Another moth threatens valley vineyards
Chardonnay, zinfandel, pinot noir most vulnerable to European grapevine moth
By Mike Trevelen
For The Weekly Calistogan
A new pest has landed in the Napa Valley.
A single European grapevine moth, along with larvae, has been detected in Oakville, according to local agricultural officials.
It is the first time the invasive moth has been found in the United States. Confirmation came from the labs at the California Department of Food and Agriculture last week.
“Anytime we see an invasive species that has never been found before, we are concerned,” Napa County Agricultural Commissioner Dave Whitmer said, adding that the U.S. Department of Agriculture describes the moth as a species of concern.
“The wine industry here does not need another pest to deal with. It takes time and resources to deal with it,” Whitmer said. His office is working with the USDA and CDFA to provide additional traps.
The European grapevine moth does its damage by getting into the fruit clusters. At certain stages, the pest can affect the development of the fruit. The moth will feed on the berries. “It has a negative impact on the quality of the fruit,” Whitmer said.
It is a different pest from the light brown apple moth, an invader from Australia that has caused concern along California’s Central Coast and prompted a quarantine that includes most of the vineyards in Napa County, but has caused no known damage in the local grape industry.
Whitmer said the European grapevine moth can be most devastating to thinner-skinned winegrape varieties, such as chardonnay, zinfandel and pinot noir.
At this time of year, as temperatures drop and the days get shorter, the moth becomes dormant and is not as active as it would have been two months ago. That also makes it harder to spot.
Rex Stults, in charge of industry relations at Napa Valley Vintners, said he recently read a 2003 report from the University of Minnesota that described the moth as having a potential economic impact that is high.
“We at the Napa Valley Vintners are concerned with any potentially damaging pest that comes into the Napa Valley. This is a new one to us,” Stults said. “The ag commissioner has our support to minimize the damaging effect for the European grapevine moth in the Napa Valley.”
Jennifer Putnam, executive director at Napa Valley Grapegrowers, said “This is incredibly unfortunate news that we have yet another pest to combat in our vineyards.
“The ray of hope is that we have caught it early and might be able to efficiently trap, identify and eradicate it before it becomes widespread.
“Napa Valley grapegrowers have been very progressive in supporting the work of Napa County Agricultural Commissioner Dave Whitmer and his staff, primarily by funding the Pest and Disease Control District Board, at the cost of $5.59 per planted vineyard acre — the only such assessment in the state. It is through this leadership that we hope to see this threat eliminated.”
Oakville winegrape grower Bruce Phillips said, “Needless to say we are all concerned. As a grower I don’t know a lot about this pest. Right now everyone has been focused on the harvest.”
Coming on the heels of the new pest discovery, Gov. Schwarzenegger signed Senate Bill 2, by Sen. Patricia Wiggins, D-Santa Rosa, which authorizes continuation of the Pierce’s disease and glassy winged sharpshooter grower self-assessment to fund research. It also expands the authority of the board to research other pests and diseases which threaten winegrapes throughout the state.
The European grapevine moth has been found in Europe, the Mediterranean, southern Russia, Japan, the Middle East, Near East and western Africa.