When the U.S. Department of Agriculture (USDA) released its August 12 Crop Production report, it delivered mixed news for the U.S. corn and soybean crops. The department forecast corn production to increase by up to 16.7 billion bushels. USDA estimates that the average corn yield will be a record-setting 188.8 bushels per acre (that’s 9.5 bushels higher than last year) with record yields expected across much of the Midwest and beyond.
The soybean crop headline is a bit different. While USDA expects U.S. soybean growers to decrease their overall production, it predicts average soybean yields will increase to 53.6 bushels per acre, with several key states poised to set record-high yield numbers in terms of bushels per acre.
But Pro Farmer, which is a division of Farm Journal, recently released some different predictions after concluding their 33rd annual Pro Farmer Crop Tour. Based on field-level observations, the group trimmed its national estimates, predicting corn yields at 182.7 bushels per acre and soybean yields at 53 bushels per acre. Their estimates are based on Crop Tour data and observations collected by more than 100 crop scouts, who sampled more than 3,200 fields in seven states.
What Our Experts Have Seen
At first glance, this year’s corn crop looks outstanding. Plants are tall, green, and uniform. But Advanced Agrilytics agronomists across the Midwest report a different story once they pull husks back. For example, some ears show reduced kernel counts, tip-back, or signs of aborted kernels. These symptoms point to stress events earlier in the season. Here are some examples:
- Periods of excess moisture or drought, which restricted root growth and nutrient uptake.
- Reduced solar radiation from persistent cloud cover and wildfire smoke, which cut photosynthetic efficiency and output.
- High nighttime temperatures, which forced plants to burn more of their stored energy rather than channeling it into grain fill.
- Foliar diseases such as southern rust, gray leaf spot, or tar spot, varying by region and hybrid tolerance.
- Insect pressure, including aphids in certain geographies.
The challenge is that none of these factors alone may devastate a field. But layered together, they erode the plant’s sucrose reserves—the “fuel tank” needed to optimize grain fill. The result: ears that look full from the window of a truck but look very different once you inspect a few ears up close.
Many Factors that Could Still Affect Yield
With weeks (or days, depending upon where you farm) to go until final crop maturity, many factors could still impact corn and soybean yields in 2025. Here’s a snapshot of what those could be:
| Corn Stress Factors | Soybean Stress Factors |
| Late-season diseases such as southern rust, tar spot, gray leaf spot can be a factor. Upper canopy infections reduce photosynthetic productivity during grain fill. | Moisture availability: timely rains are critical for pod retention and optimum seed sizing. |
| High nighttime temperatures keep plant respiration high overnight, burning up energy the plants need for grain fill. | Conditions for Sudden Death Syndrome (SDS) development have been ideal in parts of the Corn Belt, according to Iowa State University. This disease causes pod abortion or poor pod development and can severely impact yields. |
| Moisture extremes such as drought or too much moisture affect plant development and grain fill. | Other foliar diseases such as white mold, Septoria brown spot and others can thrive in humid, late-season conditions. |
| Reduced solar radiation such as cloudy days inhibits photosynthetic efficiency. | Hot and dry weather can accelerate plant maturity and cause pod abortion or poor seed development. |
| Insect pressure such as aphids and other pests increases plant stress. | Disease or weather stress can negatively impact canopy health, which can reduce the plant’s ability to finish pod fill. |
| Stalk integrity can be impacted as stressed plants use up precious sucrose reserves, creating more brittle stalks which are more prone to lodging late in the growing season. |
Soybeans: Holding Potential, But Still Vulnerable
Soybeans are entering their critical pod-fill period. While USDA projected a record yield, our Regional Agricultural Leads report that the outlook for soybean yields may not meet those expectations.
Our agronomists and several land-grant Universities are reporting outbreaks of sudden death syndrome (SDS) in Iowa, Nebraska and Minnesota. In addition, other disease pressures could limit the crop’s ability to capitalize on strong pod counts. Moisture will also be a key late-season factor. Many plants are loaded with pods, but without timely rains, those pods could abort, or seeds may not reach optimum size.
How Much Time Do We Have Left?
For corn, the race now is to optimize grain fill before the crop reaches black layer, the stage when kernels stop filling and physiological maturity is reached.
That window is critical. Stress during this late phase won’t reduce kernel counts, but it can shrink kernel size and test weight. If southern rust or tar spot explodes in the upper canopy, photosynthetic capacity could be compromised just when the crop needs energy most.
What our Agronomists Are Seeing
We’ve had a few reports from some of our Regional Lead Agronomists in the past several days. Here’s some insight on the crop progress in Illinois:
“Corn harvest has just begun for a limited number of people in our area, and more will be starting every day after Labor Day weekend,” reports Regional Agronomy Lead Chris Kallal, located in Western Illinois. “Yields are close, to slightly less than expected, and corn seems to be drying down faster than some people anticipated. Recent lower humidity and windy days are likely aiding that process. Soybean harvest is upon us as well. The early planted, early maturing soybeans are almost ready. Most people are still pretty bullish about their soybean crop, but we really could use a rain for the later-planted and later-maturing soybeans, to help them finish strong.”
“Here in Central Illinois, most growers will be getting started on corn harvesting the week of Sept. 8th or the following week,” reports Technical Agronomy Lead Jeremy Hogan. “Soybeans will likely follow the same calendar dates as corn. The recent milder daytime temperatures and cooler nighttime temperatures have significantly reduced GDD accumulation, which has the potential to extend grain fill by six to ten days in many fields that have not already black-layered. For each day of extended grain fill, we typically see an increase of 1.5 bu/A per day. Unfortunately, on ears that have already dropped, we will not be gaining any additional grain weight. In many fields, ears are dropping by the day.”
The Bottom Line
The USDA’s models suggest a record-setting crop, while Pro Farmer and our own expert agronomists see a slightly more tempered reality. For growers, the lesson is clear: September weather and disease pressure will ultimately decide the story of the 2025 harvest.
Want more agronomic insights from Advanced Agrilytics? Contact us here.