Assessment of UK hops for the occurrence of hop latent and hop stunt viroids

Abstract

The occurrences and distributions of hop stunt (HSVd) and hop latent (HLVd) viroids were assessed by a nucleic acid hybridisation assay, using samples from 476 commercial hop plantings in the UK. These samples represented about half of the UK production.HLVd was detected in c. 17% of the samples, with infection in different cultivars ranging from 0% to 89%. This viroid was found in all cultivars sensitive to Verticillium wilt except cv. Sunshine, an old cultivar grown on only one farm in the UK. Two minor wilt-tolerant cultivars were also found to be infected at low frequencies, but the main commercially-important wilt-tolerant cultivars were all uninfected. A high proportion of the nuclear stock mother plants in the "A + " house at the Institute of Horticultural Research Dept of Hops Research, Wye College were infected. Circumstantial evidence, based on the planting dates of infected gardens, suggests that infection became established in the hop propagation system during the late 1970s and that there was a major increase in the prevalence of HLVd as a result. Whether this contamination of propagating material arose because of spread from long-standing infections or because the viroid was newly introduced into the UK, is not known.All samples were also tested for HSVd but this viroid was not detected in any UK hop material.

Agents Resembling or Altering Virus Diseases

“…(B) Symptoms of PSTVd in its natural host (potato); the control tuber on the left is from a healthy plant. A study of HLVd in the United Kingdom suggests that the current prevalence of this viroid in hops is a consequence of infection becoming established in the hop propagation system during the late 1970s (Barbara et al, 1990). Left, healthy apple; right, ASSVd-infected apple.…”

PM 4/16(2): Certification scheme for hop

“…Hop latent viroid (HLVd) can be detected by nucleic acid hybridization (Barbara et al, 1990) or by RT-PCR tests (Hataya et al, 1992;Nakahara et al, 1999;Grudzin¢ska & Solarska, 2004). RT-PCR enables more sensitive testing than hybridization (Knabel et al, 1999).…”

Viruses and Viroids Infecting Hop: Significance, Epidemiology, and Management

“…HpLVd has been reported from commercial yards in the United Kingdom (10,14,24), Germany 84 The worldwide distribution of HpLVd is probably due to its efficient mechanical transmission and dissemination in vegetative propagules, the latter being made more likely by HpLVd's latent nature. In addition to the commercial hop, HpLVd also infects H. japonicus and stinging nettle (Urtica dioica) (84).…”

“…The viruses considered generally important are the three carlaviruses, Hop mosaic virus (HpMV) (3,20,94,156), Hop latent virus (HpLV) (4,21,55,150,180), and American hop latent virus (AHLV) (5,22,149); the ilarvirus Apple mosaic virus (ApMV) (27,28,46,64); and the nepovirus Arabis mosaic virus (ArMV) (6,9,50,82). The important viroids infecting hops are Hop latent viroid (HpLVd) (10,14,24,25,151) and Hop stunt viroid (HpSVd) (162)(163)(164)201).…”