Page 36 - Grapevine July-August 2015

Around The Vineyard

postulates is important because it provides a “cause reports that GRBaV is spreading rapidly throughout
and effect” for this virus being responsible for the California vineyards, there is limited field data sup-
symptoms displayed in infected vines. Recently, porting this viewpoint. Within a laboratory setting
researchers at Cornell University demonstrated that it has been reported by Washington State research-
GRBaV genetic material is capable of reproducing ers that the “Virginia Creeper” leafhopper is able
red blotch foliar symptoms in red fruited grapevine to transmit the GRBaV. While this is interesting,
varieties. other researchers have not been able to reproduce
the work to confirm transmission in the vineyard.
Grapevine red blotch associated virus also affects Presently, there is on-going research to determine if
white fruited grapevine varieties and in spite of leafhoppers or other insects are capable of spreading
its name, GRBaV does not always produce Red the GRBaV from vine to vine.
Blotch symptoms. For example, in varieties such
as Chardonnay, Pinot Gris, or Sauvignon Blanc, In spite of the recent discovery of Grapevine
infection of GRBaV displays yellow blotches or red blotch associated virus (previously known as
discoloration in leaves without showing red blotch Cabernet Franc associated virus because it was orig-
symptoms. While leaf symptoms are disconcerting, inally detected in this variety), this virus was found
more importantly, GRBaV has been reported to in a UC Davis grapevine herbarium specimen (Dr.
affect sugar accumulation in grapevines resulting in Deborah Golino personal communication) indicating
reduced Brix values and delayed fruit maturity. that the virus has been present in vineyards (at least
in the area where the specimens were collected)
Presently there is no information on the natural since the 1940’s.
transmission of GRBaV (other than it is graft trans-
missible and propagated with infected rootstock However, it is not clear why if present since the
and scion cuttings). While there are anecdotal 1940’s only recently did it attract attention from

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