Two glassy-winged sharpshooter nymphs were found last week on grapevines for sale at Costco’s Novato location, putting Marin County on high alert about a threat to the wine and agriculture industries. The sharpshooter is a vector for Pierce’s disease, a bacterial infection that blocks water movement within the plant, steadily killing it. The disease is incurable, and, if left unchecked, it can wipe out an entire vineyard in a couple of years. “It’s the highest priority for our department to find these plants, seize them, and inspect the areas around them, looking for other host plants,” Dann Walters, the supervising inspector of the Marin County Department of Agriculture, said. “We are also putting up traps at every site we go to that we will be monitoring.” The grapevines originated at a Fresno County nursery that neighbors a quarantine area where the sharpshooters were previously detected. Because of its proximity to the regulated area, the nursery operated under a compliance agreement requiring it to notify destination counties before shipping certain plants. According to Mr. Walters, the nursery failed to notify Marin, meaning inspectors did not examine plants arriving in several shipments. Fresno County plans to take enforcement action against the nursery. Of the 240 plants shipped to Novato, 172 were sold. Costco has sent an email to every customer who purchased the plants, which are either being returned to Costco or reported to the county. Meanwhile, ag department staff have traveled to 10 sites across Marin where the grapevines were already put into the ground or are about to be planted. Any vines at risk of contamination are being cut up, double-bagged, and solarized—a natural process that kills the sharpshooters using heat from sunlight over the course of several weeks. Anyone who recently purchased leafed-out grapevines from the Novato Costco should call the Agricultural Commissioner’s Office at (415) 473.7888.