First identified in Tennessee in 2008, soybean vein necrosis virus was confirmed just over a week ago in two Ontario counties. Easily confused with general plant stress, Cercospora leaf blight or scald (sunburn), SVNV often begin as light green to yellow patches near the main leaf veins which may enlarge eventually becoming necrotic (brown) areas. The veins may appear clear, yellow or dark brown in colour. The browning of the veins may be especially noticeable on the lower leaf surface but this may not always occur.
Albert Tenuta, field crop plant pathologist for OMAFRA, says that viruses like SVNS are often carried and spread via insects. He notes that spider mites and thrips were especially bad this year. There is no set yield loss estimation based on infection as of yet, as this is a new disease for the area.