Guess the Pest #20 Answer: Soybean Vein Necrosis Disease (SVNd)

Nathan Kleczewski, Extension Specialist – Plant Pathology; nkleczew@udel.edu; @Delmarplantdoc

Soybean vein necrosis disease (SVNd) is caused by the Soybean Vein Necrosis Virus, and is the most prevalent virus infecting soybeans. This virus is transmitted by several species of thrips during the early parts of their life. After the thrips have acquired the virus, they can transmit it for the remainder of their lifespan. Symptoms typically start around veins, likely because thrips focus feeding in this area. After entering the plant, the virus replicates, and the tissues surrounding the veins turn yellow and eventually brown. Recent research demonstrated that the virus may also be moved through seed, although the role this plays in disease epidemiology is currently unknown.

Adult thrips

Thrips adult and immatures.

Research we conducted in the region indicates that SVNd is more prevalent in double cropped soybeans, and that varieties differ in susceptibility. However, it is not known if varietal differences are due to reactions of the plant to the virus, or if the plants differ in features that alter thrips feeding preference. Research we recently published with colleagues indicates that the virus may impact seed quality, and research we are conducting in the region indicates that there may be some yield impacts, although this does not appear to be significant. Thus, management of this disease currently is not recommended. However, it is important to recognize the symptoms and realize that this is not a fungal disease. Fungicides will not impact foliar symptoms.

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