Natural occurrence of beet mosaic potyvirus (BTMV) on beet in West Slovakia

Natural infections of beets (fieravulgaris L.) by beet mosaic potyvirus (BtMV) was detected in West Slovakia. Virus identification was based on serodiagnosis, particle morphology, aphid and sap transmissions and host range. The Slovak BtMV isolate was designated as BtMV-Ren based on its infectivity of Renata (a beet cultivar tolerant to beet rhizomania virus). The BtMV-Ren was sap and aphid (non-persistently) but not seed transmitted in beet. The BtMV-Ren isolate had particle morphology (740 x 12 nm) typical of potyviruses and was serologically related to BtMV. The BtMV induced beet mosaic disease (BtMD) was widely prevalent in West Slovakia and occurred in all the 19-surveyed localities with disease incidence ranging from 5 to 45%. Disease incidence was lowest (5%) at Dezenice and Janiky and highest (45%) at Oponice localities. Two resistant beet genotypes (Amelie, Rizor) to the virus (BtMV) and three resistant beet genotypes (Intera, Gabriela Rizor) to its vector (Myzus persicae Sulz.) were also identified.