The Purdue Plant and Pest Diagnostic Lab (PPDL) confirmed Soybean Vein Necrosis Virus (SVNV) this week in Indiana. The virus was first detected in Indiana in 2012, but was not detected until late August. Currently, the virus has only been confirmed in LaPorte County (northwest IN), but it is likely that other fields may be affected. It is important to accurately diagnosis SVNV since it can resemble other diseases and disorders, including herbicide injury.
Symptoms caused by this virus include light green patches or mottled green and brown speckled areas associated with veins (Figure 1). As symptoms progress, affected leaf tissue may die, and leaves will appear scorched.
SVNV is a member of the Tospovirus family, which are vectored by thrips. These are tiny, winged insects that are present in all soybean fields, every year. They feed on plant juices and pollen, but they are not considered pests and have not caused damage to Indiana soybeans in the past. Although growers may be tempted to apply an insecticide to reduce thrips populations “just in case”, at this point in time we do not recommend insecticide applications in response to detection of SVNV, for two reasons: 1) the disease is not yet found widely in the state, and 2) we don’t know what, if any, effect disease may have on yield. For now, we will continue to keep an eye on this disease, and assess its potential impact so that we can make more informed future management recommendations. We encourage growers and consultants to inspect fields for symptoms of SVNV and send samples to the PPDL for diagnosis so we can gather information on the extent of this new disease in Indiana.