Environment

Glassy-winged sharpshooter no longer a threat to SLO County vineyards

A glassy-winged sharpshooter.
A glassy-winged sharpshooter. Courtesy of UC Regents

Agricultural officials have declared the glassy-winged sharpshooter — a worrisome vineyard pest — eradicated in San Luis Obispo County.

The announcement comes three years after the pest was first discovered in the San Luis Obispo residential neighborhood, The Arbors, near Islay Hill. The discovery prompted an aggressive campaign to eradicate the bug before it could do any damage to the county’s lucrative wine industry.

“The glassy-winged sharpshooter has the ability to transmit a bacterium responsible for multiple plant diseases including Pierce’s disease, which is fatal to grapevines, and other plant diseases affecting landscapes and nursery stock,” explained Marty Settevendemie, county agricultural commissioner.

Late in 2010, six live adult sharpshooters and three live nymphs were trapped in The Arbors, causing alarm in nearby vineyards.

“We were very concerned,” said George Donati, general manager of Pacific Vineyard Co., which has 1,300 acres of wine grapes in the Edna Valley near the infestation. “It was almost like a doomsday thing.”

Donati was so concerned that he traveled to the Southern California city of Temecula, where the first sharpshooter infestation occurred in 1999, to learn more about it. More than 300 acres of vineyards were destroyed there.

The sharpshooter is a large leaf-hopping insect native to the southeastern United States. It spreads the disease-causing bacterium when it pierces a plant’s stem to feed it.

Locally, agricultural officials responded by treating as many as 100 properties in the Islay Hill neighborhood. The procedure consisted of treating the soil beneath host plants, such as citrus trees, with a common flea and tick pesticide that killed the insect when it fed on the plant.

Some 300 traps were also deployed to track the infestation. The effort was successful because the pest was contained to the neighborhood and did not spread to nearby vineyards.

Monitoring continued for two years after the last sharpshooter was detected. The eradication effort was declared over last month.

Agricultural officials and area vintners praised the public/private cooperation that eliminated the infestation. Wine grapes generate $200 million in annual receipts, making it a significant driver of the local economy.

“This is an excellent example of cooperation between the urban and agricultural sectors that led to a positive outcome to help maintain the viability of these beautiful vineyards and our local tourist industry in the most sustainable manner possible,” Donati said.

The eradication effort cost about $120,000 and was paid for by the state Department of Food and Agriculture.

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