Managing Disease, Moisture and Yield Risks When Harvesting Soybeans
As harvest gets underway, soybean farmers dealing with disease or weather challenges should consider adjusting their harvest plans. Issues like sudden death syndrome (SDS), white mold and excess late-season moisture can reduce both yield and grain quality.
Sudden Death Syndrome
SDS thrives under cool, wet spring conditions and continues through the growing season. Infection begins in the soil and moves into plant roots and stems, with symptoms appearing in late summer and fall. SDS fields should be harvested last to avoid spreading infections to non-affected fields.
“As you go through fields this fall, pay attention to spots that died early or yielded poorly, especially in low-lying areas or compacted headlands,” said Eric Rice, Pioneer field agronomist in west central Minnesota and eastern South Dakota. “SDS is a soilborne fungal disease that stays in fields year after year. If you see it this fall, it’s critical to note those spots and manage them differently going forward. Variety selection, seed treatments and reducing stress on plants can all make a big difference.”
Strategies to reduce SDS in future crops include choosing soybean varieties with stronger tolerance ratings, using seed treatments, improving drainage, reducing soil compaction and controlling soybean cyst nematode (SCN), which adds stress and worsens SDS severity.
White Mold
When white mold is present, proper combine adjustments are essential for preserving grain quality. Increase fan speeds and fine-tune sieve settings to blow out sclerotia – the small, dark, seed-like bodies of the mold – as foreign material. Like SDS fields, white mold fields should be harvested last to minimize the chances of spreading sclerotia from the infected fields.
Looking ahead to next year, variety selection is one of the best defenses. Choosing soybean varieties with higher white mold tolerance scores can help reduce disease impact, though there is no complete genetic resistance.
Minimizing Moisture Risks and Pod Damage
Like anything in farming, weather can be unpredictable. Late-season wet weather can have many negative impacts on soybean harvest, including delays, increasing the possibility of pod splitting, and even triggering pods to sprout. At physiological maturity, soybean moisture is about 35% and can decline quickly, but seeds also reabsorb moisture. Swelling seeds may rupture pods, especially in drought-stressed fields with smaller, weaker pods.
Harvesting these fields as soon as conditions allow can help minimize losses. If seed moisture exceeds 50% with warm temperatures, seeds may germinate inside the pod, lowering quality. Germinated seeds may break apart during harvest or promote spoilage in storage.
Combine operation is critical in these conditions. Forward speed should be around 3 mph, slowing further in poor field conditions. Keep equipment sharp and well-maintained; knife sections, ledger plates, wear plates, hold-down clips, guards, chains, and belts all need attention. Reel speed should be adjusted carefully: too fast increases shatter, too slow may drop stalks.
“Really be mindful of what’s going on with your machine,” advised Brian Shrader, Pioneer field agronomist in Indiana. “Try to get it as tight as you can and hold on to every soybean you can. It doesn’t take very many for you to lose a lot of bushels. Take a few minutes to evaluate what’s coming out the back of the machine.”
Post-harvest handling is equally important. Damaged soybeans should be dried to about 11% moisture and aerated to prevent spoilage. Drying temperatures between 100°F–130°F help preserve seed quality. If damage is widespread, blending with higher-quality beans may be necessary.
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