A few years ago, the Iowa State University "Plant Disease Clinic" started to receive reports on diseases relatively new to soybean growers, such as soybean sudden death syndrome (SDS) and diseases that cause seed discoloration. The prevalence of these diseases is increasing, especially in the last 2 years. As of this summer, SDS has been reported in more than 40 Iowa counties. The Clinic also received seed samples with as many as 40 percent of the beans showing black seed coats.
Iowa State University
Yang, X. B., "New soybean disease slide sets" (1999). Integrated Crop Management News. 2216.