New Winegrape Pest Found In California

New Winegrape Pest Found In California

An unwanted visitor that could pose serious problems to growers of premium winegrapes on California’s North Coast the western grapeleaf skeletonizer, has been found.


GP SkeletonizerAccording to a report in the Napa Valley Register, one male moth was discovered June 24 in a vineyard sticky trap along Tubbs Lane near Calistoga, which is on the state’s North Coast. The Napa County Agricultural Commissioner’s Office on Monday asked growers and gardeners to be on the lookout for the caterpillar stages of the invasive insect.

The grapeleaf skeletonizer doesn’t spread a vine-killing disease, as does the infamous glassy-winged sharpshooter. But, as its name suggests, its larvae can damage vineyards by feasting on leaves and leaving behind only the veins — basically, a leaf skeleton.

“Excessive feeding can damage fruit and lead to secondary fungal damage and rot of grape clusters,” Agricultural Commissioner Greg Clark said in a news release. “We do not want this pest to become established in Napa County.”

Napa Valley Grapegrowers Executive Director Jennifer Putnam told the newspaper the group has sent out an alert to its 700 members. It’s better to deal with a grapeleaf skeletonizer find now than closer to harvest, when things get far more urgent and far more serious, she said.

“Right now, growers just need to keep an eye out for it,” Putnam said on Monday.

Fortunately, the pest has a distinctive look. Assistant County Agricultural Commissioner Humberto Izquierdo said the moth is an iridescent, metallic-blue. The caterpillar is yellow with bluish-purple stripes.

If all goes well, the 2015 find will end up being like a 2007 find near Mount Veeder Road west of the city of Napa. In that case, no infestation materialized.

But the county Agricultural Commissioner’s Office will do more than hope. It is deploying 25 additional traps within a 1-mile radius of the Calistoga find. It is asking growers, vineyard managers, wineries and residents transporting farm equipment or wine grapes into the county to inspect these items for the moth.

The pest is native to Arizona and New Mexico. It was discovered in California in 1940 and spread into the Central Valley.

“It’s a controllable pest,” Izquierdo said. “It is not a federal- or state-mandated pest for eradication.”

But, given Napa County’s grape-centric economy, it’s a pest that draws special attention from grapegrowers and the county Agricultural Commissioner’s Office. The county routinely sets out special traps designed to catch the grapeleaf skeletonizer, should it be present.

“This is a very serious pest,” Putnam said.

Source: Napa Valley Register