Soybean Vein Necrosis Virus Detected in South Dakota Soybeans

Originally Published: Sept. 20, 2017

Originally written with contributions by Emmanuel Byamukama, former SDSU Extension Plant Pathologist and Marie Langham.

A new soybean virus called Soybean vein necrosis virus (SVNV) was detected in South Dakota soybean fields in Davison and Union counties. Symptomatic plants were sporadic and found along the field borders. Infected plants showed mild to moderate severity. It is possible this virus is occurring in other counties but at very low incidence within the field making it difficult for the plants to be easily observed.

a green leaf with yellow and brown spots starting
Initial Soybean vein necrosis symptoms. Credit: E. Byamukama

Symptoms

Soybean vein necrosis virus symptoms start as light yellow lesions between the veins.

a green leaf with yellow and reddish brown spots
Typical symptoms of Soybean vein necrosis virus. Notice the yellow, reddish-brown discoloration between the main veins. Credit: R. Farrell

These expand out over time but are limited to within the leaf veins. The yellow lesions eventually turn to reddish brown lesions.

a green leaf with brown spots and holes
Advanced symptoms of SVNV showing tissue necrosis. Credit: E. Byamukama

Infected leaf tissues may die but do not fall out.

green leafy plants
A soybean plant with systemic SVNV symptoms amidst non-symptomatic plants. Credit: R. Farrell

Infected plants may have only a few leaves showing symptoms or the entire plant may show symptoms.

Transmission

Soybean vein necrosis virus is transmitted by thrips. Several species are thought to transmit SVNV but so far soybean thrips (Neoydatothirps variabilis) have been confirmed as the vector of this virus. The immature stage of this insect, the nymph, is the only stage that can feed on infected plants and acquire the virus. Adults that did not acquire the virus at the nymph stage do not transmit the virus, nor do they pass on the virus to their eggs. It is thought that SVNV overwinters in broadleaf weeds where thrips acquire it and transmit it to soybeans. Recently, seed transmission of this virus was reported to be around 6%.

Yield Impact & Management

The soybean fields which had SVNV symptomatic plants this season only had very few plants infected. Therefore, the yield impact in these fields should be negligible. Studies on SVNV from Iowa indicated no significant impact on grain yield. However, the authors reported significant impact of this virus on grain quality, mainly reduction in oil content. SVNV can be best managed by controlling the vector, the thrips. However, insecticide application is not recommended to manage thrips for the purposes of managing SVNV unless thrips threshold is reached.

Additional Resources:

Related Topics

Soybean Diseases, Growing Soybeans

Related Content

Three bean leaf beetles. From Left: Brown beetle with black spots on a green leaf. Yellow beetle with black spots on a green leaf. Red beetle with black spots on a green leaf.

Bean Leaf Beetles Showing Up in Soybean

Despite the prediction of low overwintering survival we have observed bean leaf beetles in soybean this week. See our latest observations and management recommendations.

corn leaf with tar spot on it

SDSU Extension to host disease scouting workshop for corn, soybeans

October 01, 2024

If you have been wondering what you’re seeing in your corn or soybean fields this season, join the SDSU Extension plant pathology team in Volga to see tar spot in the corn field and white mold in the soybean field, or to have your own diseased plant material identified.

Flooded soybean field with tan, corn residue throughout.

Replanting in Flooded Soybean Fields

If you have large, flooded areas where soybeans have died this summer and herbicides are limiting your replant options, consider trying late-maturing soybeans as cattle feed this year.