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Current and Potential Impact
For Improving Pest Management
In U.S. Agriculture
An Analysis of 40 Case Studies
National Center for Food and Agricultural Policy
Financial Support for this study was provided by the Rockefeller Foundation, Monsanto, The Biotechnology Industry Organization, The Council for Biotechnology Information, The Grocery Manufacturers of America and CropLife America.
Production California is number one in the U.S. in grape acreage and production for wine, table and
raisin grapes . In 1999, the state had 424,000 wine grape acres producing a crop of 2.7
million tons valued at $1.56 billion, 87,000 table grape acres producing a crop of 0.8
million tons worth $417 million, and 279,000 raisin grape acres producing a crop of 2.1
million tons valued at $764 million. California wine grapes are the basis for the state’s
$33 billion wine economy, which produces more than 90% of all U.S. wine .
is a plant pathogenic bacterium that causes disease in a variety of plants
. There are strains that cause leaf scorch in almonds, oleander scorch in oleander,
variegated chlorosis in citrus, and Pierce’s disease (PD) in grapevines. The bacterium is
vectored by sharpshooters, piercing-sucking insects that feed on the xylem, the water
conducting tissue of the plant. Once introduced into a host plant, the bacterium lives and
reproduces in the xylem, eventually clogging the tissue. In grapes, the bacteria multiply
rapidly, spread systemically and can reach concentrations of billions of live bacterial cells
per gram of plant tissue . The plant is deprived of water and nutrients, and dies.
Pierce’s disease is found in all southern states, and is the primary factor preventing
European grape production in the southeastern U.S . Symptoms of PD in grapes
mimic those of drought: infected leaves and twigs turn brown and dry up, fruit wilts and
dries up, and canes and roots may also die back . A vine will be killed by PD within
two years of infection . Some grape varieties have some tolerance to PD and decline
more slowly after infection is initiated. These include Riesling, Chenin Blanc, and
Thompson Seedless. Pinot Noir and Chardonnay are very susceptible to PD. A one-
year-old Chardonnay or Pinot Noir vine can die the year it becomes infected. Ten-year
old Chenin Blanc or Ruby Cabernet vines can live with chronic PD infections for several
years although they will not bear a full crop . In Temulca, the cost of replanting a
vineyard is $16,000 per acre, over five years, not including the cost of lost production .
History of Pierce’s Disease in California
The bacterium that causes PD in grapes has been in California for more than a century
. The disease was extensively studied by USDA’s Newton B. Pierce and subsequently
the disease was named for him. The first outbreak destroyed 35,000 acres of grapes and
closed 50 wineries in the Los Angeles Basin in the late 1800’s. In the 1930’s another
major outbreak devastated vineyards in the Central Valley. Since then, occasional and
localized outbreaks have occurred in the Central Coast growing region and in isolated
vineyards in the Central Valley. Although annual statewide losses to PD have been
minimal, outbreaks are devastating for the vineyards in which they occur.
In the Central Valley, there are two insects present that vector PD: the green sharpshooter
and the red-headed sharpshooter . Both are primarily grass feeders and rarely feed on
grapes. By reducing weedy grass stands in and around vineyards, PD spread by these
In coastal production areas, the insect vector of PD is the blue-green sharpshooter .
The blue-green sharpshooter has a wider host range than its Central Valley relatives,
preferring woody perennials such as trees and shrubs that line waterways. When riparian
vegetation dries up and grape leaves start to expand, the sharpshooters will move into
vineyards to feed. Removing riparian vegetation is not possible, but because the blue-
green sharpshooter has only one generation in most areas, well-timed insecticide sprays
greatly reduce their levels, and therefore reduce PD spread. Not planting vineyards close
to waterways also helps reduce PD incidence in the vines.
In areas where PD is known to be a problem, other measures can be taken to manage it.
Varieties, which are slower to show symptoms, can be planted in order to prolong
production before replanting is necessary . Because the three established vectors feed
on the new canes that emerge each year, new infections are usually removed during
normal winter vine pruning . This prevents chronic infections that carry over into
subsequent seasons. Without chronic infections, sources of PD (i.e. infected plants that
sharpshooters will feed on) remain outside the vineyards. Because the three PD vectors
are weak flyers, PD infections tend to remain along vineyard borders without progressing
By 1990, a new sharpshooter, the glassy-winged sharpshooter (GWSS) had arrived in
California . It was most likely introduced as eggs on nursery stock from the
Southeastern U.S. The sharpshooter excretes water droplets after filtering out minerals
and amino acids. They have to filter out so much water to get adequate nutrition that the
GWSS produces a fairly sizable droplet of water about every three minutes. By autumn
the leftover salts from water dripped and evaporated make infested trees look like they
have been whitewashed. The GWSS also vectors PD. Compared to the three PD-
vectoring sharpshooters already present in California, the GWSS is bigger (0.5 inch), a
stronger flyer (sometimes covering up to a half-mile radius, five times further than the
other sharpshooters, so it can move deeply into vineyards), and a more voracious feeder.
The California Department of Food and Agriculture website  lists more than 1000 host
plants for GWSS, including horticultural and agricultural plants, wild plants and weeds.
Such a large host range makes it easy for the GWSS to spread into new areas and
proliferate, and makes management of the ubiquitous vector difficult. The miles of
oleander and other plants lining the medians and shoulders of California’s highways are
Like other sharpshooters, the GWSS feed by piercing plant stems and sucking water and
nutrients out of the xylem. Unlike the other PD-vectoring sharpshooters, the GWSS
tends to feed lower on the vine and can even penetrate and infect the old wood. This
wood cannot be pruned out if infected, so infections introduced by the GWSS are more
likely to become chronic more quickly. Chronic infections mean quicker decline and
death of a vine. They also mean the infected vine can serve as a source for further spread
within the vineyard . Infections are no longer only associated with vineyard borders.
With the GWSS, Pierce’s disease spreads faster, further and cannot be pruned out of
infected vines. This vector/disease combination is a very serious threat to all grapes in
California. Because of its wide host range and its ability to vector other strains of Xylella
should they be introduced into the U.S., the GWSS potentially poses a serious
threat to other agronomic crops such as alfalfa, almonds and citrus. Currently, however,
the biggest impact of the GWSS is due to its spread of PD in grapes.
The GWSS was first detected in 1996 in Orange and Ventura counties, and has since
been detected in at least 11 counties [2, 8], with established infestations concentrated in
the southern part of the state. Currently the GWSS has been found as far north as Chico,
Contra Costa, and Sacramento counties, thought to have been transported on horticultural
crops used for landscaping new development complexes. Within two years of its arrival
into the Temecula Valley region of Riverside County in1999, the GWSS and the PD it
vectors have caused an estimated $12 million in damage as 25% of the area’s grapevines
have been removed . More than 1000 acres of premium wine grapevines in the north
coast and another 300 acres in Riverside county have been killed by the disease.
Since the detection of the GWSS in California and its escalation of the threat of PD,
almost $50 million has been raised from federal, state and local governments and
commodity groups to research and manage the GWSS and PD . In the fall of 1999,
The Pierce’s Disease Research and Emergency Response Task Force was established to
identify areas of research and strategies for fighting the crisis.
There is no cure for Pierce’s disease. The best control for it is prevention . The
biology of the GWSS – its mobility, wide host range, and ability to feed on old wood –
makes managing the plant disease by managing the vector even more complex than is
usually the case with insect-vectored plant diseases. In order to stem the spread of the
GWSS, the California Department of Food and Agriculture inspects nursery stock and
bulk grape shipments . Statewide monitoring programs have been set up to detect and
track spread of the GWSS, and extensive training programs are provided for growers,
nursery workers and others to identify the GWSS and PD symptoms.
In areas where the GWSS is already established, measures are being taken, under the
coordinated efforts of county agricultural commissioners, California Department of Food
and Agriculture, and the California Department of Pesticide Regulation, to reduce their
populations . Parasitic wasps that kill GWSS eggs are being released, vegetation that
harbors PD and GWSS is being selectively replaced with vegetation that does not, and
insecticides are being applied. Monitoring programs have found a high correlation
between a vineyard’s proximity to riparian vegetation or citrus orchards and the severity
of PD infection . Insecticide applications to stem GWSS activity therefore are not
limited to vineyards, but are used on neighboring citrus plantings as well as non-
The University of California IPM Guidelines list two insecticides for GWSS control on
grapes: imidacloprid and dimethoate . Carbaryl applications have been used on non-
agricultural vegetation . A limitation of biological and chemical control of a disease
vector, however, is that most probably control needs to be 100% to stop the spread of the
disease. In this case, feeding deterrence may be of greater value than toxicity when
controlling the GWSS and PD. Studies show imidacloprid reduces GWSS numbers and
also appears to deter them from feeding on vines . The GWSS can detect a systemic
insecticide (such as imidacloprid) in the xylem when it first starts to feed and are deterred
from further feeding. Whether or not this first feeding is sufficient to transport the
Applications of kaolin, a fine clay, also seem to discourage GWSS feeding . Kaolin
works by creating a protective plant coating to prevent feeding and also sticks to the
GWSS, acting as an irritant and deterrent. When a sharpshooter finds a vineyard treated
with kaolin it most likely will move back into citrus or the hedgerow area without feeding
. Kaolin is approved for organic use in California because it is a naturally occurring
mineral. Table 21.1 and Table 21.2 delineate the per acre costs and use amounts of
imidacloprid and kaolin treatments for GWSS control.
In the meantime, research by private industry and the University of California is ongoing
to find ways other than insecticide applications to slow down GWSS and PD. Projects
include investigating the use of barriers and trap crops against GWSS, and winter pruning
and injecting vines with micronutrients or beneficial bacteria against PD [2, 13]. The
broad-spectrum antibiotic tetracycline is also being tested.
Eradication and control efforts such as monitoring and inspection programs, vegetation
modification, biological control programs, and insecticide applications are slowing the
spread of GWSS and PD, providing temporary benefits and more time . What is
needed are long term solutions, such as a way to prevent the GWSS from transmitting
PD, a way to kill PD, or development of PD-resistant grapevines . This is
particularly true for the northern part of the state, where grape growers and communities
have already voiced objections to insecticide-based GWSS control programs .
The wine industry, and therefore California’s grape industry, is highly dependent on
varietal name recognition . The best solution to PD is one that will not compromise
the qualities of the grape varieties that are already grown. At the same time, the best
solution to PD would be the development of new, disease-resistant varieties. Many
researchers are looking to biotechnology as a solution that meets both those criteria.
Biotechnology may allow the insertion of selected resistance genes into elite grapevine
varieties without changing qualities of the berry or the wine they would produce.
Biotechnology can also greatly reduce the time it takes to develop a new resistant variety
because genetic techniques allow for testing of PD resistance on plantlets rather than
The Pierce’s Disease Research and Emergency Response Task Force concluded in its
2000 report that “breeding resistance to the disease using genetic engineering and other
biotechnology applications holds the greatest promise for eliminating Pierce’s disease in
grapes” . Accordingly, several research projects are underway studying the biology
and behavior of GWSS and PD and the biology of grapevines for clues as to how to
interrupt the disease cycle and protect plants [2, 14].
Wild and cultivated grapes from the Southeastern United States are of a different genus
than the grapes in the west. The Southeastern grapes, muscadine grapes, have natural
resistance to Pierce’s disease . Breeding that natural resistance into the Vitis
of the west may also introduce other qualities that would negatively impact grape and
wine production, such as the musky flavor of muscadines and the tendency of their fruit
to drop when ripe rather than stay on the vine until harvest. Researchers at UC Davis and
in Florida are studying the genetics of muscadine grapes in hopes of incorporating their
resistance genes into California grapevines [18, 19].
Other UC researchers are looking for resistance strategies based on the biology of PD. It
has been discovered that some plant diseases involve a particular type of enzyme that
degrades plant cell walls. Pierce’s disease may involve such an enzyme. It has also been
discovered that many plants, including pear, produce a protein, called PGIP, that inhibits
this cell wall-degrading enzyme. One strategy that is being investigated for use against
Pierce’s disease is to insert the pear gene for PGIP into grapes and test for its effects on
Pierce’s disease development in the plant .
Another project has for the first time successfully transformed a commercial grape
variety with a useful gene [24, 28]. The gene used was taken from the pupae of the giant
silkworm moth, and it produces cecropin, a protein which attaches to the PD cell
membrane, punches a hole in it, and kills the cell . Cecropin is expressed at low
levels throughout the transgenic grape plant.
Researchers at the University of Florida have transformed Thompson Seedless, Merlot
and Chardonnay plants through the insertion of the cecropin gene. The transgenic plants
are currently being tested for resistance to Pierce’s Disease.
Research is ongoing to learn more about the genetics of Pierce’s disease in order to
identify other strategies for its control within plants. But most projects on Pierce’s
disease control are in their first year and so are still gathering basic information. In the
meantime, work is being done on grape genetics and biology so that when a resistance
strategy is developed, it can be implemented quickly. Research to improve the efficiency
of grape transformation via Agrobacterium
is being conducted, as is research to improve
the efficiency of producing vines from cell culture . Because Pierce’s disease is
concentrated in the xylem tissue of plants, any resistance strategy that is developed must
be focused in the xylem. Work is therefore also being done on targeting gene expression
The coordinated efforts for areawide GWSS suppression in infested regions have been
successful in reducing populations. Preliminary research has helped to identify potential
control strategies, but it may be several years before the details of an effective PD/GWSS
Most likely, areawide suppression of GWSS populations will continue in order to reduce
their influx into vineyards. In vineyards, this may include releases of parasitoids and
applications of systemic insecticides compatible with the parasitoid releases, such as
imidacloprid, either throughout the vineyard or along borders. The recommended rate for
imidacloprid application on grapes is 0.25 lbs. a.i. per acre, at a cost of $79 per acre .
But the GWSS would have to feed on vines in order to be killed by the systemic
insecticide, so PD infection may still occur. In order to prevent GWSS from feeding on
vines, researchers are looking to kaolin, either as a border treatment or throughout the
vineyard. Researchers suggest at least three applications of kaolin at 25 lbs. per acre, at a
cost of $17.50 per acre per application [11, 21].
It is estimated that transgenic grape cultivars that resist Pierce’s disease would essentially
be planted on all of California’s grape acreage (780,000 acres) and would eliminate the
potential spraying of 59 million pounds of insecticides (75.25lbs/A) costing $105
million/year ($131.50/A). Current insecticide use in California grapes is approximately
252,000 lbs. AI/yr. . The 59 million pounds projected for GWSS control would be a
Projected costs of insecticide treatments for GWSS in grapes.
Insecticide $/Application #
Projected insecticide amounts used for GWSS suppression in grapes.
Total Lbs AI/Acre
1. USDA, Noncitrus Fruits and Nuts 1999 Summary, National Agricultural Statistics
2. Wine Institute, “Pierce’s Disease Update”, available on the internet at
3. University of California, Grape Pest Management, Division of Agriculture and
Natural Resources Publication 3343, Second Edition, 1992.
4. USDA, Crop Profile for Grapes (Wine) in California, available on the internet at
5. Craig Weaver, Calaway Vineyards, Riverside County, CA. Personal communication,
6. Purcell, A.H., “Xylella fastidiosa
Web Site”, available at
7. California Department of Food and Agriculture, “Glassy Winged Sharpshooter”,
available on the internet at http://plant.cdfa.ca.gov/gwss.
8. Blua, M.J., P.A. Phillips, and R.A. Redak, “A New Sharpshooter Threatens Both
Crops and Ornamentals”, California Agriculture 53(2): 22-25.
9. UC IPM, “Pest Management Guidelines”, Division of Agriculture and Natural
10. Redak, R., “Impact of the Glassy-Winged Sharpshooter on Pierce’s Disease Spread in
California and New Approaches to Disease Management”, American Vineyard
Foundation, Viticulture Project Summary, available on the internet at www.avf.org.
11. “Kaolin Clay Film Repels Insect Pests in Fruits, Vegetables”, Ag Alert, April 18,
12. CDFA, “Report to the Legislature”, Pierce’s Disease Control Program, January, 2001.
13. University of California, “A New Pest Transmitting Pierce’s Disease Spreads in
California; UC Scientists Study Control of the Insect and Diseases It Carries”, DANR
News, available on the internet at http://danr.ucop.edu/news/July-
14. “Report of the Pierce’s Disease Research and Emergency Response Task Force”,
available on the internet at http://danr.ucop.edu/files/reportpiercesdisease.pdf.
15. “Farmers Speak Out on Sharpshooter Control Program”, Ag Alert, April 18, 2001.
16. Meredith, C.P., Professor, Department of Viticulture and Enology, UC Davis.
17. California Rare Fruit Growers, Inc., “Muscadine Grape”, Fruit Factsheet, available on
the internet at www.crfg.org/pubs/ff/muscadinegrape.html.
18. Walker, M.A., Associate Professor, Department of Viticulture and Enology, UC
Davis. Personal communication, April 2001.
19. Walker, M.A., “Genetics of Resistance to Pierce’s Disease”, American Vineyard
Foundation, Viticulture Project Summary, available on the internet at www.avf.org.
20. Meredith, C.P., “Genetic Transformation: A Means to Add Disease Resistance to
Existing Grape Varieties”, American Vineyard Foundation, Viticulture Project
Summary, available on the internet at www.avf.org.
21. “Glassy-winged Sharpshooter Pilot Project Compliance Agreement”, Kern County
Department of Agriculture, California Department of Food and Agriculture, and
22. Pearson, Roger C. and Austin C. Goheen, eds., Compendium of Grape Disease, APS
23. Varela, Lucia G., et al, Pierces Disease, University of California, Agriculture and
Natural Resources, publication 21600, 2001.
24. “On the Grapevine”, New Scientist, May 18, 2001.
25. USDA, Agricultural Chemical Usage, 1999 Fruit and Nut Summary, National
Agricultural Statistics Service, July 2000.
26. Gray, Dennis, University of Florida, Personal Communication, October 2001.
27. Gray, D. J., et al, “Transgenic Grapevines”, In: Khachatourians, McHughen, Scorza,
Nip and Hui (Eds). Transgenic Plants, Marcel Dekker, 2001 (in press).
28. Scorza, R. and D. J. Gray, “Disease Resistance in Vitis”, US Patent No. 6,232,528
From: Mike Anderson, The Wilderness Society Re: Date: April 8, 2005 Following is a brief summary and analysis of the national forest planning directives that were published in the Federal Register on March 23, 2005 (70 Fed. Reg. 14637).1 The directives supplement the National Forest Management Act planning regulations that the Bush Administration issued on December 22, 2004 and published in the F
Protein phosphatase assay This protocol describes the standard strategy for measuring Ser/Thr protein phosphatase (PPase) activity in our laboratory using an artificial substrate (ex. Fzy-S50), a recombinant protein kinase (ex. Cdk) and [γ-32P]-ATP. This protocol can be modified/utilized to measure various PPase activity of your interest by changing substrate and kinase. 1, Purification o