TRANSMISSION AND DIFFERENTIATION OF 6 VIRUSES INFECTING HOGWEED (HERACLEUM-SPHONDYLIUM) IN SCOTLAND

Six viruses, code-named HV1-HV6, were transmitted manually and/or by aphids (Cavariella spp.) from symptomless wild plants of hogweed (H. sphondylium) in Scotland. HV1 was identified as parsnip yellow fleck virus (PYFV); anthriscus yellows virus, on which it depends for transmission by aphids, was presumably also present in the hogweed plants. HV2 was tramsmitted manually and by aphids and had very flexuous filamentous particles approximately 700-750 nm long. It has affinities with the closteroviruses, and the name heracleum latent virus is proposed. HV3, HV4 and HV5 were transmitted manually, HV3 and HV5 were also transmitted by aphids, but their particle morphology is unknown. HV6 was transmitted only by aphids and has very flexuous particles up to 1400 nm long; it is presumably a closterovirus distinct from HV2. All the viruses infected cultivated umbelliferous species experimentally but only PYFV is known to infect umbelliferous crops.