California's vineyards are facing a serious threat. The combination of a plant disease with no cure and a half-inch-long leafhopper called a glassy-winged sharpshooter has wrought millions of dollars of damage in just a few years.

Pierce's disease has existed for more than 100 years in the state, but until recently there was no carrier as effective in transmitting the bacteria more than a few feet and spreading the bacteria so rapidly.

The glassy-winged sharpshooter, first found in 1990 in Ventura County, has spread throughout Southern California. The insect is now moving northward.

Pierce's disease is caused by a bacterium,Xylella fastidiosa. The bacterium blocks the xylem, the water- and nutrient-conducting vessels of plants. The typical symptom is for leaves on the plant to begin to dry or to scorch. Infected vines can die in as little as one to two years.

X. fastidiosa also causes almond leaf scorch, phoney peach disease, alfalfa dwarf, oleander leaf scorch and citrus variegated chlorosis.

Pierce's disease decimated 40,000 acres of grapes in the Anaheim, Calif., area in the late 19th century. It was dubbed Anaheim disease, but the name was later changed because of Newton Pierce, who studied the infection. The incurable plant disease has appeared on and off ever since, but its spread was limited. The principal carrier, or vector, was the blue-green sharpshooter, a weak, small insect not able to fly much further than three feet.

The glassy-winged sharpshooter,Homalodisca coagulata, is native to the southeastern United States. It was first found in California in 1990. It is a large insect, almost a half-inch (12 mm) in length. It is a dark brown to black. Its head and back are stippled with either ivory or yellowish spots. It receives its name from its transparent wings.

The glassy-winged sharpshooter can fly up to one-quarter of a mile, and it frequently appears in high numbers. The insect is able to survive winter temperatures dipping as low as 20 degrees Fahrenheit.

The insect overwinters as an adult. It begins laying egg masses from late February through May. The year's first generation matures as adults from May through August. The year's second generation begins as egg masses laid from June through Sepetember. It is this generation that produces the next year's offspring.

Photos of the glassy-winged sharpshooter are available at:

http://danr.ucop.edu/news/MediaKit/photos/default.shtml

The glassy-winged sharpshooter is a voracious eater. It can consume 10 times its body weight in liquids per hour.

Sharpshooters can acquire the bacterium from infected plants and transmit it to healthy plants while feeding. If the adult stage of the insect has the bacterium that causes Pierce's disease, the bacterium remains in its mouthparts throughout its life, which can last over 6 months.

In some host plants, such as grape, the bacteria can spread systemically and cause disease. Once in the plant, the bacteria multiply and block the xylem, or water-conducting vessels of the plants. Plants eventually develop symptoms of dry or scorched leaves, particularly in mid-summer.

Once a plant is contaminated with Pierce's disease, the plant can act as a reservoir of the bacterium. Any sharpshooter that feeds on the plant can pass the infection to other plants. Once an adult sharpshooter acquires the bacterium, it may transmit the disease throughout the rest of its life.

The glassy-winged sharpshooter has an extremely wide host plant range.

Researchers at UCR have been working on the glassy-winged sharpshooter for several years. Scientists from the university's Entomology Department are:

• Pursuing non-pesticide biological control of the glassy-winged sharpshooter by introducing a natural enemy - a tiny stingless wasp that is successfully reducing populations of the sharpshooter in Mexico and Texas. Print-quality photos of the release.
• Researching potential use of physical barriers to prevent the glassy-winged sharpshooter from spreading.
• Investigating whether currently available pesticides will be effective in controlling sharpshooter populations.

In early October 1999, University of California President Richard C. Atkinson established a task force of experts to help find solutions to Pierce's disease. The task force reported its findings and recommendations for action.

The university has 19 people who are available. They are:

Name: Raymond Hix
Position: Extension Entomologist, University of California, Riverside
Phone: (909) 787-2064
E-mail: Raymond Hix
Expertise: The impact of the glassy-winged sharpshooter on Temecula growers and the techniques to control the damage.

Name: David Morgan

Position: Post-Doctoral Research Scientist, University of California, Riverside
Phone: (909) 787-4360
E-mail: David Morgan
Expertise: Biological control of glassy-winged sharpshooter through raising and release of the wasp Gonatocerus triguttatus.

Name: Nick Toscano
Position: Extension Entomologist, University of California, Riverside
Phone: (909) 787-5826
E-mail: Nick Toscano
Expertise: Potential management of glassy-winged sharpshooters areawide programs which includes management in citrus, grapes, urbanized and riperian areas, utilizing monitoring for, identifying potential GWSS "hot spots" and the evaluation of the use of insecticides for control.

Name: Richard Redak
Position: Professor of Entomology, University of California, Riverside
Phone: (909) 787-7250
E-mail: Richard Redak
Expertise: Integrated pest mangement of glassy-winged sharpshooters; biology and ecology of sharpshooters.

Name: Matthew Blua
Position: Research Entomologist, University of California, Riverside
Phone: (909) 787-6301
E-mail: Matthew Blua
Expertise: Pierce's disease and oleander leaf scorch; glassy-winged sharpshooter management, biology and ecology; potential use of physical barriers to prevent insect spread.

Name: Ali AlWahaibi
Position: Graduate Research Associate, University of California, Riverside
Phone: (909) 787-5443
E-mail: Ali AlWahaibi
Expertise: Molecular biology of bacterial plant diseases and biological control of plant diseases with beneficial bacteria.

Name: James Bethke
Position: Staff Research Associate, University of California, Riverside
Phone: (909)-787-4733
E-mail: James Bethke
Expertise: Integrated pest management of glassy-sharpshooters; pesticide control of sharpshooters.

Name: Don Cooksey
Position: Professor of Plant Pathology, University of California, Riverside
Phone: (909) 787-3516
E-mail: Don Cooksey
Expertise: The etiology of plant bacterial diseases including Pierce's disease, molecular biology of resistance to bactericides, and biological control of plant diseases with beneficial bacteria.

Name: Heather Costa
Position: Extension Entomologist, University of California, Riverside
Phone: (909) 787-4737
E-mail: Heather Costa
Expertise:Oleander leaf scorch; susceptibility of oleander varieties to the bacterium Xylella fastidiosa; host-plant determination of Xylella fastidiosa; transmission of Xylella by sharpshooters.

Name: Carlos Coviella
Position: Post-Doctoral Research Scientist, University of California, Riverside
Phone: (909)-787-5713
E-mail: Carlos Coviella
Expertise:Monitoring and dispersal of glassy-winged sharpshooters; biological control of glassy-winged sharpshooters

Name: Korsi Dumenyo
Position: Post-Graduate Research Scientist, University of California, Riverside
Phone: (909) 787-3516
E-mail: Korsi Dumenyo
Expertise: Molecular biology of bacterial plant diseases and biological control of plant diseases with beneficial bacteria.

Name: Beth Grafton-Cardwell
Position: Extension Entomologist, University of California, Riverside
Phone: (559) 646-6591
E-mail: Beth Grafton-Cardwell
Expertise: Effects of glassy-winged sharpshooter management on integrated pest management in citrus.

Name: Carmen Gispert
Position: Post-Doctoral Research Scientist, University of California, Riverside
Phone: (909) 787-5393
E-mail: Carmen Gispert
Expertise: Host-plant determination of Xylella fastidiosa; transmission of Pierce's disease by sharpshooters.

Name: Mark Hoddle
Position: Extension Entomologist, University of California, Riverside
Phone: (909) 787-4714
E-mail: Mark Hoddle
Expertise: Biological control of glassy-winged sharpshooters.

Name: Robert Luck
Position: Professor of Entomology, University of California, Riverside
Phone: (909) 787-5713
E-mail: Robert Luck
Expertise: Monitoring and dispersal of glassy-winged sharpshooters; biological control of glassy-winged sharpshooters.

Name: Tom Miller
Position: Professor of Entomology, University of California, Riverside
Phone: (909) 787-3886
E-mail: Tom Miller
Expertise: Insect physiology, applications of molecular biology to disrupt transmission of Xylella fastidiosa by sharpshooters.

Name: John Peloquin
Position: Research Entomologist, University of California, Riverside
Phone: (909) 787-4680
E-mail: John Peloquin
Expertise: Applications of molecular biology to disrupt transmission of Xylella fastidiosa by sharpshooters.

Name: Serguei Triapitsyn
Position: Entomology Museum Scientist, University of California, Riverside
Phone: (909) 787-4385
E-mail: Serguei Triapitsyn
Expertise: Discovery of natural enemies of insect pests.

There are two departments of the College of Natural and Agricultural Sciences that are very involved: the Entomology Department and the Plant Pathology Department.

In June, there was an emergency declaration from the federal government as part of a joint state-federal plan that will dedicate a total of $36 million to eradicating and preventing the spread of this pest.

A press release from Gov. Gray Davis about the declaration:

http://www.governor.ca.gov/briefing/pressreleases/jun00/pr00158623.html

A press release from William (Bill) J. Lyons, Jr., Secretary, California Department of Food and Agriculture about the department's response:

http://plant.cdfa.ca.gov/gwss/gwmsg.htm

http://plant.cdfa.ca.gov/gwss/gwmreCurrent.htm