Caused by tobacco ringspot virus, this disease is occasionally present in low incidence. If abundant, do not use the crop for seed. The disease is easily transmitted mechanically. Immature thrips also may vector the disease. Many weed hosts can serve as reservoirs for the disease. Infected plants are dwarfed. The pith in the upper nodes turns brown. Pods may develop brown blotches and seed development may be inhibited. There is often a distinct curling of the uppermost stem tip. Infected plants often remain green until frost occurs. Management of the disease includes using disease-free seed, controlling weeds in and around the field, and roguing of infected plants.
Taken from Kansas State University Agricultural Experiment Station and Cooperative Extension Service Publication #C-449. Soybean Diseases, Dr. Douglas J. Jardine, Extension State Leader, Plant Pathology Program.