PLANT PROTECTION AND QUARANTINE

Safeguarding America’s Harvest 

and Environment

United States Department of Agriculture

Animal and Plant Health Inspection Service

Program Aid No. 1783
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The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs 

and activities on the basis of race, color, national origin, sex, religion, age, disability, 

political beliefs, sexual orientation, or marital or family status. (Not all prohibited 

bases apply to all programs.) Persons with disabilities who require alternative means 

for communication of program information (Braille, large print, audiotape, etc.) should 

contact USDA’s TARGET Center at (202) 720–2600 (voice and TDD).

To file a complaint of discrimination, write USDA, Director, Office of Civil Rights, 

Room 326–W, Whitten Building, 14th and Independence Avenue, SW, Washington, DC 

20250–9410 or call (202) 720–5964 (voice and TDD). USDA is an equal opportunity 

provider and employer.

This publication supersedes Miscellaneous Publication No. 1557, “Plant Protection 

and Quarantine: Safeguarding American Agriculture, Fighting Invasive Species, and 

Facilitating Trade,” which was published in October 1999.

Cover photo: The U.S. Department of Agriculture’s Animal and Plant Health Inspection 

Service (APHIS) plays a vital role in protecting agriculture from plant- and animalhealth-related threats. This work protects the affordability, abundance, and quality of 

the food supply for consumers. (USDA Agricultural Research Service [ARS] image by 

photographer Keith Weller.)

For information about careers with Plant Protection and Quarantine (PPQ), phone us 

toll free on (800) 762–2738 or send an e-mail to francis.k.murphy@aphis.usda.gov.

You can learn more about PPQ programs by visiting our Web site at 

<http://www.aphis.usda.gov/ppq>.

Issued October 2004

The Plant Protection and Quarantine (PPQ) program is an integral 

part of USDA’s Animal and Plant Health Inspection Service (APHIS). 

PPQ safeguards agricultural and natural resources from the risks 

associated with the entry, establishment, or spread of animal and 

plant pests, diseases, pathogens, and noxious weeds. PPQ’s team of 

scientists, program specialists, and support personnel execute this 

complex mission through various means, including:

Collection and analysis of pest data both in the mainland United 

States and offshore,

Surveying for and detecting exotic (= foreign) pests and diseases in 

the United States,

Developing quarantine policies and regulatory requirements for 

agricultural commodities and plant resources,

Inspecting propagative plant materials for importation, and

Responding to plant health threats.

Detecting and Eradicating Pests Early

Finding new exotic pest outbreaks early, coupled with an aggressive 

eradication or management campaign, is PPQ’s game plan to prevent 

the establishment and spread of new pests in the United States. 

PPQ’s Cooperative Agricultural Pest Survey (CAPS) program identifies 

pests of concern that are high risk and then surveys to detect their 

spread. CAPS—a cooperative project with the State departments 

of agriculture—aims to detect new pests before they can become 

established.

When an exotic pest or disease outbreak occurs, PPQ immediately 

takes action to protect U.S. plant and animal resources by either 

eradicating the plant pest or weed or containing and managing the 

threat. The next step is reassuring the public and our trading partners 

that the health of U.S. agriculture is being protected. Working in 

concert with local and State officials, PPQ’s incident command teams 

provide on-the-ground support in responding to pest outbreaks and 

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mitigating their effects. These fi rst responders determine the true 

extent of the pest infestation and the appropriate risk-mitigation 

strategy.

Sometimes the mitigation strategy is basic, for example, removing 

the host material and trapping for insects associated with it at the 

infestation site. At other times, PPQ employs more sophisticated 

methods that involve the use of federally approved pesticides, 

sterilized insects, or biological control agents to contain and suppress 

exotic pest populations. Currently, PPQ conducts emergency programs 

addressing several serious agricultural threats: citrus canker, emerald 

ash borer, Asian longhorned beetle, plum pox virus, and exotic 

fruit fl ies.

Witchweed: Exemplifying Successful Partnerships

Witchweed (Striga asiatica) is a parasitic plant from Asia that 

attacks many very important crops in the United States, including 

corn, sorghum, sugarcane, and rice. Unlike most weeds, which 

merely compete with crops, witchweed taps directly into the 

host’s root system and robs the 

crop of nutrients and moisture. 

Consequently, the host wastes 

energy supporting witchweed 

growth at its own expense. A 

parasitized host, such as corn, 

experiences reduced current-year 

productivity by producing fewer 

and smaller seeds. However, 

witchweed damage to other plants 

in future years is a greater concern 

because a single witchweed plant 

can produce up to 50,000 seeds 

per year!

PPQ and State cooperators in 

the Carolinas, where witchweed 

fi rst appeared in America, have 

reduced the infested acreage by 

99 percent (from 450,000 acres 

to about 2,813).

Harmonious State and Federal quarantines have successfully 

prevented the human-assisted spread of witchweed beyond 

the infested region.

North Carolina has assumed the lead role in eradicating 

witchweed from the State, with PPQ maintaining a 

supporting role.

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Witchweed is one of many related 

parasitic plants native to Africa, 

India, the Middle East, and China. 

Invasive species introductions in the 

United States rose markedly during 

the last century as international 

travel and trade experienced 

unprecedented growth. (APHIS 

photo archives at Oxford, NC.)

The plantings of cherry trees around the Jefferson Memorial in Washington, DC, symbolize 

the natural beauty of our Nation’s capital. But trees in the original shipment received in 

January 1910—a gift from the Japanese Government—had to be destroyed by USDA after 

they were found to be infested with insects, nematodes, and diseases not known to exist 

in the United States. Followup phytosanitary practices eventually allowed importation of 

the beautiful specimens shown here. (USDA fi le photo.)
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Establishing Effective Regulations and Policies

The best and most cost-effective solution for mitigating agricultural 

damage is preventing the entry of exotic plant pests into the United 

States. As a regulatory program, it is PPQ’s responsibility to establish 

effective regulations and policies to protect U.S. agriculture through 

the exclusion of exotic pests and diseases. PPQ determines what 

plants and plant products can be imported into this country and what 

products pose a high risk and, therefore, should be kept out. Based 

on varying levels of risk, PPQ’s regulations provide multiple layers of 

protection ranging from product bans to commodity treatments or 

other actions that lessen pest risk (e.g., restricting imports to certain 

geographic regions or certain seasons).

Inspecting Plant Imports

Plants and seeds requiring permits for propagation must enter the 

United States through specifi c ports-of-entry, where such items can 

be inspected and certifi ed free of pests and diseases. At these plant 

inspection stations, PPQ also enforces the rules and regulations that 

apply to the import and export of plant species protected by the 

Endangered Species Act and the Convention on International Trade 

in Endangered Species of Wild Fauna and Flora (CITES). PPQ currently 

operates 17 plant inspection stations nationwide.

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Although inspections like the one that netted this illicitly imported material are now 

performed by employees of the Department of Homeland Security, PPQ still establishes, 

maintains, and enforces all regulations governing the import and export of plants and 

certain agricultural products. (APHIS fi le photo.)

Approximately 800 million plants are imported 

into the United States each year. At PPQ plant 

inspection stations at ports-of-entry, these plants 

are inspected to ensure they are free of pests and 

diseases. (APHIS fi le photo.)

An exotic pest like the Asian 

longhorned beetle can be very 

destructive in new environments 

that do not already support 

natural controls, such as parasites, 

predators, and diseases. Native host 

plants—innocent of previous contact 

with an exotic organism—have 

not yet adapted to or developed 

effective defenses against it. (APHIS 

fi le photo.)

Citrus canker, a bacterial disease 

affecting all kinds of citrus, is 

common in many tropical parts of 

the world. PPQ’s current cooperative 

eradication program in Florida 

began in 1995, when an Asian 

strain of citrus canker was detected 

in a residential area near Miami 

International Airport. (APHIS fi le 

photo.)
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Minimizing Pest Risks Offshore

To meet the challenges associated with rapidly accelerated travel 

and trade, PPQ’s strategic emphasis has shifted from excluding pests 

and diseases solely at ports-of-entry. PPQ’s new strategic emphasis 

includes safeguarding through surveillance and risk mitigation outside 

the United States as well. In cooperation with APHIS’ International 

Services unit, PPQ has established Safeguarding Offi cer positions 

overseas to gather pest information and to monitor trade trends. These 

Safeguarding Offi cers monitor changes in production, processing, and 

shipping practices that could increase the risk of pest introductions 

into the United States. Stationing these offi cers abroad provides an 

opportunity to mitigate risks at the point of origin of exotic pests 

rather than inside this country.

Linking Strategy and Technology

The Center for Plant Health Science and Technology (CPHST) is the 

scientifi c support organization for PPQ. CPHST identifi es, develops, 

or adapts appropriate state-of-the-art technologies for detecting, 

identifying, and mitigating risks of exotic pests. CPHST leads PPQ’s 

scientifi c research in pest detection and survey, molecular diagnostics, 

risk assessment, integrated pest management, and insect massrearing. CPHST also adapts technology applications to meet the 

ever-changing needs of PPQ’s risk-mitigation strategies.

Ensuring a High-Quality Food Supply

International trade takes place in larger volumes and with fewer 

economic and political restrictions than ever before. However, with 

increased trade comes the increased potential for introductions 

of exotic pests and weeds that could threaten the health of U.S. 

agriculture. Therefore, PPQ regulates the importation of agricultural 

products to help ensure that they are pest and disease free.

Exclusion of exotic pests and diseases is the fi rst line of defense for 

protecting the production capacity of U.S. agriculture and the U.S. 

food supply. The introduction of an exotic pest on an agricultural 

commodity can result in trade restrictions affecting its quality and 

availability in the marketplace. Hence, an unintended introduction 

can cost hundreds of millions of dollars in eradication and control 

measures and ultimately lead to higher prices for consumers. 

Consequently, APHIS bases its regulatory decisions on riskmanagement strategies that ensure safe imports.

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Introduced to the Western United 

States as an ornamental shrub in the 

early 1800s, saltcedar is now a serious 

threat to native plant communities. 

ARS and PPQ scientists are studying 

about 30 different insects that are 

natural enemies of saltcedar to 

determine their suitability for use 

as biological control agents. (Image 

taken by Steve Dewey of Utah 

State University and furnished by 

ForestryImages.org.) Americans have come to expect a diverse array of fruits and vegetables in local stores. 

To satisfy the ever-changing market demands of Americans, the United States imports 

produce from around the globe, all of which must meet PPQ’s stringent health standards. 

(USDA fi le photo.)
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Assisting U.S. Farmers and Exporters

PPQ assists American farmers and exporters by providing 

phytosanitary inspection and certifi cation for plants and plant 

products being shipped to foreign countries. These phytosanitary 

certifi cates, as required by the importing country, certify that the 

products are pest and disease free. PPQ also helps to maintain and 

expand market access for U.S. farmers and exporters by engaging in 

trade negotiations with foreign nations.

Thank you for getting to know us. For more information, please visit 

our Web site at <http://www.aphis.usda.gov/ppq>.

Roughly 42 percent of the total land area of the United States is used to produce crops 

and livestock. PPQ’s success in excluding harmful exotic pests not only secures the 

Nation’s food supply but also supports the national objective to protect the environment. 

(ARS photo by Scott Bauer.)