The Purdue Plant and Pest Diagnostic Laboratory

What's Hot at the P&PDL
September 4, 2012

Soybean Vein Necrosis Confirmed in Indiana

Gail Ruhl, Sr. Plant Disease Diagnostician and
Kiersten Wise, Associate Professor, Department of Botany & Plant Pathology, Purdue University

A soybean sample exhibiting symptoms suggestive of a new disease caused by soybean vein necrosis virus was submitted to the PPDL from Jennings county for diagnosis earlier this month. The sample was sent to Agdia, Inc. for virus testing and molecular test results confirmed the presence of a tospovirus. Additional testing with DNA sequencing confirmed the tospovirus as the newly described Soybean Vein Necrosis Virus (SVNV). Reports of soybeans exhibiting SVNV-like symptoms have been received from counties including Sullivan, Posey, Vigo, Knox, Gibson, White, Benton, Montgomery, Tippecanoe, and Decatur.

Symptoms caused by this virus include light green patches or mottled green and brown speckled areas associated with veins (Figure 1). These symptoms appear during mid to late summer. As the season progresses, affected leaf tissue may die, resulting in a scorched appearance on severely affected plants. Symptom severity appears to be variety-dependent. Symptoms may be confused with drought stress or ACCase herbicide injury (Figure 2).

These symptoms have been observed on soybeans for many years across the Mid-South and Midwest. However, it was not until 2008 that Dr. Ioannis Tzanetakis at the University of Arkansas discovered a new tospovirus in symptomatic leaf tissue collected in TN that was subsequently named soybean vein necrosis virus (SVNV). SVNV has been reported in thirteen states, including AR, DE, KY, KS, IL, IN, MD, MO, MS, NY, PA, TN and VA.

Tospoviruses are spread by thrips and although it is almost certain that thrips are vectors of SVNV, it is not known which of the thousands of species may transmit the virus to soybean. Currently, Dr. Tzanetakis and doctoral student Jing Zhou are working with plant pathologist Reza Hajimorad at the University of Tennessee and others to learn more about the association between this tospovirus and the vein necrosis observed on soybean foliage, the host range of the virus, potential vectors and impact on soybean yields.

At this point in time we do not recommend that growers change soybean production practices in response to detection of SVNV. For now, we will continue to keep an eye on this disease, and assess its potential impact before making future management recommendations. We are interested in the distribution of SVNV in Indiana and thus would like to encourage you to inspect any still-green soybean plants for possible symptoms of SVNV and send images of leaves with suspect SVNV along with field location to Kiersten Wise at kawise@purdue.edu.

 

Soybean Vein Necrosis Virus: A new pathogen in Illinois soybean fields - University of Illinois

Click image to enlarge

Figure 1: Foliar symptoms associated with SVNV.

Figure 2: Lipid synthesis inhibitor (ACCase) herbicide injury symptoms on soybean may be confused with SVNV symptoms.

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service