Pro Farmer Crop Tour, Day 3: Heat and Stress Take a Toll on Corn in Iowa and Illinois

Temperatures topped 100 °F on both legs of the 2023 Pro Farmer Crop Tour on Wednesday. The heat looks to be cooling down as in some regions, with scouts reporting less crop stress as they move across each leg of tour.

Western leg: Nebraska City, Neb., to Spencer, Iowa

As they made their way to Spencer, Iowa, scouts continued to see improvements from 2022’s drought-stricken fields. However, not all fields received the precipitation they needed. 

Roger Cerven, a farmer from Stanton, Iowa, says the region’s spotty rains made for drastic differences in corn yields in his fields this year. 

“We will have farms that will do 140 and farms that will pull 200. If we end up in that 170-bu. range it’s a win,” Cerven says.

Lack of moisture and high-heat days have Iowa locals concerned about cannibalized stalks. Ryan Beccard, a Pioneer seed rep, says it’s not so much about the heat levels as it is the timeframe.

#Soybeans averaging 1265 pods in a 3x3' plot versus 1257 last year and 1425 in 2021. That sixth stop (1800) brought the average up. Lots of flat pods still and some fields are already in the very early stages of maturity. Unsure if they can maximize current potential. #pftour23 pic.twitter.com/xt9twYJtBN — Karen Braun (@kannbwx) August 23, 2023

“The heat of 100° is nothing new for August in Iowa. How long the temps hold on — five, six or seven days in a row — will hold the crop off from finishing out,” Beccard says.

While Cerven estimates a 30-bu. blow to corn due to late-season heat, soybeans likely won’t take the same hit, according to Nate Quam, BASF’s western Iowa technical service rep.

“It is hot right now, but we started the month cooler and wet, so soybeans were getting the August rains that make good yield. We’ve seen pretty consistent numbers on soybeans this year,” Quam says.

Disease concerns, such as sudden death syndrome, were brought to question on the western leg on Wednesday. But Quam doesn’t foresee it becoming a catastrophic issue.

“Right now, I’m only seeing it in pockets of fields. I think on soybeans we’ll come out pretty good,” Quam says.

Eastern leg: Bloomington, Ill., to Iowa City, Iowa

Drought carved out a notch in crops on the eastern leg of the tour from Ohio to Illinois, but moisture drew a clear line in the sand in western Illinois, based on scout Meghan Yandell’s findings.

“Around the Bloomington, Ill., area, they were very dry earlier in the year, which created shorter nodes, thereby, short soybeans,” Yandell says. “A field in Farmington, however, had plants with pod counts around 212.”

Locals say fields were dry from May 7 until June 29. Then a derecho flipped the switch on soil moisture, according to Cody Pettit, a local Pioneer agronomist.

1st stop Lee County IL. 164 corn but not sure 1/3 of ears look this bad. Would be 200 if 3rd ear didn’t count. Still seeing plenty of 2 or less beans per pod. #pftour23 pic.twitter.com/iHTFXKm23y — Bruce Lantzky (@Lantzkyfarms) August 23, 2023

“We got from 2” to 6” of rain in Will County, Ill. It was a big stretch of time between rains, and I feel soybeans took it harder than corn. Corn got stressed, but not as bad as we thought it would,” Pettit says.

Overnight temperatures and wildfire smoke from Canada played roles in both corn and soybeans. But tar spot is adding another stressful element to corn.

“At this stage in the game, I’m not overly concerned. If tar spot does blow up, we could get some potential stock issues,” Pettit says.

But this week’s heavy morning dew, coupled with 2021’s similarly dry June, has some agronomists, such as BASF’s Vince Davis, on their toes.

“In my opinion, we’re eight to 10 days early from really determining whether tar spot is going to be problematic this year or not. There’s still 35% to 40% yield left to be packed in those kernels from a starch and dry weight standpoint,” Davis says.

While the derecho might have helped the corn crop more than hindered it, scouts don’t expect a record-breaking yield for Illinois.

Tune in tonight at 8pm to hear Day 4 results broadcast live here.