Invasive species have drawn considerable regional and national attention in recent years. In February 1999, President Clinton signed Executive Order 13112, which established the National Invasive Species Council. This council, which consists of 20 federal agencies, is charged with the establishment of a plan to minimize the ecological, economic and health impacts caused by invasive species. For clarification, invasive species are non-native (nonindigenous to North America) organisms that become established and cause harm to the native environment. In this case, the environmental focus is on the production and maintenance of ornamental plants. It is estimated that these pests cost the United States $137 billion per year (Pimentel et. al. 2000).
Here are a few other sobering facts. There are approximately 50,000 nonnative species in the United States, although only 10 to 15% are estimated as invasive (Pimentel et. al., 2000; U.S. Congress, OTA 1993). Invasive plants cover 100 million acres (USDA Forest Service 1998). Since 1985, the United States Department of Agriculture Animal and Plant Health Inspection Service (APHIS) has intercepted 7,400 species of plant pests at ports of entry. Approximately 50% of the species on the threatened or endangered species list are at risk due to competition or predation from nonnative species (Wilcove et. al., 1998). And, humans are the primary means of introduction through intentional and unintentional acts.
How do they get here, and why do they do so well? There are three primary routes of entry. Some species were intentionally brought to the United States for a specific purpose but escaped into the wild or acted in an unexpected manner after their release. Other pests have entered the country in or on host plants, or they arrived on shipping and packing material.
These introduced species perform so well because there are no naturally occurring pathogens, predators or parasites that can keep the population in check. Also, this new environment may prove to be more conducive to the growth and reproduction of the non-native species than it is to the native inhabitants.
The examples of invasive species that have impacted, or may impact, ornamental plants are numerous. They include the following:
What can the government do? Once a new species is detected, there are other factors besides its biological capabilities that can complicate its containment and eradication. The cost may prove to be excessive, and the emergence of pest populations in several areas may also slow down the management process. Thus, the most important step in management of invasive species is prevention. At the federal level, this responsibility falls primarily on USDA APHIS. Under the new Plant Protection Act, which consolidated the Plant Quarantine Act, Federal Plant Pest Act and Federal Noxious Weed Act, APHIS is authorized to prohibit or restrict the i
mportation or interstate movement of any plant, plant product, biological control organism or plant pest. A plant pest includes almost any living organism (other than human) that damages plants or causes disease.
However, APHIS is not the only federal agency involved with the exclusion or eradication of invasive species. The Fish and Wildlife Service (FWS), within the Department of Interior, regulates animals (mammals, birds, fish, amphibians, reptiles, mollusks and crustaceans) under the Lacey Act.
The Nonindigenous Aquatic Nuisance Prevention and Control Act was implemented to prevent and control aquatic nuisance species. There are a multitude of agencies that enforce this one: FWS; National Oceanic and Atmospheric Administration (NOAA); U.S. Coast Guard; Army Corps of Engineers; APHIS; Environmental Protection Agency (EPA); and the Department of State.
The Department of Defense (DOD) is also involved with invasive species management when it assists APHIS with inspection of military shipments into and out of the United States. The DOD monitors for invasive pests on all military bases. Finally, the U.S. Customs Service detains products that are awaiting APHIS or FWS inspection. (More information on the federal role in the control of invasive species is available at www. invasivespecies.gov)
In Connecticut, the Connecticut Agricultural Experiment Station (CAES) has the responsibilities of protecting nursery and landscape plants from nonnative pests, and working with federal agencies to prevent pest infestations. It ensures the protection of Connecticut's ornamental plants through three procedures:
Along with the annual nursery inspections, CAES staff conducts other regulatory duties to reduce the movement of native and nonnative pest species. Houseplants being moved to Alabama, Arizona, California, Florida, New Mexico, North Carolina, Oregon, Tennessee, Texas and Washington must be inspected prior to moving. Before plants are sent out of the country, CAES must be contacted so that the plant species can be checked to see if the importing country requires special import permits, treatments or prohibits the plants all together.
Finally, CAES is responsible for enforcing hemlock woolly adelgid, Japanese beetle and the smaller Japanese cedar longhorn beetle quarantines. Numerous states require specific treatments for Japanese beetle. In order to ship plants into these states, CAES inspectors must issue a Phytosanitary Certificate that states that the requirements have been met. Also, under the Japanese Beetle Harmonization Agreement with Canada, nursery stock must be treated before shipment. CAES inspectors also monitor this procedure. For more detailed information, visit the CAES web site at www.state.ct.us/caes or call the Office of the State Entomologist at (203) 974-8474.
What can nursery operators do? Federal and state agencies provide a high level of protection, but what can be done at the nursery? As I have discussed in other articles, regular monitoring/scouting of plant material is the key to a successful integrated pest management (IPM) program. Thus, monitoring is essential for the detection of new pests, native or foreign, in the nursery.
Knowledgeable nursery personnel should inspect plant shipments, which arrive from other states or countries, as soon as possible. A detailed visual inspection of all plant parts (leaves, woody material and roots) on at least 15% of the plants, along with a general observation of the remaining plants, should be conducted. The inspection can follow an "X-pattern" or serpentine pattern through the entire block with random stops to sample the 15%.
If the plants are not checked upon arrival, a quarantine area can be designed for placement of new arrivals. This area can be a greenhouse(s) or hoop house(s) near the loading/unloading site. This area would contain any potential pests at one location before the plants are moved to other nursery locations. At any time during the plant inspection, if an unknown organism is discovered, call CAES or transport a sample to CAES for proper identification. A quick response time limits the spread and potential damage from any pest.
Prevention is the easiest and most cost-effective step. If the nonnative species has already escaped, the control and management steps become more costly and are usually less effective. Eradication of an invasive species is extremely difficult if not impossible.
The management focus then shifts from eradication to population suppression, limiting the spread and reducing the effects. The overall goal is to restore the environment to its natural state. All of the agencies mentioned previously, that are involved with prevention (i.e., interception) of invasive species, also have research programs that focus on new prevention strategies, species biology or control options.
With the increased volume and speed of national and international trade, the risk of invasive species increases. Education of green industry professionals and the general public is crucial to reduce the risk of invasive species to the financial and ecological well being of the United States. Do your part to prevent the movement of invasive species. Follow all state and federal regulations and take the time to check incoming plants to ensure that no new pests become established.
By Tim Abbey, Nursery IPM Specialist, Connecticut Agricultural Experiment Station, Windsor, Connecticut
REFERENCES
Pimentel, D.; L. Lach; R. Zuniga; and D. Morrison. 2000. Environmental and economic costs of nonindigenous species in the United States. BioScience 50:53-65.
U.S. Congress, Office of Technology Assessment. 1993. Harmful nonindigenous species in the United States. OTAF-565. U.S. Government Printing Office. Washington, D.C. 39lpp.
USDA Forest Service. 1998. Stemming the invasive tide: Forest service strategy for noxious and nonnative plant management. P.O. Box 96090, Washington, D.C. 20090.29 pp.
Wilcove, D.S.; D. Rothstein; J. Dubow; A. Phillips; and E. Losos. 1998. Quantifying threats to imperiled species in the United States. BioScience 48:607-615.
Contact information:
Tim Abbey, 153 Cook Hill Road, P.O. Box 248, Windsor, CT 06095
Phone: (860) 687-4763 Fax: (860) 683-4987
Email: "Timothy.Abbey@po.state.ct.us
Website: http://www.state.ct.us/caes
From Yankee Grower New England Journal for Profitable Horticulture. Volume 3 Number 1 Year 2001
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