Pierce's Disease Brochure: A Decade of ProgressSummer 2009
Pierce's Disease NewsletterWinter 2006-2007
Pierce's Disease/Glassy Winged Sharpshooter ForumResearchers, winegrowers and others can join this online forum to interact with others battling the PD/GWSS threat.
Since 1998, government and industry have mobilized with $65.2 million in assistance, a statewide management program and research to combat the glassy-winged sharpshooter and the deadly Pierce's disease that it carries, which threatens California's $2.7 billion wine, table and raisin grape industry and a host of other agricultural commodities. In addition, the state's wine industry introduced and Governor Davis signed legislation to establish an assessment on winegrapes to help provide more funds for the fight. Currently, the extensive control and eradication program is slowing the spread of the glassy-winged sharpshooter and buying time for the research community to develop permanent solutions. New findings on gene sequencing of the Pierce's disease bacterium already hold promise for a cure. Damage by Pierce's disease has affected less than one percent of the state's 568,000 winegrape acres since 1994, but because the GWSS moves quickly and Pierce's disease can kill a vine in two years, California has responded now to stop this potentially devastating threat before it affects wider portions of the state's wine and grape industry.
For over a century, California winegrowers have dealt with Pierce's disease. It decimated vineyards in the Los Angeles Basin in the 1880s, and again in the 1930s and 1940s. In the last five years, Pierce's disease has been responsible for the replanting of 775 acres of vines in California's North Coast, caused by the blue-green sharpshooter. A new, more threatening insect vector, the glassy-winged sharpshooter, has spread in Southern California and has already impacted 25 percent of Temecula Valley's 3000 vineyard acres in Riverside County, resulting in an estimated $13 million in damage in that county alone.
Accidentally introduced in 1989 through nursery stock imported from the southern U.S., the glassy-winged sharpshooter has spread Pierce's disease with astonishing speed. It is voracious, an aggressive flyer, and feeds and breeds on at least 133 host plants. To date, 15 counties have been identified by the state as being infested with the glassy-winged sharpshooter, primarily in Southern California and Southern San Joaquin Valley, and there is concern about its spread throughout the state.
Pierce's disease is a bacterium, Xylella Fastidiosa, spread by sharpshooters that feed on infected vegetation and then inject the bacterium into the sap of nearby grapevines. The bacterium lives and multiplies in a plant's xylem, eventually blocking the movement of water and killing the vine. There is no known cure for Pierce's disease. It affects only plant physiology and the vine's ability to produce a crop, and does not affect wine quality and or pose a health risk to wine consumers. There are many other important California crops and commodities threatened by Pierce's disease, including almonds, citrus, stone fruits, alfalfa and oleander.
Pierce's disease has not been found north of California or equivalent latitude, and seems to thrive in the southern U.S. extending from Florida and Texas to southern California where winters are mild. This suggests that the bacterium cannot survive the low winter temperatures of areas further north.
Government Responds Quickly with Funds
With the full support of a broad bi-partisan coalition of members of congress and state legislators, Wine Institute and others have sought funds to fight Pierce's disease and the glassy-winged sharpshooter. Federal, state and local governments as well as the wine industry have committed more than $60 million as follows:
- The Agriculture Appropriation Act of 2002, signed by President Bush in November 2001, included $8.5 million in funding for glassy winged sharpshooter/ Pierce's disease contain and control measures and $5 million for Pierce's disease research. The National Viticulture Consortium, whose funds are shared by U.C. Davis and Cornell University, received 1.6 million. In addition, state university scientists in California, New York and the Pacific Northwest received approximately 2.5 million in various research initiatives in grapestock, sustainable viticulture and biological pest control management.
- USDA declared an agricultural emergency in June 2000 allocating $22.3 million for control, eradication and research.
- The U.S. Congress designated $7.14 million in its crop insurance bill, which the USDA Farm Service Agency has made available to California to compensate growers for vine loss due to Pierce's Disease spread by the glassy-winged sharpshooter. Further federal appropriations measures are also being proposed.
- On the state level, led by Governor Gray Davis, the California legislature committed $13.8 million to the effort through a measure, SB671, passed in May and the 2000-01 state budget.
- Additional funds approved in 1999 include $125,000 each from Riverside County and the City of Temecula for research.
- In October 1999, California committed $750,000 each year for three years for research, and the California wine and grape industry plans to invest $250,000 each year over that same period through the American Vineyard Foundation (AVF) in keeping with the legislation passed.
- USDA authorized $360,000 to study the efficacy of chemical treatments on citrus.
- A $500,000 research partnership was established in April 2000 between USDA/CDFA/AVF and a Brazilian research institute to identify the microbe's genetic make-up.
Governor Signs Wine Industry's Cost-Share Bill
Governor Gray Davis signed AB1394 on July 25, 2001 to assess the winegrape community an estimated $5 million annually for five years. The measure provides funds for research and other necessary activities to fight the glassy-winged sharpshooter and ultimately eradicate Pierce's Disease.
Wine Institute, California Association of Winegrape Growers and Family Winemakers supported the bill to cost-share with the California Department of Food and Agriculture (CDFA) and the U.S. Department of Agriculture in the battle against the glassy-winged sharpshooter and the Pierce's disease that it spreads. Assemblymember Patricia Wiggins, D-Santa Rosa, carried the legislation, along with co-author Anthony Pescetti. It will assess up to $3 for every $1,000 farmgate value for research and other related activities as determined by a board of industry representatives. All grapes crushed for wine, wine vinegar, juice, concentrate or brandy would be assessed, and wineries would collect the monies and pay them to the CDFA. The legislation is expected to raise an estimated $5 million each year for five years, and will sunset on January 1, 2006.
Progress on Treating and Managing the Disease
Monies have already been implemented towards a statewide program to control Pierce's disease with the following elements:
- CDFA is inspecting nursery stock and bulk grapes moving throughout the state to slow the spread of the glassy-winged sharpshooter. With a protocol proposed by the Wine Institute membership, CDFA recently approved regulations to monitor the movement of bulk grapes during harvest from infested counties and counties that haven't yet completed a survey. CDFA has also implemented statewide regulations for nursery stock shipments from infested counties, requiring inspection and treatment protocols to assure that shipments and transporting vehicles are free from any life stage of the glassy-winged sharpshooter. In 2001, CDFA inspected more than 50,000 nursery plant shipments and 100,000 grape shipments.
- Through a monitoring, trapping and reporting program, a statewide survey is underway to determine the migration of the glassy-winged sharpshooter so that emergency response programs can be carried out.
- Biological control by introducing parasitic wasps that lay eggs in the glassy-winged sharpshooter eggs is an inexpensive, long-lasting and environmentally friendly method that is suppressing the sharpshooter population. The glassy-winged sharpshooter numbers in certain areas of Temecula have already been reduced with the use of native parasitic wasps. The University of California at Riverside and CDFA have also released stingerless parasitic wasps from Mexico, which will be followed by an ongoing breeding and release program in infested or threatened areas.
- An educational outreach program is providing information to growers, nursery people and others on identifying the pest, symptoms of infection and methods to control the disease.
- Targeted ground spraying inside the vineyard and surrounding host habitat has been used in heavily infested areas in Temecula, Tulare, Fresno and Sacramento counties. Spraying in Temecula was in isolated areas. In Fresno, Tulare and Sacramento, officials held communication outreach programs to explain the ground spraying well in advance of the treatments.
- Aerial spraying and quarantines have not been seriously considered for use by state officials. No quarantines are in effect.
- Cultural practices are curbing Pierce's disease. Growers are selectively removing vegetation around vineyards and replanting with vegetation that will not carry the disease. Severe pruning of infected shoots also has had some success. Because the smaller blue-green sharpshooter feeds on the succulent new shoots, the diseased portion of the vines is cut away during normal winter pruning. The glassy-winged sharpshooter is more dangerous in that it can feed on the permanent woodier parts of the vine.
Research continues for permanent solutions, including the following projects:
- The DNA gene sequence of Xylella fastidiosa has been deciphered by researchers at the Ludwig Institute for Cancer Research in Sao Paulo, Brazil. A different strain of Xylella fastidiosa is attacking California's vineyards and work has begun to map its genes. Scientists could use this knowledge to develop a treatment for killing the bacterium without harming the vine. Researchers are already experimenting with nutrients and chemicals for this method.
- Grapevines are being bred to be resistant to disease. Identification of disease resistant characteristics and incorporating them into the vine-breeding program.
- A biological control program will develop mass rearing methods for parasitic wasps and conduct preliminary field studies to determine the efficiency of releases in infested areas. Foreign exploration in Mexico and Florida will bring in more species to combat the sharpshooters.
- Sharpshooter-associated bacteria to reduce or kill Pierce's disease is being identified. The insect-associated bacteria would produce substances that could be injected into vines to kill Xylella fastidiosa.
- A "chemotherapy" method is being developed using natural zinc, manganese, copper and iron compounds, which have shown to inhibit the growth of Xyella fastidiosa invitro.
Links to Other Resources
For further information, contact Gladys Horiuchi
Wine Institute Communications Department
415/512-0151 or firstname.lastname@example.org
Key Facts about Pierce's Disease and California Wine
Winegrapes acres damaged by Pierce's disease since 1994: 1,500 acres or two-tenths of one percent of total state wine acreage
Total California winegrape acres in 2000: 568,000 acres
California counties with portions infested with glassy-winged sharpshooter: 15, mostly in Southern California and southern San Joaquin Valley
Total number of counties in California: 58
Number of years for Pierce's disease to kill a vine: Two years
Funds committed since 1998 to fight GWSS and Pierce's disease: More than $60 million
Estimated California winegrape crop for 2001: 3.1 million tons
Average annual California winegrape crush 1995 to 2000: 2.71 million tons
Percentage of U.S. wine produced in California: 90+ percent
California is the fourth-leading wine producer in the world behind Italy, France and Spain. Retail value of California wine shipments to the U.S. in 2000: $13 billion
Economic Impact of California wine in the state: $33 billion