Cause Bean yellow mosaic virus (BYMV) is transmitted by aphid but not by seed. The disease is fairly widespread. The virus persists in crop and wild host plants including sweet clover, crimson clover, red clover, and gladioli.
Symptoms BYMV typically causes a yellow and green mottling; bright yellow spots may be present. Stunting may be severe or mild, depending on the virus strain. Some varieties may exhibit veinal necrosis. Leaves often are brittle, glossy, and cupped downward and may be malformed. Beet curly top virus (BCTV) symptoms of leaf curling and chlorosis may be confused with similar symptoms caused by BYMV infection. However, leaf curling and cupping due to BCTV infection generally affects younger leaves more severely, whereas with BYMV, the older leaves are more severely affected. Infection by BYMV also can deform pods; they may exhibit a light mottle, and their surfaces may be rough and shiny.
Cultural control
- A few resistant varieties have been developed.
- Avoid planting beans near sweet clover, crimson clover, red clover, or gladioli because the disease may be transmitted from them to the beans.