European grapevine moth (EGVM) quarantine areas have grown to almost 2,000 square miles in California grape country with the recent discovery of two EGVM moths in San Joaquin County in the Lodi area.
These finds upped the quarantine areas by 96 square miles. The quarantine boundaries in San Joaquin County are, on the west, an imaginary line near Highway 12 and N. Devries Rd.; on the north, Peltier Rd; on the east, along Jack Tone Rd. between Eight Mile Road and the community of Lockeford; and on the south, near Foppiano Ln. and N. Ashley Ln., in northeast Stockton.
A map may be located at: http://www.cdfa.ca.gov/phpps/PE/InteriorExclusion/egvm_quarantine.html.
The other quarantine areas encompass portions of Fresno, Lake, Mendocino, Merced, Napa, Solano, and Sonoma counties.
The quarantine primarily affects farmers as well as those who harvest, transport and otherwise process or handle crops. These business people generally sign compliance agreements that indicate how crops, vehicles, equipment and related articles are to be treated 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.