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FOREST INSECT & DISEASE ISSUES IN ORNAMENTAL TREES

TRA PEST MANAGEMENT WORKSHOP

GRAND JUNCTION, CO FEBRUARY 2012

Dave Leatherman daleatherman@msn.com

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.)