Page 52 - Grapevine Jan-Feb 2020
P. 52
Around The Vineyard
Booth 15 & L12
February 4-6, 2020
be isolated in pure form from a symptomatic plant, such as grapevine leafroll associated viruses have
later introduced to a healthy plant, and cause the a world-wide distribution (i.e., it is found every-
same disease symptoms seen in the original infect- where grapevines are grown). In spite of the
ed plant from which the virus was isolated. Koch’s recent discovery of Grapevine red blotch virus, it
postulates show the “cause and effect” of a virus, was found in a UC Davis grapevine herbarium spec-
in other words, demonstrate that a specific virus is imen indicating that this virus has been present
responsible for the symptoms observed in infected in Californian vineyards since the 1940s. Even for
vines. As hard as it has been for researchers to an experienced professional like me, sometimes
complete Koch’s postulates with grapevine viruses, it is difficult to distinguish leafroll from red blotch
Dr. Marc Fuchs team at Cornell University was able disease in the vineyard. This is especially true with
to show, using recombinant DNA technology, that red-fruited grapevine varieties such as Cabernet
GRBV genetic material can reproduce red blotch Franc, Cabernet Sauvignon, or Pinot Noir. That is
foliar symptoms in red fruited grapevine varieties. why it is so important to confirm the presence of
This is why now we call this virus Grapevine red the virus with laboratory diagnostic tests.
blotch and not Grapevine red blotch associated
virus (i.e., other grapevine viruses have the asso-
ciated word because Koch’s postulates have not Grapevine Red Blotch Disease
been completed). Transmission and Spread
To date it appears that GRBV is a North American Grapevine red blotch virus is graft transmissible
virus, although the virus was detected in Chinese, and predominantly propagated by producing cut-
Korean, Swiss, and most recently in Argentine tings of infected rootstock and scion material. In
vineyards, it appears that the material originat- the recent years the vectored transmission of GRBV
ed in North America. In contrast, other viruses has been determined. Work by researchers at
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