Several years ago, I was called to a field with some soybean issues and confirmed with the UNL Diagnostic Lab that it was sudden death syndrome, or SDS. SDS was first confirmed in Nebraska in 2004 and often is contained to areas within a field. Brown stem rot has been a disease of Nebraska soybean for many years.
A recent UNL CropWatch article written by Loren Giesler, Extension Plant Pathologist and Kevin Korus, Manager, Plant and Pest Diagnostic Clinic shared some information on sudden death syndrome which I have included in this week’s column. First of all, sudden death syndrome was recently confirmed in soybeans in the southeast, central, and east central districts of Nebraska. A soil-borne fungal disease, SDS produces a very resistant survival structure that is not affected by crop rotation.
Giesler and Korus shared that research at Iowa State University has shown that the SDS pathogen also survives well on corn kernels on the soil surface. This is relevant to Nebraska producers who have had SDS in their fields and this year experienced late season hail with grain loss. These kernels could serve as a site for this and other fungal pathogens to overwinter.
Foliar symptoms of SDS are similar to those of brown stem rot; however, stem damage is different. Split the stem to more closely exam symptoms. With brown stem rot the center of the stem will be discolored and typically will be brown from the soil line upward. With sudden death syndrome discoloration will be confined to the outer layers of the split stem. The center will not be discolored, but the root cortex will be light gray to brown and may extend up the stem
As with many plant diseases, the main management option is to select resistant varieties. Correct diagnosis is important so you’re aware of the pathogens in this year’s crop that may overwinter and cause problems for next year’s harvest. Fields with high SDS should not be planted early in future years and should be managed to reduce any compaction issues. Rotation will not affect SDS. Fields with brown stem rot will benefit from longer rotations. Foliar fungicides are not recommended for managing either disease.
For assistance in correctly identifying these diseases, submit a sample to the UNL Plant and Pest Diagnostic Clinic. This original article with pictures can be viewed at UNL’s CropWatch website.