By Joel M. Lerner
Saturday, April 17, 2010; E04
If you're a gardener and planning a vacation out of the United States, be aware of what your travels can deliver. You might be bringing home more than you bargained for.
Carelessly imported plant materials could become a problem because they -- or the soil attached to them -- can harbor pests or diseases. In their native habitat these insects or pathogens might not be problematic, but when transported to another environment, they can thrive.
According to Bill Aley, a senior import specialist from the United States Department of Agriculture's Animal and Plant Health Inspection Service, or APHIS, there are two categories of plant materials that are of concern: Plants intended for cultivation and those intended for consumption. Those for cultivation include flora with roots, seeds, bulbs, cuttings and tissue cultures. Edibles include fresh fruit, dried fruit and leaves for tea.
The goal of APHIS is to keep invasive insects and plant diseases that could ravage the environment out of this country. Weed seeds, insect eggs, nematodes, fungi, bacteria or viruses can also be harbored in imported soil. It's okay to bring back up to a dozen specimens from a trip abroad for planting, but for 13 items or more, you need to get an import permit.
For entry into this country, many foreign plant materials must be inspected and certified as safe. But this doesn't mean you can't buy a bag of bulbs at the airport in Amsterdam or take a tiny cutting from a camellia in southern England.
The animal and plant inspection service assesses the risk of plants coming into the country on the basis of country of origin. About 167 countries have determined what plant risks they want to keep out, and they all share information to facilitate and monitor shipment of plant materials.
Most plant material is normally examined by plant inspection services of exporting countries. If free of pests and diseases, it receives a clearance called a phyto-sanitary certification. In addition, there are pre-certification programs in which U.S. government employees overseas examine plant materials and determine if they're suitable for export.
It's highly likely that the bulbs you buy are pre-cleared and certified, but to be sure, you might want to look for this information on the package. Any plant material collection of 13 or more pieces that isn't pre-cleared could be confiscated and sent to one of a dozen or more inspection stations to be checked and cleared.
"Most plant material is enterable," Aley said, in three cases:
-- If there's no reason to keep it out;
-- If there is a reason to keep it out, but it has been identified with a phyto-sanitary certificate as being free of the possible disease or pest;
-- If it is part of a bulk shipment from shippers who have "Q37" permits, named for the government regulation allowing them to bring such things into the United States.
Tourists might be surprised by some items that are considered "plant material." A family friend had a statue shipped from Africa. When it arrived, the USDA impounded it, not because the government had suspicion about the contents, but to make sure the wood packing crate had been treated to eliminate traces of pests in the wood, such as the Asian long-horned beetle, ambrosia beetle or the emerald ash borer.
In some cases, efforts are aimed at keeping out different strains of a plant or animal pest that is already here to prevent crossbreeding that might create a "superpest." Currently the USDA is trying to keep Asian gypsy moths away from the West Coast while battling infestations of European gypsy moths on the East Coast.
Introduced in Massachusetts in 1869, the European gypsy moth (Lymantria dispar), is a plain-looking insect that wouldn't be noticed except in its caterpillar stage, when its markings make identification possible. A female moth lays an egg mass on and near trees, and each mass can hatch up to a thousand tiny caterpillars with ravenous appetites for tree leaves. They feed on more than 500 species of trees and shrubs.
The larval stages are effectively controlled with Bt, a bacteria (Bacillus thuringiensis), that only infects the larval stage of the gypsy moth. Caterpillars are large and hairy with five pairs of blue tubercles (bumps) in front and six pairs of red tubercles in back. Apply Bt to larvae and tree foliage. Caterpillars especially like oak, birch, sweetgum, willow and other hardwoods.
The Nature Conservancy, with nursery industry partners and scientists, is supporting revamped regulations in its efforts to block non-native insects and diseases. If implemented, the USDA rules would create a new category called NAPPRA (Not Authorized for Importation Pending Pest Risk Assessment), under which the nation could quickly stop the import of plants suspected of harboring pests until procedures can be implemented to ensure they are safe.
"Vigilant homeowners and gardeners have been the ones to detect the presence of foreign pests that had previously gone undetected in many areas," said Faith Campbell, senior policy representative in the conservancy's forest health program. For example, a Massachusetts homeowner who found a strange-looking bug in her backyard and reported it to the appropriate government agency helped prevent the Asian long-horned beetle from spreading through the United States.
Earlier this year, an alert greenhouse owner in Pennsylvania saw odd symptoms on his seedling bay laurel (Laurus nobilis). Experts confirmed that the plants were infected by the pathogen that causes sudden oak death (Phytophthora ramorum), a disease that has killed over a million trees in California. This is not the first detection of the pathogen in Pennsylvania or the eastern United States; however, to date, there have been no detections of the pathogen in the forestry environment on the East Coast. This disease is known to attack several kinds of oaks, magnolias, rhododendrons, and mountain laurel.
Bay laurel is a popular herb often grown by gardeners. If homeowners have recently bought bay laurel seedlings or seeds, they should examine these plants carefully. If the plants have dead or dying leaf tips or the entire plants are dead or dying, those symptoms may be caused by too much water or too little water, too much fertilizer, chilling or freeze damage -- or infection by the sudden oak-death pathogen or some other disease agent.
Make sure plant materials you want to import are certified safe. Check the labels on packaged materials. Leave the fruit behind. If you stick something into a bag and no one notices and you forget about it until you get home, dispose of it responsibly -- in the garbage disposal, not in your compost.
Don't forget the soil problem. Imported cars are checked to make sure there's no soil on the underbody that could harbor pests or diseases. If you drive off-road in Mexico, wash your tires before returning to the United States. And if you go hiking in another country, wash your boots at the hotel. Soap and water are usually effective in getting rid of pests.
Hikers are a relatively new concern. It has been only in the past 15 years or so that hiking abroad has become a popular enough trend to merit attention. The fear is that transporting soil on shoes can spread horticultural diseases to the wild environment.
Joel M. Lerner is president of Environmental Design in Capitol View Park, Md.