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FOREST INSECT & DISEASE ISSUES IN ORNAMENTAL TREES
TRA PEST MANAGEMENT WORKSHOP
GRAND JUNCTION, CO FEBRUARY 2012
Dave Leatherman [email protected]
GENERAL COMMENTS
The distinction between “wild/native” and “ornamental” is fuzzy
Native forest plant values tend to be low, which dictates fewer options & tactics
Likewise, higher-value ornamentals with issues may warrant action more often
Many ornamental causal agents are typical of the surrounding forest (i.e., mobile)
Climate change influence on all of this is real and requires constant observation
DOMINATE ISSUES IN THE NATIVE FORESTS OF COLORADO
fire
bark beetles
regional defoliators like budworm
deer and elk
borers
dwarf mistletoe
decay
INSECTS AND FIRE
Wild or out-of-prescription fires can create “habitat” for insects in the form of dead or stressed trees
Insect-caused mortality may lead to temporarily increased ignition potential and fuel-loading
Prescribed fire can be used to dispose of susceptible or insect-infested woody debris
FIRE MITIGATION
Slash creation could invite pest issues such as ips, twig beetles, and even rodents
Monitor stems
Change timing of actions if build-up of pests noted
REDUCTION OF SLASH INSECTS
PROMOTE DRYING (CHIPPING OR LOPPING-AND-SCATTERING IS BETTER THAN PILING)
IF PILES ARE PRODUCED, PLAN TO BURN PRIOR TO EMERGENCE OF BARK BEETLES
TRY NOT TO PRODUCE SLASH DURING FLIGHT PERIODS (Dendroctonus especially)
BEST TIME TO CUT IS USUALLY LATE FALL-EARLY WINTER
REMOVAL FROM SITE IS ANOTHER OPTION
Ips beetle
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MOVEMENT OF BARK BEETLES IN FIREWOOD
FIREWOOD MOVEMENT
RULES OF THUMB
*BARK BEETLE EXTERNAL EVIDENCE + NO EXIT HOLES = DANGER
*EXTERNAL EVIDENCE + EXIT HOLES = OK
*EXTERNAL EVIDENCE = PITCH TUBES, BORING DUST, WOODPECKERING, AND/OR CROWN FADING (AND, OF COURSE, LIVE LIFE STAGES UNDER THE BARK)
ENTRY EXIT
MOUNTAIN PINE BEETLE
Covered in detail in “Forest Pest Control” session (tomorrow, presenter: Roy Mask)
Main “Green Industry” activity is preventive spraying
Other activities might include:
Identifying infested trees
Removing infested trees
Thinning of live forests
Planting of replacement trees
OTHER BARK BEETLES
Secondary pine species (Ips spp., twig
beetles, Red Turpentine Beetle)
Douglas-fir species (Douglas-fir Beetle,
Douglas-fir Pole Beetle, Scolytus spp.)
Spruce Beetle
Aspen Bark Beetles
Fruit Tree Bark Beetles
RED TURPENTINE BEETLE (Dendroctonus valens)
Attacks only the lower 3 feet of trunk
Large red adults
Big pitch tubes
Often occurs following fire injury, grade change, root
damage
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IDENTIFICATION OF IPS
Various species range from 1/16 to ¼ inch long (i.e., some as big as MPB)
CO has at least 14 spp., most in pine, some in spruce
Adults all have spiny back ends (as opposed to rounded back ends of Dendroctonus spp.)
EXTERNAL IPS INFESTATION CLUES
Rarely does ips produce pitch tubes
Most common sign is boring dust in little piles within bark crevices
Woodpecker activity may indicate where the problem trees are
IPS GALLERIES
Multiple females involved, thus each gallery is branched or forked (result is a “Y” or “X” pattern)
Galleries made by adults usually clear of frass
TWIG BEETLES
VERY SMALL, MANY SPECIES
USUALLY IN BRANCH ENDS
INDICATE WATER STRESS
CAN BE IN TRUNKS OF TRANSPLANTS
AFTERMATH OF OTHER BARK BEETLE EPIDEMICS CAN INCLUDE A BRIEF OUTBREAK OF THESE
PINE TWIG BEETLES
MOST IN THE GENUS PITYOPHTHORUS
USUALLY DO NOT REQUIRE TREATMENT*
CAN BE AN INDICATOR OF DRY CONDITIONS
*Transplants are the exception
TWIG BEETLES
Pityophthorus sp.
Pityogenes sp.
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BARK BEETLES OF DOUGLAS-FIR
Douglas-fir Beetle
Restricted to large-diameter trees
Attacked trees often set-up by fire or drought
Douglas-fir Pole Beetle
Likes 6-10” diameter trees (i.e., “poles”)
Engraver Beetles in the genus Scolytus
Like “Ips” in pines, often secondary, may occur in all sizes of trees, often with the
above
DOUGLAS-FIR BEETLE (Dendroctonus pseudotsugae)
Although related to MPB, not nearly as aggressive
Rogaine user?
Likes large-diameter
blowdown, fire-charred trees, drought, and trees stressed by budworm defoliation
Flies in early summer
Photo by Contech
SPRUCE BARK BEETLES
Spruce Beetle (requires large-diameter trees, outbreaks usualy start with a wind event blowing down areas of trees, can be a major influence on the landscape)
Spruce Ips (at least 3 species: one in blue spruce in urban areas can be somewhat troublesome, others in forest situations are usually not serious)
Other minor species (twig beetles, etc.)
SPRUCE BEETLE (Dendroctonus rufipennis)
Likes standing, big, spruce near a stream
Likes fresh windthrown spruce
Epidemics start in blowdown and move into standing trees
Major outbreaks in CO in the late 1940s (Trapper‟s Lake) and late 1990s (nw of Steamboat Springs)
Presently active on Grand Mesa, elsewhere in w CO
THE “BLOWDOWN” BARK BEETLE
Area near Clark, Routt County CO. 1997
STARTED HERE
FINISHED HERE
SPRUCE BEETLE SIGNS AND SYMPTOMS
STANDING “FADER”
NEEDLE DROP
GALLERIES PITCH TUBES
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MORE SPRUCE BEETLE BIOLOGY
Sometimes produces runny pitch tubes, sometimes coagulated ones.
Crown discoloration of infested trees is difficult to detect
3-toed woodpecker is primary avian predator
TRUE FIR BARK BEETLES
Balsam Bark Beetle - in genus (Dryocoetes, pronounced “dry-o-see’-teez” acts in concert with root disease fungi and can result in large-scale mortality of high-elevation stands under moisture stress
Fir Engraver (Scolytus ventralis) can cause widespread top-kill and whole tree mortality
Other minor species
BALSAM BARK BEETLE (Dryocoetes confusus)
Affecting subalpine fir (Abies lasiocarpa) statewide
Usually acts in consort with root disease fungi such as Armillaria and Fomes (together, called “SUBALPINE FIR DECLINE”)
Prime suspect as being a consequence of climate change
males (top), females (bottom)
by Jeff Witcosky of USFS
BALSAM BARK BEETLE EGG GALLERY
Distinctive “stellate” pattern
Note central nuptial chamber
Female egg galleries (6 plus a partial 7th) radiate from the mating area
Staining fungus Ophiostoma dryocoetidis in involved in beetles‟ success
FIR ENGRAVER (Scolytus ventralis)
Ecologically similar to Ips in pine and spruce
Usually only found in stressed white fir
Often attacks upper trunk first
Egg galleries are horizontal
Has been a an issue n of Durango
CEDAR BARK BEETLES
Found only in junipers and Eastern Red Cedar in our area
Require considerable stress (usually lack of adequate water)
Galleries distinctive
We have 4 spp.
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URBAN BARK BEETLES OF DECIDUOUS HOSTS
ELM Smaller Eur. Elm Bark Beetle (Scolytus multistriatus) Banded Elm Bark Beetle (Scolytus shevyrewi)
ASH Ash Bark Beetles (few species in genus Hylesinus)
HACKBERRY Hackberry Bark Beetle (Scolytus muticus)
FRUIT TREES Shot-hole Borer (Scolytus rugulosus)
ASPEN Two minor, unaggressive species
BLACK WALNUT Walnut Twig Beetle (Pityophthorus juglandis)
ELM BARK BEETLES
Banded Elm BB
Recently from Asia
Now the default elm bb
Apparently a poor DED vector
Smaller European Elm BB
From Europe 100+ years
Being replaced by BEBB?
Has been the major vector of DED in NA
ELM BARK BEETLE GALLERIES
SMALLER EUROPEAN BANDED
ASH BARK
BEETLE
SIGNS AND
SYMPTOMS
ASH BARK BEETLE
WITH BARK WITHOUT BARK
SHOTHOLE BORER (Scolytus rugulosus)
Essentially our only bark beetle in fruit trees (cherry, plum, peach, etc.)
Usually stress is the problem, not these bark beetles
Paying attention to water/borer issues is best prevention
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ASPEN BARK BEETLES (2 spp.) WALNUT TWIG BEETLE
Vector of Thousand Canker Disease fungus (Geosmithia morbosum)
New to CO
How did they get here?
Nothing known to date to stop them
Native to Mexico and Southwest U.S.
BARK BEETLE INFO AVAILABLE FROM CSU/CSFS
CSU Cooperative Extension Fact Sheets
5.563 “Firewood & House Log Insects”
5.558 “Ips Beetles”
5.528 “Mountain Pine Beetle”
2.948 “Pinyon Pine Diseases & Insects”
Garden Insects of North America (book)
CSU Bioag Sci. and Pest Mgmt. Dept. website
Outreach and Extension
Thousand Cankers Disease/Walnut Twig Beetle
“Whitney for President”
WESTERN SPRUCE BUDWORM
MOST IMPORTANT FOREST DEFOLIATOR IN CO
DOUGLAS-FIR IS FAVORED HOST
CAN KILL TREES WITH 3+ YEARS OF HVY. FEEDING
PRESENTLY ACTIVE IN SAN JUAN AND LA GARITA MOUNTAINS
WSBW EGG MASSES
USED TO PREDICT POPULATIONS
LAID IN EARLY SUMMER ON NEEDLES
GREEN ONES ARE FRESH
GRAY ONES ARE OLD AND HATCHED
EACH MASS CONTAINS DOZENS OF EGGS
FRESH
OLD
HOW DO BUDWORMS COPE OUT THERE IN FEBRUARY?
Very tiny larvae live in shelters called “hibernaculae” up in the tree crowns
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WSBW LARVA
EARLY SUMMER
MINES OLD NEEDLES
THEN IN BUDS
THEN IN NEW NEEDLES
WSBW DEFOLIATION
STARTS AT TOP OF TREE
STARTS AT BRANCH ENDS
OCCURS IN EARLY SUMMER
CAN RESULT IN TOP-KILL OR MORTALITY
WSBW TREATMENT TIMING
SPRAYING IS NOT ALWAYS NEEDED
BUT WHEN IT IS, TIMING IS CRITICAL
BEST TIME IS WHEN BUDBREAK IS OCCURRING FOR THE MOST- VALUABLE HOST
WSBW AERIAL SPRAYING
WILL BE RARE IN THE FUTURE
BEST DONE WITH Bacillus thuringiensis PRODUCTS (low impact on non-target species)
MOST ECONOMICAL WAY TO TREAT BIG AREA
TIGER MOTH
Forms a white tent at the very top of various conifers
Larvae active in winter, stay in tent
Larval hairs irritate skin
May kill tree tops, at most
Has been an issue in p-j near Ridgway
PINE SAWFLIES
Chew mostly “old” needles
Longterm defoliation gives trees “tufted” appearance (needles at ends of branches OK, interior needles gone)
Female has sawlike egg-laying organ, deposits eggs inside needles
Tend to like smallish trees, often open-grown
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EUROPEAN FLEA WEEVIL
Leaf miner and chewer of elms, mostly Siberian
European species
Has exploded on the
scene in CO over the last 5 years (replacing Elm Leaf Beetle?)
Adults are small
weevils that “hop”
EUROPEAN ELM FLEA WEEVIL
LARVAL MINING AROUND LEAF EDGE ADULT FEEDING INJURY
ADULT
VIEWS
(actual size
about 1/8”)
ADULT
FEEDING
LARVAL
MINING
EUROPEAN ELM
FLEA WEEVIL MANAGEMENT OF ELM FLEA WEEVIL
Probably not necessary, if tree mortality is the only concern and there are not additional stresses like extreme drought, leafminer or ELB
In cases where esthetics matter and/or there
are other serious stresses:
Systemic application or foliar spray in early summer
Perhaps an additional foliar spray in mid-summer
Promote bird populations and proper watering
SAWFLY LEAFMINER OF ELM Fairly new Mostly aesthetic in impact Larval mining mostly May Would require systemic or
foliar treatment early in the growing season
Adults present in the weeks immediately after budbreak
Following larval mining, larvae drop to ground and pupate in soil in early summer (beginning ~ June1)
STAGES OF SAWFLY MINING (early at left, later at right)
eggs and
early
mines
mature
larva
within
mine
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ELM LEAFMINER (Kaliofenusa ulmi)
Used to be mostly minor miner (Am. Elm)
Now a much more major minor
„Mazing
Much more common now in Siberian elm than it used to be
Probably mostly an aesthetic issue
WOOD BORERS
Mostly beneficial
Mostly secondary
Usually best considered symptoms of the problem, not the actual problem
Insects with this habit include beetles (longhorned and metallic wood borers), moths (carpenterworms), and wasps (wood wasps/horntails)
PONDEROUS BORER
Biggest beetle in CO
Unusual to see
Usually found at the base on the north side of large pines dead about 2-5 years
Make a hole the size of your thumb
POPLAR BORER (Saperda calcarata)
Type of longhorned wood borer (beetle)
Dripping orange or purple stain on bark of living tree is best symptom
Boring dust often produced in spring-early summer at hole
Fixing stress fixes the borer
CARPENTER ANT
Carpenter ants are usually big and black, but some species are intermediate in size and may have reddish coloration
They normally live in wood and forage elsewhere
Carpenter Ants Thin waist
Usually black or red in all stages
Elbowed antennae
Flying stages with unequal wings
“ANASAZI” ANTS (aka CARPENTER ANT)
Ants do not “eat” wood but rather excavate it for nesting
Wood chosen by ant colonies is usually moist and semi-decayed
Boring dust produced
(unlike termites)
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DWARF MISTLETOE (Arceuthobium vaginatum)
Parasitic plant
Has explosively-discharged seeds (short-distance spread)
Long-distance spread via birds and mammals
Can lead to dense branching called “witches‟-brooms” (favored nesting location of certain birds, incl. Spotted Owl)
MISTLETOE “BROOMS”
SHOOTING SEEDS! EGADS!
Mistletoe seeds are
explosively
discharged in late
summer via water
pressure
May disperse by this
method up to 48
feet! (birds and
mammals can carry
them further)
Speed of seeds is
up to 55mph
MISTLETOE MANAGEMENT
Most of the time, just live with it
Ethephon (“Florel”) sprays are very difficult and expensive (not normally recommended)
If infections are light, or isolated to one area of your property: Clearcut small infected areas
If infections are very light in a given tree, prune out affected branches
Isolate infected portion of the property by cutting a buffer 1-2x tree heights
DECAY At left is a common decayer
of ponderosa pine, Red Belt Fungus (Fomitopsis pinicola)
Fruiting body (as shown) is called a “conk”. This is what produces the spores.
Decay can be either outer wood or heartwood or both & lead to tree falling within 3-to-several years of time of death
Wound = decay = hazard
GALL RUSTS
Occur on both forest and ornamental junipers/pines
Usually have a deciduous alternate host
Sporulate in moist periods
Damage minor
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SPRUCE BROOM RUST*
Forms large, round brooms
Broom are yellow during sporulation
May kill branches and top of tree
Alternate host
kinnickkinnick
* SIMILAR DISEASE ON FIRS (alternate host chickweed & other plants)
PLEASING FUNGUS BEETLE Seen these?
Larvae feed on the spore-producing undersurface of decay conks
When you see these, it means long-dead trees are nearby
Beneficial, part of the recycling process
WHITE PINE WEEVIL (Pissodes strobi)
Infests spruce terminals (“pig‟s tail” curl)
Leads to dieback and forked topped-trees
Treatment is best in late spring when adults are laying eggs in spruce tops
Chip cocoons (diagnostic) for
WPW
WESTERN CONIFER SEEDBUG
THIS AND RELATED SPECIES FEED ON SEEDS AND BERRIES OF MANY WOODY
PLANTS
HOUSE INVADER
MOSTLY A NUISANCE
PINE SCALE INSECTS
Pine Needle Scale can also occur on spruce
Most effective treatments target the “crawler” stage
To be anticipated with insecticide treatments for other things (especially chronic applications)
PINE NEEDLE SCALE (above)
BLACK PINELEAF SCALE (below)
HONEYDEW-PRODUCING APHIDS SEVERAL APHID
SPECIES INVOLVED
ELMS, OAKS, PINES AND SPRUCE, ALONG WITH BOXELDER, LINDEN, AND WILLOWS INVOLVED AS HOSTS (OTHERS?)
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COOLEY SPRUCE GALL ADELGID
Major source of phone inquiries from the public
Insect is a “woolly aphid”
Life cycle involves both spruce and Douglas-fir
Not a problem, really
COOLEY GALLS AS A FUND-RAISER ITEM
PORCUPINE “EGGS” $1 EACH
ARTICHOKE GALL MADE BY THE JUNIPER TIP MIDGE
(Oligotrophus betheli) ON UTAH JUNIPER
ERINEUM MITES ON MOUNTAIN MAPLE
Microscopic mites formation of a “felt” (erineum) made up of zillions of tiny balloons (galls) in which the mites live
Looks like confectionary sugar, with each sugar grain being one gall
In this species, the erineum is bright red
Not harmful to the tree
ASPEN ISSUES ASPEN ISSUES
LEAFMINER
DECAY CANKER
IDIOTS
TENT CAT
TORTRIX
LEAF BLIGHT
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PUTNAM‟S CICADA
This is what makes that clicking sound in the mountains in early summer
Nymphs feed on woody plant roots
Oviposition occasionally causes minor twig breakage
ROOT WEEVILS Otiorhychus spp.
Adults are black,
broad-nosed weevils
Adults feeding results
in notched leaves
Larval feeding is in the
soil to roots and is the
real damage
Several CO species
Treat with soil drench
MAGNESIUM CHLORIDE
Used as both winter de-icer and summer dust control agent
Studies by both CSU (Betsy Goodrich) and UNC found issues with trees near roads
Movement away from immediate roadside does not appear to be serious
Note resin bands = salt
LICHENS
Plants made of both fungi and algae
Foliose and fruticose types shown above
Some fix nitrogen, some are eaten by animals
Being recognized as ecosystem health indicators
Do NOT harm trees, contrary to popular opinion
Kent Simmons
U of Winnipeg
FOREST INSECT & DISEASE REFERENCE BOOKS
Western Forest Insects by Furniss and Carolin
Insects and Diseases of Woody Plants of the Central Rockies
(REVISION COMING 2013?)
(CSU Ext. Bulletin 506A)
970/491-6198 ($50)
Others (Cornell books, Kansas, Garden Insects, etc.)