Symptoms and Signs
Leaves are dwarfed, crinkled, and rolled upward and inward. Veins on the lower side of infected leaves are irregularly swollen with bumps. If large roots are cut crosswise, dark rings of vascular tissue can be seen. Young roots of infected plants are dwarfed, and rootlets tend to become twisted and distorted and are often killed. Death of rootlets is followed by production of new rootlets, leading to a "hairy root" symptom that can resemble symptoms of the unrelated disease, rhizomania.
Comments on the Disease
Beet curly top virus is vectored by the beet leafhopper, Circulifer tenellus, which has an extensive host range, a high reproductive capacity, and can migrate long distances from its breeding grounds in the coastal foothills and desert areas to cultivated areas. The leafhopper overwinters on a wide range of annual and perennial weeds and readily acquires the virus when it feeds on infected plants (for more information, see BEET LEAFHOPPER). Once acquired, the vector can usually transmit the virus for the rest of its life. In spring, beet leafhopper migrates to agricultural lands when the overwintering host plants dry out. Severity of curly top disease in sugarbeet depends on climatic factors that influence the prevalence of weed hosts of the virus and the reproductive capacity and migration of the leafhopper vector. Beet curly top virus also can cause significant losses in tomatoes, beans, peppers, and occasionally cucurbits.
Management
Curly top is not generally a problem in the Imperial Valley. In other areas, grow resistant varieties in virus-prone areas, especially along the west side of the San Joaquin Valley. In addition, control overwintered weeds and other plants that serve as hosts for the leafhopper vector or the virus.