Page 44 - Grapevine NovDec 2020

Around The Vineyard

capable of eliminating potential harmful viruses.
The block was tested using the “Protocol 2010”
that includes a list of viruses that are harmful to
grapevines. Initially, four vines were found to be
infected with GRBV in 2017, in 2018 the number
increased to 24 vines,in 2019 the positive results
were over 300 vines, while this year results showed
that 788 are infected with GRBV. Until last year,
the block was the source of California Registration
and Certification Program (CDFA R&C) material to
nurseries registered in the program. Because of
the GRBV positive status FPS suspended the sale
of vines from the Russell Ranch block. To learn
more about GRBV epidemiology, the GRBV-infected
Russell Ranch block will be used as a research block
to study the transmission and spread of the virus.

The block was tested using the “Protocol 2010”
that includes a list of viruses that are harmful to
grapevines. Initially, four vines were found to be
infected with GRBV in 2017, in 2018 the number
increased to 24 vines, and in 2019 the positive
results increased to over 300 vines infected with
GRBV. Until last year, the block was the source of
California Registration and Certification Program
(CDFA R&C) material to nurseries registered in the
program. Because of the GRBV positive status FPS
suspended the sale of vines from the Russell Ranch
block. To learn more about GRBV epidemiology,
the GRBV-infected Russell Ranch block will be used
as a research block to study the transmission and
spread of the virus.

Conclusions

This author is involved in applied research with
the goal to determine the ideal process to protect
clean planting grapevine stock and newly plant-
ed vineyards from infection of viruses and fungal
pathogens. Presently, information on what is the
distance needed at the foundation and nursery
blocks to avoid infection from diseased blocks is
lacking. The results of the research will develop the
best strategy to isolate and monitor clean planting
stock.

Until we have this information my recommenda-
tion is that nurseries and growers determine the
health status of grapevine stock prior to planting to

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