Advantages of Planting with California Certified
Text provided by FPMS.
Why should I be selective about the planting
stock used to establish a new vineyard?
The choice of planting stock will have an enormous
impact on the health and quality of the planting for
the life of the vineyard. If virus-infected planting
stock is used, no subsequent cultivation practices or
treatments will improve the diseased condition, short
of replacing the vines.
Grapevines carrying virus disease are a liability to
the grower for many reasons. The adverse effects of
virus disease range from delayed ripening and reduced
sugar, color, and yield (as is the case with leafroll)
to leaf malformation, shot berry fruit, and yields that
may drop to zero (as is the case wish fanleaf). Fanleaf-infected
vines can also serve as a source of infection if Xiphinema
index dagger nematodes are present in the soil to transmit
the virus to healthy vines. These nematodes can survive
up to 10 years on roots left behind after a vineyard
is removed and will infect healthy vines that are planted
later in the same site. Virus disease should therefore
be avoided for the betterment of current and future
It is also important to choose planting stock that
is true to variety. If the vines are found to be incorrectly
identified, they may be unsuitable for the product for
which they were planted. Costly procedures such as replanting
or grafting over are the only way to correct this kind
Can I determine whether my planting stock
is disease-free and true-to-variety with a visual inspection?
Not always. It is difficult to determine the disease
status or variety of a grapevine from a dormant cutting
or dormant plant. Some diseases do show characteristic
symptoms in growing vines, but these vary according
to the host variety and the particular virus disease(s)
involved. Consequently, it is not possible in all cases
to reliably determine the health of grape planting stock
by looking at vines.
About 30 years ago scientists responded to the problem
of determining a vine's virus disease status by developing
a technique called "indexing" to test for
graft-transmissible virus disease(s) in grapevines.
To index, chip buds from a candidate selection are grafted
onto several specific grape varieties, called indicator
varieties, that display distinct visual diagnostic symptoms
when infected with particular virus diseases. If the
candidate is virus-infected, the indicator plants will
show symptoms in about 18 months. Some viruses can also
be detected by smearing ground-up leaf tissue from the
candidate onto a greenhouse-grown weed called Chenopodium
quinoa. If the virus is present, the weed shows symptoms
in about 10 days.
To date visual inspection of growing vines has been
the only means available to determine trueness-to-variety.
Unfortunately, experience has shown that even "experts"
sometimes make mistakes this way. One way to improve
accuracy is to have a number of "experts"
look at the same vines in an established vineyard over
a period of years. New biochemical techniques for grape
identification work are being studied, but they are
not available for use at this time.
Fortunately, once a vine is found to be true to variety
and passes indexing tests, the variety and disease status
do not change. Grapevines do not readily mutate to different
varieties, and most virus diseases are transmitted only
by grafting. Good nursery practices and careful record
keeping will produce daughter vines of the same variety
and with a disease status identical to the mother vine.
How can I be sure that my planting stock
has been propagated from vines that were tested for
disease and checked for trueness to variety?
At growers' request, the California State Department
of Food and Agriculture (CDFA) developed the California
Grapevine Certification Program to provide growers with
a means for identifying grape stock propagated from
virus-indexed and true-to-variety mother vines. Foundation
Plant Materials Service (FPMS), at the University
of California, Davis, is the repository for the virus-indexed,
true-to-variety vines, and provides cuttings of these
vines to nurseries participating in the Certification
Program. State regulations require that all grape selections
in the program test negative for specified diseases
using specific indicators shown here:
|St George grapevine
||Fanleaf degeneration, fleck, asteroid mosaic,
stem-pitting, and corky bark
|Cabernet Franc, LN-33, or Mission grapevine
||Grape decline (yellow vein) and/or fanleaf degeneration
Foundation stock from FPMS is labeled with a white
certification tag and sold to California nursery participants
in the Certification Program. Under the supervision
of CDFA, Foundation stock is used by participating nurseries
to plant registered field increase blocks. When cuttings
from increase blocks are used to plant a certified nursery
row, they are labeled with a purple registered tag.
Rootings from a certified nursery row or cuttings from
an increase block to be used for budding, grafting or
planting directly into a vineyard are labeled with a
blue certified tag.
Does a certified tag mean that the stock is true
to variety and free of disease?
Buying certified stock is the best way to gain assurance
that a serious effort was made to check the health and
verify the variety of the stock. It is not, however,
a guarantee that the stock is healthy or true to variety
for several reasons:
- The indexing procedure used to qualify a candidate
for the certification program does not detect every
disease that has been or will ever be discovered
because our knowledge of grape diseases and detection
techniques is constantly improving.
- As noted above, objective methods available for
identifying grape varieties at the University and
elsewhere have not been perfected. Errors have occurred
in the past at FPMS and may continue to turn up
until a highly accurate identification method is
- The California certification program for grapevines
is a voluntary program and much of the regulation
compliance is voluntary in nature. Consequently,
CDFA cannot guarantee that all
procedures proscribed by regulation have been followed
for stock labeled with registered or certified tags.
What additional information should I ask
the nursery to supply stock I plan to purchase?
Growers can overcome some of the weaknesses of the
certification program by taking a few extra precautions
when buying stock. In addition to requiring California
Certification tags, ask your nurseryman the following
- What registered increase block did the rootstock
and scion material for these plants come from?
- What are the FPMS selection numbers for the rootstock
and scion material used to produce these plants?
- When were the source increase blocks planted?
The purpose of these questions is to establish a clear
trail from the Foundation Vineyard at FPMS to the material
to be purchased. If any gaps appear in this record,
there is greater risk in using the material.
Can noncertified material be as good as certified
Growers could privately conduct the same type of indexing
treatment and inspection procedures FPMS uses to qualify
a selection for the Certification Program and produce
their own equivalent material. Costs for duplicating
these procedures privately, however, could be prohibitive.
Material that has been propagated from currently registered
certified stock with good nursery practices, sometimes
called "first generation" or "as good
as certified" material, should also have the same
health and ID status as certified stock. Information
needed in order to make this determination would include:
- Up-to-date information about which FPMS selections
are currently registered -- this changes at least
annually and sometimes more often.
- The history of the mother vine planting site
-- if fanleaf-infected vines have been planted in
the site in the last 10 years the material could
be infected with fanleaf.
- Accurate information about rootstocks used, replants
made and/or graftwood used for topworking vines
in the source vineyard -- was it certified also?
By collecting this information a grower could reproduce
part of the procedure employed by CDFA to certify grape
stock. In addition, it would be important to ensure
that there is a clear budwood trail from the Foundation
Vineyard to the "as good as" source vineyard.
Treatments, tests and identification by the University,
as well as supervised propagation and recordkeeping
by CDFA, are the valuable although not perfect credentials
of CA Certified Grape Planting Stock. FPMS therefore
recommends that growers use CA Certified Planting Stock
for which a clear trail from the Foundation Vineyard
to stock purchased exists. Making the correct choice
when choosing grape planting stock is crucial and no
measure for checking it should be ignored. Using "as
good as" or "first generation" stock
is therefore a poor choice and is not recommended.
Who can I contact to get more information?
- California State Department of Food and Agriculture
Nursery Service/Pest Exclusion
1220 N St. -- P.O. Box 942871 Sacramento, CA 94271-0001
- Foundation Plant Materials Service
University of California
Davis, CA 95616
- Your county grape farm advisor (University of
California Cooperative Extension)
This article was written by:
- Susan Nelson-Kluk, Manager, Foundation Plant Materials
Service, UC Davis
- Andrew Walker, Assistant Professor, Department of
Viticulture and Enology, UC Davis
- James Wolpert, Extension Specialist, Department of
Viticulture and Enology, UC Davis