Soybean Mosaic Virus - Symptoms

Foliar symptoms of SMV infection: a mosaic appearance consisting of light and dark green areas. Leaves look distorted, curling longitudinally along the veins. Photo© Laura Sweets, University of Missouri.

General symptoms of SMV are plant stunting, leaf distortion and mottling, reduced pod numbers, and seed discoloration. Plant reaction to infection by SMV depends on the soybean variety.

Leaf symptoms include a mosaic of light and dark green areas, chlorosis, rugose (rough) leaves, and leaf curl. Plants can be stunted, with shortened petioles and internodes. Sometimes symptoms resemble injury from herbicide drift. The youngest and most rapidly growing leaves show the most symptoms. Symptoms are most severe at cooler temperatures (less than 25°C).

Infected pods are small, flat, have less hair, and are more curved than pods that are not infected with virus. Seed discoloration may occur, and seed germination may be reduced.

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