Incidence of viruses in white clover on the North Island of New Zealand

Twenty-nine white-clover pastures from the North Island of New Zealand were tested by enzyme-linked immunosorbent assays for five viruses: Alfalfa mosaic virus (AMV), Beet western yellows virus (BWYV) Red clover necrotic mosaic virus (RCNMV), Soybean dwarf virus (SbDV) White clover mosaic virus (WClMV) and also for potyviruses. All the pastures were infected; most with WClMV and/or AMV and SbDV. The high incidence of SbDV was an unexpected result and although SbDV has little impact on white clover productivity its effect in mixed infections with AMV or WClMV is unknown. No potyvirus and only single infections of BWYV and RCNMV were detected. There was lower incidence of SbDV in the Bay of Plenty compared to Waikato. The Bay of Plenty samples had a higher ratio of AMV to other viruses than the Waikato.