Look for New Virus Disease in Soybean

Don Hershman, Extension Plant Pathologist, University of Kentucky

A new virus disease of soybean, Soybean Vein Necrotic associated Virus (SVNaV), is fairly widespread in soybeans in west Kentucky at this time. This virus disease is thought to be transmitted to soybean by thrips. We have seen this disease at low levels in Kentucky for the last 15 years, but it has only recently been named and partially characterized. Thus far, the disease has been confirmed in AR, DE, KY, KS, IL, MS, MO, MS, NY, PA, TN, and VA. Although the SVNaV is easy to find in many fields, I do not think the disease is severe enough in any field to result in measurable yield losses. In fact, I am not aware of any instances in the U.S. where measurable yield losses have been attributed to SVNaV. It is, however, an emerging disease that merits additional study and monitoring. Look for leaves with faint oak leaf patterns that turn yellow and then brown over the course of 2-3 weeks. Brown lesions are commonly colonized by secondary fungi, especially Cercospora spp.