State and federal agricultural officials are lifting the European grapevine moth (EGVM) quarantine in Lake County, California.

A small portion of southern Lake County was included in the quarantine area after several moths were detected in nearby northern Napa County in the spring of 2010.  No moths have been detected in Lake County.

Based on an extensive review of quarantine and eradication efforts by the EGVM International Technical Working Group (TWG), the United States Department of Agriculture (USDA) and California Department of Food and Agriculture (CDFA) have determined that Lake County meets the criteria for lifting the quarantine.

In making its recommendations for determining quarantine boundaries, the TWG considered the presence of broad areas with no “host plants” to harbor the pest, as well as geophysical features such as a mountain range and other potential barriers to the spread of the infestation.

“Quarantines are a necessary step in controlling and eradicating pest infestations,” said CDFA Secretary Karen Ross.  “This quarantine has helped us substantially reduce the infestation in California’s Wine Country region in recent months, and removing Lake County from the regulated area is further evidence of that progress.”

The quarantine continues in nearby portions of Napa, Sonoma and Solano counties.  More isolated infestations have triggered smaller quarantines in portions of Mendocino, San Joaquin, Santa Clara, Merced and Fresno counties over the past year.  The quarantine areas cover a total of approximately 2000 square miles.

Maps of the quarantine and related information may be found online at:
http://www.cdfa.ca.gov/phpps/PE/InteriorExclusion/egvm_quarantine.html

The quarantine primarily affects farmers as well as those who harvest, transport and otherwise process or handle grapes and other crops.  These growers and business people generally sign compliance agreements that indicate how crops, vehicles, equipment and related articles are to be handled and tracked during the quarantine.

Residents are also affected by the quarantine.  Those who have grapes, stone fruit trees (peaches, plums, etc.) and other host plants for this pest in their yards are asked to harvest and consume their fruit on-site to further limit the risk of spreading the pest.

EGVM, or Lobesia botrana, is found in southern Asia, Japan, Europe, North Africa, Anatolia, the Caucasus and in South America. The pest 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 enter 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.