Agriculture: Dry Beans Pest Management Guidelines

Alfalfa Mosaic (Yellow Dot)

  • Alfalfa mosaic virus (AMV)
  • Symptoms and Signs

    Symptoms of alfalfa mosaic in beans vary depending on the strain of the virus. Some strains cause only localized symptoms that may include necrotic spots on infected leaves. Other strains infect the entire plant and cause symptoms ranging from yellow dots to a striking yellow mottle, which may be accompanied by leaf and pod distortion and stunted plant growth.

    Comments on the Disease

    Alfalfa mosaic has a wide host range and is transmitted from plant to plant by aphids. Alfalfa is an important perennial host for alfalfa mosaic.


    Alfalfa mosaic is considered an occasional disease of beans in California, mainly found on lima and garbanzo beans. It can cause serious yield losses. There are no effective control measures once the disease is present. Avoid planting bean fields adjacent to alfalfa fields.

    Text Updated: 01/18