Corn Gets a ‘Guaranteed’ Fungicide Pass as Southern Rust Memories Linger

Corn Belt farmers are entering fungicide season with fresh memories of last year’s southern rust outbreak — and many have a renewed commitment to protecting corn. But with tighter margins and uneven stands, some are taking a far more selective approach to fungicide applications in soybeans.

For those growers who battled southern rust in 2025, the decision on corn is straightforward.

In eastern Nebraska, farmer Luke Lauritsen says the disease left a lasting impression, taking a significant bite out of area farmers’ yield potential.

“Washington County last year got smoked with rust, so I don’t think anybody here is not spraying this year,” Lauritsen says. He plans to begin fungicide applications on corn this week and expects to treat some soybeans as well.

The decision, he says, is less about chasing extra yield than preventing a repeat of last season.

“The corn crop is moving along really fast. It’s healthy for now, but we’ll see what happens through the next couple weeks,” he says.

The same mindset is playing out for Caleb Hamer in eastern Iowa.

“Every acre of corn is going to get sprayed,” says Hamer, who farms near Hudson. “Our area got smoked with [southern] rust last year, and the guys who sprayed saw the benefit.”

Hamer expects fungicide season to ramp up quickly. “I expect to see a whole bunch of planes and drones in the air come next week,” he reports.

Corn Disease Pressure Is Low – So Far

Meaghan Anderson, Iowa State University Extension field agronomist, says she has seen her fair share of different diseases in Iowa cornfields this year, but almost all have been at “very low severity” to date.

“Bacterial leaf streak has been the most common one I’ve gotten questions about,” Anderson reports in her July 9 newsletter. “This disease cannot be treated with a fungicide and hybrids vary in their susceptibility.”

“Physoderma brown spot is also becoming increasingly apparent,” Anderson adds. “Tar spot has been found in numerous counties (but at very low levels) as of today and southern rust has not been confirmed in any state north of Texas and Georgia.”

The Crop Protection Network (CPN) has not confirmed any southern rust in Midwest fields, but says cases of tar spot are beginning to be reported.

In central Illinois, where many farmers have received heavy rainfall, Farm Journal Field Agronomist Ken Ferrie urges them to not rush making fungicide passes in fields where disease isn’t yet pressing.

“Without heavy disease pressure, I would monitor pollination to be sure we don’t have to deal with the beetles or aphids to get this crop pollinated,” Ferrie says. He adds that, “jumping the gun too soon with your fungicide could cause you to have to go back [and make an extra pass] to clean up the insects.”

Anderson encourages farmers to keep an eye on CPN maps for tar spot and southern rust to help understand their movement and development. In addition, the Corn Disease Working Group has recently updated the 2026 Fungicide Efficacy for Control of Corn Diseases.

Soybeans Still Have to Earn The Pass

While corn fungicide decisions are largely driven by disease risk, soybean applications remain harder to justify economically, the farmers report.

“We’re pretty picky on spraying fungicide on beans. We just don’t have a very good batting average on getting a response,” Hamer says.

Growing conditions haven’t helped. In eastern Iowa, alternating periods of cool, wet weather and warm, dry stretches have produced uneven emergence and thin soybean stands.

“We can grow corn, but we struggle with growing beans,” Hamer says. “This year’s emergence with the damp, cool, then warm and dry, then damp and cool again — we just have trouble getting decent stand establishment. You can see thin bean stands all over the place.”

Even so, he and Lauritsen caution against judging soybean potential too early in the season.

“It’s hard to have cool-looking beans in June and they yield in August,” Lauritsen says. “I swear, the uglier they are in June, the better they are in August. That’s just my opinion.”

Hamer says herbicide programs are adding another layer of uncertainty in soybeans.

“There’s a lot more Group 15 burners and Group 14 burners used than we’ve seen in a long time, and that’s the stress you’re talking about that gets applied mid-June,” he says. “I’m wondering what that’s going to look like come fall.”

Taken together, uneven stands, herbicide stress and inconsistent fungicide returns have left Hamer cautious about making blanket soybean applications. The CPN offers its updated 2026 Soybean Foliar Efficacy Table to help farmers make decisions regarding product use and timing.

Tight Margins Raise the Stakes

Continued economic pressure is also shaping fungicide decisions.

Lauritsen says rising crop protection costs have become increasingly difficult to justify.

“I do think our inputs are too high,” he says. “Crop protection has gone really high, and nothing ever curves down. No [farmer] is making money, so who’s making the money?”

Hamer says the higher costs extend well beyond the farm.

“Stuff’s expensive, and it’s not just for us,” he says. “Go try to go to McDonald’s like you used to go, and it’s as expensive as a sit-down restaurant anymore.”

The financial pressures have prompted Lauritsen to trim expenses where possible, including reducing some fertilizer and variable-rate applications to save “pennies out of the program.” Fungicide on corn, however, remains a priority.

“It’s hard to keep throwing money if something’s not paying you back right now with the prices,” he says. “When you plant a crop, you want to harvest a good crop, and you want to harvest a better crop than what you had the year before. It’s hard to know which way to go to make it profitable.”

For now, both farmers are acting on the same core belief: diseases are too costly to ignore in corn, but soybeans will have to earn any foliar fungicide pass.

Lauritsen sums up the mood in his neighborhood simply: “I don’t think anybody’s not spraying this year.”

Hamer puts it another way: “Every acre of corn is going to get sprayed.” The open question, he adds, is whether soybeans will justify that same level of protection.

Lauritsen and Hamer share more of their crop protection plans on AgriTalk with Host Chip Flory at the link below: