Plant Disease: Soybean Sudden Death Syndrome

Taxonomy:

Distribution:

• Found throughout the Soybean production areas within the United States. In 2004, Nebraska had identified its first case of Sudden Death Syndrome.

Symptoms:

• Foliar symptoms of soybean sudden death syndrome resemble those caused by several other plant pathogens and insects.

Plant infected with SD

• Foliar symptoms of sudden death syndrome typically do not appear prior to soybean flowering.


• Early symptoms at the R3 and later growth stages, if present, are only chlorotic (yellow) spots on the leaves between veins

• Progression to the pod forming stage, the yellow spots may coalesce, becoming yellow between the veins.


• Leaves may crinkle, resembling virus infection.


• Eventually the yellow between the veins will become brown (necrotic) as the tissue dies.

Notice grey discoloration in the crown

• Roots will exhibit an obvious root rot.


• The discoloration of the vascular tissue usually will not extend more than an inch or two above the soil line.

Unlike Brown Stem Rot the pith will remain white

• The pith will remain white.


• 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.


• Causal fungus must be isolated in a lab and the pathogen identified under a microscope.


• Occasionally the fungus will form masses of white spores on the roots that may become blue to blue-green as they mature.

Management:

• Soybean varieties with moderate-to-high levels of resistance to SDS are available.


• Varieties resistant to SDS should be considered in fields known to be affected by this disease.


• Crop rotation does not seem to affect disease severity.


• Sudden death syndrome has occurred following corn or cotton crops.