Invasive Moths Cause Concern for Grape Growers

Pheromone traps can be seen around the Healdsburg area in the ongoing effort to detect and eradicate several economically important invasive moth species.

“We’re looking for European Grapevine Moth {orange traps} and also gypsy moths, Mediterranean fruit fly, Japanese beetles, glassy-winged sharpshooter, and the light brown apple moth,” according to Sonoma County Agricultural Commissioner division manager, Lisa Correia, “It’s part of the regimen of early detection that we’ve had in place for years.”

The traps are strategically placed in February and checked every two weeks.

said his traps were inspected Thursday morning. 

“They [agricultural inspector] said, ‘You really don’t have anything out here,’” Hawley laughed. “We haven’t had problems with insects because we’re organic.”

Hawley said organic farming is better for insect control.

 “It’s more of a concern for those who farm conventionally and the fields get out of balance,” he said.

Hawley is a falconer who protects his fields, in part, with a kestrel -- a type of bird.

“Pests are insignificant because we have lots and lots of birds,”  he said.

The birds act as insect predators, particularly during nesting season, when even seed and fruit eaters will gorge on insects for the protein.

Although, as of Tuesday, none of the moth species of economic concern had been detected locally, there was a new find of the Glassy-winged sharpshooter in San Luis Obispo, according to Nick Frey, president of Sonoma County Winegrape Commission.

“Quarantine efforts are working against the GWSS.”  He cites the “diligence and efforts of the nurseries down south,” he said.

“They keep the inspections going,” Frey added.

Detection and inspections are the first line of defense against these invasive species. 

“Sonoma County personnel…place[d] and service[e] approximately 7000 traps from February through October.” according to the agricultural commissioner's website.

 “County staff will also be conducting inspections during the harvest to ensure that quarantine regulations are being implemented and followed to stop the spread of EGVM.”

 “The European Grapevine Moth is of the most concern," said Correia, the division manager. "[And] we have a strong eradication program.”

The threat of this pest is two-fold, according to Correia.

 “They lay eggs in flowers and fruit, so they destroy the fruit itself,”  she said. “They also indirectly cause scarring, so that late in the season the fruit is more susceptible to botrytis bunch rot late in the season.”

The most serious destruction occurred in Napa County in 2009.

“There is always a chance of [re-importation]," Frey said. "The key is how successful Napa County [is in eradication]. If Napa can get it under control, it will be promising.”

 According to Frey, "awareness going forward makes the possibility of reintroduction lower," he said. "Hhowever, risks are never zero.”

, Healdsburg Regional Library Branch Manager and current Sonoma County Wine Library manager said the growers and inspectors have their work cut out for them.

“From where I sit, it’s a tough thing to try to control biology,” Simons said “They’re doing an admirable job trying to stop movement of plants.  They seem to have gotten a handle on that.”

Simons, who has a finger on the pulse of the wine industry, said growers tend to be fearful about insects.

 “They’re always scared," he said. "[But] there isn’t the same level of concern as with Pierce’s disease [caused by the glassy-winged sharpshooter].  They growers are more steady in meeting the challenge of new pests.”

One of those new pests is the Light Brown Apple moth (LBAM).  This moth, too, threatens the Healdsburg area economically.  Not only does it injure grapes, it attacks citrus, deciduous fruit tree crops, feeds on endangered species host plants and can destroy, stunt and deform redwood, oak and cypress trees.

The Ag Commissioner’s office’s response is the same as with many other pests.  According to their website, they deploy additional pheromone traps to pinpoint and monitor populations and create new state quarantine areas.

Quarantine areas, though, require ramped up inspections and a lot of diligence to prevent the spread of several of these pests.

“The quarantine makes movement difficult,” said Frey.  All parties involved want to eradicate the pests and end the costly quarantines. 

Frey said that budget constraints and competition for lesser amounts of resources are always a concern in California.  He noted, though, that, “These are priority programs.”

“It’s discouraging,” Frey goes on, “The vine mealy bug, GWSS, EGVM and LBAM occurred in quick succession.  Some methods will probably need to change to do better.”

Meanwhile, both commercial growers and backyard gardeners can help the efforts.  Backyard gardeners should remove the fruit from their grapevines by June to help eradicate these pests. 

“You’re not supposed to move the traps," Correia adds. " If you need to, please contact this office with the address of the trap.” 

The Agricultural Commissioner’s office number is 707-565-2371.