MSU Extension Soybeans

Soybean Sudden Death Syndrome (SDS) is a relatively new fungal pathogen in Michigan soybean fields, first confirmed in the state in 2008-09. The disease has potential to cause devastating yield losses, which is what happened in Iowa and Illinois during the 2010 growing season.

SDS is caused by a soil-borne fungal pathogen, Fusarium virguliforme, which often infects the roots of soybean plants early during the growing season, especially under prolonged exposure to cold and wet conditions. Infected plants usually do not show visible symptoms on the leaves until later in the season when the soybean plants are in the grain fill stage. Infected plants exhibit a rapidly progressing yellowing wilt in the upper leaf canopy, which can lead to premature plant death. Plants under stress are more prone to showing SDS symptoms. Yield losses on infected plants can range from minor to catastrophic, depending upon the timing of the onset of symptoms. Soybean cyst nematodes (SCN) are often found in fields where SDS becomes established, especially in sandy fields.

One of the biggest challenges with SDS is that the disease tends to build up in soils. Rotation to other crops such as corn or wheat has not been shown to be effective at reducing the level of infection in subsequent years when soybeans are produced on infected fields. SDS is considered the most important threat to soybean yields in several soybean producing states.

Research conducted at an irrigated field near Decatur in Van Buren County investigated the effect of the source of soybean cyst nematode resistance on SDS showed a marked improvement in yield on a variety that derived SCN resistance from two breeding sources (PI 548402 x PI 88788) compared to an SCN susceptible and a PI88788 SCN resistant variety. It also performed well in comparison to a SDS tolerant variety with PI88788 resistance that was planted in an adjacent white mold study. An MSU Soybean Breeding trial screening for SDS tolerance was also established at this site. With support of the Michigan Soybean Promotion Committee, MSU Researchers are planning on expanding SDS research at this location to further investigate SDS tolerance levels of varieties, select breeding lines that are tolerant to the pathogen and investigate the role that SCN play in the incidence and severity of the disease.

For more information on soybean sudden death syndrome, see MSU plant pathologist Martin Chilvers’ SDS website and his July 29, 2010 article on SDS in the MSU Field Crops CAT Alerts.