Califonia Bountiful

Don't pack a pest

May/June 2008 California Country magazine

While California travelers are settling in after a long trip, so too are a host of damaging pests, plants and diseases that have hitchhiked home with them.

Vacationers urged to bring back memories, not pest

On a recent morning at San Francisco International Airport, travelers coming from the Pacific Rim clustered around luggage carousels to retrieve their bags. Before they passed though the U.S. Customs and Border Protection checkpoint to enter California, a trained sniffer dog scanned luggage with his highly perceptive nose, picking up whiffs of meat and fruit.

Passing the luggage through X-ray equipment turned up piles of banned items--glazed beef and pork candies, fresh fruit, dried orange peels and beef jerky in a variety of packaging.

Although they may seem harmless, discoveries like these illustrate that while California travelers are settling in after a long trip, so too are a host of damaging pests, plants and diseases that have hitchhiked home with them. These unwelcome, even dangerous, pests hide in suitcases, backpacks, sports gear, souvenirs, food, plants and soil. They can go undetected for months, even years, only to erupt into full-blown infestations.

"I'm concerned about the increasing volume of travelers coming into California and our ability to effectively screen out pests and diseases that may come with them," said Frank Carl, Sacramento County agricultural commissioner. "We've all read recent federal government reports that question the effectiveness of protections against this national threat."

California's mild Mediterranean climate makes it particularly vulnerable to infestations, he said. It's a desirable place to live, not just for the state's 38 million residents, but also for a variety of non-native pests whose voracious appetites can easily turn backyard landscaping, public parks and commercial crops into a virtual smorgasbord--pests munching, sucking and wreaking havoc as their numbers multiply.

Carl recently got a behind-the-scenes tour of SFO's federal pest inspection activities with a group of agriculture officials. He said the experience was "an eye-opener" given the number of travelers streaming through the airport and the amount of material confiscated each day at Customs and Border Protection inspection points.

"I think, in general, public awareness is lacking about the risks involved in the introduction of invasive pests and diseases and the threat they pose to our state and the nation," Carl said. "I realize most people would think: 'It's just one little papaya. What can that hurt?' The answer is a lot. Most people don't realize the hours invested and the billions of taxpayer dollars being spent responding to these pest emergencies."

He said right now Sacramento County is working to eradicate glassy-winged sharpshooter, a pest that spreads plant-killing bacteria. In addition, the county is acting aggressively to control the spread of West Nile virus, which is carried by mosquitoes and can cause illness and death in humans, as well as horses and some birds.

Carl also noted that residents and farmers in nearby Yolo County are coping with a Mediterranean fruit fly quarantine and counties to the north of Sacramento are dealing with the effects of various field crop diseases.

But insects are only part of the problem. There also are an endless variety of noxious weeds and aquatic species that damage the environment. The state's waterways are choked with non-native aquatic plants that threaten fish and destroy native ecosystems.

Mitten crabs, quagga mussels and New Zealand snails can damage levees, clog pipes and disrupt the state's water delivery system.

These non-native organisms can also introduce parasites and diseases, force genetic changes in native species through interbreeding and compete with local species for resources, sometimes driving fragile organisms to extinction. Beyond that is the threat of deadly diseases like avian influenza and foot-and-mouth disease.

Customs and Border Protection
Customs and Border Protection agriculture specialist Julie Stroeber says hard-working canines, like Colt, have been trained to detect a range of smells, including apple, mango, citrus, beef and pork.

"In San Mateo County, which is home to SFO, we find ourselves continuously in quarantines," said Jack Olsen, executive manager of the San Mateo County Farm Bureau. "Our location makes us particularly vulnerable to pest infestations. For example, we're a county with active finds of sudden oak death, which creates national and international compliance requirements for our plant nurseries who want to ship their farm products to international markets.

"Eradication efforts not only impact farmers, they also affect our communities," he said. "We're under quarantine right now for light brown apple moth, which is a native of New Zealand that attacks more than 2,000 kinds of plants."

These government-imposed quarantines restrict movement of such things as nursery plants, fresh produce, cut flowers, animals and soil to prevent the infestations and diseases from spreading out of control.

Olsen points out that SFO is one of the world's busiest airports, with about 30 million travelers hopping on and off planes there each year. Los Angeles International Airport is the state's busiest, with more than 60 million passengers a year passing through its terminals and where tons of prohibited material are confiscated from travelers each year.

In the San Francisco Bay Area alone, Olsen said that between the Golden Gate Produce Terminal, one of the largest wholesale markets in the nation, and domestic package shipments through the airport cargo facilities, officials find about 2,200 invasive pests a year.

"Our farmers and ranchers realize they're operating at a crossroads of the world and that makes them particularly vulnerable to attacks from invasive pests," Olsen said. "They also agree that more needs to be done to prevent infestations from occurring in the first place."

Of California's estimated 14 million international visitors each year, 4.6 million traveled from overseas in 2006, according to the California Travel and Tourism Commission.

But, Mexico and Canada still account for more visitors than all overseas points combined: about 9 million Mexican travelers enter California by air and land each year. In 2005 (most recent statistics), about 5 million day-visitors legally crossed the border to shop and work, often bringing lunches and fresh produce with them.

Whether introduced on purpose or by accident, the result is the same--a soaring number of non-native, invasive pest infestations that have the potential to damage California's backyards, public parks, waterways and working farmland.

"Farmers aren't the only ones hit by these continuous infestations," said Rayne Thompson, California Farm Bureau Federation director of international trade and plant health.

"Besides the threat to our native and commercial plants, families who depend on their local farmers markets for fresh fruits and vegetables also pay the price. In some cases, commodities aren't available or grocers have had to source from other areas of the country or the world, which greatly adds to food costs.

"For those who want to buy California produce, animals or plants, it's a lot harder if they cannot be moved out of a quarantine zone," Thompson said.

Thompson, who travels frequently on Farm Bureau business and just returned from Mexico, said, "Travelers need to enjoy their vacations and bring back mementos from their trips. But they also need to realize the potential threats non-native species pose for our environment. That's why we'd like the public to have a better understanding of the vital role they play in helping protect California."

Be careful not to pack a pest
The possibility that an invasive pest or serious disease might tag along with travelers to California is a real concern. Experts say the public can help reduce this threat by recognizing the problem and being careful not to pack a pest.

Back at SFO, recent baggage inspections revealed a whole shrink-wrapped piglet and a rice straw pillow from Mongolia with potentially diseased grain still attached. One enterprising 18-year-old brought home from Mexico a blue agave plant, which is used to make tequila. And in a particularly unusual incident, a California executive returning from Asia was caught with plant seeds sewn into pouches in his underwear. Agriculture specialists with Customs and Border Protection had flagged him as a high-risk traveler because of earlier seed-smuggling incidents.

"Over the past several years, the rate of new introductions of exotic, invasive pests and diseases has increased markedly, and it's no surprise that we see parallel trends in international travel and commerce," said California Food and Agriculture Secretary A.G. Kawamura. "Travelers, shipments, packages and the like give invasive pests and diseases ample opportunity to enter our state and threaten our environment, habitat and agriculture.

"California has an aggressive system in place to detect and deter invasive insects, as well as birds, fish, animals, weeds and diseases, and we do prevent a lot of infestations through those efforts," Kawamura said.

"But the public has an important role to play in keeping these pests out, too, by not bringing prohibited produce or plants back to California when they travel."

Experts say the invasion of non-native species, from combustible cheat grass to voracious carp to West Nile virus, is spreading into U.S. lands and waters at an accelerating pace. The damage to economic activity, ecosystems and human welfare is accumulating.

"There are several pieces to the puzzle of how to keep invasive species out, and travelers can really help," said Thompson. "While a piece of fruit or a plant cutting from a relative or friend may seem harmless, what it carries can have a devastating impact on our environment."

Tips for the traveler

When returning home to California, don't bring back plants, seeds, insects or animals.

  • When camping, check tents, tarps, ice chests and other gear for dirt and pests. Rinse and shake before stowing.
  • Leave firewood behind, likewise kindling, sticks and leaves.
  • Don't bring fresh fruit and vegetables back across the state boundaries, particularly from backyard or roadside trees and gardens.
  • Don't bring animal houses back--dog houses, poultry cages or rabbit hutches.
  • Hose off bikes, motorcycles and boats.
  • Check tubular equipment for dirt--hollow poles, pipes, folding chairs and rods.
  • For boaters, never move live fish or other aquatic animals or plants from one body of water to another.
  • Drain and dry all water and dry boats, equipment and gear and clean live-wells.
  • Check waders and boots for caked-on dirt.
  • Keep foodstuffs tightly closed to prevent bringing infestations home. If in doubt, throw it out.
  • Don't dump aquarium plants and exotic fish into sewers, creeks or lakes.
  • Know what you're planting in your garden by checking online at Most plants sold for use in gardens and landscaping do not invade or harm wildland areas, but a few vigorous species can--and do.

Click or call...
To report a suspected invasive plant or pest, call the California Department of Food and Agriculture's Plant-Pest Hotline at 800-491-1899.

For an official list of what not to bring back to California, go to For further detail, call 916-654-0312.

For information on aquatic invaders, check the Department of Fish and Game's Web site:

For international travelers, get a copy of the brochure "Know Before You Go" from U.S. Customs and Border Protection or visit CBP online at

To report suspected smuggling of prohibited exotic fruits, vegetables or meat products across international borders and into the United States or California, call the confidential anti-smuggling hotline at 800-877-3835.

California copes with ongoing invasions

Officials say they're seeing an increasing number of non-native pest infestations in California. Here are some of the current quarantines in which the movement of plants, produce and other vital materials is being restricted:

Diaprepes root weevil Diaprepes root weevil: Found last year in the La Jolla area of San Diego County, this Caribbean native feeds on 270 different plants, including citrus and ornamentals. It was accidentally introduced into Florida in the 1960s where it now causes about $70 million in damage each year.


Glassy-winged sharpshooter Glassy-winged sharpshooter: First reported in California in 1994, this pest probably arrived undetected in the state in the late 1980s. Native to the southeastern United States and northeastern Mexico, it can damage a large number of plants, including grapes, citrus, almonds, cherries, plums and oleander.


Light brown apple moth Light brown apple moth: This pest threatens more than 2,000 plant species, including California native plants, many garden plants and a wide variety of crops. Federal quarantine now restricts movement of host material from nine California counties, including urban counties like San Francisco, Alameda and Contra Costa.

Mediterranean fruit fly Mediterranean fruit fly: Medfly populations have been found in Dixon, San Jose and Rancho Palos Verdes/Rolling Hills. Quarantines have been established and eradication efforts are ongoing. The Medfly can attack peaches, pears, plums, apples, apricots, avocados, citrus, cherries, figs, grapes, guavas, kumquats, loquats, nectarines, peppers, persimmons, tomatoes and several nuts. If the Medfly were to become established, the U.S. Department of Agriculture predicts that consumer prices for fresh fruit would go up and it would become less available.

Mexican fruit fly Mexican fruit fly: Last year a 78-square-mile quarantine zone was established in San Diego County due to infestations by this pest. The fly attacks more than 40 kinds of fruits, including popular backyard trees like citrus and avocado.


Red imported fire ant Red imported fire ant: This pest, which has become widespread in 11 Southeastern states, poses a serious danger in urban settings, particularly to children, because of its painful bites and stings. Currently state and federal officials have placed Orange County and portions of Los Angeles and Riverside counties under a quarantine due to infestations.

Sudden oak death Sudden oak death: This fungal disease kills native and commercial trees and woody shrubs such as rhododendrons, huckleberry, bay laurel, madrone, bigleaf maple, manzanita and California buckeye. Federal quarantine now restricts movement of these plants from 10 California counties. Damage to the environment from the disease is extensive, particularly in Marin County.

New Zealand mud snail New Zealand mud snail: Since they were first discovered in 2000 in the Owens River in Mono County, these tiny snails have been confirmed in numerous other California waterways. Protective measures are in place to control the snail and a growing list of other aquatic invasive species, including quagga and zebra mussels.

Kate Campbell is a reporter for the California Farm Bureau Federation. She can be reached at 800-698-FARM or

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