Grape Yellow Vein: Symptomatology, Identification, and the Association of a Mechanically Transmissible Virus with the Disease

Abstract

The grape yellow vein disease was identified on the varieties `Carignane,9 `Emperor,9 `Valdepenas,9 and `Grenache9 <i>Vitis vinifera</i> L.) Symptoms of the disease occurred on both leaves and fruit clusters. Leaf symptoms consisted of chlorotic line patterns and chrome yellow flecks. The yellow flecks, which were the leaf symptoms seen most commonly, occurred in pebbly texture along veins or over areas of the leaf. On `Emperor,9 the yellow flecks along the veins merged to form continuous yellow bands. Clusters on diseased vines bloomed, but set less fruit than those on healthy vines. Individual clusters contained various numbers of normal and seedless berries. The presence of the disease in the Sacramento and San Joaquin valleys of California was confirmed, and its presence in Sonoma County established. A mechanically transmissible virus was constantly associated with diseased vines. This virus was transmitted mechanically to herbaceous plants from leaves, roots, and pollen of diseased vines, but was not transmitted from healthy vines. The symptomatology and host range of the virus were similar to those of the tobacco ringspot virus. It was still infectious in crude juice (a) after 10 minutes at 60°C, but not at 62°C; (b) after 6, but not after 8, days at 21°C; and (c) at 10-³ but not 10-⁴ dilution. The virus was transmitted from <i>Nicotiana tabacum</i> L. to grape seedlings by mechanical inoculation and was readily transmitted from newly developed leaves on these seedlings back to tobacco.