Sudden Death Syndrome in Soybean: Tips for Diagnosis and Management | CropWatch

By Dylan Mangel - Extension Plant Pathologist, Ritika Lamichhane - Extension Educator

Soybean field with sudden death syndrome symptoms, inset close-up showing blue fungal growth on infected roots. — Sudden death syndrome is showing up across Nebraska soybean fields — learn how to identify this season’s infections and make management decisions for 2026.

Key Takeaways

SDS is appearing now in Nebraska soybean fields, with symptoms visible at R3 and later growth stages.
Cool, wet spring conditions set the stage for early infection; heavy rains around flowering intensified symptoms.
Scouting is critical to distinguish SDS from brown stem rot and other diseases.
Blue fungal growth on roots and petiole retention are strong SDS indicators.
Management focuses on resistance and timing: Use tolerant varieties, adjust planting dates in high-risk fields, and consider seed treatments for 2026 planting.

Sudden death syndrome (SDS) is showing up in soybean fields across Nebraska, with symptoms becoming more visible as plants move through late reproductive stages. While there’s no way to reverse yield loss this season, scouting now will help growers confirm disease presence, evaluate its impact, and make informed seed and management decisions for 2026.

The following overview highlights how SDS develops, key symptoms to watch for, and management options to consider for future seasons.

Pathogen

Cool spring rains and prolonged wet soil conditions after planting this spring promoted soybean infection from the soilborne pathogen (Fusarium virguliforme) that causes SDS. This fungal pathogen infects soybeans early and grows without observable symptoms often until late July or early August, when the interaction between stresses and plant development reveal symptoms that range from patches of foliar chlorosis to entire declining fields.

Disease Symptoms

Foliar symptoms of SDS typically do not appear prior to soybean flowering. Early symptoms at the R3 and later growth stages consist of the presence of chlorotic (yellow) spots on the leaves between veins. As the symptoms advance, the yellow spots may coalesce but stay between the veins at the leaf margin. Eventually, the yellow areas between the veins will become brown (necrotic) as the tissue dies.

Roots will exhibit a root rot on the tap root. The discoloration of the vascular tissue is contained to the outer stem area (xylem vessels) and can extend up the stem from the soil line. The pith will remain white, which is a key symptom to differentiate SDS from brown stem rot.

Split soybean stems showing brown crown discoloration from sudden death syndrome while pith remains white. — **Figure 1.** The crown of infected soybean stem is often discolored to brown or cream. (Ritika Lamichhane | Nebraska Extension)

Pods may be aborted and plants may defoliate early. Defoliated plants will retain their petioles. Retention of the petioles is a symptom frequently associated with SDS.

Symptoms on the root system are difficult to distinguish from other soybean root rots. When roots are removed from soil, the fungus is sometimes visible on the outer root surface. In some, but not all cases, this fungal growth will be blue.

Soybean rows showing sudden death syndrome symptoms, with yellowed patches in susceptible varieties between tolerant rows. — **Figure 2.** SDS symptoms differ between tolerant varieties and susceptible varieties. This image shows four rows of a tolerant variety planted between two susceptible varieties. (Dylan Mangel | Nebraska Extension)

Soybean root with blue fungal growth from sudden death syndrome infection. — **Figure 3.** Blue growth of the Fusarium virguliforme fungus growing on soybean roots. This blue growth is more commonly found on infected plants in southeast Nebraska. (Dylan Mangel | Nebraska Extension)

Soybean demonstration plot with a pocket of plants showing sudden death syndrome symptoms. — **Figure 4.** A pocket of SDS-infected plants in a demonstration plot at the Eastern Nebraska Research and Extension Center near Mead. (Dylan Mangel | Nebraska Extension)

Soybean leaf showing yellowing between veins and browning edges from sudden death syndrome. — **Figure 5.** Foliar symptoms of plants infected with sudden death syndrome. (Dylan Mangel | Nebraska Extension)

Favorable Environmental Conditions

SDS is favored in high-yield environments. The disease is more prevalent during cool, wet growing seasons and favored by early planting in cool soils. Hot, dry weather appears to slow disease development, but depending on the stage, it can become severe under these conditions. Heavy rains around the flowering time promote foliar symptom development.

Management

Genetic Resistance

Soybean varieties with moderate to high levels of resistance to SDS are available. Varieties with partial resistance or tolerance to SDS should be considered in fields known to be affected by this disease. These varieties will not prevent disease completely, but they can protect yield.

Cultural Practices

Avoid early planting in fields know to be severely affected by SDS. Rotation out of soybean production and maintaining good crop nutrition have been shown to reduce the severity of SDS.

Chemical/Biological Control

There are chemical seed treatments that provide protection against SDS. Find up-to-date efficacy information on product performance at the crop protection network or in the “Guide for Weed, Disease, and Insect Management in Nebraska” (Nebraska Extension NebGuide EC130).

Additional Information

Crop Protection Network Efficacy Guides: https://cropprotectionnetwork.org/publications/fungicide-efficacy-for-control-of-soybean-seedling-diseases
Nebraska Extension NebGuide EC130: https://marketplace.unl.edu/extension/ec130.html

Soybean field with scattered yellow patches from sudden death syndrome infection. — **Figure 6.** SDS symptoms across an infected soybean field. (Ritika Lamichhane | Nebraska Extension)

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