Focus On Stalk Quality To Maximize Harvest Results

As Caleb Hamer evaluated his corn last weekend, he says the crop looked like it flipped a switch and decided it was done growing for the season.

“Between the southern rust, some tar spot, and I think the heat, that’s all pushed stuff along. I think the corn shut down probably sooner than need be, which is slightly alarming,” says Hamer, who farms in northeast Iowa.

Farmers Adjust Corn Yield Expectations
Some combination of extreme disease pressure, moisture at the wrong times and too much heat are factors likely to pull some states’ corn yield averages down from USDA’s August 12 WASDE report, which made a record 188.8 bushels per acre average yield projection.

Hamer says he has already adjusted yield expectations for his corn crop.

“I kind of had us shooting for some sort of single digit percentage over last year, and last year was a really good crop in our area. Now I’m hoping we’ll be on par with last year, but I don’t think we’re going to beat it at this point,” Hamer told AgriTalk Host Chip Flory. “I think a lot of that’s related to how fast the crop matured in August, because you’d like it to be slow, not fast in August.”

The fast maturation underway means a lot of corn in the Midwest, especially in parts of Iowa and Illinois, had a more shallow kernel fill than desired which will result in lower yields, according to Ken Ferrie, Farm Journal Field Agronomist.

“I still expect an average crop in Illinois, but not the bin buster we thought was possible early on this season,” he says.

Make A Harvest Plan For Each Field
Ferrie says some central Illinois fields were caught in wind events last week and corn went down, and fields were also plagued by foliar disease pressure in much of the state.

Iowa fields have also been hit hard by foliar disease, especially southern rust, according to Alison Robertson, Iowa State University Extension field crops pathologist. What she says commonly happens is when severe leaf disease impacts corn plants, they remove carbohydrates from the stalk and roots in order to fill kernels in the ears.

“That leads to stalk rots, which leads to poor standability,” Robertson explains “If you have a field that has shut down, you will need to get into that field and harvest early.”

The severity of southern rust across Iowa this summer has Robertson thinking corn yield losses could reach up to 30% in those fields where no fungicide was applied. She discussed the issue on Monday with Chip Flory, host of AgriTalk. Listen to their discussion here:

Ferrie offers advice similar to Robertson’s. “Put these fields high on your harvest list to get corn out before the plants go down anymore and ear molds set in. Spend a little money on dryer gas and keep the harvest loss as low as possible,” he says.

Kentucky farmer Ryan Bivens says he is trying to stay positive despite seeing much of his corn crop die prematurely from a combination of foliar disease and too much heat.

“We’re probably 25%, 30% off our yield expectations, so it’s really tough out here,” says Bivens, who farms south of Louisville. “I’ve said all along, if we can come out of this year with 150- to 160-bushel yield, which is substantially lower than our APH, I think we better be happy.”

As farmers evaluate and prioritize fields for harvest, Missy Bauer recommends three steps that can help you in the process:

1. Split stalks open to gauge stalk health.
“When you split stalks open this time of the year, we should still see some integrity down in these stalks,” says Bauer, Farm Journal Field Agronomist. “If the stalk is cannibalized, and has a Styrofoam appearance, there’s little to no integrity left in the stalks.”

2. Do the pinch test. Pinch the stalk at one of the lowest two internodes with your thumb and fingers. If the pressure causes the stalk to collapse, it fails the pinch test, and that field needs to be toward the top of your harvest calendar.

3. Try the push test.
Another way to evaluate stalk integrity is with the push test. “You grab the plant right about the height of the ear, and extend the stalk over toward the other row a full arm length,” says Bauer.

If the stalk snaps off, or stays leaning over, then you know you have a greater potential for down corn in that field. Again, move that field toward the top of your harvest list.

For your planning purposes, here’s a summary of harvest considerations from Pioneer:

When prioritizing fields for harvest:
· Estimate corn yield. The Pioneer Corn Yield Estimator or the Yield Estimator in the Granular Mobile app provides quick, in-field yield estimates

Manually estimating corn yield:
· Measure one one-thousandth of an acre
· Count harvestable ears
· Determine average kernels per row (avoid tip kernels)
· Count kernel rows per ear
· Calculate: Estimated yield (bu/ac) = (ears × kernel rows × kernels per row)/90 — Example: (32×16×28)/90 ≈ 159 bu/ac

Assess stalk strength:
· Scout 2–3 weeks before harvest and use the push test; harvest weaker fields first to reduce lodging risk
· Check ear molds and calibrate monitors
· Watch for mold issues, especially in corn-on-corn or high-population fields

Calibrate yield monitors and re-check periodically during harvest.

Identify disease, insect and weather stress:
· Flag stressed fields and move them up in the harvest sequence

Operational tips:
· Consider starting at 20–25% grain moisture to spread workload and reduce field and standability risk
· After harvest, review the season’s performance to inform next season’s hybrid selection

Your next read: Corn Market Resilience Continues