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

Scout fields after mid-August at pod set. Scout fields with high yield potential closely, especially areas with high moisture. Early symptoms of SDS appear on apparently healthy plants in patches within a field. The first symptoms to appear are interveinal chlorotic (yellow) blotches that progress to large irregular patches. The vein tissue remains green. .

SDS may be overlooked because its symptoms are similar to those of brown stem rot (BSR), a common soybean disease in the north central region. Although the foliar symptoms of brown stem rot and SDS are very similar, the absence of internal stem browning is a key symptom to distinguish SDS from BSR in the field.

Another key distinguishing feature is that SDS causes root rot while root systems of plants affected by BSR remain healthy. Diseased plants are easily pulled out of the ground because the taproots and lateral rots have deteriorated. Symptoms present on both the leaves and roots is diagnostic for SDS (Table 1).

Table 1. Comparison of the signs and symptoms of brown stem rot, sudden death syndrome, stem canker.

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