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preventionan ounce of

How to Stop Invasive Insects and Diseases from Devastating U.S. Forests

A Report from The Nature Conservancy’s Global Forest Partnership, Forest Health Program

COVER PHOTOGRAPH Port-Orford-cedar is a major component of the unique plantcommunities of southwest Oregon. The treeis also a beautiful landscape plant and its timber has a high value. Port-Orford-cedar has been virtually eliminated from lower elevations by a disease introduced onimported plants early in the 20th century.© Oregon Department of Forestry

AREAS AT RISK TO SUDDEN OAK DEATH(RIGHT) At least 40 North American tree,shrub and herb species are susceptible tosudden oak death, a disease thought to havebeen imported on nursery stock. If suddenoak death is transported to eastern states—and there have been several close callsalready—species of oak, black walnut andsugar maple, as well as rhododendrons andmountain laurel, might be killed. Oaks alonecomprise 38 percent of the total hardwoodsaw timber volume in the United States and their timber value is estimated to be $3 billion annually.

An Ounce of Prevention: A Report from The Nature Conservancy | 1

Invasive insects and plant diseases are taking adisastrous toll on U.S. forests. From the spread ofsudden oak death through California’s woodlands,to the fungus steadily killing eastern dogwoods, tothe standing ghosts of dead Fraser fir on mountainpeaks in North Carolina, infestations of ournation’s forests by invasive insects and diseases arewidespread and on the rise.

Imported nursery stock—trees, shrubs, gardenplants, roots and cuttings brought in from othercountries for sale to the U.S. consumer—is one oftwo chief pathways that bring invasive insects anddiseases into American forests. Once the pests areestablished, their eradication is, at a minimum,costly and politically difficult. Often it is simplyimpossible. These infestations not only damageforests but also threaten to cost private landowners,state governments, municipalities and a range of timber- and horticulture-related businesses billions of dollars.

The U.S. Department of Agriculture’s Animaland Plant Health Inspection Service (APHIS) isthe primary agency tasked with preventing theentry of potentially invasive pests and pathogensvia nursery plants and other pathways. Thanks to anemphasis in federal policy and international agree-ments on facilitating trade, combined with theglobalization of the economy, however, the numberof nursery plants imported into the United Stateshas skyrocketed in recent years. The existingAPHIS regulations governing plant imports datefrom more than a generation ago, and were craftedto deal with a much lower volume of imports froma much more limited set of exporting nations. Theydo not afford adequate protection in today’schanged economic environment.

In fact, APHIS regulates imports of fruits andvegetables more tightly than it regulates imports ofliving plants. But imported living plants clearly posethe greater risk of spreading pests and diseases

because the infested plants are already suitablehosts for the pest; the plants are placed in nurserieswhere many other potential hosts are in close prox-imity; and then, as they are planted by consumers,the plants are transported into landscapes aroundthe country.

APHIS’s current approach to stopping invasiveinsects and diseases is inadequate to the task.Currently, the agency restricts plant imports onlyafter it undertakes a meticulous risk assessmentprocess—a process so slow that the invaders areoften well-established by the time the agency actsto stop them. Furthermore, the risk assessmentsaddress known pests only, even though many of the most damaging pests have been unknown toscience at the time of their introduction. Indeed,millions of potentially damaging pests and diseasesremain unknown today.

Aware of these shortcomings, APHIS is widelyexpected to move toward an approach that relies on

Executive Summary

2 |An Ounce of Prevention: A Report from The Nature Conservancy

improved pest management practices by importersand their overseas suppliers—referred to as “cleanstock” programs. More immediately, APHISintends to create a temporary holding category,which it calls “Not Approved Pending Pest RiskAssessment” (NAPPRA). The creation of a NAP-PRA category would allow APHIS to suspendimportation of suspected pest carriers until a fullrisk assessment has been completed.

Although APHIS’s proposals tend in the rightdirection, the agency will not succeed in fulfilling itsobligations to protect U.S. forests and trees unless itmoves much more assertively in implementingNAPPRA and in developing more comprehensiveprograms. For example, APHIS proposes under itsnew NAPPRA regulations to assume that plantimports are safe until an abbreviated assessmentprocess identifies a specific disease or insect thatmay be imported. But harmful insects and diseasesimported in the past were often unknown to scienceuntil they began killing American trees. Moreover,the number and variety of plant species importedmakes such an approach too slow.

The Nature Conservancy recommends a five-point implementation plan for NAPPRA thatwould enable APHIS to effectively prevent futureinfestations, while saving public funds and relievingsome of the regulatory backlog that currently hampers the agency.

1. Publicly adopt a high level of pest protection as a national mandate.

2. Create a temporary holding category forimported plants (NAPPRA) and immediatelyput into it all imported plants and cuttingsexcept those plants with exceptional characteris-tics that indicate safe importation can continue.To be exempt from the NAPPRA list, plantsshould at a minimum a) have been widelyimported in the past with few interceptions ofknown pests or diseases and b) be characterizedby stable conditions of production and import(volume, origin, cultivation techniques) so thatpast experience remains a reasonable guide tofuture risk. Plants on the NAPPRA list couldstill be imported as tissue culture or seeds, underan approved clean stock program, or under strict quarantine.

3. Create a process that allows reasonably fastdecision-making to remove from NAPPRAplants posing little risk.

4. Speed up the pest risk analysis process by firstassessing the likeliest pathways of infestation.

5. Work with stakeholders and Congress tosecure more resources for risk analyses, prompt

regulation updates, improved methods ofdetection and pest control and outreach.

The Nature Conservancy believes that such an approach to NAPPRA would be an importantfirst step toward an integrated approach, one thatwould engage all stakeholders in solving the prob-lem of forest pests introduced on living plants. The organization invites a broad and inclusive discussion of this proposal and other approachesthat fairly balance risk, trade and the value of America’s native forests.

U.S. FORESTS FACE A NEW ARMY OF KILLERS: invasiveinsects and diseases that are arriving on imported nurseryplants. For example, many beech trees (above left) are suf-fering from an imported fungus that is carried by aninvasive scale insect and kills the tree (above right).Infestations of foreign insects and diseases have risensharply in recent years because of the burgeoning international trade in nursery plants. © F.T. Campbell and www.bugwood.org


American forests are under attack by invasive,tree-killing insects and disease-causing organismsthat originated in other countries. According to theU.S. Department of Agriculture’s Animal and PlantHealth Inspection Service (APHIS), more than400 non-native insects and 24 non-nativepathogens are now permanently established in North American woodlands.1

Imported plants, cuttings and seeds, brought tothe United States by nurseries for sale to the public,have repeatedly served as the pathway that allowsdevastating pests to reach our country.2 Of the 25most damaging forest pests introduced since themid-1800s, 18 are believed to have arrived on nurs-ery stock. Half of the 18 serious pests associatedwith nursery stock entered the country in the past35 years (Table 1). With no specialized predatorsor resistant hosts to keep them under control, thesepests can spread aggressively and raise havoc withour forests.

APHIS and USDA Forest Service reported in2000 that 5 percent of known exotic insects andhalf of the exotic pathogens “threaten the health,productivity, stability, merchantability and . . . veryexistence of some trees and forests.”3

And that report didn’t reflect damages inflictedby the Asian longhorned beetle, emerald ash boreror sudden oak death—the three non-nativeinvaders that the U.S. government has spent $420million since 1997 trying to eradicate or contain.4

Those efforts have been not only expensive but alsopolitically challenging, since they have required cut-ting down mature trees in yards, parks andalongside streets. While the success of Asian long-horned beetle control in Chicago and Hoboken,New Jersey, shows the value of such efforts, NewYork City and the many locations afflicted withemerald ash borer have not received the necessaryfunding to stop these insects. Thus the UnitedStates has fallen far short of what is needed to con-

trol just these three invasive pests, much less thefull range of introduced insects and diseases.

Imported Plants: An Invitation for Trouble

Imported nursery stock poses a particular haz-ard because these plants often harbor insects anddiseases that prove to be invasive in our forests, yetthe invaders can be difficult to spot during inspec-tion by APHIS at the U.S. border. Difficulties withinspection include the relatively small percentage of plants inspected (presently less than 2% of anexponentially increasing volume of imports), andthe fact that many diseases and pests that liveunder bark can be difficult to detect in an inspec-tion. Because the pests and pathogens arrive on live hosts, they can survive a relatively long time. In many cases, they survive long enough to arrive at a nursery, where they can spread to other plants,including new host plants, or even develop new

I. Forests Under Siege Imports of Non-Native Pests and Pathogens Are on the Rise

characteristics by breeding with related diseases orinsects already present.

The other significant problem with importednursery stock is that these plants are distributed allover the United States. Many end up planted inplaces where it is a short hop to local forests.

Unfortunately, the diversity of U.S. forestsmakes them particularly susceptible to these kindsof invasions. Representatives of almost every typeof vegetation that occurs worldwide can be foundwithin the United States or its territories; forexample, more than 150 of America’s tree generaare shared with Europe or Asia.5 In addition, thou-

sands of non-native plant species are grown for hor-ticulture, Christmas trees and other uses, and stillothers have established themselves in the wild.6 Thiscombination of native and non-native species acrossthe United States provides ample opportunities forimported pests to find suitable hosts.7

Yet despite these risks, the United States currently imposes very few restrictions on imports of nursery stock. This is a significantdeparture from earlier policies, with potentiallycatastrophic consequences.

In the past, imported plants were subjected to stringent regulations intended to prevent theintroduction of plant pests. APHIS strictly regu-lated the number and types of plants imported,typically limiting imports to either seed or fewerthan 100 plants. It also fumigated all importedplants to kill insect pests. Finally, APHIS restrictedor prohibited imports of plants that might carrypathogens that fumigation could not control.

Today, APHIS allows unlimited numbers ofplants to be imported into the United States, evenif those plants have not been analyzed regardingtheir pest risk. One reason for this relatively unre-stricted flow is the requirement under internationaltrade agreements that APHIS justify any perma-nent regulation by first completing a pest riskanalysis that evaluates specific, named pests.

In fact, APHIS regulates imports of fruits andvegetables more tightly than living plants, even

The Mandate to Stop Plant Pests and DiseasesUnder the Plant Protection Act of 2000 (7 U.S.C. 7701, et seq.), APHIS is charged withfacilitating trade in items that pose a risk of har-boring plant pests “in ways that will reduce, tothe extent practicable, as determined by theSecretary [of Agriculture], the risk of dissemina-tion of plant pests or noxious weeds.” APHIS is to base decisions affecting trade in these goodson sound science. Furthermore, APHIS isauthorized to take actions to eradicate or con-tain plant pests or noxious weeds that are newto the country or not widespread. In so doing,APHIS may “hold, seize, quarantine, treat, applyother remedial measures to, destroy, or otherwisedispose of” any plant, article, or means of con-veyance that the Secretary has reason to believethreatens to assist the survival or dispersal of thatplant pest or noxious weed. “Plant pest” isdefined to include plant disease organisms.

DISEASES AND INSECTS that arrive on imported nurseryplants pose a particular hazard because they enjoy a built-in free ride: their hosts are distributed to nurseries all overthe country and then planted by unsuspecting consumers.These imported geraniums are infected with a non-nativepathogen that kills potatoes, tomatoes, peppers and otherimportant crops. © USDA APHIS


though pests that arrive on living plants are morelikely to survive and spread. This discrepancy prob-ably arose from APHIS’s past focus on threats toAmerican agriculture. This has now been expandedto include natural resources, but live plant rules arestill under revision. The less-effective regulationsgoverning nursery plants unfairly ignore the risk tothe $231 billion forest products industry, as well asto municipalities and homeowners.

Additionally, APHIS relies almost entirely onvisual inspection of the imported plants to detect alimited set of organisms already known to be dan-gerous. Although inspection takes place at aspecialized plant inspection station, it remains an

inadequate safeguard. To quote APHIS in a recentdescription of its program, published in the FederalRegister,8 “[Visual] inspection may not always pro-vide an adequate level of protection againstquarantine pests, particularly if the pest is rare,small in size, borne within the plant, an asympto-matic plant pathogen, or not yet recognized andregulated as a quarantine pest.”9 As Table 1 illus-trates, the American people are paying a heavy pricefor this change in policy, which supports tradewithout attention to its consequences.

Meanwhile, the flow of foreign plants into theUnited States continues to grow. Some 450 millionplants were imported into the United States in

1993.10 More than 2 billion plants were imported in2005.11 A 2006 analysis noted that China plans toramp up its exports of live plants substantially inthe next few years.12

Compounding the problem is a lack of staff atAPHIS, a shortcoming well recognized by theagency itself and many of its stakeholders. In brief,while the volume of incoming shipments of plantshas increased dramatically, APHIS staff and budgethave not increased commensurately. There is ashortfall in the number of inspectors, risk analysts,regulatory analysts and other key staff positions.

As a result, APHIS cannot initiate neededamendments to its regulations to reduce pest risks


INSECT OR PATHOGEN HOSTS APPROXIMATE DATE INTRODUCED

Dogwood anthracnose Flowering and Pacific dogwoods Before 197614

Sudden oak death Oaks and other hardwood and coniferous trees; numerous hardwood shrubs Actual time unknown, but best estimate is during the 1980s15

Bromeliad weevil more than 12 native species of bromeliads (air plants) Before 198916

Citrus longhorned beetle Variety of hardwood species 1999; 200117 (believed to have been eradicated)

lobate lac scale more than 120 species in 44 families of woody plants 199918

Asian cycad scale Cycads Probably 200019

Erythrina gall wasp Trees and shrubs in the Erythrina genus (coral trees; native coral bean in the southwest, red cardinal shrub in the southeast, and wiliwili tree in Hawaii 200420

`o`hia rust Trees in Myrtaceae family, including `o`hia (the dominant native tree in Hawaii) 2004 in Hawaii21; earlier in Florida22

Cycad blue butterfly Cycads 200523

TABLE 1Recent Introductions of Damaging Insects and Diseases Via Imported Nursery Stock

in a timely manner. Staffing shortfalls are particu-larly troublesome because of the extensive riskanalyses that must be conducted before a regulationmay be updated. Only in emergencies does APHISact before completing a risk assessment. Accordingto the agency itself,13 this lack of resources hasdelayed evaluations of a significant number of peststhat could be introduced to the United States viaimports of nursery plants.

High Ecological StakesBecause U.S. trees and plants did not evolve

with the invaders from other continents, they oftenhave limited genetic resistance to them.24 In somecases, imported insects and diseases virtually eradi-cate American plant species from their naturalhabitat (Table 2). Such was the case with chestnutblight, which between 1900 and 1950 all but elimi-

nated the native chestnut tree from eastern forestsand set off a cascade of changes not only to forestcomposition but also to the diversity of plants andanimals throughout the East.

Today, many forests and plants are at similar risk:

n A fungal disease, dogwood anthracnose, issteadily eliminating the eastern, or flowering,dogwood from North American forests.Dogwood fruits are a valuable food source formigratory birds and mammals, and the twigs arebrowsed by a variety of animals.25 The tree’sfallen leaves provide a significant amount of cal-cium to forest soils.26 It is also a belovedornamental tree of suburban yards in the mostdensely settled portion of the East Coast.

n A pathogen from tropical South America knownas ò`hia rust threatens the most abundant and

widespread tree species in Hawaiian forests —ò`hia trees. At least six additional species of treesand shrubs endemic to Hawaii are also vulnerableto the foreign rust, including one federally listedendangered species, nioi (Eugenia koolauensis).Ò`hia forests protect the state’s watersheds andprovide essential habitat for all survivingHawaiian honeycreeper birds, including 14species that appear on the federal or state endan-gered species lists.

n The introduced bromeliad weevil (Metamasius cal-lizona) is killing native bromeliads (air plants)throughout southern Florida’s forests. Already,the state has declared two species of bromeliadsendangered because of the impact of the weevil.The weevil appears likely to spread to all vulnera-ble parts of Florida, including Big CypressNational Preserve and Everglades National Park.

The consequences of uncontrolled infestationscan be both profound and permanent. As trees die,forest productivity often declines, especially whenthe tree species that fill the gaps are themselvesprone to insects and diseases. If a new tree speciesbecomes dominant, its fallen leaves and branchesrelease different nutrients into the soil, which canfurther influence which species grow well andwhich do not. The rapid die-offs that follow in thewake of insect and disease invasions can also dis-

TABLE 2Native Tree Species That Have Been or Are Being Virtually Eliminated by Imported Insects and Diseases


SPECIES IMPORTED INSECT OR PATHOGEN DATE INTRODUCED

western white pines white pine blister rust early 20th century

flowering dogwood dogwood anthracnose before 1976

Port-Orford-cedar Port-Orford-cedar root disease approximately 1920

American chestnut chestnut blight late 19th century

butternut butternut canker 1930s

rupt a forest’s hydrology, increase vulnerability towildfire and increase soil erosion.27 Eventually, thecycle of disturbance and change can so alter a for-est’s ecology that it cannot support its originalcomplement of native wildlife, and its beauty andeconomic usefulness may be irreparably damaged.

While we can prevent non-native pests andpathogens from arriving, once they are here, theoptions for controlling them are limited andunpopular. Tree bark shelters many pests fromsprays and other control agents. Cutting downinfected trees often meets with public opposition,especially when it occurs in urban and suburban

The Demise of the ChestnutFirst detected in New York City in 1904, chestnutblight probably entered the eastern forests of the United States from Japanese chestnut treesimported as nursery stock in the late 1800s.28

Within 50 years, chestnut blight had spreadthroughout the chestnut’s range from Maine to Alabama. Despite efforts to control thepathogen soon after its discovery, the blightcaused the death of trees constituting one-quarter of the standing timber in eastern forests.29

The chestnut produced large crops of nutseach and every year, unlike the oaks, hickoriesand other trees that have replaced it. Scientistsmay never be able to quantify exactly how impor-tant those nuts were to wildlife, partly becausewildlife biology was not well-developed at theturn of the 20th century and partly becausewidespread timber harvesting compounded theeffects of chestnut blight. Historical accountsand old photographs, however, clearly indicatethat wildlife was much more abundant before the blight decimated the chestnut. The disap-pearance of the chestnut probably drasticallyreduced populations of black bears and turkeys.The American chestnut also provided timber,food, tannin and wood products that were important to early European settlers.30


THE INFAMOUS CHESTNUT BLIGHT that all but eradicated chestnut trees from Eastern forests in the last century got itsfoothold in the U.S. by hitching a ride. The disease arrived on imported trees from Japan that were sold through the nurserytrade sometime around 1900. See sidebar, at right.© Andrej Kunca, National Forest Centre - Slovakia, www.forestryimages.org


settings. Even when control measures are success-ful, forests suffer from cutting, spraying andinjecting. The forest may lose decades or even centuries of growth.

Mounting Economic Costs As of early 2007, no published study has tallied

the total economic costs exacted by non-native for-

est pests and pathogens. Those costs include notonly the expenditures of public agencies to controlinvasive species but also the value of destroyed tim-ber, a decrease in nature tourism and declines inproperty values. The impairment of key ecologicalservices provided by forests, such as water filtrationand prevention of soil erosion, creates additionalcosts, such as the need for greater purification by

public water utilities. Invading insects and diseasesalso reduce the ability of our commercial forestsand preserves to sustain wildlife, which may forcepublic agencies to spend more time and resourceson protecting endangered species.

A general understanding of how these economicdamages mount can be deduced from the examplesof a few individual pests, imported on nursery plants,that are currently invading U.S. forests:

n Sudden Oak Death: At least 40 North Americantree, shrub and herb species are susceptible to theimported disease known as sudden oak death.More than 1 million trees in California and south-western Oregon have died already31, and millionsmore are at risk along a 1,500-mile stretch of thePacific Coast. In 2004, millions of nursery plantsexposed to the disease were shipped throughoutthe country. APHIS adopted more stringent reg-ulations to prevent a repetition of this event.However, small numbers of infected plants con-tinue to be found in nurseries.

If sudden oak death is transported on nurserystock to eastern states, several species of oak,black walnut and sugar maple, as well as rhodo-dendrons and mountain laurel, might be killed(see inside front cover). Oaks alone comprise 38percent of the total hardwood saw timber volumein the United States.32 The timber value of oaks isestimated to be $3 billion annually.33


n White Pine Blister Rust: White pine blister rustwas introduced early in the 20th century on pineseedlings imported for forestry plantings.34 The dis-ease attacks a dozen North American tree species35,including one of the most important timber speciesin the West: western white pine.36 In the first half ofthe 20th century, authorities spent more than $100million in a largely futile effort to contain the dis-ease.37 White pine blister rust is believed to havekilled or damaged 80 to 95 percent of westernwhite pine, sugar pine and eastern white pine (seemap). Forests on 9 million acres in Idaho, Montana,Oregon, Washington and California have beenaffected by losses that range from reduced timbervalues because of damaged wood to the death ofboth mature and seedling trees.38 In some areas, theDouglas-fir and grand fir trees that have replacedwhite pines experience chronic poor health and arevulnerable to native root diseases and insects.39

The USDA Forest Service has spent decadesbreeding rust-resistant pines for the westerntimberlands, an endeavor described as “expensivebut promising.” However, there are credible con-cerns that the pathogen might evolve toovercome these forms of resistance.40

n Citrus Longhorned Beetle: The citrus long-horned beetle kills a wide range of hardwoodspecies, including maple, oak, willow and poplar.The beetle was discovered in 2001 on quaran-

THE SPREAD OF WHITE PINE BLISTER RUSTA century after its introduction, white pine blister rust is now reaching mountaintop ecosystems where it is attacking key treespecies such as the bristlecone pine (far left)—a species that can live up to 4,000 years. Indeed, the disease is now affecting adozen North American tree species and has spread throughout much of the northern United States.Map © USDA Forest ServicePhoto (far left) © John Dittli

tined, imported maple trees in a plant nurserynear Seattle. During the summer of 2002,APHIS and the Washington Department ofAgriculture cut and chipped 1,000 trees locatedon nearby city streets and in yards—in hopes oferadicating this dangerous pest.41 Subsequentsurveys appear to confirm that the insect waseradicated, but government agencies remain con-cerned and vigilant.

As these examples illustrate, the costs of inva-sive insects and diseases introduced via importednursery stock go far beyond federal dollarsexpended in efforts to control them. First, there aredirect losses to horticultural importers when newlyintroduced pests damage their crops. Second, quar-antines imposed to contain the pest can require thedestruction of nurseries’ inventory and the disrup-tion of sales. Third, as the pest becomes establishedand spreads, landowners unrelated to the originalimporter suffer economic losses from the reducedproductivity or outright death of infected trees andshrubs. Finally, the removal of infested trees createssubstantial burdens not only on federal agenciesbut also on state governments, municipalities andhomeowners. For example, although not introducedvia nursery stock, the Asian longhorned beetle is anon-native insect currently causing great damage inNew Jersey and New York. If it spreads, it couldcreate an estimated $669 billion in costs for munic-ipalities across the nation.42

What Is a Forest Worth?Urban and rural forests cover one-quarter ofNorth America, sustaining biological diversityand providing clean air and water to hun-dreds of millions of people. Forest productsand related industries employ more than 1.6million people and contribute $231.5 billion to our nation's economy.43 Forests also pro-vide enjoyment to millions of hikers, campers,hunters, anglers, birders and other recre-ational users, whose activities and buyinghabits contribute tens of billions of dollars to local economies. Perhaps most important,our forests—urban, suburban, rural and wild—are part of our national heritage, providing beauty and shade to our homesand comfort to our spirits.


IN 2002, FEDERAL AND STATE AGENCIES cut and chippedsome 1,000 trees in a neighborhood outside Seattle (beforeand after, above) to eradicate a voracious invasive insect: thecitrus longhorned beetle, which was discovered on importedmaple trees at a local nursery. State agencies, municipalitiesand private landowners often bear significant financial bur-dens—through no fault of their own—when imported nurseryplants carry insects and diseases into the country.© Washington State Department of Agriculture


In 2004, APHIS published an Advance Noticeof Proposed Rulemaking (ANPR) in the FederalRegister44 in which it stated, “… [current import]conditions are believed to have led to several pestintroductions in recent years.” To address the prob-lem, APHIS has proposed modifyingQuarantine-37 (Q-37), the federal quarantine regu-lating the importation of nursery plants, roots, bulbs,seeds and other plant products into the UnitedStates. This proposal is still under consideration, and the agency expects to request public commentson a series of specific proposals over coming years.APHIS is widely expected to move toward anapproach that relies on so-called “clean stock” programs, in which importers and their overseassuppliers implement better pest management.

But all of this will take years to develop andimplement. In the meantime, we need temporaryregulations to slow the flood of imported pestswhile we build a comprehensive system. As a first

step in the revision of the Q-37 regulations,APHIS proposes creating a category called “NotApproved Pending Pest Risk Assessment,” abbrevi-ated as NAPPRA. This would be a temporaryholding category for plants that are suspected ofharboring damaging pests. The plants in NAPPRAwould be listed as host/origin combinations, mean-ing a specific species from a specific place, such asrhododendrons from China.

APHIS has said that the NAPPRA categoryprovides the flexibility needed to act quickly underinternational trade agreements. Since the combina-tions of a given plant produced in a given nation or region (called plant/origin combinations in therest of this report) are placed in the NAPPRA category on an interim basis, the agency is notrequired to complete a pest risk analysis before taking this action.

But the NAPPRA approach is likely to fail toreduce either the flow of pests or APHIS’s workbacklog unless the criteria for placing plants inNAPPRA are altered. In its initial characterizationof the approach, APHIS proposed that plants beplaced in the NAPPRA category only if they meetall three of the following criteria:

• There is credible evidence that one or more specific pests has the potential to cause ecological or economic harm; and

• the pests can be identified and defined; and

• the pests are not already present or widely distributed in the United States.

If a plant/origin combination does not meet allthree of the above criteria, it will not go into theNAPPRA category.

Furthermore, APHIS also proposes a phasedapproach to the use of the NAPPRA category.

II. An Inadequate Game PlanProposals by APHIS Do Not Go Far Enough

First, NAPPRA would include only the small groupof plant/origin combinations that are known hoststo internationally recognized quarantine pests andthat have not yet been imported into the UnitedStates. Later, APHIS would expand NAPPRA toinclude plants that are hosts to internationally rec-ognized quarantine pests and are infrequentlyimported to the United States. It would alsoinclude plants from countries that do not instituteadequate safeguards to prevent the introduction ofthe quarantine pest. Finally, after years of collectingand analyzing plant import data, APHIS would addto NAPPRA all plants that had not been assessedor otherwise regulated.

1. Phase in regulations, both in U.S. policy andthrough international trade organizations,that ensure that only pest-free plants areshipped in international trade.

2. Improve the identification of potential pests.For example, ask botanical gardens overseasto monitor their plantings of North Americanspecies for pests and diseases.

3. Develop contingency plans for eradicatingany outbreaks of the pests so identified.

4. Provide incentives to producers to implementclean stock programs and to shift to planttypes that are unlikely to transport pests,such as tissue culture plantlets.

5. Inspect plants at their places of origin, beforethey are shipped to the United States.

6. Strengthen quarantines of imported plants to prevent the escape of any pests.

7. Create an insurance program under whichnurseries that participate in clean stock andearly detection programs can be reimbursedfor losses suffered when pests damageinventory despite the nurseries’ best efforts.

8. Improve measures to prevent the movementof infected nursery stock within the country.

9. Charge a modest user fee for the full range of plant imports to help fund the overall pestprevention and eradication programs.

Developing a comprehensive approach thatmeets the requirements of international tradeagreements will be time consuming. In the shortterm, APHIS should institute the temporary NAP-PRA category to free up time and resources forthe development of a long-term, effective system.


The Elements of an Effective Importation PlanThe United States can participate in international trade in nursery plants and protect its forests, butonly if it develops a comprehensive pest detection and containment system that includes at least thefollowing components:

APHIS’s TENTATIVE PROPOSALS don't address the problemof imported pathogens that evolve into more harmful formsonce they arrive. Scientists have found as many as five speciesof the pathogenic genus Phytophthora (see sidebar, p. 15) on a single nursery plant—an indication that the pathogenmutates and hybridizes on the nursery plants themselves.© Canadian Food Inspection Agency; thanks to CaliforniaOak Mortality Task Force


Why APHIS’s Proposal Does Not Go Far Enough

Although NAPPRA itself is an excellent idea,the approach to its implementation proposed byAPHIS doesn’t address four key realities of inva-sive insects and pathogens.

• The proposal does not address speciesunknown to science.

Conservationists and government officials areincreasingly confronting damage caused by organismsthat were unknown to science at the time of theirintroduction. Table 3 lists several examples of seriousforest pests that were unknown when they arrived inthe United States. But APHIS proposes to build itsprogram based on lists of known pests or organisms.Specifically, criterion two for inclusion in NAPPRAspecifies that pests must be identified and defined.At present this can occur only by the slow risk assess-ment process or by the unfortunate experience ofpast harmful introductions. In the future, a networkof scientists and botanical gardens could track infes-tations on North American tree species plantedabroad, but such data will not be available for years.Thus, APHIS’s approach will fail to prevent intro-ductions of a group of pests known to have causeddamage in the past and likely to cause significantdamage to our trees and forests in the future.

• Cryphonectria parasitica chestnut blight

• Discula destructive dogwood anthracnose

• Phytophthora lateralis Port-Orford-cedar root disease

• Phytophthora ramorum sudden oak death

• Sirococcus clavigignenti-juglandacearum butternut canker

TABLE 3Serious Forest Pests Unknown to Science at the Time of Their Introduction

OREGON OFFICIALS AND THE U.S. FOREST SERVICE are trying to eradicate sudden oak death by cutting and burning allhost trees near the site of the infestations. APHIS has the authority to temporarily halt plant imports until it can assess howmuch risk certain species and places of origin pose to U.S. forests, which would help avoid expensive and damaging controlefforts like those shown above. © Oregon Department of Forestry

It is quite likely that unknown or poorly knownorganisms will continue to enter the United States,since scientists know little about several biologicalgroups that include many plant pests. The numberof insects, mites and other arthropods on Earth isunknown. Estimates range from a few million totens of millions, but fewer than 1 million have beendescribed.45 Only an estimated 7 percent of fungalspecies have been described and studied.46 Nativeranges are unknown for many of the organisms thathave been described. APHIS acknowledged thislow level of knowledge in the 2004 ANPR.

• The proposal does not address the unpredictable behavior of invasive insects and pathogens.

Even when an organism is known to science, itsbehavior in its native environment is an unreliableindicator of its behavior in a new ecosystem.“Experience shows that the pestilence of an organ-ism cannot be predicted from its status in its nativecountry,” wrote William Wallner, a forest patholo-gist with the USDA Forest Service. “For example,only 18 percent of immigrant insects and mites inthe United States behaved exactly as one would haveexpected from their behavior in their country of ori-gin.”47 According to another report, among 212significant plant pest species that were reviewed,only 73 had been expected to be pests based on their

behavior elsewhere. The other two-thirds surprisedagricultural officials with their virulence.48

• The proposal does not address the risksposed by hybridizing insects and pathogens.

A further complicating factor is the potential for introduced organisms to hybridize with related species. The resulting hybrids can have new characteristics that allow them to increasetheir virulence, displace native species and modify or expand host ranges.

As the British forest pathologist Clive Brasierhas pointed out numerous times, nurseries holdinga range of plants imported from countries aroundthe world offer ideal situations to promotehybridization of any pathogens that have accompa-nied the plants into the nursery. “As many as fivedifferent Phytophthora species have been isolatedfrom a single potted nursery alder seedling,” hewrites. “This indicates a considerable potential for evolution—via hybridization between species—of entirely new or genetically modified forestPhytophthora species.49

Brasier’s reference to the genus Phytophthorais particularly apt as this genus has caused immensedamage in forests, including the current sudden oakdeath syndrome on the Pacific Coast. According toDr. Everett Hansen, of Oregon State University, 11 different genotypes of Phytophthora ramorum—


Scientific Justification for the NAPPO Regional StandardA concept paper developed by the Plants forPlanting Panel of the North American PlantProtection Organization (an organization thatcoordinates efforts among Canada, theUnited States and Mexico to protect eachcountry’s plant resources from regulated plantpests, while facilitating international andintraregional trade)51 notes that risk assess-ments based on lists of known quarantinepests do not address adequately numerousuncertainties, including the following:

• Many potential pests are obscure orunknown and most pathogens are poorlyunderstood.

• The impact of insects and pathogens intheir native environment is an unreliableindicator of their behavior in a new ecosys-tem.

• There is great potential for genetic changeor variability in pests and hosts.

In addition, countries’ reliance on visualinspection at the ports is undercut by the fail-ure of resources to keep pace with the rapidlyincreasing volume of imports.

A Brief Biology of Phytophthora

The genus Phytophthora includes many of the world’s most destructive plant diseases,including the species that caused the Irishpotato blight†in the mid 1800s as well as thecause of today’s sudden oak death. In aninvaded plant, the Phytophthora organismpenetrates the spaces between plant cellsand even the cells themselves, eventuallyinfesting much of the plantís tissue.Phytophthora species have shown the abilityto shift hosts, sometimes infesting speciespreviously thought to be resistant. The genusis not closely related to fungi, but shares a lineage with brown algae (better known as diatoms).50


the pathogen that causes sudden oak death—havebeen found on infected plants in Oregon nurseries.In California nurseries, Dr. Matteo Garbelotto, ofthe University of California at Berkeley, has identi-fied six separate genotypes of the pathogen. This genetic variability within nursery populationsis likely the result of multiple introductions andsubsequent hybridization.

• The proposal doesn’t acknowledge theresource issues that constrain APHIS

The APHIS proposal keeps the burden of provingrisk on the agency and allows continued importsuntil that burden is met. Yet it seems all but certainthat APHIS will continue to face staffing short-falls, which will inevitably delay additions of evenhigh-risk species to the NAPPRA list.

APHIS’S PROPOSED NEW REGULATIONS won’t stop new,damaging diseases like sudden oak death (infected plants,right) from slipping into the United States because the regulations don’t consider pathogens that are not yet wellknown. By contrast, The Nature Conservancy’s plan doesaddress the risk from insects and pathogens not yet known.© Above: Jennifer Parke, Oregon State UniversityBelow: Diseased plants in a nursery; © Jonathan Jones, USDA APHIS.


Given the pace of invasive insect and diseaseintroductions and the acknowledged weaknesses of the current program, APHIS needs to movequickly to close the door on these importedinvaders. APHIS should do so by making signifi-cant improvements to the Q-37 regulations withinthe next three to four years. Specifically, APHISshould make realistic assessments of risk and shiftits focus to prevention. A five-point approachwould make this possible.

1. APHIS should adopt a goal of allowingfewer than one new forest pest to enter thecountry via the nursery stock pathway duringa 30-year period.

Achieving this goal will be challenging—morethan 10 pests have entered the country via nurserystock in the past 30 years—but the American peo-ple deserve nothing less.

Publicly adopting a high level of protection isessential. Such a stance not only acknowledges thereal costs of invasive insects and pathogens, but alsoensures that APHIS remains in compliance withthe terms of international trade agreements. Underthe agreements, the United States government isallowed to set its acceptable level of risk and canthen adopt more stringent measures, as long as itcan demonstrate that those restrictions are neces-sary to achieve the clearly stated goal.52

2. By the end of 2007, APHIS should put inplace a rule establishing a temporary holdingcategory for plants suspected of harboringdamaging pests—NAPPRA—and immedi-ately put into that category all importedwhole plants and cuttings except those thatmeet a narrowly defined set of exemptions.Plants in the NAPPRA category could con-tinue to be imported under certainconditions, outlined below.

Such an approach is needed because nearly allimported plants present a significant risk of bring-ing damaging pests and pathogens with them.APHIS should work with stakeholders and scien-tific experts to determine if these risks can beminimized before imports are allowed.

While a plant is in the NAPPRA category,APHIS should allow imports of it only if it isimported in the form of tissue culture or seed; or if it is held in quarantine at a secure containmentfacility long enough to ensure that it is pest- anddisease-free; or if it is imported from a third-partycertified clean stock program.

The secure containment facilities should beunder the supervision of APHIS or a state depart-ment of agriculture. If a state accepts the burden ofsupervising such facilities, APHIS should grantauthority to the state to reject any import deemedtoo risky. The agency should also allow participatingstates to charge a fee for quarantine service.

III. Common-Sense Measures That Can StopInvasive Insects and Pathogens


In assessing plants that could be exemptedfrom the NAPPRA category, it is important toconsider the rapidly changing structure of the hor-ticulture industry worldwide. Pest interceptionrecords from plant/origin combinations that havebeen imported in the past could provide some pre-dictive value as to whether those plant/origincombinations might be safe in the future. But evenplant/origin combinations with few past intercep-tion records may not reflect present or future risk.

There are at least three additional criteria thatneed to be examined. First, the volume of importsof a given plant/origin combination may haveincreased radically in recent years. If one assumesthat the probability of a pest being found on anygiven individual plant remains constant, increasingthe volume of plants imported increases the overallprobability that an introduction will occur. But asvolumes of plants produced increase in a givenregion, it is likely that there will be changes in plantrearing practices that may increase risks. Changesin plant-rearing practices in the country of origin isa second factor that must be considered. Finally, asglobal trade moves insects and diseases to newparts of the world, there may be new pests or dis-eases available for transport to the United States,even from long-time trading partners. For example,Phytophthora kernoviae is a plant disease now presentin Europe that is not native to that continent. Allthree criteria must be assessed along with past pest

interception records in deciding whether evenplant/origin combinations with a history of impor-tation can be exempted from NAPPRA. It is vitalthat imports of new plant species or imports of

well-known species from new nations or regions beincluded in NAPPRA.

The Nature Conservancy recommends that tobe eligible for exemption from NAPPRA, a plant

USDA APHIS relies on visual inspections alone to detect pests and diseases on imported plants. Unfortunately, many damag-ing insects or diseases are likely to escape detection, so this strategy by itself cannot protect U.S. forests. The citruslonghorned beetle kills a wide range of hardwood species. Its larvae are two inches long, but they have escaped detection byU.S. inspectors several times.© Washington State Department of Agriculture; www.forestryimages.org


must at minimum a) have been widely imported inthe past from a specific region or country with fewinterceptions of pests or diseases, and b) be charac-terized by stable conditions of production andimport (number of plants imported, cultivationtechniques, pest and pathogen environment in theorigin country), so that past experience remains areasonable guide to future risk.

3. APHIS should create a process that allowsreasonably fast decision-making to removefrom NAPPRA plants posing little risk.

A speedy review will get low-risk plants backon the market with little delay.

4. APHIS should speed up and improve itspest risk analysis by first assessing likely andbroadly defined pathways of infestation.

APHIS faces a huge backlog of risk assess-ments in part because it targets those studies toonarrowly—for example, for one or a few genera ofplants to be imported from a single country. TheNature Conservancy recommends that APHISdefine these pathways broadly. One approach mightbe to evaluate risks and determine effective meas-ures to counter pests associated with any bare-rootwoody plants from a particular region, for exampleEast Asia. Alternatively, APHIS might assess pestsassociated with roots or stems, without limiting the

study to particular kinds of plants or geographicregions of origin. A third approach might be todetermine how to prevent the presence on anyimported plant of a particular type of pest, such as afungal pathogen. By assessing the highest-risk path-ways first, the agency can use its resources mostefficiently. Defining these pathways broadly mini-mizes the number of separate assessments needed.

5. APHIS and its stakeholders must worktogether to secure a substantial increase inresources for the agency to undertake riskanalyses, update regulations promptly,improve pest detection and control andengage in outreach to producers, importersand partners in state and federal agencies.

With adequate staff resources, the agency couldnot only speed up its risk assessment and regulatoryprocesses, but also develop a more comprehensiveprogram for ensuring that imported plants are freeof damaging pests. APHIS also could work moreclosely with all affected interests to raise awarenessabout the risk of pests that travel on plants that aremoved from place to place.

Over the long term, APHIS should aim to putin place requirements that ensure that plantsimported into the United States are free of virtuallyall pests. Such pathway regulations might be mosteffective if implemented for all trading countries,

under the leadership of the International PlantProtection Organization. The International Unionof Forest Research Organizations has called forsuch a pathway approach for nursery stock.

The differences between this effectiveapproach to NAPPRA, the APHIS approach andthe current situation are summarized in Table 4.


APHIS acknowledges that the current situa-tion of unfettered plant importation is costingAmericans and American forests dearly. The agencyis moving in the right direction by suggestingchanges to quarantine regulations, and there areindications that APHIS may move toward a des-perately needed comprehensive pathway approach.The NAPPRA proposal is intended to create thetime and free up the regulatory resources needed todesign a quality comprehensive regulation. But thecurrent proposal for NAPPRA is inadequate.

If the agency’s proposed criteria had been inplace 30 years ago, for example, they still would nothave blocked the arrival of sudden oak death nor theimportation of the emerald ash borer, because nei-ther was well known at the time of its introduction.

There is a solution: Take preventive measuresto keep the harmful invaders out. The UnitedStates need not continue to suffer economic andecological damages at the hands of imported insects

and diseases. A few regulatory modifications willenable APHIS to take account of risks before dam-age occurs, rather than after the invasion is under

way. The agency can make these modificationswithout violating international trade agreements or unfairly restricting the sale of nursery plants.

IV. Conclusion

CURRENT RULES APHIS PROPOSAL NATURE CONSERVANCY PROPOSAL

Prevents well-known insects and pathogens from invading U.S. forests n n n

Prevents likely insects and pathogens from invading U.S. forests n n

Addresses the risk of new or little-known insects and pathogens invading U.S. forests n

Addresses the risk of hybridization of insects and pathogens n

Addresses the risk of harmful behavior of formerly benign organisms n

Meets obligations of international trade agreements n n n

Helps relieve regulatory backlog at APHIS n n

TABLE 4Comparison of Proposals for Preventing Future Pest Infestations


1 Mattson, W. J., P. Niemela, I. Millers, and Y. Ingauazo. 1994. Immigrant phytophagousinsects on woody plants in the United States and Canada: an annotated list. USDA For.Ser. Gen. Tech. Rep. NC-169, 27 pp; Liebhold, A. M., W. L. MacDonald, D. Bergdahl, andV. C. Mastro. 1995. Invasion by exotic forest pests: a threat to forest ecosystems.Forest Sci., Monograph 30. 49 pp.; United States Department of Agriculture Animal andPlant Health Inspection Service and Forest Service 2000. Pest Risk Assessment forImportation of Solid Wood Packing Materials into the United States. USDA APHIS andForest Service. August 2000.

2 Kenney, M. and S.J. Bagenski, USDA APHIS The role of USDA Animal and Plant HealthInspection Service (APHIS) Plant Pathologistgs in protecting American agriculture andthe environment from exotic diseases. Poster for Annual Meeting, Mycological Societyof America 1998.; National Plant Board. 1999. Safeguarding American Plant Resources:A Stakeholder Review of the APHIS-PPQ Safeguarding System. July 1, 1999.

3 United States Department of Agriculture Animal and Plant Health Inspection Serviceand Forest Service 2000. Pest Risk Assessment for Importation of Solid Wood PackingMaterials into the United States. USDA APHIS and Forest Service. August 2000.

4 United States Government Accountability Office. 2006. Invasive Forest Pests LessonsLearned from Three Recent May Aid in Managing Future Efforts. GAO-06-353

5 cf. United States Department of Agriculture Animal and Plant Health Inspection Serviceand Forest Service 2000. Pest Risk Assessment for Importation of Solid Wood PackingMaterials into the United States. USDA APHIS and Forest Service. August 2000.

6 Kartesz, 1999; United States Geological Survey (USDI USGS), 1998

7 United States Department of Agriculture Animal and Plant Health Inspection Serviceand Forest Service 2000. Pest Risk Assessment for Importation of Solid Wood PackingMaterials into the United States.; Niemela P. and W.J. Mattson. 1996. Invasion of NorthAmerican Forests by European Phytophagous Insects. Bioscience Vol. 46 No. 10(November 1996), pp. 741-753).

8 APHIS. Federal Register: December 10, 2004 (Volume 69, Number 237)

9 APHIS. Federal Register: December 10, 2004 (Volume 69, Number 237)

10 APHIS Federal Register July 23, 2001 (Volume 66, Number 141).

11 Groot, Norm and Janet Kister.2006. Commentary: Wanted--An environment of pest-freeimports. California Farm Bureau Federation. Issue Date: November 29, 2006

12 Rae, Allen, Funing Zhong, Yingheng Zhou, and Xianhui Geng. 2006. China’s ExpandingRole in Global Horticultural Markets. Working Paper 3/06. Centre for Applied Economicsand Policy Studies. Massey University. Palmerston North. New Zealand. August 2006.

13 APHIS. [Federal Register: December 10, 2004 (Volume 69, Number 237)

14 Daughtery, M. L., and C. R. Hibben. 1994. Dogwood anthracnose - a new diseasethreatens 2 native Cornus species. Ann. Rev. Phytopath. 32: 61-73.

15 Susan Frankel, USDA Forest Service, pers. comm..

16 Urgent Peril to Florida's Endangered Species of Bromeliads Ed Hall, Save Florida's Native Bromeliads Project Director, Florida Council of BromeliadSocieties, 1111 Glen Garry Circle, Maitland, FL 32751. Tel. (407) 647-2039

17 Urgent Peril to Florida's Endangered Species of Bromeliads Ed Hall, Save Florida's Native Bromeliads Project Director, Florida Council of BromeliadSocieties, 1111 Glen Garry Circle, Maitland, FL 32751. Tel. (407) 647-2039

18 University of Florida Institute of Food and Agricultural Sciences, Department ofEntomology and Nematology “Featured Creatures”http://creatures.ifas.ufl.edu/orn/scales/lobate_lac.htm

19 Thomas Marler, Ph.D. plant physiologist, University of Guam [[email protected]]pers. comm.

20 Anne Marie LaRosa, Forest Health Coordinator, Institute of Pacific Islands Forestry,USDA Forest ServiceMail: P.O. Box 4370, 60 Nowelo St. Hilo, Hawaii 96720-0370, 808-933-8121 ext. 115.FAX: 808-933-8120 [email protected]. Pers. comm.

21 Anne Marie LaRosa, Forest Health Coordinator, Institute of Pacific Islands Forestry,USDA Forest ServiceMail: P.O. Box 4370, 60 Nowelo St. Hilo, Hawaii 96720-0370, 808-933-8121 ext. 115.FAX: 808-933-8120 [email protected]. Pers. comm.

22 Lloyd Loope, US Geological Survey Biological Resources [email protected]. pers. comm.

23 Anne Brooke. Ph.D., Wildlife Biologist, Guam National Wildlife RefugePOB 8134, MOU-3, Dededo, Guam 96929 USA [email protected] 671-339-7051.pers. comm.


25 Mitchell, W., P. Gibbs, and C. Martin. 1988. Flowering dogwood (Cornus florida): Section7.5.9., U.S. Army Corps of Engineers Wildlife Resource Management Manual, Tech.Report EL-88-9, U.S. Army Engineer Waterways Exp. Sta., Vicksburg, MS. 25 pages.Rossell, I. M., C. R. Rossell, K. J. Hining, and R. L. Anderson. 2001. Impacts of dogwoodanthracnose (Discula destructiva Redlin) on the fruits of flowering dogwood (Cornusflorida L.): implications for wildlife. Amer. Midland Naturalist 146: 379-387.

26 Hepting, G. 1971. Disease of forest and shade trees of the United States. United StatesDepartment of Agriculture, Forest Service Agricultural Handbook No. 386. 658 pages.


28 Dr. Sandra L. Anagnostakis, Department of Plant Pathology and Ecology, TheConnecticut Agricultural Experiment Station, “Chestnuts and the Introduction ofChestnut Blight,”http://www.caes.state.ct.us/FactSheetFiles/PlantPathology/fspp008f.htm.

29 Campbell, Faith T. and S. Schlarbaum. 1992. Fading Forests. Natural Resources DefenseCouncil.

30 Campbell, Faith T. and S. Schlarbaum. 1992. Fading Forests. Natural Resources DefenseCouncil.

31 California Oak Mortality Task Force, Host & Associated Plants.http://nature.berkeley.edu/comtf/html/host_plant_lists.html

32 http://www.fs.fed.us/database/feis/kuchlers/k100/kuchler_type_management_consider-ations.html.

33 Congressional Testimony given November 17, 1995 by Jack Swanner, TimberProcurement Manager for T&S Hardwoods in Sylva, North Carolina addressing theTimber Salvage Bill and other Forest Health Issues

34 Mielke, J.L. 1938. Spread of blister rust to sugar pine in Oregon and California. J. For. 36:695-701; cf. Tainter, F. H., and F. A. Baker. 1996. Principals of Forest Pathology. JohnWiley & Sons, Inc., New York. 805 pp..

Endnotes


35 Borys Tkacz, USDA Forest Service, pers. comm. Nov. 2006

36 USDA Forest Service. Pest Risk Assessment on the Importation of Larch from Siberiaand the Soviet Far East. Miscellaneous Publication No. 1495. September 1991.

37 Ibid.

38 Ibid.

39 Ibid.

40 Ibid.

41 United States Department of Agriculture, Animal Plant Health Inspection Service. 2002.Citrus longhorned beetle program. King County, Washington. EnvironmentalAssessment. April, 2002. USDA, APHIS, 12 pp.

42 Nowak, D.J., J.E. Pasek, R.A. Sequeira, D.E. Crane, V.C. Mastro. 2001. Potential Effect ofAnoplophora glabripennis (Coleoptera: Cermabycidae) on Urban Trees in the UnitedStates. Forest Entomology. February 2001.

43 United States Department of Agriculture Forest Service New Forest Partnerships,Northeastern Area Association of State Foresters, (NAASF) (no date). People and Trees:Partners in Time

43 U.S. Department of Agriculture Animal and Plant Health Inspection Service FederalRegister: December 10, 2004 (Volume 69, Number 237)

44 U.S. Department of Agriculture Animal and Plant Health Inspection Service FederalRegister: December 10, 2004 (Volume 69, Number 237)

45 Odegaard, F. 2000. Biological Journal of the Linnean Society. 71:583-597

46 Carroll, G.C. 1998. Letter to Dan Glickman, Secretary of Agriculture on behalf of theMycological Society of America. December 11, 1998.

47 W.E. Wallner, 2004. Assessing Exotic Threats to Forest Resources. In K.O. Britton, Editor.Biopollution: An Emerging Global Menace. APS Press

48 McGregor, R.C. 1973. The Emigrant Pests. Report Prepared for USDA APHISAdministrator Francis J. Mulhern.

49 C. Brasier. 2003. Phytopthoras in European forests: Their rising significance. SuddenOak Death Online Symposium. www.apsnet.org/online/SOD

50 Kamoun, S. 2001. Nonhost resistance to Phytophthora: novel prospects for a classicalproblem. Current Opinion in Plant Biology† 4:295-300.

51 http://www.nappo.org/Standards/Consultation/RSPM24-ConceptPaper3-8-04-e.pdf

52 WTO/SPS Art. 5 Para. 6

This report was prepared by Faith Campbell, Senior Policy Representative,

and Frank Lowenstein, Director of The Nature Conservancy’s Forest Health

Program, with much-appreciated input and advice from co-workers and

partners. Edited by Danielle S. Furlich.

The Nature Conservancy’s mission is to preservethe plants, animals and natural communitiesthat represent the diversity of life on Earth by protecting the lands and waters they need to survive.The Nature Conservancy develops policies based on sound science and a history of successful collaborative conservation. The organizationworks with a wide range of partners, including corporations, other privatelandowners and nearly every U.S. federal agency associated with land man-agement and natural resource protection to further cooperative conservationmanagement of both public and private lands. Since 1951, the Conservancyhas helped protect more than 15 million acres in the United States.

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