It is difficult to identify a disease issue by a photo alone.  Environmental information and a live sample for a closer look would be helpful to define the disease at hand. I suspect the disease may be one of the three Mosaic Viruses; common, southern or Yellow.  Please see below information for management of the disease.  Please feel free to contact me for further discussion.

Commercial Snap Bean Production in Georgia (B 1369)

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Compiled by the UGA Vegetable Team

 Viruses

A number of viruses, including common bean mosaic, Southern bean mosaic and yellow bean mosaic, may affect snap beans. Common bean mosaic and Southern bean mosaic may be seed transmitted. All three virus diseases may be spread by insects. Yellow bean mosaic is usually spread from clover fields to beans by aphids, and is found only on pole beans in north Georgia. It is usually widespread only where beans are planted after clover or adjacent to clover fields. Mosaic is considered a minor bean disease in Georgia, except in North Georgia near clover fields.

Symptoms

Symptoms of the different virus diseases are very similar and difficult to separate. All the mosaic virus diseases cause some stunting and reduced yields. The affected bean leaves have irregular, light green or yellow areas merging with darker green patches, which produce the familiar mottling or mosaic effect. The mottling of contrasting yellow and green areas serves as a means of distinguishing yellow bean mosaic from common bean mosaic.

Plants infected by yellow bean mosaic are more dwarfed and bunchy. Bean pods on infected plants are quite often undersized and sometimes curled. They may contain fewer beans than those produced on normal plants. Leaves may be long and narrow and show some puckering or downward cupping at the margin. The overall symptoms may differ slightly with the variety and age of the plants and, to some extent, with growing conditions.

Disease Management

• Rotation — Fields planted to beans or red clover should not be planted back to beans the following year.
• Sanitation Management — Clean up all weed host plants adjacent to the bean field that could serve as a reservoir for the virus.
• Certified Seed — Since common bean mosaic and Southern bean mosaic may be seed transmitted, use certified seed.
• Resistant Varieties — Use resistant varieties when available. Disease resistance will be listed on the variety description in a seed catalog.