Soybeans for Sudden Death Syndrome

 

Sudden death syndrome (SDS) was detected in mid-April-planted soybeans at the University of Illinois' Northwestern Research Center in Warren County, Illinois. This confirmation comes three weeks earlier than the first sign of the disease in 2014.

Weather throughout the 2015 planting and growing season has been favorable for SDS, according to Purdue Extension. The disease is worst when soybeans are planted early into cool, wet soils and when soils are saturated from ample rainfall throughout the summer. SDS affects soybeans in many Midwest states and some areas to the south, including Illinois, Indiana, Iowa, Kansas, Kentucky, Minnesota, Wisconsin, Mississippi, Missouri, Nebraska, Ohio, and Tennessee. 

On July 15, Arkansas Research and Extension announced a confirmed case of SDS in Desha County, Arkansas. Since 2012, 38 counties have had confirmed distribution of SDS in Minnesota. 

Symptoms
The onset of SDS usually occurs early in the season, beginning by infecting the roots. Symptoms usually don’t surface until late July or August.  SDS is a soilborne fungus Fusarium virgulifome, which overwinters in the soil and may survive for an extended period of time.

SDS infects the roots and sends a toxin up through the plant that causes yellowing and dead tissue between veins. When scouting, look for yellow between leaf veins, and split open the lower stem and taproot. The lower stem and taproot will appear tan to light brown compared to a healthy plant, and the middle portion of the stem will remain white or cream-colored.

Yellow spots become larger, brown lesions as the disease progresses, and leaves may cup or curl. Eventually, leaves will detach from petioles, and brown to grey-color areas will form in the tissue of the lower stem.

Management
While few in-season management options exist, there are things you can do to protect future soybean crops.

University of Minnesota Extension suggests planting soybean varieties with the highest level of SDS resistance soybean cyst nematode (SCN). Minimizing soil compaction and improving drainage to reduce excess soil moisture will also help ward off the disease. Crop rotation and tillage practices can reduce the risk of SDS in soybeans.

“While there is some evidence that changing planting dates or tillage practices may have an effect on SDS control, we don’t recommend farmers change these practices solely for this reason,” said Daren Mueller, ISU plant pathology assistant professor. “Farmers should use the most effective tillage practices and planting dates for their entire operation, not in an attempt to control one disease because of all the factors involved.”

This year, a new fungicide seed treatment, ILeVO, was introduced to the market with the potential to protect against SDS. The On-Farm Network is testing ILeVO in a collaborative project with Iowa State University and Bayer CropScience. Learn more here.