Putative virus disease of sunflower in Zambia

Symptoms of a virus-like disease of unknown aetiology were observed in sunflower in five provinces of Zambia during the 1998 growing season. In the 20 surveyed farmers'fields, disease incidence was 80–100%. Yield loss in seed production as a result of the putative virus (or virus complex) was estimated at 60%. The virus was not seed-borne in sunflower. The weed Tridax procumbens was found to be an alternative host of the virus, and the virus was transmitted by Aphis gossypii from the weed to sunflower. Serological analysis suggests that the virus (or virus complex) is closely related to luteoviruses. It is tentatively named sunflower yellow blotch virus (SYBV).