Corn and Soybean Diseases Spread This Season

Sep 10, 2025
By Farms.com

Southern rust emerge as the leading corn disease of 2025

As reported on the OMAFRA website fieldcropnews.com, as well as in previous articles by Farms.com, the 2025 growing season is nearing its end with corn and soybean farmers in Ontario and the U.S. Corn Belt facing disease challenges that reflect changing weather conditions.

For corn, two diseases have received the most attention—tar spot and southern rust. Tar spot detections began in early July, following patterns from previous years. The disease is firmly established across southwestern Ontario, from Essex to Niagara, and is spreading north toward Toronto. Hotter, drier conditions earlier in the summer kept tar spot levels low, but late-season humidity has triggered new outbreaks. Fortunately, this resurgence, along with fungicide use, is expected to limit yield losses compared to past years.

Southern rust, however, has emerged as the leading corn disease of 2025. Warm, humid conditions across the U.S. Midwest provided ideal conditions for its spread, and higher disease pressure has also reached southwestern Ontario. Test plot research shows that fungicide applications help reduce severity, but the full impact is still being evaluated.

Soybeans have also faced disease issues this season. Sudden death syndrome and soybean cyst nematode (SCN) have been noticeable in many fields. Fall is the best time for farmers to test soils for SCN while also preparing next year’s fertilizer plans. Sampling now helps identify yield losses and supports variety selection for 2026 planting.

Adding to management tools, the Crop Protection Network has launched a new Crop Disease Forecasting Tool. This web-based system provides daily updates and 7-day forecasts for major corn and soybean diseases. It now also includes risk assessment for Gibberella ear rot and DON, helping farmers make timely fungicide decisions and manage food safety risks.

With changing weather and increasing disease pressure, growers are encouraged to plan ahead, scout fields regularly, and use resistant varieties where possible.

For more information about the soybean cyst nematode, please visit the Farms.com Field Guide Pest pages.

Photo Credit: istock-urpspoteko

Video: From Conventional to Regenerative: Will Groeneveld’s Journey Back to the Land

"You realize you've got a pretty finite number of years to do this. If you ever want to try something new, you better do it."

That mindset helped Will Groeneveld take a bold turn on his Alberta grain farm. A lifelong farmer, Will had never heard of regenerative agriculture until 2018, when he attended a seminar by Kevin Elmy that shifted his worldview. What began as curiosity quickly turned into a deep exploration of how biology—not just chemistry—shapes the health of our soils, crops and ecosystems.

In this video, Will candidly reflects on his family’s farming history, how the operation evolved from a traditional mixed farm to grain-only, and how the desire to improve the land pushed him to invite livestock back into the rotation—without owning a single cow.

Today, through creative partnerships and a commitment to the five principles of regenerative agriculture, Will is reintroducing diversity, building soil health and extending living roots in the ground for as much of the year as possible. Whether it’s through intercropping, zero tillage (which he’s practiced since the 1980s) or managing forage for visiting cattle, Will’s approach is a testament to continuous learning and a willingness to challenge old norms.

Will is a participant in the Regenerative Agriculture Lab (RAL), a social innovation process bringing together producers, researchers, retailers and others to co-create a resilient regenerative agriculture system in Alberta. His story highlights both the potential and humility required to farm with nature, not against it.