SDS Re-Emerges as Major Threat in Soybeans This Year
Cool early planting, persistent soil moisture, and rising SCN pressure set the stage for widespread Sudden Death Syndrome outbreaks
Sudden Death Syndrome (SDS) reasserted itself across soybean country this year, with agronomists from Iowa to Illinois and into parts of the eastern Corn Belt reporting some of the most noticeable field symptoms since the mid-2010s. It also occurred in Nebraska (see box for details). The surge came after a spring marked by extended cool soil temperatures, prolonged saturation in many river-bottom and no-till fields, and expanding soybean cyst nematode (SCN) pressure — three conditions that provide ideal footing for Fusarium virguliforme, the soilborne fungus that causes SDS.
Early Planting + Cold, Wet Soils Created the “Perfect SDS Year”
Producers, eager to maximize yield potential, pushed planting earlier again this year, often into soils that hovered in the low 50s. While early planting boosts yield in many seasons, it also greatly increases vulnerability to SDS infection when fields stay wet. Extension pathologists note that this year’s planting conditions were “a classic setup”: cool soils at planting, frequent post-planting rains, and limited drying periods.
Under those conditions, the SDS pathogen infects the soybean root system shortly after germination. Foliar symptoms—burned leaf margins, interveinal chlorosis, and sudden defoliation—show up later in the season, often confusing growers who mistake SDS for herbicide injury, nutrient deficiency, or stem canker.
Soybean Cyst Nematode Intensifies Disease Pressure
Another driver of this year’s outbreaks is the continued expansion of SCN across the Midwest. Researchers emphasize that SCN and SDS act synergistically: SCN feeding wounds roots, creating more openings for Fusarium virguliforme to take hold. This year’s higher SCN egg counts, particularly in rotating corn/soybean fields, helped push SDS severity higher and extend its footprint into fields with no recent history of the disease.
Seed Treatments Provided Relief — But Didn’t Eliminate Losses
Seed treatments containing fluopyram (ILeVO) and pydiflumetofen (Saltro) again proved to be the most effective commercially available tools for reducing SDS severity. Retailers reported strong demand for both products heading into planting, and university trial plots this fall confirmed that treated fields generally showed lower foliar symptoms and stronger root health. (See table below.)
However, the severity of conditions in some areas overwhelmed even treated acres. Yield monitors in several high-pressure pockets recorded double-digit bushel losses, and untreated or late-planted soybeans saw some of the most dramatic foliar symptoms in recent years.
Field Variability Highlights the Need for Integrated SDS Management
One hallmark of SDS is its intense variability — entire zones of fields may be devastated while nearby ridges or sandier areas remain largely unaffected. The same pattern emerged this year, underscoring what agronomists consistently advise: SDS cannot be managed with a single tool.
The most effective strategy remains an integrated approach that includes:
• Seed treatments (ILeVO or Saltro)
•SDS-tolerant or resistant soybean genetics
•Active SCN management, including resistant SCN varieties and rotation
• Improved drainage in wet-prone areas
• Avoiding very early planting in historically affected fields, especially if soil temperatures are still low
| Product | Active Ingredient / Mode of Action | Targets | Key Findings / Notes | When & Where to Use (Recommendations) |
| ILeVO | Fluopyram (SDHI — FRAC Group 7) | SDS; partial SCN suppression | Approx. 35% reduction in SDS severity; ~4–5 bu/acre yield gain; temporary halo effect. | Fields with SDS history; early planting in cool/wet soils; moderate SCN pressure; combine with resistant varieties. |
| Saltro | Pydiflumetofen (SDHI — FRAC Group 7) | SDS; improved seedling vigor; some SCN-related suppression | Strong protection; often better early vigor; equal or superior suppression under heavy pressure. | High SDS pressure; early planting; no-till systems; growers prioritizing stand vigor. |
| General Limitations | — | — | No cure once infection occurs; performance depends on SDS pressure; both are SDHI so rotation doesn’t reduce resistance. | Use where SDS or SCN history exists; integrate with resistant genetics and good drainage. |
Looking Ahead: 2026 Could Bring Similar Risks
With more growers continuing to plant soybeans early to capture yield potential, and with SCN populations rising in many counties, university pathologists warn that SDS risk is unlikely to diminish next year. If early spring soils trend cool and wet again, “another SDS year” is possible.
Researchers continue monitoring the pathogen for potential resistance to SDHI fungicides, though no widespread resistance concerns have surfaced. Still, reliance on a single mode of action increases long-term risk, further elevating the importance of resistant genetics and SCN control.
Bottom Line:This season served as a reminder that SDS remains one of the most damaging and unpredictable diseases in soybeans. While modern seed treatments significantly reduce risk, they cannot fully offset the combination of early planting, saturated soils, and rising SCN levels. For many growers, 2025 reinforced the importance of pairing seed treatments with genetics, drainage, and SCN management to protect yield potential in the years ahead.
| SDS Surges in Nebraska Soybeans — First-Ever Outbreak Reports from Farmers Signal Growing RiskCool, wet spring and rising SCN pressure fuel SDS outbreaks; some Nebraska growers say 2025 marks their first encounter with the disease SDS has re-emerged as a major threat across U.S. soybean country in 2025 — and in Nebraska, the surge took a worrying turn as several farmers reported experiencing SDS in their fields for the first time. Long-time producers from eastern and southeast Nebraska told agricultural extension agents that pockets of soybeans they’d grown for decades without SDS were showing foliar collapse, root rot, and characteristic root-fungus signs this fall. Nebraska’s Wet Spring Set the Stage for First-Time SDS Outbreaks According to the latest from University of Nebraska–Lincoln Extension (UNL Extension), extended rainfall and saturated soils after planting left large swaths of Nebraska particularly vulnerable to SDS this season. The soilborne fungus Fusarium virguliforme — which causes SDS — thrives in moist, compacted soil, and this year’s soil conditions allowed early root infection that remained hidden until reproductive stages. UNL Extension pathologists noted that symptoms began appearing at the R3 and later reproductive stages in many fields. Visible signs included yellowing between leaf veins, browning leaf tissue, root rot, and, in some cases, a distinctive blue fungal growth on roots — a tell-tale sign of SDS infection confirmed in southeast Nebraska fields. First-Time SDS Reports Signal Shifting Disease Risk What’s particularly striking about this year’s Nebraska outbreak is the number of farmers who said they never had SDS before. For many, soybeans have been grown for years — even decades — without ever needing to consider SDS seed treatment or special management. The sudden onset of pockets of disease in these fields is raising fresh alarm across the state’s soybean belt. USDA-allied researchers and extension agents now warn that SDS can appear in fields with no prior history when environmental conditions align. Moreover, fields with Soybean Cyst Nematode (SCN) infestation — already widespread in Nebraska — seemed especially prone to severe SDS damage. SCN can weaken plant roots, creating more entry points for SDS fungus; a 2025 press release from SCN-control advocates underlined how unchecked SCN populations “silently” make beans more vulnerable to diseases like SDS. Seed Treatments, Resistant Varieties, and Record-Keeping Key for 2026 Given the unexpected expansion of SDS this year, UNL Extension is urging all Nebraska growers — even those with no previous SDS history — to reevaluate their 2026 seed and variety plans. Key recommendations:• Use soybean varieties rated for SDS tolerance/resistance.• Apply proven seed treatments (e.g., SDHI fungicide-based treatments) especially on fields with saturated soils, past SCN pressure, or heavy residue.• Monitor and manage SCN — via soil testing and rotation or SCN-resistant varieties — to reduce root stress and susceptibility.• Document field history carefully (planting date, soil moisture, prior disease/pest history) to better assess risk year to year. Implications: SDS Risk May Be Growing Even in “Safe” Fields The wave of first-time SDS reports should sound an alarm bell across the Corn Belt: fields historically immune may no longer be safe. As planting dates trend earlier and weather variability increases, SDS — once confined to a few “hotspot” regions — may become a more widespread, unpredictable threat. For Nebraska growers, 2025 may mark a watershed year. Those who escaped SDS in the past now face new vulnerability. The coming offseason will be crucial: choices about variety, seed treatment, SCN management, and record-keeping could determine whether next year’s crop faces the same fate. |
