Image credit: Iowa State University Extension

A soybean disease that mimics sudden death syndrome (SDS) is turning up across the Midwest, and plant pathologists say a quick glance won’t tell the two apart. Red crown rot has now been confirmed in at least eight Midwest states, including a new detection in Iowa. Estimated national losses jumped from roughly 121,000 bushels in 2024 to 7.7 million bushels in 2025 with potential to expand. Both diseases cause similar yellowing and leaf scorch above ground, but the real difference shows up at the base of the plant, where small, bright-red fungal structures point to red crown rot rather than SDS.

No resistant soybean varieties or in-season treatments are currently available, so getting the diagnosis right matters most for next year’s planting and variety decisions, not this year’s crop. Farmers seeing SDS-like symptoms in their soybean fields are encouraged to dig up plants and check the crown for those red markers, and many state Extension offices, including Iowa State University, offer free diagnostic testing to confirm which disease is at play.

Read more on red crown rot and what to look for from AgWeb.