Managing for Healthy White Pine Ecosystems in the UnitedStates to Reduce the Impacts of White Pine Blister Rust

Executive Summary

of this disease, from understanding the basicbiology of the pathogen and its hosts andidentifyingnatural disease resistance in sugarpine, western white pine and eastern white pine todeveloping improved planting stock and initiatingbreeding programs with other species. We now

realize that blister rust is apermanent resident of NorthAmerica. Therefore, ourefforts have shifted towards

facilitatingthe survival ofwhite pine species in thepresence of the disease andminimizing its ecological,economic and aestheticimpacts.

I n this report we outline the urgent need forvision, focus, and leadership to manage anon-native invasivedisease that threatens

the stability and survival of white pineecosystems in 40 of our 50 states. All nine of ournative white pine species are at risk and includesome ofthe oldest, mostmajestic, and ecologically orculturally significant pinespecies in the United States.White pines play criticalroles in forest developmentand integrity.Without whitepines these forestcommunities would be

altered dramatically.Historically, white pinesthrived because of their

ability to regenerate inopenings created by fire,outgrow their competitors,and resist many nativeinsects and pathogens. Allspecies of white pine aresusceptible at all ages to anon-native fungus whichcauses white pine blisterrust.

This plan is designed toestablish direction to restorewhite pines where they havebeen catastrophicallydecimated, to sustain whitepines where the rust ispresent but not yetdevastating, and to planmitigating actions when therust spreads into areas whereit is not yet present. Unlesswe take a bold andscientifically soundapproach, we risk losing asignificantcomponent of ournative forests, and with it,

considerable irreplaceablebiodiversity,as well asgenetic and cultural resources. This effort willrequire the applicationof existing managementtools and continued research and developmentusing integrated genetics, pathological,silvicultural,disease management and ecosystemrestoration strategies over several decades.

White pine blister rust iscaused by a non-nativeinvasive pathogen,Cronartium ribicola that

was introduced to North America ITomEuropealmost a century ago. Despite significanteffortsto contain it, this fungus has continued to spread(Fig. 1) and may be poised to invade the lastuninfected white pine ecosystems, includingtheancient bristlecone pine forests of the Southwest.

Figure 1. Westernwhitepine mortality.

Much has been accomplished since the discovery

i-Summary

The USDA Forest Service, with its expertise inforest health protection, forest management, andecosystem and disease research, is uniquelypositioned to implementthis plan, a blueprint toensure white pine survival through management,restoration, research, and public involvement.

Integrated Strategy to Protect, Sustain, andRestore White Pines. The survivalof whitepines and their ecosystems in North Americadepends upon a combination of traditional andinnovative scientific and management strategies:

=> Genetic Strategies. The best solutionknown to save white pines ftom whitepine blister rust is to enhance numbers ofrust resistant white pines (Fig. 2) inappropriate ecosystems. It is critical toprotect existing white pines that havesurvived the effects of this disease and

Figure 2. Rust resistance testing.

foster their regeneration in order tobroaden the base of genetic resistance.The identificationof resistant trees in

species such as whitebark pine andbristlecone pine is also necessary wherewe do not yet have well developedbreeding programs in place.

=> Silvicultural Strategies. Enhanceplanting of rust resistant white pineseedlings in openings created by naturaldisturbances and silviculturalmethods.Creating openings near surviving whitepines will enhance planting andregeneration opportunities.

Summary - ii

Tools such as prescribed burning,pruning, thinning, alternate host control(demonstrated to be effectivein theNortheast), and hazard rating projects willbe used to improve survival of plantedpines (Fig. 3).

Figure 3. Pruned western white pine plantation.

=> Research and Information Needs. Even

though much ofthe basic biology ofthepathogen and its hosts is known, vitalresearch is stillneeded to understand theintricate mechanisms and inheritance ofhost resistance in order to incorporatethemeffectivelyintobreedingprograms.Long-termperfonnanceof

dlin Figure 4. UninfectedRibes.see gswith improved resistance, as well as theepidemiologyof the disease affectingthese seedlings, will be monitored. Therole of different species of Ribes (Fig. 4)in maintainingand spreading disease alsoneeds further study.

=> Public Outreach and Partnerships.Federal, State, Tribal, and non-governmental organizations, and thepublic willwork together to protect,restore, and sustain these ecosystems.

The Resource: White Pines and Their

Ecosystems

Nine species of white pines are nativeto U.S. forests: eastern white pine(Fig. 5), western white pine, sugarpine, whitebark pine, limber pine,

southwestern white pine, Rocky Mountainbristlecone pine, Great Basin bristlecone pine,and foxtail pine. White pines occur naturally in

Figure 5. Eastern white pine.

40 of our 50 states, :tromseashore to timberlineand ttom isolated desert mountain ranges toextensive inland forests. These pines includesome of the oldest, most majestic, and mostculturally significanttrees in the United States.An ancient bristlecone pine in eastern Californiais believed to be the oldest livingthing on Earthat over 4,700 years of age.

The great size and superior wood quality ofmature eastern white, western white, and sugarpines made them the chief prize of lumbermenasthey worked westward across the continent.

White pines play an important role in maintainingwatershed health and wildlifehabitat as well asproviding commercialproducts and desirablerecreational experiences. White pine ecosystemscontain white pines as a significantor dominantpart of their coniferous tree cover and playcritical roles in forest development and integrity.Examples of white pine ecosystems range ttommixed-conifer ecosystems where white pines are

a minor to moderate component, to white pine-dominated ecosystemswhere they are the majortree species, to harsh high-elevationsites wherewhite pines are the only conifers that can survive.

Historically,white pines thrived in many forestsbecause of their abilityto regenerate in openingscreated by fire, outgrow their competitors, andresist many native insects and pathogens. Today,white pine ecosystems are being transformed andimpoverishedby the combined effects of whitepine blister rust and lack of openings forregeneration (Fig. 6). Without fire or otheropenings, white pines fare poorly and arereplaced by other species that can regeneratebeneath the pine canopy. In many cases inwestern forests, a few conifer species, such asgrand fir and Douglas-fir, will become dominantresulting in forests that are less diverse, denselyoverstocked, especiallyfire-prone, and moresusceptibleto insects and disease. Eastern whitepine is also favored by fire and other openings,although it is more shade tolerant. However,with limitationson active management, LakeStates pine forests convert into disease prone,unthrifty hardwood stands.

Figure 6. This whitebarkpine ecosystemhas been impactedextensively by blister rust and bark beetles.

1

The Disease: White Pine Blister Rust

and Its Impacts

W hite pine blister rust, a fungusnative to Asia, was introduced tothe eastern and western coasts ofNorth Americaaround the turn

of the 20thcentury on infected white pine nurserystock grown in Europe. In spite of a complicatedlife cycle requiring the presence of gooseberriesor currants (Ribes species) as well as pines, thepathogen has spread into 38 states (Fig. 7),causing substantial damage and mortality inseven of the nine native white pine species.Infected trees may lose much of their canopy,where cones are produced, years before deathoccurs. Two white pine species, the long-livedRocky Mountain and Great Basin bristleconepines, remain untouched by this disease, but forhow long?

Figurt: 7. History af whitt: pint: blistt:r rust spread.

2

Ecological Impacts

The effects of blister rust go far beyond the lossof individualtrees. There is a cascading effect onassociated plant and animal communitiesthroughout affected ecosystems. Naturalregeneration and intermediate age classes havebeen rapidly killed by blister rust resulting indramatic changes to normal successionalpathways. In some cases, the impact of blisterrust combined with lack of regenerationopportunities threatens to eliminatethe whitepines as functioningcomponents of forestecosystems. This outcome has significantnegative impacts for watershed health, wildlifehabitat, and the abilityof these ecosystems torespond to changes brought on by fire, insects,pathogens and other agents of change. Forexample,western white pine was once thedominant species on five million acres in theInlandNorthwest.

1920

1925

1953

Current

!-~ Forestedlands

B.o."".,.",,,,...,.. Forested lands at risk

Today, less than ten percent of that area has asignificantwestern white pine component.Where western white pine have been killed byblister rust or removed to ''pre-empt'' blister rustlosses, the forest becomes dominated primarilyby Douglas-fir, grand fir, western red cedar andhemlock (Fig. 8), species which are moresusceptible to root diseases, bark beetles,windthrow and drought. The increased mortality

regimes, and reduced wildlife diversity.

Bristlecone, foxtail, limber and whitebark pinesare among the few conifers adapted to arid andhigh elevation environments. They aresometimesthe only tree species present in themost austere parts of these ecosystems,or act aswindbreaks for other species to grow. Theycontribute to the regulation of snow accumulation

Change in Forest Type 1930-1980Idaho PanhandleNationalForests

Douglas-fir

Forest Type

Grand firlhemlock

[J Historic %

III Current %

Figure 8. The acreage of whitepine in one part of the Idaho Panhandle National Forest was once larger thanthe state of Rhode Island and is now less than l/lO'h of that. Similar changes have occurred throughout the west.

caused by these agents, along with changes inspecies and stand structures and subsequent fuelsbuildup, has led to a pattern of increased risk ofcatastrophic fire. Loss of white pine also meansless old growth trees, and less large wood forfish, wildlife habitat and nutrient cycling.

Other white pines, such as sugar pine,southwestern white pine and eastern white pinegrow in mixed species stands where theydiversifYforest composition, making theseecosystems more resilient to changes wrought bydrought, fire, and insects and diseases. The largeseeds of these species are also important food forwildlife. Mortality of these pines is resulting inmore homogeneous forests, changes in fire

and soil stabilization. Many animals depend onthese trees for food and shelter. For example,whitebark pineseeds are a criticalfood source forClark's nutcrackers(Fig. 9), pinesquirrels, blackbears and grizzlybears, as well as anumber of small,seed-eating birdsand mammals.

Figure 9. Clark s nutcracker is an

essentialcomponentinwhitehal'kpine ecosystems.

3

35.0%-30.0%-25.0%--<F.>20.0%-oS

'5 15.0%-'$-

10.0%-

5.0%-

0.0%-White Pine

Economic Impacts

Historically,eastern and western white pineswere the mainstays of the lumber industrythroughout their ranges (Fig. 10). They wereprized for their rapid growth and clear, straight-grained wood that commanded premium prices,

Figure 10. Marketable white pines are in decline.

often more than double that paid for otherspecies in the region. On good sites, westernwhite pines grew to more than 150 feet tall and36 inches in diameter. Mixed western white pinestands commonlyproduced 50,000 board feet peracre, while the best mixed fir stands on the samesites today are projected to produce only half thatmuch.

Although bristlecone, foxtail, limber andwhitebark pines are not typicallyused for lumberor pulp, their presence enhances the ruggedbeauty of many of our national parks (Fig. 11),forests, and wilderness areas. Devastation ofthese species, as seen today in the stands of deadand dying trees in Crater Lake, Glacier, andNorth Cascades National Parks, erodes the scenicgrandeur of these treasured landmarksand mayaffect the tourist economies of adjacentcommunities.

In light of these impacts, and the key role whitepines play in maintaining ecosystem health andresilience, the following integrated strategy has

4

..

Figure 11. Remnant whitebarkpines add beauty tonational historic treasuressuch as Crater Lake.

been developed to protect, sustainand restorewhite pine ecosystems.

Integrated Strategy to Protect, Sustainand Restore White Pines

W idespread cooperative efforts tosave white pines were initiated in1909 in both eastern and westernNorth America. These efforts,

largely focused on eliminatingthe alternate host,Ribes (Fig. 12), were not effectivein stopping the

,;..:i......

Figure 12. Blister rust infected Ribes.

J

spread of blister rust. Also, the number of Ribesplants was not shown to affect the amount ofinfection in the west, although they weredemonstrated to have a long-lastingeffect oninfection and survival of trees in Maine. By thelate 1960s, the combined effects of blister rust,harvesting, fire and bark beetle-caused mortalitydevastated the white pine forests in many areasacross North America. In the West, most westernwhite pine management was abandoned.

Fortunately, by the 1960s, USDA Forest Servicescientists identifiedrust resistant western white

pine, eastern white pine, and sugar pine trees.Rigorous selection of disease resistant trees,

~"I>

breeding for disease resistance, and application ofsilviculturaltreatments such as thinning andpruning infected branches effectivelycaptured thegenetic resistance, offering an effectivestrategyfor growing white pines in the presence of blisterrust. This began a pivotal shift in focus fromdirect control of the alternate host (reducingexposure to the rust pathogen) to breeding for rustresistance (Fig. 13) and using silviculturalstrategies to augment restoration. In the past 40years, genetic breeding programs have produced

Figure 13. 1) rust-resistant sugar pine (inset - blister rust cankers), 2) testing for rust resistance, 3) sugar pine seed orchard,4) rust-resistant plantation.

5

rust resistant seedlings that have been effective inmaintaining a smallbut significantcomponent ofthese three species in disease-affected forests.

We realize that blister rust is now a permanentresident of North America, affecting even thehigh-elevation and drier forest ecosystems thatwe once thought would escape infection. Ourgoal in managing white pine forests is to promotethe establishment and growth of white pine trees,stands and populations that will thrive whilecoexisting with blister rust. We have theexpertise and technological tools necessary toreach this goal. This effort will require anintegrated approach using genetic, silviculturaland disease management strategies. The intentwill be to restore white pines where they havebeen catastrophically affected by rust infection(e.g., western white pine in the InlandNorthwest), to sustain white pines where the rustis present but not yet devastating (e.g., parts ofthe range of southwestern white pine [Fig. 14]),and to plan and prepare for potential spread of thedisease where the rust is not yet present (e.g., thebristlecone pines (Fig. 15) in California,Nevada,Utah, Colorado, and New Mexico). Restoring

Figure 14. Infected southwestern whitepine.

6

oil'

Figure 15. Bristleconepine.

white pine ecosystemscontributes to the maingoals ofthe "HealthyForest Initiative" and the"National Fire Plan" by improvingand restoringforest ecosystem conditions. To enhance naturalpine resistance, we will focus our efforts on thefollowingfour general work areas.

Genetic Strategies

The most effectivestrategy availableto combatthis disease is to capture and deploy plants withnatural genetic resistance to the rust. Althoughnatural resistance is inftequent, we are workingwith the natural disease resistance present inwhite pines to identifYresistant trees that can beused as parents of new generations of trees.Genetic conservation and breeding programshave already made considerableprogress towardsmaintainingsugar pine and western white pine asviable components of ecosystems. The breedingprograms continue to discover and develop rustresistant varieties of white pines. In California,atotal of 1,329proven rust resistant sugar pineseed trees have been identified,and two seedorchards are established.

In the Pacific Northwest, resistance breedingprograms support 40 seed orchards. The RockyMountain Region has identifiedmore than 3,100rust resistant western white pine trees andplanted 96,255 acres with blister rust resistantwhite pine seedlings. A breeding program is alsoestablished for eastern white pine and programsfor whitebark pine and southwestern white pineare in the early stages of development.

Where blister rust is present, researchers and landmanagers can accelerate the followingactions ofthe established breeding programs:

=> Locate and protect potentially resistanttrees, and test seedlings from these treesfor resistance.

=> Characterize resistance mechanisms andinheritance of observed resistance.

=> Evaluate test plantations to confirmthedurability of resistance.

=> Breed a new generation of white pineswith a mixture of known resistancemechanisms.

=> Plant rust resistant seedlingsor seedwherever possible.

=> Manage areas around identifiedresistanttrees and stands to allow openings forregeneration.

=> Conduct long-term monitoring to assessthe survival of natural regenerationcompared to planted resistant stock.

Figure16. Prunedwesternwhitepineplantation.

=> Maintain broad-based breeding programsto prevent the loss of potentiallyimportant sources of genetic variation.

For white pine species where no diseaseresistance has yet been discovered, such as high-elevation white pine species, land managers can:

=> Collect seed from disease resistant trees

to "bank" genetic diversitywithin speciesand populations. This is a stopgapmeasure to ensure that potentiallyvaluable white pine genotypes at risk inthe wild will be maintaineduntil we canreduce the threat. Concurrently,testseedlingsof these selected trees forresistance.

=> Implementa conservation strategy (Fig.16) to protect the remainingtrees andenhance regeneration.

Silvicultural Strategies

Historically,fires created large openings, whichpermitted natural regeneration of white pines.Today, land managers can plant rust resistantwhite pine seedlings in the openings created bylarge fires. However, we are unlikelyto makesignificantprogress without active management,removal of invading species and/or prescribedfire. We need to implement silviculturaltools tocreate the openings necessary for white pineregeneration. The followingactions arenecessary to implementgains made in enhancingnatural blister rust resistance through thebreeding programs:

=> Use rust hazard assessment models to

select the best sites for planting andmaintaining white pines.

=> Regenerate stands with harvests thatcreate suitable openings for white pineswhile saving uninfected and infection-tolerating seed trees to promote naturalgenetic resistance.

7

~ Use prescribed fires to prepare seed bedsand reduce competing vegetation.

~ Plant resistant seedlingsor seed inopenings created by natural disturbancessuch as windthrow, fires, root diseases, orbark beetles.

~ Use pruning and thinning whereappropriate to remove rust infectionstoextend the life of planted pines.

~ Plant rust resistant seedlings in frostpockets, taking advantage of white pines'superior frost resistance.

Where blister rust is not currently present or notyet causing extensive losses, strategies will focuson encouraging natural regeneration and, undersome circumstances, protecting existing stands.These activities must be integrated with otherland use objectives such as hazard fuel reduction,and improving or maintaining wildlife habitat(Fig. 17), watershed values and scenic quality.Land managers and researchers can:

~ Emphasize the importance of sustaining,protecting, and restoring white pineecosystems in revisions to NationalForest plans.

II'J'"'

'" I' ".. { "I'. I "

(I.rJ,., , ,..,

Figure 17. Whitebark pine seeds are an important high-caloric

part of the grizzly bear diet. essential to their survival throughharsh winters.

8

~ Conduct periodic surveys to accuratelymap rust occurrence, monitor spread andintensificationof rust incidence, andidentifynew introductions or changes inrust behavior.

~ Develop hazard rating systemsand otherpredictive models to better prescribe thebest set of managementpractices forvarious white pine sites.

~ Use pruning and thinning whereappropriate to remove existingrustinfections and extend the life of existingregeneration.

~ Use locallygrown nursery stock to avoidintroduction of blister rust into new white

pine ecosystems.

Research and Information Needs

Past research and management efforts haveprovided us with critical knowledge, technologiesand strategies that are used today to sustain,protect and restore white pine ecosystems.However, there are stillmany questions to answerin order to improve our abilityto cope with thisdisease. The followinglist describes some of thehighest priority research and informationneeds:

~ Identify resistance mechanisms, theirheritability,and geographic distribution inall white pine species.

~ Evaluate the linkage of resistancemechanismsto important survival andgrowth traits, and identifYenvironmentalfactors affecting these characteristics.

~Inwst~mevariatIDninRw~susceptibilityand develop species ofRibes that will resist rust without

impacting commercial gooseberryproduction.

~ Determine impacts of fire, prescribedburns, thinning, and other managementactivities on numbers and species of Ribesthat may regenerate from seed banks.

~ Examine genetic variation in the rustfungus includingthe potential for newraces with differences in virulence,

aggressiveness and adaptation to differentclimates.

=> Develop techniques needed tosuccessfully regenerate species at highelevation, naturally or ITomnursery stockor seeds (Fig. 18).

=> Develop seed transfer guidelinesfor allwhite pine species.

Figure 18. Foxtail seed and pollen cones.

Public Outreach and Partnership

Both internal and external participation andcollaboration among Federal, Tribal, State, andprivate land managers, and non-governmentalorganizations (Fig. 19) are essential for protectionand restoration of the white pines. Forest Servicemanagers and researchers partner in manycollaborative efforts to:

=> Provide information on forest conditions

and encourage participation in forestmanagement.

=> Incorporate white pine restoration andsustainabilitygoals into forest plans andfield project decisions.

=> Provide rust resistance testing capabilitiesfor partners.

=> Provide financial and technical assistanceto small landowners.

Conclusion

T his plan focuses on protecting,sustaining and restoring white pineecosystems that are either devastatedor threatened by a non-native invasive

pathogen, Cronartiumribicola, the cause ofwhite pine blister rust. It complementstheimplementationof the Healthy Forest Initiativeand the National Fire Plan and their associated

strategic documents by developing a sensibleapproach to restoring fire-adapted resilientecosystems in the areas where white pine oncedominated. It also complementsthe WesternBark Beetle Report by maintainingand restoringhigh numbers of white pines in ecosystems thathave become dominated by other species that aremore vulnerableto bark beetles and root

pathogens. Increased collaborationandpartnerships among land managers andresearchers will facilitate the long-termrestoration of white pine ecosystems. Theserestored white pine ecosystems will have thecapacity for self-renewal,recovery and retentionof ecological resiliencywhile meeting currentand future needs of people for desirableexperiences, products, and services.

Figure 19. Land managers and researchersfrom all agenciesare involved in collaborative efforts to restore whitepines.

9

Team Leaders and Members

Team Leaders:

Safiya Samman, Geneticist/Forest Health Specialist,Forest Health Protection (FHP), USDA Forest Service,Washington,DCJohn W. Schwandt, Pathologist, Northern Region FHP,Coeur d' Alene Field Office, Coeur d' Alene, illJill L. Wilson, Coeur d' Alene Field OfficeGroup Leader,Northern Region FHP,Coeur d' Alene, ill

Team Members and Contributors:

V. Clark Baldwin, National Silviculture Research ProgramLeader, VegetationManagement and Protection ResearchStaff,Washington, DCJames T. Blodgett, Pathologist, RockyMountain RegionFHP,Rapid City Service Center, Rapid City, SDDavid A. Conklin, Pathologist, Southwestern Region FHP,New Mexico Zone Office,Albuquerque, NMJoan M. Dunlap, Forester/Geneticist, Placerville Nursery,Pacific SW Region, Camino, CABrian Geils, Research Pathologist, RockyMountain Forestand Range Experiment Station, Flagstaff,AZJohn T. Kliejunas, Regional Forest Pathologist, PacificSouthwest Region, Vallejo,CA

~!!II

~III

~!II

,

Mary F. Mahalovich, Geneticist, Northern, RockyMountain, Southwestern,and Intermountain Regions,Moscow, illJoseph O'Brien, Pathologist, Eastern Region, St.Paul,MNJohn A. Petrick, Center Silviculturist, Dorena GeneticResource Center, Cottage Grove, ORAnna W. Schoettle, Research Plant Ecophysiologist,RockyMountain Research Station, Fort Collins, CO.Eric Smith, Biological Statistician, Forest HealthTechnologyEnterprise Team,Fort Collins, CO.Richard A. Sniezko, Center Geneticist, Dorena GeneticResource Center, Cottage Grove, ORDetlev Vogler Research Geneticist/Plant Pathologist,Institute of Forest Genetics, Pacific SouthwestResearchStationArt Zack, Forest Ecologist, Idaho Panhandle NationalForests, Coeur d' Alene, illPaul Zambino, Research Pathologist, RockyMountainResearch Station, Moscow,ill

Acknowledgements:

The development of this document would not have beenpossible without the collaboration and review of numerous

individuals within the Forest Service, other landmanagement agencies and universities.

~

Weare strivingfor the day white pines will coexist with blister rust

10