First record of Beet western yellows, Chickpea chlorotic dwarf and Faba bean necrotic yellows viruses affecting faba bean (Vicia faba L.) crops in Iraq

A survey to identify virus diseases affecting faba bean (Vicia faba L.) in Iraq was conducted during April, 2000. Around 4400 samples were collected from 36 faba bean fields distributed in five governorates (10 in Baghdad, 9 in Al-Anbar, 3 in Diyala, 5 in At-Tamim and 9 in Ninawa). These samples were tested for the presence of 12 different viruses by tissue-blot immunoassay (Lin et al., 1990), using a battery of polyclonal and monoclonal antibodies. Rabbit polyclonal antisera specific for Chickpea chlorotic dwarf virus (CCDV) (Horn et al., 1993), Broad bean true mosaic virus (BBTMV) (from H. Rohloff, BBA, Braunschweig, Germany), Broad bean wilt virus (BBWV), Pea enation mosaic virus (PEMV) (from IPO, Wageningen, The Netherlands), Alfalfa mosaic virus (AMV), Bean yellow mosaic virus (BYMV), Broad bean mottle virus (BBMV), Broad bean stain virus (BBSV), Cucumber mosaic virus (CMV) and Pea seed-borne mosaic virus (PSbMV) (from Virology Laboratory, ICARDA, Aleppo, Syria) were used, in addition to a monoclonal specific for Faba bean necrotic yellows virus (FBNYV) (Franz et al., 1996) and a broad-spectrum legume luteovirus monoclonal (5G4) (Katul, 1992). To identify specific luteoviruses, samples which tested positive using monoclonal 5G4, were tested against five further monoclonals: Beet western yellows virus (BWYV) (ATCC PVAS-647), Soybean dwarf virus (SbDV) (ATCC PVAS-650), Potato leaf roll virus (ATCC PVAS-649), Bean leaf roll virus (BLRV) (4B10) and 6F9, which reacts with either BLRV or SbDV (Katul, 1992).

BYMV was the most abundant virus in faba bean in Iraq, identified in 68% of test samples. In 50% of the fields surveyed, BYMV was identified at extremely high levels (80-100% infection). BWYV was detected in 135 samples collected from 15 fields from all five governorates. Two fields in the Ninawa governorate were highly infected (62 and 96%) with BWYV. CCDV was detected in 8 samples collected from three fields (two in El-Anbar and one in Ninawa) and FBNYV was detected in 7 samples collected from two fields in Ninawa governorate. This is the first record of BWYV, CCDV and FBNYV affecting faba bean in Iraq. Other viruses such as AMV, BBWV and CMV were detected in less than 1% of the samples tested. BBMV, BBSV, BBTMV, PEMV and PSbMV were not detected in any of the samples.