Symptoms and Signs
Beet yellow stunt causes pronounced yellowing of older leaves; later, infected plants collapse prematurely and die. Internally, the phloem tissue of the stem and crown is brown and necrotic.
Comments on the Disease
The host range of Beet yellow stunt virus includes plants in the families Chenopodiaceae, Asteraceae, Geraniaceae, Portulacaceae, and Solanaceae. In most years, beet yellow stunt only causes minor losses, but occasionally it is responsible for major losses in individual lettuce fields. The virus is transmitted by aphids. The sowthistle aphid, Hyperomyces lactucae, is the most efficient vector. Sowthistle (Sonchus spp.) is the primary source of the virus, and the disease is damaging only where large concentrations of sowthistle are present.
Control weeds, especially Sonchus spp., to reduce the incidence of this virus in lettuce.