MSU Extension

Sudden death syndrome (SDS) is a fungal disease of soybeans caused by the pathogen Fusarium virguliforme. The soil borne fungus infects the root tissues, traditionally thought to occur following prolonged periods of wet and cold conditions at planting. However, some highly productive irrigated fields in southwest Michigan have seen significant infection of SDS, regardless of soil conditions following planting. Soybean cyst nematodes (SCN) populations are thought to be an important factor in these infections. This particularly seems to be the case in sandy soils, where saturated conditions for extended periods of time are rare. The disease is fairly new to Michigan, with widespread incidence, and fairly low severity, occurring recently during the 2010 growing season.

Advanced sudden death syndrome symptoms on a soybean trifoliate leaf.

We are beginning to see foliar symptoms of SDS in later vegetative growth stages in soybeans at an MSU field research site located near Decatur in Van Buren County. These symptoms are most pronounced on areas that look consistent with irregular-shaped pockets of high SCN activity. Initial symptoms appear as yellowing of the leaves. These are followed by the classic SDS symptoms on the leaves, interveinal yellowing with browning necrosis in the middle. The plants show stunted growth. Our experience in last year’s research showed that the earlier the plants exhibit foliar symptoms of SDS, the more yield reduction occurs. Some of the plants that show SDS symptoms in the vegetative growth stages do not produce economic yields.

SDS infection of V4 soybeans at the Michigan Soybean Disease Research Center, located near Decatur. This portion of the field was planted to corn in 2010.

Crop rotation is not thought to be effective in reducing the incidence of SDS in infected fields. The field research site in Decatur was partially planted to soybeans in 2010, and the remaining area was planted to corn. The entire field was used by MSU this year for SDS research. Symptoms of the disease are evident on both the area that was planted to soybeans in 2010 and in the area planted to corn.

We would encourage producers that saw SDS in fields for the first time in 2010 to monitor for development of the disease. Sometimes SDS symptoms occur under conditions that cause plant stress. There is no rescue treatment to control SDS in infected soybeans. However, selection of varieties that are the most tolerant of the disease can impact the timing that the beans show foliar symptoms and subsequent yields. Identification of SDS and the time frame and growth stage that the plants become infected can help you make decisions about what soybean varieties to plant next season.

The Michigan Soybean Disease Center, located near Decatur, is dedicated to help producers identify varieties that can tolerate SDS and white mold. It is located on an irrigated field owned by Carl and Amy Druskovich. The site features a MSU Variety Performance Trial, a MSU Soybean Breeding Variety Screening Trial, a MSU Seed Treatment Trial, and several Industry Supported Germplasm and Seed Treatment Screening Trials. The project is funded by the Michigan Soybean Promotion Committee (MSPC) and by grants from the participating companies.

Treatments showing varying degrees of SDS tolerance and infection at the Decatur research site.

The MSPC and MSU Extension are planning a field day at the site on Wednesday, August 24. The event will feature a field tour of the SDS trials with various stops to visit with the researchers involved from each trial. We are also planning to have a market update, crop maturity update and information on other pest management issues at that time. A steak lunch is being prepared by Scott’s Pig Roast of Marcellus. The program and the meal are being sponsored free of charge by the MSPC. For more information or to reserve a meal at this meeting, you can contact the Van Buren County MSU Extension office at 269-657-8213. For more information on SDS, you can contact Bruce Mackellar at 269-657-8213, or Martin Chilvers, MSU field crops pathologist, at 517-898-3049.