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Bean common mosaic virus

Bean common mosaic virus is spread in seed and by aphids. Infected beans develop a mosaic of light and dark green, leaves pucker and curl down, and crops fall. Resistant varieties are the main defence.

Viral diseases
A bean leaf with mosaic mottling and puckering
A bean leaf with mosaic mottling and puckering

What it looks like

Mottled, puckered leaves.

  • Light and dark green patches.
    Mosaic Light and dark green patches.
  • Leaves pucker and blister.
    Blistering Leaves pucker and blister.
  • Leaves curl or cup downward.
    Down-curled leaves Leaves curl or cup downward.
  • Small plants with few pods.
    Stunted plants Small plants with few pods.

How to confirm it

Check pattern and seed.

  1. From emergence

    Seedlings mottled early suggest infected seed.

  2. Scattered plants

    Individual plants affected.

  3. Aphids

    Aphids spread it later in summer.

What to do

Remove and prevent.

  1. Remove infected plants

    Pull and bin mottled plants.

  2. Control aphids

    Keep aphids down.

  3. Grow resistant varieties

    Most modern French beans resist BCMV.

  4. Use certified seed

    Do not save seed from infected plants.

Prevent it next time

  • Buy certified, resistant seed.
  • Control aphids.
  • Remove volunteer beans.

What not to do

Do not save seed from mottled plants; the virus passes to the next crop.

In the growing guides

Where the guides mention it, with plant-specific advice.

Sources

  1. Bean: common and yellow mosaics, Washington State University Extension
  2. Bean common mosaic virus, Utah State University Extension