On September 15 2009, one EGVM was detected in Gilroy, and confirmed by the USDA’s Systematic Entomology Laboratory. Three males at 2 sites had been detected, triggering a 94 square mile quarantine and treatment area. In January 2013, the Santa Clara County quarantine area was removed.
Portions of three counties are under quarantine for the European grapevine moth: Napa, Sonoma, and Solano. The pest is known to occur in southern Asia, Japan, Europe, North Africa, Anatolia, the Caucasus and South America. It primarily damages grapes, but has also been known to feed on other crops and plants.
The EGVM larvae, not the adult moths, are responsible for the damage to grapes. Larvae that emerge early in the spring feed on grape bud clusters or flowers and spin webbing around them before pupating inside the web or under a rolled leaf. If heavy flower damage occurs during this first generation, the affected flowers will fail to develop and yield will be reduced. Second-generation larvae chew into the grapes to feed before pupating in the clusters or in leaves. Larvae of the third generation — the most damaging — feed on multiple ripening grapes and expose them to further damage from fungal development and rot. These larvae overwinter as pupae in protected areas such as under bark, and emerge as adults the following spring. During this period, traps are serviced every two weeks throughout the growing season and removed by November when the larvae overwinter.
Commercial Vineyards, Wineries, and Home Vintners: The quarantine primarily affects grape farmers, transporters, processors, green waste receivers, and others who handle agricultural commodities that could harbor or spread the pest. County agricultural biologists have begun visiting affected growers and businesses in the region to ensure that they understand and comply with the quarantine restrictions.
Both growers and vintners need compliance agreements to receive grapes and equipment from the EGVM quarantine area. Compliance agreements are being issued by our department.
You can reach us at our San Jose Office at (408) 918-4610 or the South County, San Martin Office at (408) 201-0640.