Facts on Soybean Vein Necrosis Virus

• First identified in 2008 in Tennessee.
• Widely established throughout Ark., Tenn., Ky., Ill., Mo., Miss., Del., Md., Va., Penn., NY and possibly Iowa.
• Belongs to the genus Tospovirus, a group of plant viruses normally transmitted by thrips.
• Because the disease is newly discovered, much is not yet known or confirmed about the disease.
• Information presented here includes assumptions based on related tospoviruses, primarily regarding:
  • alternate disease hosts, thrips vector, conditions for disease development and effects of other viruses

• Virus-infected alternate weed or crop hosts must be present, as well as thrips, the vectoring insect.
  • Thrips are tiny insects only 1/32 to 1/5 inch in length that reproduce quickly and feed primarily on the underside of leaves, especially along the veins. Dry, hot weather increases the threat of damage.
• Thrips must feed on infected weeds, other crop hosts or infected soybeans to acquire the virus and be capable of transmitting it.
• Environmental conditions that favor thrips growth and reproduction most likely favor disease development.

• Infected soybeans, other crop hosts or weeds are fed on by thrips larvae early in the season.
  • Feeding continues throughout the growing season if conditions favor thrips reproduction.
• Thrips acquire the virus, resulting in virus transmission throughout their life.
• Infected thrips feed on soybean plants during plant vegetative and early reproductive stages.
• Virus overwinters in southern areas in thrips and in surviving susceptible plant hosts.

Management of Soybean Vein Necrosis Virus

• Robust disease management strategies are yet to be developed for this newly discovered disease.
• Currently, the best disease control strategy is to manage thrips, the insect vector of the disease, using traps and insecticides (see Table 1 below.)
  • Note that disease symptoms of SVNV have been mild to moderate in most fields, with only a minor impact on plant growth, development and yield.
  • Insecticide application should be considered primarily in fields with a known risk of yield loss.

Table 1. Some commonly used insecticides for control of soybean thrips¹.

• Following better host, virus and vector characterization, control strategies and disease management recommendations will likely include:
  • Soybean variety selection – Select varieties determined to be or bred to be SVNV resistant.
    • Soybean varieties and breeding lines are being evaluated in order to map any SVNV resistance genes or quantitative trait loci (QTLs).
  • Cultural practices to identify and remove infected soybean and alternate or overwintering weed and crop hosts (of both the virus and thrips vector)
    • Targeted weed control focused on removing alternate weed hosts or overwintering soybeans
    • Crop rotation to eliminate alternate crop hosts

Acknowledgement / Further Reading

• Special thanks to Dr. Ioannis Tzanetakis, Assistant Professor, Plant Virology, University of Arkansas, for his expert contributions to this article.
• Domier, LL. 2011. Soybean vein necrosis virus: A new pathogen in Illinois soybean fields.
• Tzanetakis, I., R. We, M. Newman, and R. Hajimorad. 2009. Soybean vein necrosis virus: a new threat to soybean production in Southeastern United States. Phytopathology 99:S131.
• Soybean thrips. Purdue University Field Crops IPM.