The 8-page full-color bulletin Soybean Vein Necrosis Virus is an excellent scouting resource with close-up photos of SVNV symptoms and seven look-alike diseases.

View the SVNV scouting video

SVNV

Leaf symptoms caused by soybean vein necrosis virus. Click on the image to view a larger version.

SOYBEAN VEIN NECROSIS VIRUS

Soybean farmers should be aware of a new disease caused by soybean vein necrosis virus (SVNV). The virus has likely been present in soybeans for some time, but was probably overlooked or misdiagnosed before recent detections. The disease has been identified across the United States (including many states in the North Central region) and in Ontario, Canada.

SVNV is a tospovirus, a group of viruses capable of causing spotting, wilting, reduced vigor and death of many food and ornamental crops. The long-term implications of this disease are not yet known, and we are currently working to better understand the disease and potential for yield loss in soybean.

How SVNV spreads

Tospoviruses are transmitted by a group of insects called thrips. To date, as many as 14 thrips species are known to be vectors of tospoviruses, but only a smaller subset of these are likely vectors of SVNV. The soybean thrip (Neohydatothrips variabilis) has recently been confirmed as a vector of SVNV. Additional investigation may reveal other vector species.

Symptoms

Confirming virus infection is difficult since virus diseases often resemble other foliar diseases or disorders such as herbicide injury or nutrient imbalances. Several common soybean diseases can be confused with SVNV — consult the bulletin Soybean Vein Necrosis Virus for descriptions and photos of the seven most common look-alike diseases. It is important to accurately diagnose SVNV, and other soybean diseases, to prevent unwarranted management decisions that will not work.

Symptoms of SVNV infection start as a yellowing (chlorosis) along the leaf vein. Over time, yellowing develops into red-brown, irregular-shaped lesions, which eventually leads to tissue death.

SVNV symptoms are typically found randomly distributed throughout the soybean canopy.

Yield loss, economic impact and management

We do not currently recommend insecticide applications in response to SVNV detection since vector control of other insect-transmitted diseases has not typically been successful.

Researchers are monitoring this disease to assess its potential impact in an effort to determine the best management options. Future recommendations will be developed as we learn more about this disease.