of weed competition. If corn emerges to weed pressure, it will grow quickly to get above it, sacrificing root growth.

“If a dry spell hits later in the season, a crop that competed with weeds early will have less root mass to take up water and nutrients and be under more stress than a plant that had a clean field from the start,” says Nick Groth, Syngenta agronomist in Wisconsin. “Corn plants need to have a good day every day from planting through harvest to maximize yield potential.”

For some weeds, it’s even more critical to make sure they never see the light of day. Palmer amaranth caught some producers off guard last season, Gustafson says.

This heavy hitter can knockout corn yields — losses have been shown to reach 91 percent in corn¹. Palmer amaranth plants can produce up to 100,000 seeds per plant, grow quickly, and are prone to developing resistance. It takes discipline to defeat this opponent.

“We can’t take a wait-and-see approach with tough weeds like waterhemp, marestail and Palmer amaranth,” says Gustafson. “In my area, once the weed is up, it’s nearly impossible to kill. Producers can’t cut corners on residual herbicide.”

Groth says producers in his area are having to adjust their thinking as they face waterhemp.

“Waterhemp isn’t like every other weed they’ve faced throughout their career. They can’t spray it over the top once it’s up and expect it all to die,” Groth says. “Growers should plan an aggressive herbicide program to stay ahead of it, and you don’t want to fall behind and risk developing a resistance problem.”

Reinforce Resilient Weed Control

Choosing the correct residual herbicide is just as critical as following label instructions and making timely applications at full recommended rates.

“The key to having an effective program that is resilient to varying weed spectrums is using an herbicide with multiple, effective sites of action targeted to key driver weeds for optimal control and resistance management,” Groth says.

Choosing a corn herbicide like Storen^®, for example, delivers two sites of action and four residual active ingredients, including the unique component bicyclopyrone, which is also included in Acuron^® corn herbicide. These options consistently deliver high levels of weed control, Groth says.

Using the higher recommended labelled rates of residual herbicides can be a make-or-break decision when facing tough weeds. The residual needs to hold out until the field is fit for the next herbicide pass.

“You need to control the weed seed, not the weed itself. Bolstering rates and getting as much residual control as possible in the soil will be critical going forward,” Groth says.

Plan Ahead For Preventive Fungicide Applications

Late-season foliar diseases are tough to predict since pressure can vary season to season. Some growers take a “wait and see” approach with disease outbreaks, but that could mean losing out on plant-health benefits or losing yield to late-emerging diseases if they don’t apply a fungicide.

Wet conditions in 2024 had producers in Groth’s region rightly concerned about tar spot. Many applied fungicides. In areas where it hit, producers saw great benefit. There were a lot of areas, however, where tar spot didn’t develop. In those areas, growers that used Miravis^® Neo fungicide, part of Syngenta’s Cleaner & Greener fungicide portfolio, still saw a yield bump thanks to its proven plant-health benefits.

“Using a fungicide like Miravis Neo that controls a broad spectrum of diseases and delivers plant-health benefits allows producers to get a benefit from that application and a return on their investment in a wide variety of scenarios,” Gustafson says.

Plant-health benefits can help corn overcome stress like excessive heat and lack of moisture. They keep the corn crop greener and healthier longer, absorbing more light to produce more yield. Healthier crops use water more efficiently and have stronger stalks to reduce lodging at harvest.

Groth says producers shouldn’t wait for diseases to appear. Instead, they should plan to apply a broad-spectrum fungicide with plant-health benefits between tassel and R1-R2 every year to get the best long-term return on investment from a fungicide program. At this critical point, pollination and fertilization are occurring. Any additional stress on the crop can reduce the number of kernels per ear, kernel size and yield potential.

“We just don’t know what will happen after application. It might stay wet, and disease becomes an issue. Or it might turn dry and you need to rely on plant-health benefits. Some years it will be a home-run and other years a moderate ROI will be maintained,” Groth says.

Formulate a Crop Protection Plan

Weeds or disease, corn producers should go into the season with a solid crop protection plan in place. Being aggressive early in the season can help head off problems that could otherwise tank profit per bushel.

With weed control, waiting too long or not using a product with a long enough residual can mean a costly additional application.

“Cleanup options for weeds like waterhemp aren’t always effective and they’re definitely expensive. It is best practice to apply two timely passes of a herbicide to make sure the crop doesn’t struggle with competition” Groth says.

For disease control, using a product at R1 that sticks around longer to provide more protection spreads the value of that investment over more days. Trivapro^® fungicide and Miravis Neo have the longest residuals on the market for tar spot and Southern rust, diseases that had pockets of heavy pressure in corn-producing states in 2024. They also mitigate stress from variable weather to help keep fields cleaner & greener.

“When you don’t have to make another application, the cost per day of weed control goes down. In other words, the longer the residual is, the less expensive the cost per day of protection will be,” Gustafson says. “At the end of the day, you’re providing excellent crop protection and increasing bushels produced at the end of the season.”

¹ Purdue Extension 2013.