A warm-season vegetable, beans are prized in the garden because of their easy care and abundant production. Beans are susceptible to mosaic virus, which is often spread to the plants via the aphid insect. Mosaic infections can lead to a substantially reduced crop or even kill the plant off entirely. The two types of bean mosaic, bean common mosaic virus (BCMV) and bean common mosaic necrosis virus (BCNMV), cannot be eradicated once a plant is infected. You can control the mosaic viruses to prevent them from spreading to other bean plants, though.
Purchase disease-free seed from a reputable garden center or seed supplier. Check the seed package and purchase types that are listed as resistant to BCMV and BCNMV. Heirloom seeds are less likely to be resistant, so plant these nonresistant varieties only if you haven't had mosaic problems in your garden in the past.
Rotate the bean crop each year and avoid planting beans in the same place for at least three years. This prevent plants from becoming infected with mosaic virus organisms living in the soil. Rotating the crop is especially vital if you have had a mosaic infection in the past.
Check the underside of leaves regularly for signs of aphid infestation. Aphids are small green, white, yellow or brown insects that live and feed in colonies on the leaves. Treat infestations immediately by rinsing the plants with an insecticidal soap daily until the infestation is gone.
Dig up and destroy any plants infected with mosaic as soon as they are noticed to control the spread to nearby healthy plants. Symptoms include light green or yellow mosaic patterns on the leaves, stunted growth and premature plant die-back.