Alfalfa mosaic virus (AMV) is the only member of the alfamovirus genus. The virus is commonly found in alfalfa. Aphids feed on infected alfalfa, acquire the virus, and transmit it to healthy potato plants. Although the problem is not usually a major concern, sections of fields can be severely affected. Plants infected in an early growth stage are likely to remain small. The best management option is to avoid planting potatoes close to alfalfa fields.
AMV symptoms can be bleached leaves and leaves exhibiting yellow-white mosaic patterns. Leaves of infected plants are very noticeable and clearly stand out in a field. They are bright yellow with a smooth surface, often shiny. Some strains of AMV can cause severe stunting of plants and tuber necrosis. Sometimes corky or brown areas will develop in potato tubers.