Planting corn later – as in May versus April – has resulted in higher yields for some central Illinois growers the past three years in a row. Each time, May-planted corn edged out the yields of the April plantings because of moisture availability. With that frustration top of mind, one Illinois corn grower asked Ken Ferrie this week whether it’s time to throw in the towel on planting corn in April.
“My advice for farmers here in central Illinois is if we have a green light in April, plant some corn,” says Ferrie, Farm Journal Field Agronomist, who’s based just south of Bloomington.
However, Ferrie says Illinois farmers shouldn’t be afraid to wait until May to get a green light from Mother Nature to start the planting process.
“We never know how the rest of the year will play out. So, breaking the planting window up is a good way to mitigate risk and take the jam out of the fall of having everything ready at the same time,” he explains.
What Happens At Pollination Time Is Huge
A case in point is one hybrid that Ferrie and team planted on April 28 and again on May 7 in a Farm Journal large-scale test plot this year.
The corn planted on April 28 ended up getting caught trying to pollinate during a three-and-a-half day stretch of foggy weather.
“It was only about 50% pollinated when the fog came in, and we sat four days without dropping pollen,” Ferrie recalls. “Once it dried up, we got pollinated, but we had half an ear on the bottom that was yellow and the top half was white. The top half aborted hard, as it always does.”
When doing yield estimates for the April 28 planting, Ferrie anticipated harvesting between 215 and 220 bushels per acre. Surprisingly, the hybrid delivered a 241-bushel-per-acre average.
He attributes the better than anticipated yield result to the hybrid being a D hybrid – one that increases yield late season by packing on starch during grain fill. Increasingly, Ferrie notes, seed companies are producing more D-type hybrids.
“I knew from our hand harvest plots that it could produce 57,000 kernels per bushel, but that’s still a lot of kernel fill, especially compared to how ugly the tip back looked,” he says.
What Ferrie didn’t anticipate is how much better that specific hybrid would perform yield-wise, in a field planted on May 7 – just nine days after the April 28 planting.
“It had a 263-bushel per acre average. I was no longer happy with my 241 performance, once I found out the May 7 corn was 22 bushels better,” Ferrie laughs.
He attributes the difference in how that hybrid performed to the fog that impacted pollination negatively in the April 28 field.
“But it took field scouting to explain what went on in this plot. Without scouting, we’d have blamed the yield loss on the April planting date. This plot is a good example of why you don’t want all your eggs in one basket when it comes to pollination,” Ferrie says.
Soybeans Are A Different Story Altogether
Soybean yields in Illinois continue to show a strong positive correlation with earlier planting dates, Ferrie reports.
Early planting allows soybeans to take advantage of the long days leading up to the summer solstice by extending their vegetative growth and triggering earlier reproductive stages. This leads to more robust plants, increased pods and seeds per plant, and ultimately, higher yields – barring a hard frost, which is always a risk.
Data from 2025 Farm Journal test plots revealed that soybeans planted on April 14 achieved 101 bushels per acre, significantly outperforming those planted on May 13 (84 bushels) and May 29 (81 bushels).
Poor Fungicide Applications Play Havoc With Yield Results
Farmers have been sending Ferrie pictures of fungicide streaking in their corn crops where the fungicide was sprayed by air. In some cases, the fields were sprayed twice by air. That issue was caused by not keeping a tight spray pattern during the application process.
“Guys are seeing 20- to 40-bushel swings in these skips,” Ferrie says.
He encourages operators who see fungicide streaks to make notes of their location, because they will likely come up during yield map meetings this winter and potentially cause confusion.
“Fungicide streaks and pollination issues can create some wild swings from field to field, or even within a plot in the same field, that’ll leave you scratching your head this winter without some timely ground truthing from your field scouts,” Ferrie says.