This year is a different story.

All summer he’s been scouting for brown and wilting leaves or ears of corn with kernels missing, and now it’s becoming clear that every kernel will count this harvest. “It’s almost kind of depressing to go out there and look at it and say, ‘oh yep, it does look bad,’” he said.

Across major corn-growing states, climate change is fueling conditions that make watching the corn grow a nail-biter for farmers. Factors like consistently high summer overnight temperatures, droughts and heavier-than-usual rains at the wrong time can all disrupt the plants’ pollination — making each full ear of corn less of a guarantee and more of a gamble.

Overall, corn growers got lucky this year with late-season weather that contributed to what is now predicted to be a record bumper crop. But experts say bouts of extreme weather are intensifying the waiting game during a critical time of year between planting and harvest.

Human-caused climate change has worsened multiple U.S. extreme heat events this year and has steadily increased the likelihood of hotter overnight temperatures since 1970, according to Climate Central, an independent group of scientists who communicate climate science and data to the public.

”The hot nights too, like the corn’s never getting a break. It’s just hot all the time,” Rynd said. “I know it’s wearing on me.”

How excessive heat and rainfall can impact corn pollination

As a corn plant grows, the leaves unroll to reveal the tassel, the part that sheds pollen, explained Mark Licht, an associate professor of agronomy and an extension cropping systems specialist at Iowa State University. If the plant grows too fast, which can happen when it’s consistently very hot, the tassel may be wrapped too tightly by the leaf, meaning less pollen gets released.

That can lead to patchy ears of corn. Tight tassel wrap was reported in pockets across parts of the Midwest and the Plains, according to some agricultural trade publication reports during the growing season. Licht said he’d only seen tassel wrapping issues once before in his 20 years as an agronomist.

High temperatures can stress corn in other ways, lowering pollen production, reducing pollen’s viability or drying out other parts of the plants, reducing fertility. “I think any of the pollination issues that we might be having are more because the nights have been so exceedingly warm,” said Larry Walton, who farms near Rynd in southwestern Michigan, where many farmers irrigate because it’s a drier area.

“We tend to see pollination issues being more problematic when we have high temperatures and drought conditions or lack of rainfall,” Licht said. Yet Iowa had plenty of rain and still saw some pollination issues. Excessive moisture can cause corn smut, a type of fungus that grows on the ears.

He said farmers are having to pay more attention to this because “there’s just more variable weather.”

Overall ‘monster’ yield expected despite tricky weather conditions

This winter, the U.S. drought monitor reported drought in nearly 60% of corn production areas in the Midwest. But near or above normal rainfall nearly everywhere east of the Rockies this summer brought that down to just 3% as of the beginning of August, said Brad Rippey, a meteorologist with the U.S. Department of Agriculture.

That, combined with consistent heat, means that “we are expecting a monster U.S. corn crop in 2025,” Rippey said.

But it wasn’t easy for everyone. “This has probably been one of the most difficult growing seasons that I’ve experienced in my career,” said Philip Good, a farmer in Macon, Mississippi and chair of the United Soybean Board. He planted his corn and soybeans 60 days behind schedule because it rained nearly every day for two months.

They lost some fertilizer and some plants died in standing water, Good said, but they made up for it with some lucky weather later in the season.

“The rain does fall in heavier bursts,” Rippey said. He said that can be an issue for farmers because even when it doesn’t cause flash floods, the moisture doesn’t necessarily percolate into the soil. It runs off and carries fertilizer with it, which is a problem for rivers’ health and farmers’ pocketbooks.

The trend toward higher humidity levels and warmer ocean temperatures, contributing to hotter nights, could be a bigger issue going forward, putting stress on crops like corn and soybeans, Rippey added.

Climate variability adds stress to a critical time for farmers

Late summer is a make-or-break time for farmers: They’re trying to gauge how much they’ll make from the year’s crop and planning their next steps, and patchy pollination doesn’t help.

“We’d like to upgrade a tractor … or we’d maybe try to pick up some more ground,” Rynd said. “It’s hard to want to go do those things when you have a bad year like this.”

When the uncertain pollination is at its worst, if 15% to 25% of every ear of corn doesn’t have kernels, that could mean a significant yield loss over a large field, said Nicolle Ritchie, a Michigan State University extension agent who helps Walton and Rynd survey their crops.

Jason Cope co-founded a farm tech company called PowerPollen whose equipment can mechanically collect pollen and then pollinate future crops. He said that due to extreme weather events, the number of “rescue” pollination jobs they’ve done for customers — to save fields that didn’t naturally pollinate very well — has nearly doubled since they started in 2018.

Walton said he can manage as long as the pollination issues don’t get too bad.

“You learn to roll with the stress part of it because most of that you can’t control anyway,” he added.

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