Pierce’s Disease and GWSS: A Deadly Combo for Grapes

Dan Grapes, Nuts & Grapes


Pierce’s Disease and the insect that spreads it, the glassy-winged sharpshooter, are nothing new to California and it keeps grapes from being grown in prime areas of the state. “What we’ve seen is that Pierce’s disease bacterium will kill grapevines in short order. Nobody wants to invest so much in a vineyard and then have the pest, then the disease, followed by the death of all of the vines,” Monterey County Agricultural Commissioner Henry Gonzalez said.

Gonzalez held the same position in Ventura County prior to his current office. He said the southern coastal area he used to oversee is perfect for grape production, but it isn’t feasible. “In Ventura County, for instance, they have great soil, great climate and they could grow some really good grapes, but they don’t because they have the combination of the pest and the disease,” Gonzalez explained.


California put measures in place to contain the glassy-winged sharpshooter many years ago. Gonzalez said this keeps the issue from reaching areas that are already producing grapes. “The state about 13 or fourteen years ago developed a really great inspection program,” he said. “The commissioners in infested areas of Southern California inspect potted plants that are being shipped north to grape-producing counties.”

Gonzalez added that therefore identifying and quickly putting measures in place on any pest is critical for the entire state of California. “The trick is to find that invasive pest, whichever it is like the glassy-winged sharpshooter, the Asian citrus psyllid, whatever it is. You want to have early detection and have a rapid response before it becomes established,” he said.

Pierce’s Disease and GWSS: A Deadly Combo for Grapes
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Taylor Hillman

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AgNet Media Operations Manager and Farm News Director for AgNet West.