Mark Duff Certified Forester Board Certified Master Arborist 1 The Impact of Oak Wilt Oak wilt is one of the most destructive tree diseases Young 1949 this disease has the potential of becoming one of the ID: 933254
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Slide1
Oak Wilt: Identification & Management
…
….
Mark Duff
Certified Forester, Board Certified Master Arborist
1
Slide2The Impact of Oak Wilt
“Oak wilt is one of the most destructive tree diseases”
(Young, 1949).
“…. this disease has the potential of becoming one of the
worst diseases to attack the forests of the state.”
( True and Gillespie,
1961
).
“
Ceratocystis fagacearum
, the cause of oak wilt, is a fungus
with the
potential to
be one of the most destructive of all
tree pathogens.” (Gibbs and French,
1980
).
“Oak wilt is now one of the most serious forest diseases
in the country” ( Johns and Phelps,
1992
).
Slide3The Impact of Oak Wilt
Thousands of acres
throughout
central and west
Texas have been adversely affected by oak wilt.
Slide4The Impact of Oak Wilt
Oak wilt may reduce urban and suburban property values by 15-20%.
Slide5What Is Oak
Wilt?
Caused by the fungus
Ceratocystis fagacearum
Primary vascular pathogen
Relies on insects for transportation
Produces fungal mats
Heat sensitive
Unknown origin
Slide6Where is Oak
Wilt?
Slide7Where is Oak
Wilt?
Slide8Where is Oak
Wilt?
Slide99
What Trees Are Susceptible?
Red Oaks
are extremely susceptible to the pathogen and play a unique role in disease spread.
White Oaks
are more tolerant of the disease;
however, they are
NOT
IMMUNE
to infection!
Live
Oaks
are
intermediate in
susceptibility; however, they are
seriously affected
due
to
their vast
, interconnected root
systems that allow for disease spread among trees.
All Oaks
and other members of the Beech family (Fagaceae)
Slide10Above
ground (long distance) via sap-feeding
beetles:
Fungal spores are picked up from certain infected
RED oaks and carried to fresh wounds on other oak species. New infection centers are started in this manner.
How Is Oak Wilt
Spread?
Sap Beetle
Fungal Mat
Fresh Wound on Oak
Slide1111
How Is Oak Wilt Spread?
Underground
(localized) via interconnected root
systems:
This occurs primarily in
LIVE
oaks and is responsible for the majority of spread and tree deaths in central Texas.
Root Grafts
Rate of spread averages
50
feet to 75 feet per
year.
Live Oak Mott
Slide12How Is Oak Wilt
Spread?
Slide13Red Oak Center
Live Oak Center
Diagnosis in a
Population of Trees
Slide14Rapid defoliation
Death in 3 to 6 months
Spread
to adjacent trees
No fungal mat formation
~
5 - 15%
survival rate
Diagnosis
in
Individual
Live Oaks
Slide15Maintain
leaves, then defoliate
Death in
4
to
6
weeks
Possible spread to adjacent trees
Possible formation of fungal mats
100% mortality (no survivors)
Diagnosis
in
Individual
Red Oaks
Slide16Foliar Symptoms in
Live Oaks
Veinal chlorosis /
necrosis
Tip burn
/
Marginal necrosis
Slide17Foliar Symptoms in
Red Oaks
Bronzing or water soaking
Slide18Fungal mats contain spores
Form
only on
RED
oaks
Form
under bark
Can have multiple
mats per tree
Produce a sweet odor like rotting
fruit
Mat production accelerated by cool, moist
weather (springtime in Texas)
Trees infected
in
fall / winter
produce
mats
Presence of Fungal Mats
Slide19Taking Samples
Bole (preferred) or
branch samples
Confirms presence of pathogen
Slide20Oak Wilt Management
Early detection and prompt action are essential for successful management of oak wilt.
There are four primary approaches used to manage oak wilt:
These measures will
not cure
oak wilt but can significantly reduce tree losses.
Prevention
Trenching
Fungicide Injection
Planting
Slide21Prevention - Pruning
Peak beetle activity and fungal mat production occur in the spring; therefore, avoid wounding oaks from
February through June
.
Regardless of season,
immediately paint
all pruning cuts and other wounds to oaks. This discourages contaminated sap-feeding beetles from visiting these wounds and introducing oak wilt into these trees.
Slide22Prevention - Red Oak Management
Destroy infected
red
oaks to prevent fungal mat
formation.
Never
use infected
red
oaks for firewood!
Slide23Prevention - Firewood
Transport and use only dry, well-seasoned firewood
Leave unseasoned wood on site one year before
moving
Do not store infected wood near healthy trees
Cover wood with clear plastic and bury the edges to prevent insects from leaving the pile
Slide24Trenching
Trenches must be placed a
minimum
of 100
feet ahead of the disease, excavated to
at
least
4 feet
(sometimes
deeper
), and
sever
all root
connections
to be effective.
100’
100’ minimum
Diseased
Healthy
Slide25Trenching
Soil depth and
texture will
determine equipment choice.
Slide26Pushing / Rouging
Removing all
oaks within the boundaries of the trench, specifically the healthy and pre-symptomatic trees, can
improve barrier
effectiveness.
Slide27Fungicide Injection
Used
to protect high-value oaks in advance of an expanding oak wilt center
Best
candidates
are
healthy or
pre-symptomatic
live oaks
50 feet
to
150 feet
from symptomatic trees
Injection
does
not
stop root transmission of the fungus!
Slide28Fungicide Injection
Success depends upon the health of the tree, application
rate,
and injection technique.
Slide29Fungicide Injection
Several products are currently labeled and registered for this treatment; however, only macro-injections of Alamo® have been
scientifically proven
effective and continue to be the industry standard.
Slide30Bark is thinner below the soil line
Increases the number of potential injection sites
Spreads out the wounding, especially if future injections are needed
Research has demonstrated superior distribution of fungicide in the tree
Macro-Injection Advantages
Slide31“Alternative”
Products and
Methods
Tebuject
Slide32Criteria for Successful Injections
Reliable
Verifiable documentation of research resultsMust increase survival of treated trees over natural population
SafeEconomical
Reasonably easy to applyLegal
Slide33Native or adapted to the local environmental conditions
Tolerant of temperature extremes, amount and pattern of
precipitation, and local soil conditions
Not invasive nor detrimental to the local environment
Preferably multi-functional in the landscape
Tree Planting
Slide34Tree Planting
Avoid
planting
monocultures
Create diversity in the landscape
Avoid wounding oaks during planting
Slide35Tree Planting
Site
Season
Hole
Drainage
Pruning(?)
Foreign Materials
Depth
Backfill
Staking(?)
Mulch
Protection
Maintenance
Slide36Tree Planting
Slide37Recommended Trees
American smoketree
Arizona walnut
baldcypressbigtooth maple
bur oakCarolina buckthorn
cedar elm
chinkapin oak
desert willow
escarpment cherry
Lacey oak
littleleaf leadtree
mescalbean
Mexican plum
pecan
possumhaw
TX or MX redbud
rusty blackhaw
Texas crabapple
Texas sophora
Slide38“The
overall goal of the Texas A&M Forest Service’s Cooperative Oak Wilt Suppression Project is to minimize the spread of oak wilt (Ceratocystis fagacearum
) in central Texas.”
Provide public awareness and education about the disease
Identify and map mortality centers with ground verification of oak wilt
Provide treatment recommendations and cost-shares (when applicable) to private landowners
Conduct post-suppression evaluations on cost-shared treatments
Establish and maintain detailed and accurate records
Oak Wilt Suppression Project
Slide39Cost Shares
Cost-shares,
disbursed through the
Oak Wilt Suppression Project,
may be available to private landowners for the following
efforts:
Containment trenching around oak wilt centers
Pushing
or rouging of all oaks within the
boundaries of
cost-shared trenches
Removal
of diseased red oaks in urban
areas
Cost-shares shall consist of 40% of actual costs not to exceed $2000.00 per individual per year with a maximum of $10,000.00 per
project per year.
Slide40Cost Shares
Complete
containment of the disease center (natural
land features and existing underground infrastructure can be used in select cases)
Relative isolation of the disease
center from other disease centers
High
potential
for
fungal mat formation (red oaks)
Compliance
with Cultural Resources Preservation Act
The following criteria
are required
to qualify for cost-shares:
Slide41Cost Shares
Removal
of dead trees
Trenching around healthy stands of trees
Secondary trenchesEngineering charges,
consulting fees, or
permit fees
Loss or reduction in revenues from the land
Stump grinding
Fungicide treatments (injection)
Replanting or landscaping
Items
NOT
eligible for cost-shares include:
Slide42Cost Shares
Cost-share Application
Treatment Plan
Cultural Resources Survey Form
TARL Records Check
Treatment Maps
General Location Map
Underground Utility Waiver
Cultural Resources Acknowledgement Form
W-9 Tax Identification Form
There
is an application
process:
Slide43Texas A&M Forest Service Central Texas Regions
Oak Wilt Resources
Slide44Oak Wilt Resources
Oak Wilt Information Partnership website:
www.texasoakwilt.org
HOW TO
Identify and Manage Oak Wilt in Texas brochure
Slide45Other Informational Websites
http://texasforestservice.tamu.edu
http://texastreeplanting.tamu.edu
http://texasinvasives.org
http://www.treesaregood.org
http://www.texasconservation.org
Slide46Questions?
Slide47Thank You!
Texas A&M Forest
Service