Plant Health Initiative

Sudden Death Syndrome - Scouting

Typical leaf symptoms of SDS are easy to see. Note green veins. Be aware, however, that some types of BSR fungi cause a similar foliar symptom. Photo credit: Craig Grau, University of Wisconsin

The same conditions that lead to high yields are also conducive to the development of SDS, especially fields with high fertility and water availability that are planted early.

Cool temperatures favor SDS, as well as brown stem rot (BSR), a disease that causes foliar symptoms similar to those of SDS. It is important to correctly distinguish BSR from SDS because management for the two diseases are different. One simple way to identify the two diseases is that SDS causes root rot and the pith of the infected soybean stem remains white, while with BSR, the pith is brown and there is no root rot.

Five important clues to identify SDS:

• Watch for foliar symptoms. Foliar symptoms can appear early but most often are visible after flowering. The first symptoms to appear are yellow blotches between the veins that progress to large irregular patches. The vein tissue remains green.

• Sudden death syndrome and brown stem rot in soybeans Paul Esker, plant pathologist at UW-Madison shows what to look for when you scout soybean fields. Click on image to view video. Video credit: UW Cooperative Extension

  Split the stems to determine whether the problem is SDS or Brown Stem Rot (BSR): if the center of the stem is brown, it is BSR; if white, it is SDS.
• Dig up roots and examine. SDS causes root rot, while root systems of plants affected by BSR remain healthy. Plants infected with the SDS pathogen are easily pulled out of the ground because the taproots and lateral rots have deteriorated. While not always present, a bluish color to the roots (fungal spores) is diagnostic for SDS.
• Note that SDS symptoms appear earlier than BSR.
• Be aware that stem canker is not as common as SDS. Stem canker can occur in the same year and fields as SDS. In addition to foliar symptoms, stem canker will often have cankers on the lower stem, and defoliation is not as pronounced as with SDS..
  

 

Comparison of the signs and symptoms of brown stem rot, sudden death syndrome, stem canker.

Adapted from: Agronomy Guide for Field Crops (Soybeans: Brown Stem Rot, Stem Canker and SDS). Ontario Ministry of Food and Agriculture.