Crops vs. Foliar Diseases: A High-Stakes Race Underway in Midwest Fields

Two words sum up the concerns Pro Farmer Crop Tour scouts expressed about the corn and soybean crops they evaluated on Thursday in Minnesota and northeast Iowa: disease pressure.

Corn crops infected by southern rust and tar spot were a common sight in fields across both states during the fourth and final day of the tour.

“We saw disease in all of the fields we sampled today, though one of them really wasn’t too bad,” says Lane Akre, host of the eastern leg of the tour. “We saw a lot of early stages of tar spot, and we saw a lot of southern rust throughout.”

So it was no small surprise to the crowd attending Thursday night’s live broadcast when the final tally showed Pro Farmer’s corn estimate for Minnesota actually surpasses USDA’s 202-bu.-per-acre yield projection made August 12.

Pro Farmer estimates the Minnesota corn crop will average 202.86 bushels; that’s up 23.02% versus 2024 and up 13.41% versus the three-year average, according to Emily Flory Carolan, Pro Farmer Crop Tour data consultant.

“This crop is huge; it absolutely is,” Carolan says. “Minnesota is the only state on tour where we have recorded over a 200-bu. average this year. It is a record-year yield for the state.”

She adds that scouts recorded the longest grain inches in the crop that have ever been measured on the tour. “That’s definitely what pulled up that yield average for us,” she says.

Minnesota soybeans show similar yield promise, with final numbers pegged at 1247.86 pods in a 3' x 3' area. That’s up 20.38% versus last year, and up 19.9% versus the three-year average, Carolan reports.

(ProFarmer)

(ProFarmer)

A Much Better Growing Season, So Far
The findings in Minnesota were a pleasant change from what scouts found in 2024, when weather seemed to jog between two extremes – drought and flooding – for much of the season.

Jaden Serbus, Pro Farmer tour scout and farmer based near Renville, Minn., says he was relieved to see Mother Nature had course corrected.

“Last year, the corn crop was only as high as my head, all yellow and stunted with very, very poor yields with all the rain,” Serbus recalls. “This year, many areas are like a garden spot.”

Northeast Iowa Crops Look Good, But…
As Akre and his team of scouts moved into northeast Iowa on Thursday morning, early yield estimates had Akre concerned results there could bring the state’s overall averages down.

“We saw a lot of drowned-out parts of fields, and that’s limited some of the ear size and counts as populations are down due to skips,” he says.

Despite some agronomic challenges, scouts recorded strong numbers that put the Iowa corn crop at 198.43 bu.-per-acre yield average for 2025. That’s up 2.93% versus last year, and up 6.4% versus the three-year average.

“This Iowa crop has a very, very strong ear count, great grain inches — just a very consistent equation putting that corn yield together,” Carolan reports.

Iowa soybeans are also looking to break yield records. The 2025 crop delivered a 1384.38 pod estimate average in a 3' x 3' area on Thursday; that’s up 5.49% versus last year and up 12.94% versus the three-year average.

(ProFarmer)

(ProFarmer)

“For the most part, the Iowa beans are pretty lush and the pod counts have been there, the soil moisture is up, so the potential is pretty high on beans...I think that’s been the real story the last couple of days — how many pods are out there,” Akre says.

But foliar diseases rearing up in Iowa fields have the potential to put the kibosh on record yields between now and harvest, reports Chip Flory, host of AgriTalk and lead scout on the western leg of the tour.

That concern is one reason he reminded crop tour listeners on Thursday that Pro Farmer’s current yield estimates could change before combines roll.

“When we put the corn yield estimate out, it comes with a plus or minus 1%. The soybean crop estimate comes with a plus or minus 2%, and that’s because things can change. We all know that,” Flory says.

“The other thing is the yield models that we use give us a range, and then, based on conditions, we can move within that range with the yield estimate that we’re going to pull,” he adds, noting that he wonders whether the soil moisture currently available will offset some of the discount scouts put on the crops because of the disease pressure that’s present.

At the end of the day, August 21, no one knows how the final corn and soybean yields will net out. As Flory notes, while there’s optimism about better yields coming in this harvest versus a year ago, the outcomes depend on how well the crops cross the finish line.

Watch On-Demand: Pro Farmer Crop Tour Day 3 Results from Illinois and Iowa

Watch On-Demand: Pro Farmer Crop Tour Day 2 Results from Indiana and Nebraska

Watch On-Demand: Pro Farmer Crop Tour Day 1 Results from Ohio and South Dakota