Grapevine Moth Spreads in California
San Joaquin and Yolo counties implement measures to contain European vineyard pest
Two of the Lobesia botrana moths were trapped by San Joaquin County Agricultural Commissioner staff on Aug. 2 and 4 in a vineyard east of Lodi and the United States Department of Agriculture (USDA) and the California Department of Food and Agriculture (CDFA) have confirmed the sighting.
The moth is an invasive pest new to California that can cause substantial damage to vineyards and is under intensive eradication in other parts of the state. Napa and Sonoma County growers, wineries and haulers are already under quarantine regulations that require special efforts to keep the pests from spreading beyond their present limited areas, and growers are spraying and using mating disruption to reduce the impact.
Quarantine likely in Lodi
Finding two moths in the same area in Lodi will likely trigger a similar agricultural quarantine to prevent spread of the EGVM. Typically, the EGVM quarantine area encompasses a 5-mile radius around the site where the moths are found, usually in sticky traps baited with moth hormones.
In this case, the boundary will be in a circle, with the circumference drawn approximately from Peltier Road to the north, Jack Tone Road on the east, Morada Lane to the south and Davis Road in the west.
Growers will be allowed to move their grapes, but not until they enter into a compliance agreement with the agricultural commissioner's office prior to harvest, said San Joaquin County ag commissioner Scott Hudson.
The moths were found in traps set as part of a statewide program in conjunction with USDA and CDFA to detect this invasive moth. "As a result of these finds, our local inspectors and state staff will place nearly 2,400 traps in commercial vineyards within a 97-square mile area around the discovery," Hudson said. "It is critical we determine if there are any more of these pests in our area."
Prior to this detection of EGVM, San Joaquin County had approximately 2,200 EGVM traps in place throughout commercial vineyards.
The CDFA and USDA are expected to establish and announce the quarantine boundaries shortly, and the ag commissioner will then announce quarantine measures such as those in use in Napa and Sonoma, which require compliance certificates for moving any grapes or grape materials.
European grapevine moth was first detected in Napa County in September 2009. Since that time, EGVM has also been found in Sonoma, Solano, Mendocino, Merced and Fresno counties, where grower pest management efforts are underway.
The EGVM is a grape pest of significant economic importance in Europe, North Africa, the Middle East, southern Russia, Japan and, more recently, Chile. The larvae feed on grape flowers and developing fruit. Second and third generations cause the most damage by direct feeding on mature grape berries and indirectly by predisposing the crop to fungal infections, like gray mold (caused by Botrytis cinerea.) Damage is greatest in grape cultivars that have compact clusters or are sensitive to rot.
Measures in Yolo County
Because of infestations of the European grapevine moth in neighboring counties, the Yolo County Agriculture Department has asked commercial and home winemakers and others who receive bulk grapes to contact it before receiving grapes from outside Yolo County.
Officials say the European grapevine moth is particularly fond of grapes but also is drawn to olives, a crop that is becoming increasingly important in Yolo County. Winegrapes are Yolo County's second largest agricultural top commodity, with a value over $56 million last year.
The movement of bulk, unprocessed grapes is suspected to be the pathway of movement of the moth within California. Based on this, CDFA and the USDA have developed standards for importing grapes from counties where the pest is present.
Producers of grapes within infested areas, as well as haulers and receivers of the grapes, must assure through inspection and treatment that the product is free from the pest to prevent the spread of the insect. All associated green waste, such as stems, leaves, twigs, pomace, etc., are also under quarantine and require special handling.
"In Yolo County we are particularly concerned about home winemaking activities, since home winemakers operate outside traditional regulatory channels and may be unaware of the risks associated with the movement of small bulk grape shipments," said Yolo County Agricultural Commissioner John Young.