Soybean Mosaic Virus

Particles of a potyvirus, similar to SMV. Photo © Rothamsted Experiment Station

Soybean aphids can spread Soybean Mosaic Virus froim plant to plant as they feed.

Soybean mosaic virus (SMV) infects mostly legumes, with soybean as the primary agronomic host. The main concern about SMV is the effect on seed quality. Virus-infected plants may produce fewer, smaller, and often mottled seed.

The virus consists of rod-shaped particles of RNA and protein that can only grow and reproduce inside a living plant cell. Like all viruses, SMV is not a cellular organism and can not spread by wind, water, soil or plant debris.

How SMV spreads

Infected seed is the most important way that soybean mosaic virus is introduced into a soybean field. Seed transmission depends on variety, ranging from 5-75%. In most modern soybean varieties, rates of seed transmission are 0%-5%.

Once the virus is in the field, aphids can spread it from plant to plant as they feed. Over 30 species of aphids transmit SMV worldwide. Recent research has confirmed that the soybean aphid, (Aphis glycines) is a vector of soybean mosaic virus.

If you save seeds for next season, check your seeds for virus infection if you find that a significant proportion of your seeds from an aphid-infested field are discolored.

Synergy with other viruses

The risk of yield loss or reduced seed quality is much greater with a dual or multiple virus infection than with one virus alone. With the recent increase in incidence of bean pod mottle virus (BPMV) in the region, the potential for synergism between SMV and BPMV has increased.

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