Oak WiltOak Wilt

Identification & ManagementIdentification & Management

Robert EdmonsonRobert Edmonson

Biologist II / Certified ArboristBiologist II / Certified Arborist

Texas A&M Forest ServiceTexas A&M Forest Service

Master NaturalistsHill Country Chapter

The Impact of Oak WiltThe Impact of Oak Wilt

• ““Oak wilt is one of the most destructive tree diseases” Oak wilt is one of the most destructive tree diseases” (Young, 1949).(Young, 1949).

• “… “…. this disease has the potential of becoming one of the. this disease has the potential of becoming one of the worst diseases to attack the forests of the state.”worst diseases to attack the forests of the state.” ( True and Gillespie, 1961).( True and Gillespie, 1961).

• “ “Ceratocystis fagacearumCeratocystis fagacearum, the cause of oak wilt, is a fungus , the cause of oak wilt, is a fungus with the potential to be one of the most destructive of all with the potential to be one of the most destructive of all tree pathogens.” (Gibbs and French, 1980).tree pathogens.” (Gibbs and French, 1980).

• ““Oak wilt is now one of the most serious forest diseasesOak wilt is now one of the most serious forest diseases in the country” ( Johns and Phelps, 1992).in the country” ( Johns and Phelps, 1992).

The Impact of Oak WiltThe Impact of Oak Wilt

ThousandsThousands of acres of oaks of acres of oaks have succumbed to oak wilt have succumbed to oak wilt throughout central and west throughout central and west

Texas.Texas.

The Impact of Oak WiltThe Impact of Oak Wilt

Oak wilt may Oak wilt may reduce urban and reduce urban and

suburban property suburban property values by 15-20%.values by 15-20%.

What Is Oak Wilt?What Is Oak Wilt?

• Caused by the fungus Caused by the fungus Ceratocystis fagacearumCeratocystis fagacearum

• Primary vascular pathogenPrimary vascular pathogen

• Relies on insects for transportationRelies on insects for transportation

• Produces fungal matsProduces fungal mats

• Heat sensitiveHeat sensitive

• Unknown originUnknown origin

Where is Oak Where is Oak Wilt?Wilt?

What Oaks Are Susceptible?What Oaks Are Susceptible?

AllAll Oaks! Oaks!

Red oaksRed oaks are extremely susceptible to oak wilt, probably due to are extremely susceptible to oak wilt, probably due to large summerwood vessels. They also play a unique role in disease large summerwood vessels. They also play a unique role in disease

spread by forming fungal mats. spread by forming fungal mats.

White oaksWhite oaks have very small vessels and seem to tolerate oak wilt; have very small vessels and seem to tolerate oak wilt; however, they are NOT IMMUNE to the disease! however, they are NOT IMMUNE to the disease!

Live oaksLive oaks are semi-ring porous and intermediate in susceptibility. are semi-ring porous and intermediate in susceptibility. They spread by root sprouts and readily root graft with other live They spread by root sprouts and readily root graft with other live

oaks. They are seriously affected by oak wilt due to these vast, oaks. They are seriously affected by oak wilt due to these vast, interconnected root systems that allow movement of the fungus interconnected root systems that allow movement of the fungus

among trees. among trees.

Above GroundAbove Ground (long distance) via sap-feeding beetles. (long distance) via sap-feeding beetles.

Fungal spores are picked up from certain infected Fungal spores are picked up from certain infected RedRed oaks and carried to fresh wounds on other oak species. oaks and carried to fresh wounds on other oak species.

New infection centers are started in this manner. New infection centers are started in this manner.

How Is Oak Wilt Spread?How Is Oak Wilt Spread?

Sap Beetle Sap Beetle

Fungal Mat Fungal Mat Fresh Wound Fresh Wound

on Oak on Oak

How Is Oak Wilt Spread?How Is Oak Wilt Spread?UndergroundUnderground (localized) via interconnected root systems. (localized) via interconnected root systems.

This occurs primarily in This occurs primarily in LiveLive oaks and is responsible for the oaks and is responsible for the majority of spread and tree deaths in central Texas.majority of spread and tree deaths in central Texas.

Root Grafts Root Grafts Live Oak Mott Live Oak Mott

Rate of spread averages Rate of spread averages approximately 50 feet to 75 feet approximately 50 feet to 75 feet

per yearper year

Red Oak CenterRed Oak CenterLive Oak CenterLive Oak Center

Pattern of Disease in the Pattern of Disease in the Population of TreesPopulation of Trees

Rapid defoliationRapid defoliationDeath in 3 to 6 monthsDeath in 3 to 6 months

Eventual spread to adjacent treesEventual spread to adjacent treesNo fungal mat formationNo fungal mat formation

~ 20% survival rate~ 20% survival rate

Pattern in Individual TreesPattern in Individual Trees

Live OaksLive Oaks

Red OaksRed Oaks

Maintain dead leavesMaintain dead leavesDeath in 3 to 4 Death in 3 to 4 weeksweeks

Possible spread to adjacent treesPossible spread to adjacent treesPossible formation of fungal matsPossible formation of fungal mats

100% mortality (no survivors)100% mortality (no survivors)

Pattern in Individual TreesPattern in Individual Trees

Foliar Symptoms Foliar Symptoms in Live Oaksin Live Oaks

Veinal chlorosis / necrosisVeinal chlorosis / necrosis

Tip burnTip burn

Marginal necrosisMarginal necrosis

Vein bandingVein banding

Foliar Symptoms in Foliar Symptoms in Red OaksRed Oaks

Bronzing or water soakingBronzing or water soaking

Contain spores for spread by the beetleContain spores for spread by the beetle

Produced Produced onlyonly on red oaks on red oaks

Mats form under bark Mats form under bark

Multiple mats per tree Multiple mats per tree

Produce a sweet odor like rotting melonsProduce a sweet odor like rotting melons

Mat production accelerated by cool, moist weatherMat production accelerated by cool, moist weather

In Texas, trees killed in late summer produce mats In Texas, trees killed in late summer produce mats the following springthe following spring

Presence of Fungal MatsPresence of Fungal Mats

Taking SamplesTaking SamplesBole and/or branch samplesBole and/or branch samples

Confirms presence of Confirms presence of pathogenpathogen

How to Manage Oak WiltHow to Manage Oak Wilt

Early detection and prompt action are essential for successful Early detection and prompt action are essential for successful management of oak wilt.management of oak wilt.

There are four primary approaches used to manage oak wilt:There are four primary approaches used to manage oak wilt:

These measures will These measures will notnot cure oak wilt but can cure oak wilt but can significantly reduce tree losses.significantly reduce tree losses.

PreventionPrevention

TrenchingTrenching

InjectionInjectionPlantingPlanting

PreventionPrevention

Peak beetle activity and Peak beetle activity and fungal mat production occur fungal mat production occur

in the spring; therefore, in the spring; therefore, avoid wounding oaks from avoid wounding oaks from

February through June.February through June.

Regardless of season, Regardless of season, immediately immediately paintpaint all pruning all pruning cuts and other wounds to oaks. cuts and other wounds to oaks. This discourages contaminated This discourages contaminated

sap-feeding beetles from visiting sap-feeding beetles from visiting these wounds and introducing these wounds and introducing

oak wilt into these trees. oak wilt into these trees.

PreventionPreventionDestroy infected Destroy infected RedRed oaks to prevent oaks to prevent

fungal mat formation fungal mat formation

Do not use infected Do not use infected RedRed oaks for oaks for firewood! firewood!

PreventionPrevention

Transport and use only Transport and use only dry, well-seasoned dry, well-seasoned

firewoodfirewood

Leave unseasoned wood Leave unseasoned wood on site one year before on site one year before

transportingtransporting

Do not store infected Do not store infected wood near healthy treeswood near healthy trees

Cover wood with clear Cover wood with clear plastic and bury the plastic and bury the

edges to prevent insects edges to prevent insects from leaving the pilefrom leaving the pile

TrenchingTrenching

Trenches must be placed a Trenches must be placed a minimumminimum of 100 feet of 100 feet ahead of the disease and dug at least 4 feet deep ahead of the disease and dug at least 4 feet deep

(sometimes deeper) to sever all root connections! (sometimes deeper) to sever all root connections!

100’100’

Diseased TreeDiseased Tree

Healthy TreeHealthy Tree

TrenchTrench

100’ minimum

TrenchingTrenching

Soil depth and texture Soil depth and texture determine equipment choice determine equipment choice

for trench installations for trench installations

TrenchingTrenching

Removing all oaks, especially Removing all oaks, especially healthy oaks along the trench can healthy oaks along the trench can

improve barrier effectiveness improve barrier effectiveness

InjectionInjectionInjection is used to Injection is used to protect high-value protect high-value

oaks in advance of an oaks in advance of an expanding oak wilt expanding oak wilt

centercenter

The best candidates The best candidates for treatments are for treatments are

healthy or non healthy or non symptomatic live oaks symptomatic live oaks

within 50’ to 150’ within 50’ to 150’ from symptomatic from symptomatic

treestrees

Injection does Injection does notnot stop root transmission stop root transmission

of the fungus!of the fungus!

InjectionInjection

Success depends upon the Success depends upon the health of the tree, application health of the tree, application rate and injection technique.rate and injection technique.

InjectionInjectionSeveral products are currently Several products are currently labeled and registered for this labeled and registered for this

treatment; however, only treatment; however, only macro-injections of Alamomacro-injections of Alamo® ®

have been scientifically proven have been scientifically proven effective and continue to be the effective and continue to be the

industry standard.industry standard.

Bark is thinner below the Bark is thinner below the soil linesoil line

Increases the number of Increases the number of potential injection sitespotential injection sites

Spreads out the wounding, Spreads out the wounding, especially if future especially if future

injections are neededinjections are needed

Research has demonstrated Research has demonstrated superior distribution of superior distribution of

fungicide in the treefungicide in the tree

Macro-Injection Macro-Injection AdvantagesAdvantages

Alternative Products and TechniquesAlternative Products and Techniques

Tebuject

Criteria for Successful Criteria for Successful Oak Wilt InjectionsOak Wilt Injections

• ReliableReliable

• Verifiable documentation of research resultsVerifiable documentation of research results

• Must increase survival of treated trees over natural populationMust increase survival of treated trees over natural population

• SafeSafe

• EconomicalEconomical

• Reasonably easy to applyReasonably easy to apply

• Legal Legal

Tree PlantingTree Planting

Select trees that are Select trees that are native or adapted to native or adapted to

the regionthe region

Avoid planting Avoid planting monocultures; create monocultures; create

diversity in the diversity in the landscapelandscape

Avoid wounding oaks Avoid wounding oaks during planting during planting

Native or adapted to the local Native or adapted to the local environmental conditionsenvironmental conditions

Tolerant of temperature Tolerant of temperature extremes, amount and pattern of extremes, amount and pattern of

precipitation and local soil precipitation and local soil conditionsconditions

Not invasive nor detrimental to Not invasive nor detrimental to the local environmentthe local environment

Preferably multi-functional in Preferably multi-functional in the landscapethe landscape

Tree PlantingTree Planting

Tree PlantingTree Planting SiteSite

SeasonSeason

HoleHole

DrainageDrainage

Pruning?Pruning?

Foreign MaterialsForeign Materials

DepthDepth

BackfillBackfill

Staking?Staking?

MulchMulch

ProtectionProtection

MaintenanceMaintenance

Tree PlantingTree Planting

Recommended TreesRecommended Trees

American smoketreeAmerican smoketree

Arizona walnutArizona walnut

baldcypressbaldcypress

bigtooth maplebigtooth maple

bur oakbur oak

Carolina buckthornCarolina buckthorn

cedar elmcedar elm

chinkapin oakchinkapin oak

desert willowdesert willow

escarpment cherryescarpment cherry

Lacey oakLacey oak

littleleaf leadtreelittleleaf leadtree

mescalbeanmescalbean

Mexican plumMexican plum

pecanpecan

possumhawpossumhaw

TX or MX redbudTX or MX redbud

rusty blackhaw rusty blackhaw

Texas crabapple Texas crabapple

Texas sophoraTexas sophora

Texas A&M Forest Service’s RoleTexas A&M Forest Service’s Role““The overall goal of the Texas A&M Forest Service’s The overall goal of the Texas A&M Forest Service’s

Cooperative Oak Wilt Suppression Project is to minimize Cooperative Oak Wilt Suppression Project is to minimize the spread of oak wilt (the spread of oak wilt (Ceratocystis fagacearumCeratocystis fagacearum) in central ) in central

Texas.”Texas.”• Provide public awareness and education about the diseaseProvide public awareness and education about the disease

• Identify and map mortality centers with ground Identify and map mortality centers with ground verification of oak wiltverification of oak wilt

• Provide treatment recommendations and cost-shares (when Provide treatment recommendations and cost-shares (when applicable) to private landownersapplicable) to private landowners

• Conduct post-suppression evaluations on cost-shared Conduct post-suppression evaluations on cost-shared treatmentstreatments

• Establish and maintain detailed and accurate recordsEstablish and maintain detailed and accurate records

Cost SharesCost SharesFederal cost-shares disbursed through the Texas A&M Federal cost-shares disbursed through the Texas A&M Forest Service’s Oak Wilt Suppression Project may be Forest Service’s Oak Wilt Suppression Project may be

available to private landowners for the following available to private landowners for the following suppression efforts:suppression efforts:

• Containment trenching around oak wilt centersContainment trenching around oak wilt centers

• Pushing or rouging of Pushing or rouging of allall oaks within the boundaries oaks within the boundaries of cost-shared trenchesof cost-shared trenches

• Removal of diseased red oaks in urban areas Removal of diseased red oaks in urban areas

Cost-shares shall consist of 40% of actual costs not to Cost-shares shall consist of 40% of actual costs not to exceed $2000.00 per individual per year with a maximum exceed $2000.00 per individual per year with a maximum

of $10,000.00 per projectof $10,000.00 per project

Cost SharesCost Shares

• Complete containment of the disease center (natural land Complete containment of the disease center (natural land features and features and existing underground infrastructure can be used in select existing underground infrastructure can be used in select cases)cases)

• Relative isolation of the disease centerRelative isolation of the disease center

• High potential of fungal mat formation (red oaks)High potential of fungal mat formation (red oaks)

• Compliance with Cultural Resources Preservation ActCompliance with Cultural Resources Preservation Act

The following criteria must be met in The following criteria must be met in order to qualify for cost-shares:order to qualify for cost-shares:

Cost SharesCost Shares

Items Items NOTNOT eligible for cost-shares include: eligible for cost-shares include:

Removal of dead treesRemoval of dead trees

Trenching around healthy stands of treesTrenching around healthy stands of trees

Secondary trenchesSecondary trenches

Engineering charges, consulting fees or permit feesEngineering charges, consulting fees or permit fees

Loss or reduction in revenues from the landLoss or reduction in revenues from the land

Stump grindingStump grinding

Fungicide treatments (injection)Fungicide treatments (injection)

Replanting or landscapingReplanting or landscaping

Cost SharesCost Shares

Cost-share ApplicationCost-share Application

Treatment PlanTreatment Plan

Cultural Resources Survey FormCultural Resources Survey Form

TARL Records CheckTARL Records Check

Treatment MapsTreatment Maps

General Location MapGeneral Location Map

Underground Utility Waiver Underground Utility Waiver

Cultural Resources Acknowledgement FormCultural Resources Acknowledgement Form

W-9 Tax Identification FormW-9 Tax Identification Form

As with all cost-share programs, there is As with all cost-share programs, there is an application processan application process

Texas A&M Texas A&M Forest Service Forest Service Central Texas Central Texas

RegionsRegions

Oak Wilt Oak Wilt ResourcesResources

Oak Wilt ResourcesOak Wilt Resources

Oak Wilt Information Partnership website:Oak Wilt Information Partnership website:

www.texasoakwilt.orgwww.texasoakwilt.org

How To Identify and Manage Oak Wilt in How To Identify and Manage Oak Wilt in TexasTexas brochure brochure

Other Informational WebsitesOther Informational Websites

http://texasforestservice.tamu.eduhttp://texasforestservice.tamu.edu

http://texastreeplanting.tamu.eduhttp://texastreeplanting.tamu.edu

www.texasinvasives.orgwww.texasinvasives.org

www.treesaregood.orgwww.treesaregood.org

www.texasconservation.orgwww.texasconservation.org

QuestionsQuestions

??????

Thank You!Robert EdmonsonRobert Edmonson

Biologist II / Certified ArboristBiologist II / Certified Arborist

Texas Forest ServiceTexas Forest Service