A wet spring and a humid summer have set the stage for heavier-than-normal disease pressure across the eastern Corn Belt, according to Carl Joern, a Pioneer field agronomist who covers counties in northwest Indiana and northeast Illinois. Joern told Agriculture of America that 2026 has been a season defined by variability. Some fields are performing well, others are not, and the difference often comes down to how much rain a farm caught during pollination and grain fill.
“You’re seeing areas that got way too much water at a couple of key growth stages,” Joern said. He pointed to repeated 10-inch rain events in northwest Indiana this year, conditions no management plan can fully offset. “We’ve got a good crop. I’m not going to say we have a great crop.”
Disease Pressure Builds With the Humidity, Below-Ground Protection Matters
The same moisture driving crop stress has also fueled disease. Joern said he found more gray leaf spot than usual this year, along with tar spot, northern corn leaf blight and, in an unusual turn, frogeye leaf spot near Lake Michigan, a disease he does not typically see that far north. Southern rust also showed up early for a second consecutive year, though moderating temperatures have slowed its spread.
Joern said white mold in soybeans and sudden death syndrome in early-planted beans remain concerns heading into harvest, both tied back to the wet spring and humid summer.
Also, with conditions swinging between too wet and too dry, Joern said a strong root system is critical. He pointed to Pioneer’s Vorceed Enlist hybrids, which are bred to guard against corn rootworm, the top below-ground pest in corn. Root wounds from rootworm feeding limit a plant’s ability to take up moisture, a bigger liability when dry stretches follow wet ones.
What to Look for Before Harvest
Joern recommended growers start scouting from the ear leaf upward. A clean upper canopy signals the hybrid and management plan did their job. He also suggested pushing on stalks near the ear to test standability and splitting a few stalks open to check for stalk rot pathogens before deciding which fields to combine first. On late fungicide applications, Joern said the calculus often comes down to how long a field will need to stand before harvest rather than a flat bushel threshold. Once kernels reach the dent stage and the milk line starts moving down the kernel, he said, the window to protect yield and standability with a fungicide has largely closed.
Looking ahead to 2027 seed selection, Joern cautioned against overweighting this year’s southern rust pressure, since disease pressure shifts year to year. He said growers should instead focus notes on late-season plant health, stalk integrity and kernel fill as they walk fields ahead of harvest.
Pioneer breeders, Joern said, are prioritizing late-season plant health over raw yield potential in hybrid selection, a shift he said pays off directly in bushels by keeping plants alive longer through grain fill.
Growers can find more information on Vorceed Enlist hybrids and local seed recommendations at pioneer.com or through a local Pioneer sales representative.
Late-Season Disease Pressure Tests 2026 Corn and Soybean Crop, Pioneer Agronomist Says
A wet spring and a humid summer have set the stage for heavier-than-normal disease pressure across the eastern Corn Belt, according to Carl Joern, a Pioneer field agronomist who covers counties in northwest Indiana and northeast Illinois. Joern told Agriculture of America that 2026 has been a season defined by variability. Some fields are performing well, others are not, and the difference often comes down to how much rain a farm caught during pollination and grain fill.
“You’re seeing areas that got way too much water at a couple of key growth stages,” Joern said. He pointed to repeated 10-inch rain events in northwest Indiana this year, conditions no management plan can fully offset. “We’ve got a good crop. I’m not going to say we have a great crop.”
Disease Pressure Builds With the Humidity, Below-Ground Protection Matters
The same moisture driving crop stress has also fueled disease. Joern said he found more gray leaf spot than usual this year, along with tar spot, northern corn leaf blight and, in an unusual turn, frogeye leaf spot near Lake Michigan, a disease he does not typically see that far north. Southern rust also showed up early for a second consecutive year, though moderating temperatures have slowed its spread.
Joern said white mold in soybeans and sudden death syndrome in early-planted beans remain concerns heading into harvest, both tied back to the wet spring and humid summer.
Also, with conditions swinging between too wet and too dry, Joern said a strong root system is critical. He pointed to Pioneer’s Vorceed Enlist hybrids, which are bred to guard against corn rootworm, the top below-ground pest in corn. Root wounds from rootworm feeding limit a plant’s ability to take up moisture, a bigger liability when dry stretches follow wet ones.
What to Look for Before Harvest
Joern recommended growers start scouting from the ear leaf upward. A clean upper canopy signals the hybrid and management plan did their job. He also suggested pushing on stalks near the ear to test standability and splitting a few stalks open to check for stalk rot pathogens before deciding which fields to combine first. On late fungicide applications, Joern said the calculus often comes down to how long a field will need to stand before harvest rather than a flat bushel threshold. Once kernels reach the dent stage and the milk line starts moving down the kernel, he said, the window to protect yield and standability with a fungicide has largely closed.
Looking ahead to 2027 seed selection, Joern cautioned against overweighting this year’s southern rust pressure, since disease pressure shifts year to year. He said growers should instead focus notes on late-season plant health, stalk integrity and kernel fill as they walk fields ahead of harvest.
Pioneer breeders, Joern said, are prioritizing late-season plant health over raw yield potential in hybrid selection, a shift he said pays off directly in bushels by keeping plants alive longer through grain fill.
Growers can find more information on Vorceed Enlist hybrids and local seed recommendations at pioneer.com or through a local Pioneer sales representative.
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