An ear of corn with patchy kernels, which is likely due to pollination issues. — Photos: AP
Robb Rynd and his brother grew up farming in the United States and wanted to do more of it outside their day jobs, so they went in together on what’s now a little over 80ha of corn, soybeans, wheat and sorghum.
Last year was a good year, and Rynd said he enjoyed walking the fields with his kids in Michigan, to see how the corn was doing.
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 in the US, climate change is fuelling 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.
Bad to be hot
Human-caused climate change has worsened multiple extreme heat events in the US this year and has steadily increased the likelihood of hotter overnight temperatures since 1970, according to Climate Central, an independent group of scientists in the US who communicate climate science and data to the public.
“The nights (are hot) 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.”
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.
High temperatures can stress corn in many ways, resulting in low or low-quality yields.
That can lead to patchy ears of corn. Tight tassel wrap was reported in pockets across parts of the Midwest (north-central region) and the Plains (covers 10 states) in the US, 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”.
In winter, the US 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 US Department of Agriculture.
That, combined with consistent heat, means that “... we are expecting a monster US 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 fertiliser 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 added 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 fertiliser with it, which is a problem for rivers’ health and farmers’ pocketbooks.
Rynd pulling the husk off of an ear of corn during an inspection of his crops in Paw Paw, Michigan.
The future
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.
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. – AP
