Soybean Sudden Death Syndrome

Key Takeaways

• SDS infects soybean roots early, but symptoms often appear later in the season.
• Yellow interveinal chlorosis, leaflet drop, and a white stem pith are key diagnostic symptoms.
• Cool, wet soil and presence of soybean cyst nematode (SCN) can increase disease risk.
• It is important to choose soybean products with strong SDS and SCN tolerance.
• Seed treatments can help reduce disease severity and protect your yield potential.

What is Sudden Death Syndrome (SDS)?

Soybean sudden death syndrome (SDS) is a major soybean disease across North America.¹ It is caused by the soilborne fungus Fusarium virguliforme. While most foliar symptoms are identifiable during the late vegetative to early reproductive growth stages, infection typically occurs shortly after germination.

Identifying Symptoms of Sudden Death Syndrome in Soybean

Foliar symptoms typically appear later in the season as yellow (chlorotic) blotches between leaflet veins. These blotches expand into irregular patches that turn brown and necrotic over time. In advanced stages, leaflets often drop from the plant while petioles remain attached (Figure 1). Additional indicators include a white, intact stem pith with tan to light-brown streaking (Figure 2 and Figure 3). In some cases, roots may develop a bluish-white fungal spore mass (Figure 4). Often, plants affected by SDS may also abort flowers and pods.

Soybean stem canker (northern and southern) and brown stem rot (BSR) can cause similar foliar symptoms to SDS. Therefore, it is important to properly identify the causal disease. One key difference is that the leaflets infected by soybean stem canker or BSR remain attached to the plant. In addition, BSR causes internal pith discoloration ranging from tan to dark brown near the crown and stem nodes (Figure 5), whereas SDS generally maintains a mostly white pith.

Environmental Conditions Favoring Sudden Death Syndrome

Fusarium virguliforme, a soil-borne fungal pathogen, overwinters in crop residue and soils and can be spread from field to field with equipment. Its thick-walled spores help to make the pathogen resilient to harsh environmental conditions, allowing it to persist for multiple years. SDS development is favored by:

• Soil temperatures below 60°F at or shortly after planting
• Cool, wet conditions early in the growing season
• Compacted soils or poor drainage
• The presence of soybean cyst nematode (SCN)

SDS is also often associated with high-yield production practices and environments.

Tips for Managing Sudden Death Syndrome in Soybean

Management of SDS should begin before planting by reducing risk factors for infection:

• Improve field drainage through tiling or land leveling where needed
• Minimize soil compaction through appropriate tillage and field compaction management
• Select soybean products with strong tolerance or resistance to SDS and SCN
• Consider earlier-maturing products to help reduce late-season disease impact²
• Use fungicidal seed treatments where appropriate
• Delay planting until your soil is warmer and drier, when possible

Note that, foliar fungicides have not been effective for managing SDS, and crop rotation alone is generally ineffective due to the pathogen’s long-term survival in soil and crop residue.³

Importance of Soybean Seed Product Selection and Seed Treatments For Managing SDS

Research from 2020 to 2022 evaluated seed treatments containing fluopyram and pydiflumetofen for SDS management. At two Minnesota locations with low SCN pressure, both treatments reduced the foliar disease index (FDX, which takes into account the percent incidence and severity of symptoms of SDS), with reductions of up to 75% observed for pydiflumetofen.⁴

A separate three-year study (2018 to 2020) conducted by Bayer Crop Science across 15 different soybean fields in seven states evaluated the effects of natural varietal tolerance and seed treatments on SDS severity and yield. The pressure from SCN was low at these sites. Soybean products were divided into five classifications ranging from susceptible to resistant ratings for SDS. Seed treatments included Acceleron® STANDARD Seed Applied Solutions and STANDARD plus ILEVO® Seed Treatment (active ingredient is fluopyram). The data indicated that across all seed product SDS tolerance categories, the disease index was lowered with the addition of ILEVO® Seed Treatment. Observed yields trended from highest (for seed products rated as resistant) to lowest for susceptible products, and regardless of resistance category, yields were improved with the use of ILEVO® Seed Treatment. Additional details of the study can be found at Evaluation of Disease Management Systems in Soybean – Sudden Death Syndrome | Crop Science US. This study, along with results found at Managing Sudden Death Syndrome in Soybean | Crop Science US help to illustrate the importance of selecting soybean seed products with high levels of tolerance to SDS as an important step in managing this disease.

Sources

¹Jardine, D.J. 2020. Sudden death syndrome. Soybean Diseases. Soybean Research & Information Network. https://soybeanresearchinfo.com/soybean-disease/sudden-death-syndrome/.
²Meiring, B., Dorrance, A., and Mills, D. 2011. Sudden death syndrome of soybean. AC-44. Ohioline. The University of Ohio State. https://ohioline.osu.edu/factsheet/AC-44.
³Marburger, D., Conley, S., Gaska, J. and Gerber, L. The relationship between the causal agent of SDS and SCN in Wisconsin. University of Wisconsin Extension. https://soybeanresearchinfo.com/wp-content/uploads/2019/03/SCN_SDS_2015_FINAL.pdf
⁴Malvick, D. K. and Floyd, C. M. 2025. Management of soybean sudden death syndrome with seed treatments in Northern U.S. field and greenhouse environments. American Pathological Society. https://apsjournals.apsnet.org/doi/10.1094/PHP-06-25-0163-RS.
Web sites verified 5/6/2026.

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