There’s cautious optimism for bumper Iowa corn and soybean yields to occur at harvest.
“On the eastern side of the state, timely rains will be crucial to finish this crop in a sufficient fashion,” said Michael Fosdick, a Pioneer field agronomist who covers eastern Iowa.
“As you look at this crop, we still have a lot of [good yield] potential out there,” said Kurt Eischeid, a Pioneer field agronomist who covers western Iowa.
Both Eischeid and Fosdick spoke at a recent Corteva media day.
This optimism has increased since rainfall occurred last week across much of central and southern Iowa.
John Fischer, who farms with his wife, Mary, near Neola in southwestern Iowa, reported that they were on the verge of major yield losses in some fields before 3.4 inches of rain arrived in late July and early August.
“From June 14 to July 30, there was very little rain in that time frame — maybe 0.9 inch in four different events,” Fischer said.
Such rainfall is welcome, as drought exposes even the tiniest of flaws.
“When we get dry and stressed, it shows every little sin we made in the spring, such as sidewall compaction,” Eischeid said.
Reduced corn disease
Southern rust ran rampant across many Iowa cornfields at this time last year. That has changed in 2026.
This fungal disease that blows in from the south has surfaced across Iowa, but it came later and not to the same degree as in 2025.
“It’s been some singular plants in a field versus last year, when we saw it in early July on a majority of plants in a field,” Fosdick said. “We had the environment to really ramp that disease up in a pretty quick fashion.”
Diseases that overwinter in Iowa — such as northern corn leaf blight, gray leaf blight and tar spot — also have surfaced.
“We can find them through the state, but they’re at lower levels right now,” Eischeid noted.
In Fischer’s cornfields, diseases have played hooky so far.
“Crops are extremely healthy,” Fischer said. “There’s been some brown stem rot in soybeans, but corn has been disease-free.”
Genetic tolerance helps manage diseases such as tar spot, Eischeid said. Fungicides also remain a valuable tool.
One tool Eischeid said helped with disease management this year is a data-based Corteva fungicide timing tool.
Good news for soybeans, too
Like corn, soybeans have fared better on the disease front compared with 2025.
“We had a lot of disease pressure last year, particularly sudden death syndrome in beans,” Eischeid said.
So far in 2026, however, this hasn’t occurred.
Just as in corn, dry weather exposes limiting yield factors, such as soybean cyst nematode.
“Cyst has always been a silent yield robber,” Eischeid said. “It’s not everywhere, but we have found from testing that there is cyst pressure in some of these fields that have hit a yield ceiling.”
SCN-resistant varieties deter this pest, but even this method has been fading in some cases. That’s because most soybean varieties contain the same resistance source: PI 88788. Just as with herbicide-resistant weeds, the more a control measure is used, the more likely a pest will grow a resistance to it.
Fortunately, more SCN-resistant varieties now contain a new resistance source: Peking. This gives farmers a new tool to manage SCN, Eischeid noted.