TREES ARE STRESSED BY: What s Killing My Trees? Planting site is important! AVOID/MITIGATE DAMAGE: Tree Health Problems in Northwestern Oregon Forests

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1 What s Killing My Trees? Tree Health Problems in Northwestern Oregon Forests Tree School 2017 Clackamas Christine Buhl Entomologist Oregon Department of Forestry Christine.J.Buhl@oregon.gov Holly Kearns Plant Pathologist USDA Forest Service hkearns@fs.fed.us TREES ARE STRESSED BY: Species/cultivars not suited to climate, location, etc. Poor or inappropriate site quality Drought Competition Old age/low vigor Mechanical injury Fire, ice, wind damage Vertebrate, insect, pathogen damage Drought damage in Doug-fir STRESSED TREES = SUSCEPTIBLE TREES AVOID/MITIGATE DAMAGE: Planting site is important! Plant appropriate species (natives!) in appropriate places Avoid mechanical damage (mowers) Avoid soil compaction (driveways, walkways) Avoid chemical damage (drift or runoff of broadspectrum insecticides knock out natural enemies) Avoid over fertilization Water deeply Preventative management of vertebrates, insects and pathogens 1

2 Drought Storm damage Temperature Precipitation Black Bear Deer and Elk Jackrabbits and hares Mountain Beaver Pocket Gophers Porcupine Woodrats Livestock Vertebrates Vertebrate damage Problematic in reforestation and young plantations Bear damage peel lower bark to eat cambium in pole size stands Porcupine and squirrel damage tops and trunk. Look for: tracks, teeth marks, claw marks, antler rubbing, scat, tunnel characteristics 2

3 Forest insect pest groups Bark beetles make galleries under bark, introduce stains Wood borers tunnel through wood, some cause stain o Longhorned and metallic borers, ambrosia beetles, wasps, caterpillars Defoliators partially or fully defoliate trees o Moth and butterfly caterpillars, sawfly larvae, leaf beetles BARK BEETLES Sapsucking insects remove nutrients and moisture from trees o Scales, aphids and adelgids There are also insects that specialize on terminals, roots, cones, buds, within needles, etc. How bark beetles work Smaller than a grain of rice All life stages are under bark Galleries under bark not in wood Chemical communication to identify trees and communicate Mass-attacks Can vector stains Bark beetle development 1. Adult identifies a stressed tree (via volatiles) 2. Tunnels under bark and emits attractant pheromones 3. One or more of the opposite sex arrives to mate 4. Anti-aggregation pheromones are emitted = 5. Eggs are laid in the nuptial chamber 6. Larvae hatch and feed on cambium/phloem 7. Larvae undergo several molts then pupate 8. Adults emerge, leave the tree to seek out another host 3

4 Signs and symptoms of bark beetles Infested vs. vacant tree Pitch / frass Galleries Many exit holes (diameter of gran of rice) indicate most of the beetles have left Stains Color change often happens after beetles have left, peel bark to see if infested Doug-fir beetle Associations: storm blowdowns, root disease Prefers: >10 Doug-fir blowdown or stressed trees Signs: frass, streaming clear pitch, gallery with alternating groups Timing: April-June attacks (July Oct smaller flight) Management Remove downed trees before April of the: 1 st year after storm (before beetles infest and vector stain) OR 2 nd year after storm (when beetles are trapped ) Remove overly-mature, damaged or stressed trees Apply MCH repellent before April following storm DOUGLAS FIR BEETLE Infestation/Outbreak Cycle Winter 1) Storm event causes blowdown and broken tops Remove blowdown or apply MCH before beetles can enter 2 nd April 3) DFB exits blowdown and attacks >10 dbh standing trees (preference for overly mature, damaged or stressed trees) Remove blowdown before beetles can leave to attack standing trees 1 st April 2) DFB attacks >10 dbh blowdown and takes 1 year to develop 4

5 MCH (anti-aggregation pheromone) Apply before April 1 blister pack per tree in a grid (~30/acre) $80-100/acre Also in flake form for aerial application More efficacious if paired with silvicultural management Ips spp. beetles Associations: drought, poor slash management Prefers: >3 fresh slash, small trees, branches and tree tops Signs: tiny pitch tubes, red tops, X or Y galleries Timing: April-Oct attacks (several overlapping generations) Management Oct.-Dec. leave slash on ground to dry Jan.-Sept. chip/burn >3 fresh slash (either before April flights or within a month if created spring/summer) Verbenone repellant not proven for Ips 1) Forest operations or storm event creates 3 8 diameter slash Burn, chip, remove from site IPS SPP. Infestation/Outbreak Cycle More generations into early fall 3) Ips move to standing trees (preference for dense, polesized or tops and branches of larger, stressed trees) Thin and remove stressed trees well before beetles can attack Following April 2) Ips attacks slash and a new generation develops in as little as 2 months Mountain pine beetle Associations: overly dense and mature stands Prefers: dense >60yr. >6 dbh pine Signs: pitch tubes, J gallery, woodpecker damage Timing: late spring - Aug attacks Management Manage stocking levels (particularly dog-haired lodgepole) Remove trees with >50% crown scorch or >25% cambium damage, mechanical damage Manage slash for Ips! Verbenone has variable efficacy 5

6 Western pine beetle Associations: drought, fire-stressed trees Prefers: >6 diameter ponderosa Signs: pitch tubes, spaghetti galleries inside bark, woodpecker damage Timing: April-Aug attacks Management Manage stocking levels Remove trees with >50% crown scorch or >25% cambium damage, mechanical damage Remove trees with woodpecker damage without exit holes Manage slash for Ips! Verbenone has variable efficacy Fir engraver* Associations: drought, root disease Prefers: >4 fresh slash and pole-mature true fir Signs: streaming clear pitch, horizontal galleries, branch or top kills Timing: June-Sept attacks Management Manage for root disease Reduce true fir on dry sites Remove fresh >4 slash before June *secondary pest Wood boring beetles WOOD BORING INSECTS Flathead and roundhead beetles Round or oval exit holes Tunnels through wood (some just stay under bark) Ambrosia beetles Tiny exit holes Black stains White frass *Most woodborers are only secondary pests and important decomposers 6

7 Flatheaded fir borer Associations: poor site quality, drought, fires Prefers: damaged or drought/fire stressed DF Signs: concentric meandering galleries, woodpecker damage, D shaped exit holes Timing: attacks in summer Management Reduce DF in poor sites oak pine Remove trees with: >50% crown or >25% cambium damage Remove trees with woodpecker damage without D shaped exit holes Flathead larvae relative to bark beetles Bronze birch borer Associations: overexposure to sun or dry conditions Prefers: European & Asian varieties Signs: branch dieback starting at top of tree Management Plant correct varieties in shaded/moist locations Deeply water and mulch birch Prune out dead/dying/thinning branches early INVASIVE! Emerald ash borer INVASIVE! Asian longhorned beetle SIGNS: D shaped holes or dead branches in ash Report find: INVADER More info: Round holes and chewed niches in various hardwoods Report find: INVADER More info: 7

8 Sequoia pitch moth Prefers: ornamental pines, pines with pruning wounds, previously infested pines Signs: large pitch masses Management Prune October-February to allow healing time Remove soft pitch masses Lure traps Carpenterworm Prefers: oaks and other hardwoods Signs: wide and deep tunnels, dark sap spots on trunk, frass, weakened limbs Management Remove infested branches to reduce populations and hazard risks Skewer larvae through tunnels Apply nematodes into tunnel and plug entrance Silviculture for forest health Remove slash and blowdown Remove infested trees Thin before outbreaks can occur Plant native species and cultivars in appropriate sites Diversify species and structure Manage for root disease Do not fertilize during droughts Defoliators HEALTHY TREES = RESILIENT TREES 8

9 Western tent caterpillar Prefers: alder, other broadleaves Signs: cyclical outbreaks, partially or fully chewed leaves, tents Western oak looper Prefers: white oak Signs: cyclical outbreaks, partially or fully chewed leaves, webs Management Broadleaves will reflush Prune tents Bt, spinosad NPV, natural enemies INVASIVE! Gypsy moth Massive defoliation of hundreds of species of hardwoods and some conifers Report find: INVADER Sucking insects More info: 9

10 Black pineleaf scale Associations: mosquito and agricultural sprays Prefers: pine, spruce, DF Signs: chlorotic spots, needle loss/lion s tail, dieback and mortality (if chronic) Galls Prefers: oaks and other hardwoods Signs: galls in leaves, twigs, etc., can trigger debarking by squirrels and tip dieback Management Soaps & Oils: Insecticidal soap / Horticultural oil Systemic insecticides: Acephate / Imidacloprid What is a Disease? Environment Time Pathogen Host An interaction between a host, a pathogen, and the environment that results in some sort of malfunctioning of the host What causes disease? Fungi Parasitic plants Bacteria/Viruses Nematodes 10

11 Roles of Forest Diseases Most diseases are native. A main driver of forest succession, structure, and composition. Outbreak = response to forest conditions, host availability, and environmental conditions. The best way to deal with most diseases is to prevent them through sound management. Types of Diseases Diseases are often grouped by part of tree attacked Root diseases Stem/Branch diseases Cankers Dwarf mistletoes Decays Foliage diseases Root Diseases Caused by fungi that live underground Attack and kill tree roots Limiting water and nutrient uptake Cause decay in roots and butt Weaken trees Cause windthrow & breakage Predispose trees to bark beetle attack Difficult to manage Primary spread from dead material All conifers are susceptible to this type of infection when they are young (up to about 20 yrs. old). 11

12 Root Diseases landscape patterns Recognize by pattern on the landscape Trees in various stages of decline Trees of all size/age classes are dying Tree species being killed Tipped out or broken off trees Brushy openings Bark beetle attacks Off color foliage Short growth Symptoms of Root Disease Thinning Crown Stress cones Laminated Root Rot Delaminated decay Caused by: Phellinus sulphurascens (formerly P. weirii) Major Hosts: Douglas fir, white & grand fir, mountain hemlock Other Hosts: Western hemlock, Subalpine and Noble firs Trees of all sizes, ages, vigor are susceptible Fungus lives long term in dead roots W. OR Est. 8.6% of Douglas fir forest occupied by LRR centers with 50% mortality (Hansen and Goheen 2000) 12

13 Pits and Setal Hyphae Laminated root rot: stain in fresh stump Hollow stumps Armillaria Root Disease Different fungal species on conifers and hardwoods: Armillaria ostoyae on conifers Armillaria mellea on hardwoods Major Hosts: Varies by site Grand and white firs highly susceptible West side: young Douglas fir All conifers may be affected Widely distributed Often found affecting trees weakened by other agents: insect defoliators, overstocking, drought, soil compaction, etc. Armillaria Root Disease on Oaks Typical root failures of Oregon white oak in irrigated landscapes 13

14 Heterobasidion Root Disease Caused by: Heterobasidion occidentale Wide host range Western hemlock, grand & white firs highly susceptible Also acts as butt and stem rot Results in toppling and windthrow of live infected and killed trees Potential for damage increases with wounding and harvest activities Spores colonize wounds and freshly cut stumps Heterobasidion Root Disease Most diagnostic: the presence of conks in stumps Heterobasidion annosum Sporophores Heterobasidion Root Disease Decay = pitted, laminated, irregular white pockets, black flecks, stringy & spongy 14

15 Schweinitzii root and butt rot Caused by: Phaeolus schweinitzii Major Hosts: Douglas fir Other Hosts: All conifers Major cause of breakage & wind throw in older conifers Produces conks on ground and base of tree Schweinitzii root and butt rot Velvet top fungus (fresh conks) Cow pie fungus (old conks) Schweinitzii root and butt rot Decay = Brown cubical Black Stain Root Disease Major Hosts: West side: y.o. Douglas fir Wilt disease NOT a decay Associated w/disturbed areas, roads, compacted soils, etc. Can cause significant mortality 31% of trees killed in 5 28 y.o. Douglas fir plantations (Hansen and Goheen 1988) Not believed to compete well as a saprophyte 15

16 Port Orford Cedar Root Disease Major Host: Port Orford Cedar Distribution: Range of POC on SW Oregon Coast, areas with standing or flowing water, poorly drained sites Introduced species, first report in natural range of POC 1952, near Coos Bay, OR Water mold, requires free water for infection Extensive mortality of all ages and size classes Root Disease Management 1. Monitor & identify: Root disease is sneaky!! Diseases of the site. 2. Survey site when cutting and mark infected stumps 3. Favor tolerant & resistant species: Cedars, Hardwoods, Pines 4. Other options depend on your management objectives and site: stump pulling, push falling, buffer cuts, thinning Cankers Dead tissue resulting from colonization of tree branch or bole by fungi or dwarf mistletoe Douglas fir canker Cankers are often associated with stress, such as from drought. Forestryimages.org Branch flagging 16

17 White Pine Blister Rust Imported from Europe Girdles branches Causes top kill Kills young trees Attacks all 5 needled pines western white pine Complicated life cycle Obligate parasite 5 spore stages 2 hosts Cankers easiest positive diagnosis 17

18 Manage by: Planting stock with improved resistance Pruning to increase survival Leaving healthy seed trees Parasitic Plants: Mistletoes Mistletoes are aerial parasitic plants of forest trees. Leafy mistletoes have berries dispersed by birds. Dwarf mistletoes have berries that explode and shoot the seed. Oak mistletoe, Phoradendron villosum Copyright Teresa Miller Dwarf Mistletoe Oak Mistletoe Phoradendron villosum Obligate parasites of living hosts Host specific (but on most conifers) Cause loss of vigor, growth loss, branch dieback, even tree death Slow spread (by seed) Can take 6 8 years from infection to seed production Paul Hennon, USDA Forest Service, Bugwood.org 18

19 Decays Decay in the wrong place can be a problem Important to wildlife Are Nature s recyclers Produce distinctive decay & fruiting bodies Not usually tree killers Red Ring Rot White pocket rot Most western conifers esp. white pine and larch Early decay red stain in the heartwood Advanced decay white pocket rot Pouch Fungus Small, round, white to tan fruiting bodies usually develop on conifers 1 3 years after beetle attack 19

20 Red Belt fungus One of the most common wood decay fungi in NW Decays nearly all dead conifers and many hardwoods Minimizing Decay Damage Much of decay is desirable Nutrient recycling Wildlife habitats Avoid wounding Harvest early Species manipulation Use less susceptible species Foliage Diseases Symptoms of Foliage Diseases Usually on a single species Usually on one age group of needles Usually worst near the bottom of crowns Favored by moist weather conditions Most are weak pathogens Rarely kill trees, but can make them look pretty ugly 20

21 Swiss Needle Cast Swiss Needle Cast Healthy Diseased Rhabdocline Needle Cast Foliar pathogen versus Natural browning & shedding 21

22 Foliage Disease Management Species manipulation (change species) Avoid off site seed sources Remove most susceptible individuals Thin/prune to dry out environment Let em out grow it Fungicides (last resort nurseries, homes, Christmas trees) Forest Health Ecological: A healthy forest maintains its unique species and processes (structure, composition and function) Social: A healthy forest provides needs for products and services The ability to sustain itself ecologically while providing what society wants RESOURCES USFS Forest Health Protection fidl Oregon Department of Forestry, Forest Health foresthealth Oregon State University, Forestry Extension Service: Questions? Technical assistance: sarah.navarro@oregon.gov (ODF Pathologist) christine.j.buhl@oregon.gov (ODF Entomologist) 22