Sonoma, Napa plants found to contain sharp-shooter eggs

Inspectors in Sonoma and Napa counties destroyed plants last week that contained egg masses of the glassy-winged sharpshooter, an insect that spreads a disease that can kill grapevines.

Napa inspectors on March 7 discovered the eggs on some plants that were transported to the Walmart Supercenter in American Canyon, said Napa County Agricultural Commissioner Greg Clark.

The shipment came from an Orange County supplier, Nakase Brothers Wholesale Nurseries of Lake Forest, Clark said.

Inspectors destroyed eight plants where the egg masses were found. No other problems were found on the remaining plants.

The next day, Sonoma County inspectors destroyed plants that also were found to have egg masses. They also were on the shipment from Nakase Brothers, according to Clark.

Local agricultural officials have been on guard for years against the glassy-winged sharpshooter because it can transmit Pierce’s disease into a grapevine. Besides the inspection programs, they also have carried out public education efforts.

The bacteria from the disease impede water flow in the grapevine and ultimately kills it.

Pierce’s disease has already forced some vineyard owners in both counties to pull out and replant their vines in recent years. The culprit in spreading the disease in those cases has been the blue-green sharpshooter, a relative of the glassy-winged sharpshooter, which thrives in mild winters and riverside areas. The two incidents last week were the first reports of the glassy-winged sharpshooter in the area this year.

“Over the last two to three years, there has been an increased amount,” Clark said of the disease.

As scientists work to find a cure for the plant disease, local agricultural offices have worked hard to ensure that it does not spread, especially via plant shipments from nurseries in southern California.

In this case, the supplier will be under a compliance agreement with the Orange County Agricultural Commissioner’s Office to fix the problem, said Dan Curtin, deputy agricultural commissioner for Sonoma County.

For instance, the nursery will have to spray insecticide on the plants it ships to Northern California for the next 30 days, Curtin said.

The supplier has been “very cooperative” and the county has not had any previous problems with the company, he added.

You can reach Staff Writer Bill Swindell at 521-5223 or bill.swindell@pressdemocrat.com. On Twitter @BillSwindell.