Sudden Death Syndrome

Sudden death syndrome (SDS) is a soybean disease characterized by leaf spots and root decay. The name sudden death syndrome is descriptive in that normal-appearing plants turn yellow and die rather quickly. The disease is of major concern because of its potential ability to reduce yields significantly. Yield losses due to SDS range from slight to 100%, depending on the soybean variety and the stage of crop development when the symptoms first appear. SDS disease tends to be most severe on well-managed soybeans with a high yield potential.

 

SDS symptoms
Soybean plants infected with the SDS pathogen, showing leaf symptoms and beginning signs of pod abortion.
Photo credit: Craig Herzog, Southern Illinois University.

 

Sudden death syndrome is caused by the soil fungus, Fusarium verguliforme. Root infection can occur very early in the growing season, within 2 to 3 weeks after planting. The fungus produces a toxin that is translocated throughout the plant and interferes with the vascular system of the plant. This can cause sudden yellowing and death of the leaves as the water supply is cut off.

How SDS spreads

SDS is a soil borne disease and is spread mainly when soil is spread: equipment, human and animal feet, birds, and wind and water erosion. Cysts of soybean cyst nematode have been found to carry the SDS fungus.

The pathogen

The SDS pathogen, Fusarium virguliforme, has a blue pigmentation and a blue coloration is sometimes found on the tap roots of plants that are severely infected with F. virguliforme due to the large number of conidia (spores) produced on the surface. This fungus also produces a thick-walled survival structure, a chlamydospore, in the cortical tissue of soybean roots. The chlamydospore can overwinter and can possibly survive for several years in the soil. This fungus is very closely related to another soybean pathogen that causes seedling disease and root rot of soybean, Fusarium solani form B.

 
Site Index  |  For Researchers  |  Contact Your Local Extension  |  PHI Home  
 

Information on these pages is from the cooperative effort of researchers throughout the North Central states. Information from this site can be copied and distributed for educational use. Please credit the source with our name and URL: NCSRP Plant Health Initiative at www.planthealth.info. Please do not use copyrighted photos without permission.