Plants from abroad can carry hazards

Gardeners are fond of purchasing promising plant specimens while traveling abroad -- a few seed packets here, some live stem cuttings there.

But many are surprised when those prized collectibles are weeded out and dumped upon their return.

Customs and Homeland Security officers are looking for prohibited plant materials, meat, poultry and animal byproducts that could pose long-term economic or ecological threats to the nation's agriculture industry.

Many of those plant materials conceal insects or diseases relatively benign on their home turf that could become troublesome when introduced into new surroundings with no natural defenses.

"A lot of pathogens we don't know are going to become problems until they're established in the environment," said Bill Aley, a senior import specialist with the U.S. Department of Agriculture's Animal and Plant Health Inspection Service.

"Then they come up on our radar screen and they're already displacing native flora and fauna."

On a typical day in 2007, Customs and Border Protection agents inspected 251,000 incoming international air travelers, 74,100 passengers and crew arriving by ship and 304,000 people returning to the United States via privately owned vehicles.

In the process, they seized 4,296 prohibited meat or plant materials, including 164 agricultural pests at ports of entry, officials said.

"That's a very important mission for this agency although it's not as visible," said Erlinda Byrd, a spokeswoman for the Department of Homeland Security. "The most effective way to stop diseases and pests from destroying our natural resources is to keep them from coming in."

So what's the harm in returning home with just a few tiny seeds or plants? In a word: Plenty.

"Each year, invasive species are estimated to cost the United States $120 billion in control efforts and environmental and economic damage," The Nature Conservancy said in a recent study about plant screening systems.

"Folks that go and visit another country may see a plant they like and take some cuttings," the USDA's Aley said in a telephone interview. "Or they'll gather some grapevines and put them in their baggage."

The result? Something like the Glassy-winged Sharpshooter bugs that Aley said have established a sizable population in California's vineyards, eating grapes and passing on disease.

"Sometimes the problem isn't as much the bugs as it is the diseases the bugs bring to the environment," he said.

Lois Berg Stack, an ornamental horticulture specialist with University of Maine's Cooperative Extension Service, helps develop itineraries for international garden tours and frequently joins as a participant.

Stack has four basic rules the casual traveler should know:

• Plants or plant parts must be declared at U.S. Customs upon your return.

• Anyone transporting plants or plant parts (stem cuttings, seeds, fruits that contain seeds, among them) that are intended for propagation must fill out a phytosanitary (clean of pests or disease) certificate in advance.

• Many fruits, vegetables and ornamental plants can easily be transported in small quantities across the border from Mexico and Canada. There are exceptions, however, that require a permit.

• It is illegal to transport soil into the U.S. without a permit issued in advance. That means potted plants in soil can't be brought in, and travelers who have visited farms must present their shoes at Customs and their footwear may need to be disinfected.

Soils can harbor a great many diseases or pests which might get loose and wipe out entire gardens and crops, said Leonard Perry, a herbaceous perennials specialist with University of Vermont Extension and a frequent tour group leader.

"Personally, I wouldn't want to think I might have been responsible for the next big pest or diseases of food or forests due to bringing in plants. Nor would I want to think I unknowingly had collected some endangered plant, especially in the tropics, helping further its demise," Perry said.

Sanctions depend upon what was being brought into the country and how it was done.

"Travelers are given several chances to declare their items," Homeland Security's Byrd said. "If they still say they don't have anything to declare, they're looking at penalties starting at $300 and up."

In the end, it may be simpler to buy your exotic new plants online.

"What I tell my tour folks (is) take pictures, not plants, and leave the importing to the professionals," Perry said.

How to bring plants in safely

The lists of plants and food products that are allowed into the United States from abroad changes frequently with any new disease outbreak or pest infestation.

Check the lists before you go, and follow these tips if you plan to bring foreign fruit, vegetables or plant specimens back to your garden.

• Seek help if you aren't certain what is allowed through Customs. Check a telephone book for the numbers of the nearest U.S. Department of Agriculture Animal and Plant Health Inspection branch or Plant Protection and Quarantine office. U.S. embassies and consulates in host nations also may be able to assist.

• Nursery stock, roots, bulbs, seeds and other plant parts must be accompanied by a phytosanitary (clean plant) certificate issued by the national plant protection service of the exporting country.

• Flower bulbs and seeds often are admitted, but the packages must be stamped with a phytosanitary certificate. They also must be free of any soil that could harbor diseases or plant pests.

• Beware any packing materials containing such unprocessed plant materials as grass or straw. They're often prohibited. Wood can be used for packaging but only if it fits certain guidelines.

• Be selective about what you buy. Plants that grow well in exotic locations may not survive a dramatic habitat or hardiness zone change.

"Buying something that is on the approved list the day you purchase it is no guarantee that the item will still be on the approved list when you arrive in the U.S.," a USDA fact sheet says. "In any case, you will be required to declare all food and plant items to inspectors. Failure to do so will result in the automatic seizure of the goods, even though they would have been otherwise admissible."

• On the Net: U.S. Department of Agriculture: http://www.aphis.usda.gov.