California Ag Network

Tag: Pierce’s Disease

  • Funding Committed to Fight Pierce’s Disease

    The Consolidated Central Valley Table Grape Pest and Disease Control District Board of Directors authorized the use of up to $1.7 million in district reactionary funds, generated through the California table grape industry, to support CDFA activities related to the prevention and control of Pierce’s Disease (PD) and the Glassy-Winged Sharpshooter (GWSS).

    The action was taken during the district’s board of directors meeting on Friday, August 21, 2026, in response to an approximately $1.7 million funding shortfall associated with current PD/GWSS program activities.

    The district recognizes continued GWSS surveillance, treatment, and suppression as critical to limiting the spread of Pierce’s Disease and protecting California’s table grape, wine grape and raisin industries. Since there is currently no cure for Pierce’s disease, preventing the movement of the disease and controlling populations of GWSS remain essential to protecting California vineyards.

    Background

    The Consolidated Central Valley Table Grape Pest and Disease Control District was formed pursuant to Article 8.7 of Chapter 9 of Division 4 of the California Food and Agricultural Code.

    Under California Food and Agricultural Code Section 6047.87, the district is authorized to take actions necessary to control, eradicate, remove, or prevent the spread of GWSS, Pierce’s Disease and other designated pests and diseases injurious to table grapes. GWSS presents a significant threat because it can spread the bacterium that causes Pierce’s disease as it feeds on grapevines.

    Historically, USDA and CDFA have provided funding for the GWSS Area-Wide Treatment Program. Due to federal and state funding shortfalls, the funding toward the GWSS program has been cut year-over-year. The district’s board of directors is providing emergency industry funding to prevent disruption of the program while longer-term state and federal funding solutions are pursued.

    Protecting Kern and Tulare Counties

    GWSS and Pierce’s Disease do not recognize county, crop, or district boundaries. A

    coordinated, area-wide approach to surveillance and treatment is critical to reducing GWSS populations and limiting the potential movement of the pest into vineyards and other agricultural areas.

    Citrus plays a particularly important role in GWSS management because citrus trees serve as a primary year-round host for the pest. Area-wide programs use trapping and monitoring to identify areas with elevated GWSS populations and coordinate treatments in citrus and other host areas when necessary.

    The funding commitment from the district will help support continued CDFA-coordinated PD/GWSS activities, including area-wide efforts that provide resources for eligible citrus growers to conduct approved treatments designed to suppress GWSS populations. These activities complement trapping, monitoring, and other preventative measures intended to reduce the movement of GWSS and protect nearby vineyards.

    By committing up to $1.7 million from accumulated district reactionary funds, the board is

    investing industry-generated funds directly into efforts intended to protect table grape

    growers. For growers in Kern and Tulare counties, there will be no assessment change.

    The district remains committed to working collaboratively with CDFA, county agricultural

    commissioners, growers and other agricultural partners to protect California’s grape industry from Pierce’s Disease and Glassy-Winged Sharpshooter.

    For additional information, please contact the Consolidated Central Valley Table Grape Pest and Disease Control District at 559-210-0118. — Story contributed by the Consolidated Central Valley Table Grape Pest and Disease Control District

  • Wine Grape Industry Commits Additional Funding to Stop GWSS

    To stop the glassy-winged sharpshooter from spreading a fatal grapevine disease into Northern California, the Pierce’s Disease and Glassy-Winged Sharpshooter (PD/GWSS) Board at the California Department of Food and Agriculture committed $820,000 to the ongoing emergency response.

    Preventing the glassy-winged sharpshooter from becoming established in new areas protects winegrapes and other agricultural and landscape plants. California’s wine industry generates about $73 billion in annual economic activity and supports more than 422,000 jobs statewide. A 2025 economic study estimated that if glassy-winged sharpshooters spread unchecked, outbreaks of Pierce’s disease could cost winegrape growers an additional $56 million a year in lost production and vine replacement.

    Since May, county agriculture officials have been tracking down nearly 10,000 grapevines from a Fresno nursery that may have carried the invasive pest into 40 counties. The Board’s special emergency funding is intended to support those efforts. Officials have contacted more than 3,100 customers who purchased the grapevines, inspected and/or destroyed more than 2,900 plants and set more than 2,700 additional insect traps.

    Glassy-winged sharpshooters have been found on customer plants in 23 counties. Inspections and trapping must continue for at least three years to track if the pest spreads beyond customers’ properties.

    “California’s winegrape industry is facing some of the hardest economic times in a generation, but we recognize what is at stake if this destructive pest becomes established in Northern California,” said Board chair Trey Irwin. “Putting $820,000 from the Board’s limited reserves toward this effort is a major commitment for our industry and shows how seriously we’re taking this threat.”

    The funding comes from assessments paid by California winegrape growers to support pest and disease research and prevention. Since 2001, the Board has invested $99 million in research, outreach, prevention and control for Pierce’s disease, grapevine viruses and the insects that spread them.

    “It is important that we continue with inspections and trapping to closely monitor the situation,” said Michelle Pham, response lead with the CDFA Pierce’s Disease Control Program. “This effort depends on close coordination among growers and county, state and federal agencies. For 25 years, that partnership has helped keep the glassy-winged sharpshooter from spreading throughout California.”

    People who suspect they have found a glassy-winged sharpshooter should contact their local agricultural commissioner’s office (bit.ly/CountyAg). For pictures of the pest and for more information, visit bit.ly/GWSS-Costco.

  • CDFA Urges Immediate Reporting of Grapevines Purchased at Costco

    The CDFA is urging anyone who purchased grapevines from Costco stores in Northern California between April 21 and May 21 to contact their local agricultural commissioner after an invasive pest was discovered among the 13,000 vines shipped during that period.

    Grapevines from a Fresno nursery shipped to California Costco stores in April and May were found to be carrying the glassy-winged sharpshooter (GWSS), an insect capable of spreading a potentially lethal vine disease.

    On May 19, the first glassy-winged sharpshooter was detected on vines sold at the warehouse retailer, triggering an immediate and widespread containment effort by CDFA, agricultural commissioners and winegrape growers throughout Northern California. Officials are responding to public reports, conducting inspections and public outreach and trapping near stores and locations where purchased vines were taken. They are also ensuring that potentially infested plants are safely contained and disposed of.

    In addition to destroying infested stock still in Costco warehouses, CDFA is working with agricultural commissioners and conducting public outreach to locate vines sold to consumers across 24 counties, as well as neighboring at-risk counties.

    “While many vines have been intercepted and destroyed, locating the thousands that may still be in customers’ hands remains our top priority,” said California Ag Secretary Karen Ross. “Anyone who purchased these vines should contact their local agricultural commissioner immediately.”

    Costco is offering a full refund to anyone who purchased these vines. Customers do not need to return the vines to receive a refund.

    To prevent the potential spread of the pest, CDFA officials urge customers to:

    •Immediately contact your county agricultural commissioner

    •Keep the plant in its original pot or container and away from other plants

    •If possible, place the plant inside two trash bags, one inside the other, and seal them closed

    •Do not place the plant in the trash or compost bin

    •An agricultural inspector will come, inspect the vine for GWSS and — if necessary — remove and dispose of the vine

    Winegrapes are one of California’s largest cash crops, generating approximately $73 billion annually in economic activity and supporting more than 422,000 jobs statewide. A 2025 economic study estimated that Pierce’s disease, which is spread by the glassy-winged sharpshooter, could cost California approximately $166 million annually if left unchecked.

    California first recognized the full threat of the glassy-winged sharpshooter in 1999, when a major Pierce’s disease outbreak in the Temecula Valley led to the destruction of more than 300 acres of vineyards. Winegrape growers quickly responded by working with the CDFA to create the Pierce’s Disease Glassy-Winged Sharpshooter Board to control the pest and find solutions to the disease it carries. The program has successfully contained GWSS for over 25 years. Visit cdfa.ca.gov/pdcp/PD_GWSS_Board.html. — Story Contributed by the California PD/GWSS Board

  • Glassy-Winged Sharpshooter Outbreak in Turlock has Regional Grape Growers on High Alert

    A Glassy-Winged Sharpshooter find in Turlock back in August 2024 has led to an expanding quarantine in Stanislaus County. The primary vector for the grapevine-killing Pierce’s Disease, this insect pest is a top concern for the regional grape industry and the Stanislaus County Ag Department. At Malcolm Media’s Tree & Vine Expo in Turlock and in an interview with Matthew Malcolm on California Ag Network, Stanislaus County Ag Commissioner Linda Pinfold shared the details of the quarantine and their efforts with the community in eradicating this invasive pest from the county. Watch this brief interview and read more about it in the January issue of American Vineyard Magazine.

  • Why this Grape Grower Urges a Yes Vote on the Pierce’s Disease Glassy-Winged Sharpshooter Referendum

    California wine grape growers have the opportunity to vote on whether to continue assessments to support the Pierce’s Disease Glassy-Winged Sharpshooter (PD/GWSS) Board. Ballots are being sent in the mail this month. Administered by CDFA and led by the wine grape industry for the last 25 years, this program funds research and activities to lessen the impact of threatening vineyard pests & diseases. Watch this brief interview with Lodi wine grape grower Aaron Lange as he shares with Matthew Malcolm on California Ag Network why he is voting “yes” on the referendum and explains what the Board has been working on that he finds so critical to the future of the industry.

    Please thank this video’s sponsor SIPCAM AGRO USA for their industry support.

  • Pierce’s Disease Investment Saves Wine Grape Growers $56M Annually

    According to a new economic impact study, the California Department of Food and Agriculture’s Pierce’s disease (PD) and glassy-winged sharpshooter (GWSS) prevention, control and research efforts save California winegrape growers $56 million annually by reducing losses from the fatal grapevine disease. Without the program’s efforts, growers’ losses would more than double from $48 million to $104 million. The study found that if GWSS spread unchecked, outbreaks of PD could cost winegrape growers an additional $56 million a year in lost production and vine replacement.

    The Costs of Pierce’s Disease in the California Grape and Wine Industry

    “This study highlights the serious threat Pierce’s disease and the glassy-winged sharpshooter pose to our industry and reinforces the importance of grower-funded research,” said Randy Heinzen, a Paso Robles winegrape grower on the Pierce’s Disease and Glassy-Winged Sharpshooter Board. “The public-private partnership led by the Pierce’s Disease Control Program is vital, allowing grower assessment funds to drive research that improves pest and disease management and to develop practical, sustainable solutions for the long-term viability of our industry.”

    The unique funding partnership the winegrape industry forged between growers, the state and federal government and industry fuels the essential research and control operations that have significantly blunted the most severe impacts of PD and GWSS. Even with these efforts, PD still costs an estimated $110 million annually in California, including $45 million for control, prevention and research, $48 million in lost winegrape production and vine replacement and $17 million in lost table and raisin grape production and vine replacement. Without these critical programs, the industry’s losses in production and vine replacement would be even higher, putting greater financial strain on growers and threatening the long-term stability of California’s vineyards.

    With industry and government support keeping PD and GWSS in check, grower-funded research continues to drive advancements in pest and disease management while supporting field trials for promising solutions. According to the study’s authors, the economic burden of PD and GWSS could decrease as this research yields practical, vineyard-ready innovations.

  • Harnessing the Power of Natural Volatile Compounds in Grapevines that Thwart Sharpshooters

    Grapevines have a natural defense mechanism against Glassy-winged sharpshooter, a notorious vector for Pierce’s disease, that researchers are trying to learn more about. Watch this brief interview with Julie Pedraza from the Fresno State Viticulture & Enology Research Center and read more about it n American Vineyard Magazine.

    Please thank this video’s sponsor Suterra for their industry support.

  • Glassy-Winged Sharpshooter Numbers Threaten Resurgence of Pierce’s Disease in SJV Grapes

    When it comes to Pierce’s Disease and Glassy-Winged Sharpshooter, it’s critical for growers to pay attention to both the disease and the vector.  Although collaborative efforts within the grape industry have kept disease levels down in recent years, population levels of the Glassy-Winged Sharpshooter have been elevating in the San Joaquin Valley. Watch this brief interview with UC Cooperative Extension Entomology Farm Advisor David Haviland as he addresses these concerns and read more in American Vineyard Magazine.
     
    Please thank this video’s sponsor Suterra for their industry support.

  • Crop Update With Sonoma Wine Grape Growers Bill & Lauren Hipp

    Wine grapes in Sonoma County are going through veraison and the crop is progressing well. Watch this brief interview with Bill Hipp who talked about this year’s crop, from the perspective of his vineyard, and what he is doing to keep Pierce’s Disease out of the Vineyard.

  • Dealing with the Resurgence of Pierce’s Disease in Vineyards

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    At the Annual Grape, Nut & Tree Fruit Expo in Fresno, Allison Ferry-Abee gave an update on Glassy Wing Sharpshooter and Pierce’s Disease as it has become more prevalent, particularly in the Southern San Joaquin Valley. Watch her interview as she shares more about identifying the pest and disease, and read more in American Vineyard Magazine.