Karen Rane, UMD Plant Diagnostic [email protected]
http://dnr.maryland.gov/forests/Pages/MarylandersPlantTrees/Recommended-Tree-List.aspx
White Oak Group Rounded lobes on leaves Acorns mature in one season
and sprout when they fall in autumn
Species include: White oak Bur oak Swamp white oak Chestnut oak
White Oak – Maryland State Tree
Red Oak Group Pointed or bristled lobes on
leaves Acorns mature in 2 seasons and
sprout in spring Species include:
Red oak Black oak Pin oak Shingle oak Willow oak**
Oak Wilt:Native fungusCeratocystis fagacearumNow Bretziella fagacearum
1881/1944 – Wisconsin1942 – se MN & IA1973 – IL, WV, AK, NE, IN1977 – TXNOW Found in 21 states+
Oak WiltRed oak group more susceptible
than white oak group Vascular wilt disease – fungus
infects xylem (water conducting tissue)
Fungus spread by sap beetles (Nitidulids) feeding in crownBeetles attracted to pruning
wounds Also spread through root grafts
between healthy and infected trees
Robert Wright UNL Lincoln
USDA
Oak Wilt SymptomsLate spring to mid-summer, off-color, wilted foliage in upper
crown In red oak group, extensive leaf drop in summerFallen leaves still have green tissue at base or near
midveinRed oak group – trees die rapidly (a few weeks to a few
months)White oak group – no extensive leaf drop, trees die within
a few yearsHard to distinguish from decline
Discoloration (brown streaking) in sapwood in red oak group
Oak Wilt
NY State Urban Forestry Council
J. O’Brien, Bugwood.org
Oak Wilt Symptoms
Red oak group Defoliation within 3-4 weeks of first symptoms!
Oak Wilt in White Oak Group
Trees can live for 4-10 years, symptoms not as distinct as red oak
Oak Wilt Symptoms and Signs
Streaking in sapwood Photos: S. Jensen, Cornell Univ, Bugwood.org.
N. Pataky, Univ. of Ill.
Pressure Pad/Spore MatBark cracks
On Dead Trees
Disease Cycle
http://www.forestpathology.org/graphics/oakwilt.png
Root Grafting- Movement from Tree to Tree
Distribution of Oak Wilt – May 2013
US Forest Service
Oak wilt, 2008, New York
NYS Dept of Envirnmental Conservation
Diagnosing Oak Wilt Branch pieces at least 1” in
diameter, 10” long from branches with recent symptoms
Ship with ice packs – keep branches cool!
Sample trunk base of dead trees
Iowa State Plant Clinic
Texas Plant Disease Diagnostic Lab
Culture of C. fagacearum
G. Ruhl, Purdue
Managing Oak Wilt
Remove infected trees promptly Disrupt root grafts Protect high-value trees with
fungicide injection “Industry Standard” – Alamo
(propiconazole) Prevent spread by nitidulid beetles –
prune oaks in winter- Wound paints – water-based latex
IF Oak Wilt is confirmed…
NYS Oak Wilt Infection Area- AfterNYS Dept of Environmental Conservation
Trench dug to break root grafts.
NYS Dept of Environmental Conservation
Key Oak Wilt SymptomsLeaf discoloration during growing season Half green, half brown
Leaf drop on red oak group during summer!
....But what problems occur on oaks in Maryland??
Oak Anthracnose
Caused by fungus Apiognomoniaquercinia (Discula quercinia)
All oaks affected, white oak very susceptible
Symptoms: irregular leaf spots and blotches Often following along leaf veins Infected leaves can be distorted Mostly on lower branches
Young leaves are most susceptible
Photos: Joseph O’Brien, USDA Forest Service, Bugwood.org
Oak Leaf Blister
Caused by fungus Taphrina caerulescens
Red oaks most susceptible Yellow-green blister-like lesions that
turn brown Spores overwinter on bud scales Spring infection (cool, wet weather) Usually no impact on tree health
Tubakia leaf spot
Caused by the fungus Tubakiadryina
Occurs late summer to fall Usually on red oak group Circular brown leaf spots Little impact on tree health
* A different Tubakia species causes bur oak blight in Midwest
S. Tirpak, Rutgers Univ.
Cankers on Oaks
Caused by fungi (Diplodia/Botryosphaeria, Endothia, Hypoxylon)
Infection of small twigs to large branches/trunk
Most severe on trees under stress Often associated with wounds
Edward L. Barnard, Florida Department of Agriculture and Consumer Services, Bugwood.org
Endothia canker
Cankered region on northern red oak caused by Diplodiacorticola infection Cankered region and necrotic lesion on black oak
caused by Diplodia corticola infection
Twig cankers caused by D. corticola
Photos: Danielle Martin, USDA Forest Service
Diplodia Canker
Hypoxylon Canker Caused by Biscogniauxia
atropunctata var. atropunctata(syn. Hypoxylon atropunctatum).
Opportunistic pathogen – infectsstressed trees
Many oak species, as well as other hardwoods
Bark loss, revealing silver- gray fungal stroma
Stroma turns black over time
Robert L. Anderson, USDA Forest Service, Bugwood.org
Root Rot Diseases Some infect fine roots, some infect larger
woody roots Lower trunk (crown) may also be infected Fungi or fungus-like microorganisms
(water molds) Soil-borne pathogens Damage to root system results in
twig/branch dieback and poor growth Some cause wood rot – creating hazard
trees
Armillaria Root rot
Common wood decay fungus Wide host range Can infect stressed trees as well as
apparently healthy trees Symptoms – dieback, decline Impact on structural integrity of tree Survives in the soil, and on dead fallen
logs or tree stumpsJ. O’Brien, USFS Bugwood.org
Armillaria root rot: Signs Rhizomorphs
Mycelial fan
Honey mushroom
Phytophthora root rot - Oak
Caused by several Phytophthoraspecies (water molds)
Death of fine roots, sometimes death of phloem at crown or bleeding cankers
Does not cause wood decay Soil-borne pathogens, infect many tree
and shrub species Often associated with poorly drained
sites Symptoms: poor growth, dieback
M. Putnam, Oregon State Univ.
Sudden Oak Death
NOT in Maryland oaks (yet!) Caused by Phytophthora ramorum Causes bleeding cankers and death
of west coast oaks and tanoaks Also causes leaf and stem blight on
nursery crops (rhododendron, pieris, camellia, etc)
Has been introduced to MD on nursery stock from West Coast –regulated pathogen!
Bleeding canker on Red oak – NOT Sudden Oak Death
May be caused by other Phytophthora species, or insect borers
Inonotus dryadeus Root Rot
White rot of wood, sometimes no other symptoms
Bacterial Leaf Scorch Caused by the bacterium Xylella
fastidiosa Infects grape (Pierce’s disease), oak,
elm, sycamore, sweet gum Spread by sharpshooter leafhoppers Invades the xylem, blocking water
transport Marginal necrosis of leaves, often with
yellow border Discoloration spreads branch by
branch Symptoms develop in mid-summer
Bacterial Leaf Scorch
Red Oak
Bacterial Leaf Scorch
Sharpshooters
Managing Bacterial Leaf ScorchNo cure for infected treesCultural practices to reduce
moisture stress may help slow symptom developmentReplacement plan!
Tree Decline Loss of vigor/health due to
multiple factors Symptoms include off-color
foliage, smaller than normal annual twig growth, death of small twigs, thinning crown, early fall color
Symptoms develop over several years
Tree Decline – Two TypesRecently Transplanted Trees:Transplant Shock Older, Established Trees
Oak Decline in Maryland Found in older oaks (red oak, chestnut
oak) 50-70 years old Large trees in home yards – wooded
home sites History of root disturbances Environmental stress (drought) Clients often think symptoms happened
“overnight”! Also occurs in forested areas, but
causal factors may be different
http://www.forestryforum.com/board/index.php?topic=91515.0
MD Factors in Oak DeclineEnvironmental Stress (drought)Defoliation from insects or disease (more than one year)Damage to root zone from construction, soil compactionBacterial leaf scorch in landscape trees (possibly forest
trees also)Root diseases (Armillaria, Inonotus, sometimes
Phytophthora)Secondary borers – twolined chestnut borerHypoxylon cankersOak Wilt – possibly….
Avoiding Tree Decline
Match the tree to the site. Make sure site has adequate
space for root growth. Maintain health and vigor of trees
by proper watering and fertilizing. Avoid any changes to site after
trees are in place.
Managing Trees in Decline
Prune out dead branches – in winter in oak wilt areas! Protect the tree from additional site
disturbance. Maintain health and vigor of tree by
watering during dry periods. Very difficult to regain full canopy
once tree is in decline
J. O’Brien, USFS, Bugwood.org
University of Maryland Plant Diagnostic Laboratory
Dept. of EntomologyUniversity of Maryland4112 Plant Sciences Building4291 Fieldhouse DriveCollege Park, MD 20742-4454
[email protected]://extension.umd.edu/plantdiagnosticlab
When Field Observations are not Enough…..