Moth quarantine may cause grape harvest delays

Issue Date: September 3, 2008

By Kate Campbell
Assistant Editor

Discovery of a second light brown apple moth (LBAM) in the Carneros winegrape-growing district--an area that straddles the Napa-Sonoma county line--has triggered a state-sanctioned 19-square-mile quarantine area.

Government inspectors are working with plant nurseries and winegrape growers in the area to inspect facilities and advise of treatment, if infestations are found. The quarantine prohibits movement of uninspected nursery stock, all cut flowers and host fruits and vegetables from residences and farms in the quarantine area.

This is not good news for winegrape growers who are gearing up for harvest, local officials said. Some sparkling winegrape varieties already have been harvested and sent to the crusher. The height of harvest, however, has not been reached.

"We think these moth finds are a function of Mother Nature," said Phyllis Gillis, Carneros Wine Alliance executive director. "Carneros is situated so we catch the wind from three different directions. It's like a vortex. We often find we're the recipient of unwanted creatures that get blown in."

She said growers had been working with the agricultural commissioners from both counties in advance of official announcements to ensure compliance with quarantine restrictions when imposed. Basically compliance requires inspection before shipping to obtain a "free-from" certificate or tarping of loads being taken from the vineyards.

A native of Australia, the small, tan moth feeds on a variety of California native plants, ornamental landscaping and more than 250 food crops, including grapes. The Napa County Agricultural Commissioner's office said the quarantine area will cover about 6,800 acres; about 2,300 of those acres on the Napa side are planted to winegrapes. In Sonoma County, about 750 acres of vineyards will need inspection and certification for winegrape shipment.

The California Department of Food and Agriculture has installed more traps in the quarantine area. Trapping in nearby Bay Area counties indicates high levels of infestation.

In San Francisco County, government agencies have trapped nearly 10,000 moths, about 1,340 in Alameda County, 550 in Contra Costa County and more than 450 in Marin County.

A total of three LBAM have been trapped in Napa, while two have been trapped in Sonoma. Statewide about 35,000 moths have been found since trapping began last year.

"We're proud to be a popular tourist destination," Gillis said. "But, when it comes to the light brown apple moth, we want to revoke its travel visa. Although this is a significant statewide problem, it's not one that will hamper our harvest or the operation of our visitor destinations. Growers don't want these isolated pest detections to be blown out of proportion. Growers are working with the appropriate agencies, protocols and compliance requirements."

Other nations and territories also want to keep LBAM out, and they typically impose trade restrictions such as plant and crop prohibitions, additional inspections or other requirements. Now that LBAM has been detected in California, officials in Canada and Mexico have imposed restrictions on exports from the affected areas.

LBAM caterpillars feed on and damage the leaves and new growth of plants. On some crops, including grapes, apples, citrus and avocados, LBAM larvae also feed directly on the fruit, rendering it unmarketable.

Greg Clark, assistant agricultural commissioner in Napa County, said, "We're talking to growers and wineries to let them know what's going on."

In Napa County the quarantine area impacts about 55 farmers--53 are grape growers, one farms olives and one has pasture land, according to the Napa County Agricultural Commissioner's office.

For growers, getting compliance agreements signed and vineyards inspected before harvest is in full swing is the best idea, said Nick Frey, president of the Sonoma County Winegrape Commission.

Because harvest is imminent, Frey said state and federal agencies will supply some addition inspectors to ensure that growers will be able to ship out of quarantined areas. He said pinot noir and chardonnay for sparkling wine are being harvested now. Harvest of other winegrapes is expected to begin this week.

In May, a 15-square-mile quarantine was established in Sonoma County after two LBAM were discovered. Grape growers, plant nurseries and other businesses moving or shipping plant material must be inspected and receive a "free-from" certificate before shipping outside the quarantine zone.

"Unfortunately, we have to deal with several pest threats," Frey said. "We always hope we're responding appropriately. Glassy-winged sharpshooter poses a threat, but fortunately, we've only had one find."

He said vine mealybug also is a pest of concern and growers are taking steps to minimize its spread in Sonoma County vineyards.

"My biggest concern about LBAM is the potential negative impact this pest is going to have on California's unique wilderness areas," said Mark Hoddle, director of the UC Riverside Center for Invasive Species Research.

In his report, "Invasive Species and their Impact on California," Hoddle pointed out that exotic pests cost the United States $138 billion a year and more than 40 percent of threatened or endangered species in the United States are at risk because of non-native species.

"Many of our forest species are under attack from invasive pests, especially beetles and diseases that have originated from overseas," Hoddle said. "Given the drought conditions we're under and the attacks on forests by exotic pests, another identifiable pest such as LBAM that eats native forest trees is a bad situation for the quality and longevity of California's wilderness areas."

He said progress in managing this pest has been slowed by legal, social and political obstacles. He said a ground swell of public support for controlling and then eradicating LBAM is possible, but better public understanding of the threat is needed.

"Every day, invasive pests that have established in California are chipping away at our quality of life," Hoddle said.

In a prepared statement, California Food and Agriculture Secretary A.G. Kawamura said, "Since we discovered LBAM in California in early 2007, we have invested in the development of alternatives that would improve our eradication efforts.

"That work is bearing fruit earlier than expected. We are fast-tracking an approach known as the Sterile Insect Technique (SIT), in which large quantities of sterilized, infertile insects are released so that the wild population cannot reproduce. SIT has been successful for more than 30 years in California and around the globe against a variety of insects--most famously the Medfly," he said.

Online information on LBAM can be found at www.cdfa.ca.gov. The report "Invasive Species and their Impact on California" is available online at www.cdfa.ca.gov.

(Kate Campbell is a reporter for Ag Alert. She may be contacted at kcampbell@cfbf.com.)

Permission for use is granted, however, credit must be made to the California Farm Bureau Federation when reprinting this item. Top