Diagnosing Tree Problems Linn/Benton Master Gardener Training Rick Fletcher OSU Extension Service
May 16, 2015
Diagnosing Tree Problems
Linn/Benton Master Gardener Training
Rick Fletcher
OSU Extension Service
Tree Death in the City
Big Trees- Big Problem
Fungal Mat in Decayed Wood
The Real Culprit: Human Damage
Why Trees Die
• Complex interaction of biotic and abiotic factors……
– And a little bad luck.
What Kills Trees?
• Separately or in combination:– Insects– Animals– Diseases– Abiotic Factors
Environmental Setting
• Look to the underlying situation before making judgments about why a tree died.
• ALSO: Many insects and diseases occur on declining trees but are not the primary cause of death.
Conifer Diseases
• Root rots• Stem/branch cankers• Needle casts
Root Rots
Annosus root rot
Oak root rot
Laminated root rot
Cedar root rot
Diseased trees Healthy trees
Disease pathway tree
Nancy Boriack
ODF Photo
Short leaders
Oak Root Disease
• Caused by the fungus Armillaria ostoyae.
• The most common root disease in Oregon.
• Affects all conifers and hardwoods to some degree.
• Particularly damaging to stressed trees.
The honey mushroom
Annosus root disease
• Can attack many species of conifers.
• Especially bad on the Abies genus.
• Spreads rapidly from wounds, and cut stumps.
Dead Trees in Alsea- 2010
Laminated Root Rot Damage
Laminated Root Rot
• Attacks all conifers, but particularly bad on Douglas-fir.
• Trees attacked lose vigor and crown mass.
• Many times blow over before they die.
Cedar Root Rot
• Port-Orford Cedar Root Disease: Phytophthora lateralis.
• Avoid soil movement from infested to uninfested sites.
• Plant other species or disease-resistant cedar seedlings in infested areas.
E. Hansen photoPhotos from USFS Dorena Tree Improvement Center (html)Photos from USFS Dorena Tree Improvement Center (html)
Stem and Branch Cankers
• Gall rust• Dermia cankers• Phomopsis cankers• Grovesiella
Phomopsis canker
• Attacks stressed trees. Commonly Douglas-fir.
A New Threat- SOD
• Disease caused by Phytophora ramorum
• Wide host range• Disease has
spread from California north to Oregon.
Oregon Conifer Hosts of Concern
Douglas-fir and grand fir
Needle Casts and Rusts
• Swiss needle cast• Rhabdocline needle
cast.• Pine needle cast.• Poplar rust
Why the Yellow Trees?
Swiss Needle Cast
• Serious forest problem along the Oregon Coast.
• Only impacts Douglas-fir.
• Can be controlled in Christmas trees with fungicides.
Pine Needle Cast
• Caused by several fungal organisms.
• Worse in areas of poor air drainage.
• Especially bad on 2 needle pine species.
Poplar rust on D. Fir
• Alternate hosts are Douglas-fir and populus species.
• Orange pustules appear on Douglas-fir in late spring.
• Can cause substantial defoliation.
Different Insects Attack Different Parts
of the Tree
Sucking Insects
• Aphids• Adelgids• Scales• Mites
Adelgids
• Balsam wooly adelgid• Aphid like insects that
do both chewing and sucking damage.
• Cause distorted growth, but rarely kill trees.
Cooley Spruce Gall Adelgid
• Seven different life stages.
• Forms cone-like galls on spruce.
Cooley Spruce Gall Adelgid
• On Douglas-fir, crawlers form cotton ball like spots on leaves.
• Only damages current needles.
Needle scales
• Wide variety of conifers affected.
• Most severe on cedars and pines.
• Foliage damaged, but trees not killed.
Pine Needle Scale
• Common on many species of pine
• Damages foliage and weakens trees.
Spruce Spider Mites
• Attack several conifer species.
• Worse during summer hot, dry weather.
• Drought worsens attack.
Boring insects
• Bark Beetles• Twig Weevils• Root Weevils• Wood Borers• Needle Midges
2007 Vineyard Mountain Bark Beetle Attacks
Bark Beetles
• Most common insects linked with death of local conifers.
• Individual insect species only attack certain species and/or genuses of conifers.
• Can have epidemic outbreaks with the right conditions.
• Most are native insects and are always present.
Douglas-fir Bark Beetles
Ipps Damage to Ponderosa Pine
5 Spined Ipps Damage to Pine
Bark Beetle Signatures
Population Control
• Important to understand life cycle of insects.
• Wood containing insects should be destroyed or treated to kill them.
Douglas-fir Twig Weevil
• Boring insect that infests small branches.
• Associated with stress weakened trees.
• Rarely cause death, but further weaken trees.
Close up of Twig Weevil
White Pine Weevil
• Serious problem on young spruce trees.
• Attacks and kills tree leader.
• Infested leader will show boring holes
A big pine problem
Sequoia Pitch Moth
Flat Headed Wood Borers
• Bore beneath bark and into wood.
• Attack weakened trees. Will attack healthy trees during droughts.
• Found many times in firewood.
Douglas-fir Needle Midge
• Douglas-fir is only tree attacked.
• Damage to needles done by tiny worms.
• Infested needles fall of tree by Christmas.
• Problem mainly for Christmas tree growers
Needle Feeders
• Can be very scary for homeowners.
• Rarely are epidemic in our climate.
• Can cause severe problems in native forests.
2010 Benton County Sample
Field Damage Near Summit
Look at the Litter Carefully Reveals- Sawfly Larvae Damage
Hoodoo Pass Disaster
Spruce Budworm
• Serious pest in Cascades and Eastern Oregon.
• Killed millions of acres of forest nationwide.
• Damage is cyclical.• Little problem in local
area.
Douglas-fir Tussock Moth
• A serious epidemic insect in Eastern Oregon in the 1980’s
• Found in Willamette Valley, but not a big threat.
Silver Spotted Tiger Moth
• Attacks mostly Douglas-fir
• Voracious feeder.• Can defoliate small
tree in a couple of days.
• Doesn’t kill trees.
Gypsy Moth
• Serious non-native insect.
• Attacks nearly all tree species.
• Is especially damaging to conifers like Douglas-fir.
• Population currently under control in OR.
Other Tree Damage
• Air Pollution• Sunburn• Frost injury• Nutritional deficiency• Stem rots• Animal damage
Air pollution damage
SO2 and alder.
Sun & Heat Damage
• Drooping foliage.• Necrotic needles in
late summer.
Sunscald to Trunk
• Problem on small trees with thin bark.
• Made worse by pruning lower limbs too soon.
Cold Damage
• Foliage desiccated by cold, dry winds.
• Buds/tissue killed by early or late frosts.
Current Season Needle Necrosis
• Impacts grand fir and noble fir grown on Valley floor.
• Serious Christmas tree problem.
• Cause is calcium deficiency in late spring.
• Best cure is genetics.
Stem Rots
• Common problem around homes.
• Conifers vary in response to injury.
• Long term rot and breakage is main problem.
December 2007
Storm Damage
The “Root” of the Problem
Important Clue to Damage
Butt Rot from Phellinus pini
Animal Damage Problems
• Rodents• Deer & Elk• Others
Deer/Elk in the Home Landscape
• Conifers used to browsing.
• Main long term damage to browsing is slowed growth and extra leaders.
• Antler rubbing can be severe-don’t prune to soon.
Controlling Browse
• Fences work best.• Small trees can be
protected by plastic tubes or other devices.
• Repellants have variable effect.
Mice/Vole Damage
• Serious problem in new planting.
• Girdling of bark near ground line can kill small trees.
• Best treatment is to remove hiding cover around trees.
Gopher Damage
• Worst on pines.• All conifers are
somewhat susceptible
• Fleshy rooted weeds are a magnet.
• Trapping is most effective treatment
Porcupine Damage
• Serious problem, particularly on pines.
• Can kill limbs or tree tops.
• Can be confused with squirrel damage.
• Populations are currently building in Willamette Valley
Culprit?
2010 Damage to Pines
The Culprits: Silver Gray Squirrels
Bob McNitt, aka, the pine guy examines
damage to native
ponderosas
Mike Melcher
Who’s been
messing with my trees?
The Damage and the Culprit
Human Damage to Trees
• Wires left on trees.• Nails or other metal in
trees.• Wounding by mowers,
vehicles or other source.
Construction Damage
Roots
Chemical Damage
• Each chemical has distinct damage pattern on various tree species.
• Resistance to damage varies greatly by species and time of application.
Diagnosing Tree Problems
• Identify species involved
• When injury noticed• Part of plant showing
injury– Roots, top, stem– Age of foliage– South vs north side
More Diagnosis Questions
• Species affected?• Distribution of
damage- on plant, on planting.
• Disturbance around tree anytime recently?
• Chemical applications?
Bottom Line for Conifers• Conifers are hardy and
tough to injure.• When injured severely,
conifers seldom recover.
• Death in conifers usually linked to several causes.
• It takes decades to replace a nice one.
References for Diagnosis
• Tree Identification Books• Insects that Feed on Trees and Shrubs• Diseases of Trees and Shrubs• PNW Insect and Disease Control
Handbooks from OSU• Several other reference books in MG
reference library and Rick’s office.
Linn-Benton Pest Scene Investigator Team
QUESTIONS?