Pierce’s Disease in Grapes

Dr. Ali Sarkhosh hosted an exciting, interactive and informative Grape Field Day in at the UF/IFAS Plant Research and Education Center in Citra on May 18, 2023.  It was filled with talks and field activities for both hobbyists and commercial grape growers.  A major focus of the day was on a new technology for preventing Pierce’s disease in grapes.  In the 1920’s grapes covered the Florida landscape, but Pierce’s disease along with population growth wiped out most of the booming industry.  Pierce’s disease is a bacterial infection caused by Xylella fastidiosa that infects the plant xylem and is easily spread throughout the vineyard by insects.  The disease causes leaves to wilt, turn yellow and eventually fall off and the fruit to shrivel.  Plants that contract Pierce’s disease should be removed from the vineyard at the onset of the symptoms to avoid spreading.  The easiest way to prevent Pierce’s disease is to select disease-resistant grape varieties including Blanc DuBois and Southern Home.  Muscadine grapes from American descent (contrary to those of European descent) are generally considered to be resistant and/or tolerant of Pierce’s disease.  More about muscadines grown in Florida can be gleaned from the following document: https://edis.ifas.ufl.edu/publication/HS100.

Preventive Treatment for Pierce’s Disease

Researchers from A&P Inphatic came to demonstrate some of the latest technology being used to prevent Pierce’s disease in vineyards.  It involves a bacteriophage (XylPhi-PD) that is injected into the xylem of the plant at the base and at the upper branches that attacks the bacterium.  This is an actual virus that is labeled for use in Florida grapes.  The bacteriophages enter the bacterium, reproduce themselves and eventually kill the bacteria throughout the plant.  If the plant is not infected with the bacteria, then the bacteriophages will only persist for a limited time.  Dr. Jean Rodriguez and his team brought injection guns and allowed everyone to practice on mature vines to familiarize themselves with the equipment.  Most of their work is with the commercial vineyards in California and they have 30 industrial partners that have adopted this biological treatment approach.  The research trials to date support this approach as a preventative measure for Pierce’s disease rather than a treatment for vineyards that are already severely impacted.

Florida Wine and Grape Growers Association

J.R. Newbold III, President of the Florida Wine and Grape Growers Association (FWGGA), was in attendance and he is a commercial wine grape grower in Putnam County.  He grows approximately 10 acres of muscadine wine grapes and partners with Lakeridge Winery in Clermont, FL, to commercially harvest the grapes for wine production.  Lakeridge Winery sells their products directly or through local distribution outlets such as Publix, Target, ABC Liquor, Total Wines, and San Sebastian Winery.   J.R. updated the group on how to become a part of the organization that just celebrated their 100-year anniversary in January 2023.  Whether you are a hobbyist, a wine maker or a grape grower you can certainly benefit from joining the association or attending their annual convention.  To learn more please visit their website (https://www.fgga.org/).  Although the 2017 USDA Agriculture Statistics report that there are approximately 1500 acres of grapes grown in Florida, J.R. estimated that number was now less than 1000 acres.

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