Page 51 - Grapevine Jan-Feb 2020

Around The Vineyard

Close up view of Grapevine red blotch virus foliar symptoms

RED BLOTCH DISEASE:

Update & Importance of Producing

Clean Planting Stock By: Judit Monis, Ph.D.
E arly this year I wrote about the Grapevine Grapevine Red Blotch Disease

is Caused by GRBV
red blotch virus (GRBV) infection status of
vines in the University of California at Davis
Foundation block (also known as the Russell Ranch Grapevine red blotch virus is different from most
Foundation block). In this article I will update the other known grapevine infecting viruses in that its
reader on GRBV biology as well as the disease genetic material is DNA, rather than RNA. Both
status of the Russell Ranch foundation block. In the molecular and structural characterization has
spite of all the management activities performed placed GRBV in a new genus Grablovirus within the
to control the spread of the virus, the latest testing Geminiviridae family. Because grapevine viruses
results showed a drastic increase in infection of are not mechanically transmissible to grapevines,
the vines planted in the Russell Ranch foundation it has been difficult to demonstrate Koch’s postu-
block. lates. The postulates state that a pathogen must

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