Prevalence and Incidence of Viruses in New Zealand Hop (Humulus Iupulus) Gardens

Viruses pose a significant constraint to hop (Humulus lupulus) production worldwide. The incidence of Hop latent carlavirus (HpLV), Hop mosaic carlavirus (HpMV), American hop latent carlavirus (AHLV), Arabis mosaic nepovirus-hop strain (ArMV-H), and Apple mosaic ilarvirus (hop ApMV-H and intermediate ApMV-i serotypes) was assessed in 60 gardens at 11 locations (farms) in the Motueka province of New Zealand. The survey included 10 New Zealand-bred hop cultivars. Within each garden, one basal shoot was sampled from each of 50-75 plants and bulk-tested in groups of five by enzyme linked immunosorbent assay (ELiSA). Viruses were prevalent, with HpLV, ApMV (H+i), ArMV-H, HpMV, and AHLV occurring in 55, 41, 37, 37, and 17 of the 60 gardens, respectively. ApMV and HpLV occurred at highest incidence, with 22 and 15 gardens, respectively, having >50% incidence. HpMV, ArMV-H, and AHLV occurred at lower incidence with only four, two, and one gardens, respectively, having >50% incidence. Results suggested the prevalence and incidence of viruses was high and of concern to the continued production of high yields in New Zealand. © The Royal Society of New Zealand 2009.