Standing in a 50-acre field near his farm shop, Ben VanRoekel opened his hand to reveal a palm full of discolored soybeans. Some are moldy and shriveled, while others are purple-stained.
“Those right there are my good pods,” says Van Roekel, his voice tinged with frustration.
VanRoekel had originally benchmarked the field for a 60-bushel-per-acre average — roughly 3,000 bushels total. Now, the south-central Iowa farmer faces an uncertain yield outcome and, given the quality of the beans, potential dockage or rejection when he goes to sell them.
“I don’t know what I’m going to do with them yet. I’m trying to figure that out,” VanRoekel told Farm Journal via text on Tuesday.
VanRoekel’s experience is echoing through parts of the Corn Belt — from Nebraska to Ohio — as soybean growers start or try to continue harvest in fields where rains fell off and on the past few weeks.
Not All Growers Are Having Problems
The resulting issues are not uniform across all acres. Much of the quality problems are concentrated in early-planted, early-maturing soybeans that reached physiological maturity just as rains moved in, according to Meaghan Anderson, Iowa State Extension field agronomist.
“The big thing with the beans was whether the crop was mature when it started raining,” Anderson says. “If you had rain and the beans were mature, you should expect that you’re likely to see some quality issues at harvest.”
Soybeans that had already turned brown or were approaching leaf drop (R8) when the rainfall started were exceptionally vulnerable to repeated wetting and drying cycles. Conversely, Anderson says later-maturing soybeans in Iowa that remained green when the wet weather arrived have fared better so far, though their maturity was likely delayed.
The deterioration is driven by a combination of field pathogens and structural pod failure:
- Purple Seed Stain (Cercospora kikuchii): Favored by prolonged warm, humid conditions during seed fill and maturity, this fungus causes pink-to-lavender seed discoloration. While it often affects appearance more than structural seed integrity, severe pressure can reduce grade and contribute to dockage.
- Diaporthe/Phomopsis Seed Decay: Prolonged moisture on mature pods allows fungi to breach the pod wall, causing shriveled, chalky-white, or mold-covered seeds.
- Pod Splitting & Insect Injury: Alternating wet and dry cycles weaken pod seams. Once a pod splits or suffers pod-worm/bean leaf beetle feeding punctures, ambient moisture directly contacts the seed, accelerating decay.
“If you’re seeing it on some seeds, depending on the percentage, it’s probably in other seeds as well,” Anderson warns. Field appearance can also be deceiving: while combines will blow light, severely shriveled beans out the back, substantial latent infection and discolored seed will can still end up in the grain tank.
Along with disease issues and discoloration, pre-harvest pod shattering can occur when dry pods are rewetted. Harvest pod shattering occurs when grain moisture content is less than 13%. As soybean moisture decreases, shatter and harvest losses increase, reports Dylan Mangel - Extension Plant Pathologist at University of Nebraska.
When assessing harvest shatter losses, approximately four soybean seeds per square foot equal 1 bushel per acre of loss.
Field Triage: Rethink Your Harvest Order
Agronomists encourage soybean growers to throw out any pre-determined harvest schedules and let current crop conditions dictate field harvest order.
“I would not be dilly-dallying right now,” Anderson says. “We have an incredible window of opportunity in Iowa to get stuff out of the field (the next couple of days), but farmers should use crop condition to determine harvest priority.”
High-yield corn and soybean grower David Hula agrees, advising farmers to focus what he calls “relentless operational capacity” on deteriorating acres.
“Let’s focus on getting the crop that’s worst off out of the field now before it gets any worse,” Hula says. “Once pods begin splitting and beans go through additional wetting and drying cycles, quality can deteriorate exponentially.”
However, Anderson cautions against forcing machinery into fields that aren’t harvest ready. Rutting fields that are soggy causes long-term compaction issues, and harvesting wet, green-stemmed, or bushy soybeans can cause header loss or cylinder wrapping.
If on-farm drying capacity is constrained, allowing relatively sound, later-maturing soybeans to dry naturally while aggressively harvesting decaying fields strikes the best operational balance, Anderson reports.
Storage Management and Segregation Strategies
Managing weather-damaged soybeans does not end at the grain tank. Transporting compromised seed straight into a standard aerated bin without a clear management plan can turn a localized field problem into storage loss. Here are four considerations:
1. Separate the Grain
Hula stresses the importance of segregating grain at the farmstead: “Put the compromised stuff in a bin to separate it; put the good stuff in a different bin, and blend it on your way out,” he advises.
Keeping questionable grain isolated provides flexibility. Mixing compromised beans with high-quality grain in the same bin risks infecting the sound portion of the crop, driving up moisture pockets, and creating potential hot spots. For growers without on-farm storage, Hula says to communicate directly with local grain elevators before hauling to understand potential dockage or even identify alternative delivery points.
2. Dry and Cool Immediately
If storing damaged soybeans, Anderson recommends growers target a storage moisture of 13% or below (11%–12% is even better, if you plan to hold the beans very long). Run aeration fans to bring grain temperatures down below as ambient temperatures drop.
3. Monitor Bins Aggressively
Questionable beans should be marketed earlier than later. “Don’t hold on to it for long,” Anderson says.
She advises growers to inspect bins regularly to monitor quality:
- Olfactory Checks: Smell the exhaust air when aeration fans turn on. A musty or sour odor indicates potential mold activity.
- Carbon Dioxide () Monitoring: Utilizing sensors in storage bins can provide an early warning of biological activity and grain spoilage long before temperature cables pick up a hot spot.
4. Manage Insurance and Rejection Risks
Elevators under strict export or processing specs may reject severely stained or moldy loads. If you face discounts or load rejections, contact your crop insurance agent immediately — before commingling grain or altering storage arrangements — to ensure proper documentation for quality adjustment claims.
More information on that is available here.
Long-Term Management: Mitigating “Phantom Yield Loss”
For 2027 crop planning, high-yield strategist Randy Dowdy suggests that harvest experiences growers are having this fall highlight some of the risks of field-drying mature soybeans.
Dowdy says repeated wetting and drying cycles can cause phantom yield loss — yield that was produced by the plant but disappears through dry-matter loss, pod shattering, and field decay.
To mitigate risks in future soybean crops, Dowdy recommends farmers:
- Stagger Maturity Groups: Spread soybean planting dates and relative maturities across multiple maturity groups (e.g., mixing Group 2.5 and Group 3.1 in the same region) to prevent the entire farm from reaching R8 simultaneously.
- Harvest at Higher Moisture Levels: Consider harvesting soybeans at 15% to 16% moisture and utilizing supplemental heat or aggressive air-drying in the bin rather than leaving dry, mature beans exposed to late-season weather conditions.
