What Makes the Green Bean Plants Yellow?

Mosaic Virus

• The bean yellow mosaic virus causes the leaves to crinkle and cup downward. The leaves also develop a yellow mottling that creates dead areas along the veins of the infected leaves. This disease is transmitted to the bean plant through aphids. When aphids visit red or white clover or other legume weeds, they pick up the virus and carry it through the garden. If this is a problem in the garden, plant only bush type beans. Also remove any legume weeds from along fence rows and do not plant near clover or other legumes. Another approach is to create a living barrier by planting sweet corn upwind from the beans and plant successive crops of beans. Infection levels of this disease can fluctuate from one week to the next.

Common Blight

• All blights are caused by a bacteria. The common or Fuscous blight appears as dry, brown spots that have a narrow yellow halo around these spots.

Halo Blight

• Halo blight starts out as large yellow halos that form on older leaves. As the plant disease progresses, the newly formed leaves begin to turn yellow. Once this happens, the plant dies shortly after this symptom appears. When the plants begin to exhibit the disease, spray them with a chemical bactericide that contains copper.

Planting Tips

• To prevent problems before they start, first only plant beans that are disease resistant. Before planting beans in the garden, always perform a soil test. Plants that are healthy have an easier time of protecting themselves from diseases. Do not use a fertilizer high in nitrogen. This will cause the bean plants to grow quickly and expose more vegetation to possible disease. Do not plant beans near gladiolus. This plant attracts aphids and in turn invites them into the garden. Inspect the bean plants twice a week. Remove any infected plant parts or whole plants that show disease symptoms. Remove the bean plants as soon as they stop producing. This will prevent disease problems from building up in the soil.