Surveys of Beet necrotic yellow vein virus, Beet soil-borne virus, Beet virus Q and Polymyxa betae in sugar beet fields in Iran

The main Iranian sugar beet (Beta vulgaris) growing areas were surveyed for the occurrence and incidence of Beet necrotic yellow vein virus (BNYVV), Beet soil-borne virus (BSBV) and Beet virus Q (BVQ). Root samples from 3,486 plants were collected from 184 commercial sugar beet fields of 14 provinces from randomly selected and symptomatic plants and analysed by tissue-blot immunoassay (TBIA). Serological diagnoses were confirmed by reverse transcription-polymerase chain reaction tests (RT-PCR) using specific primers. Based on TBIA data, BNYVV was prevalent (overall incidence of 52.4%), followed by BSBV (9.8%) and BVQ (1.4%). High levels of virus infections (more than 70%) were found in Ardabil, Esfahan, Fars, Khorasan and Zanjan provinces, whereas Khuzestan was apparently "virus-free". The putative vector of the soil-borne viruses, Polymyxa betae, was also detected by RT-PCR in 179 fields surveyed.