Balsam Woolly Adelgid Adelges piceae

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Balsam Woolly AdelgidAdelges piceae

• Presented by Allison Kanoti

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Balsam Woolly Adelgid

• Reading
• http//www.fs.fed.us/r6/nr/fid/fidls/fidl118.htm

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Introduction

• Forest Management Natural Regeneration
• Tree Adaptations Refer to SBW notes

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IntroductionBalsam Woolly Adelgid

• Introduced from Europe in early 1900s
• Susceptible Species
• True firs (Abies sp.) in North America

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Tree Symptoms

• 2 general types of infestation
• Crown infestation
• Stem infestation

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Tree Symptoms Crown Infestation

• Gout Phase
• swollen branch nodes
• stunted terminal growth
• Needle Mortality
• Bud Suppression

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Crown Infestation (Contd)

• Crown thinning and Mortality
• abnormal crown shape
• prone to breakage

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Tree Symptoms-stem infestation

• Trunk Phase
• rotholz (rotred, holzwood)
• Red-colored wood
• Purple patches beneath bark
• Broken, blocky bark

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Diseased Functions

• Tissues initially affected
• Needles mortality
• Buds suppression
• Sapwood uncontrolled, abnormal growth, poor
  water conduction
• Impact on tree
• crown deformity
• dieback
• predisposition to windthrow and root disease
• death

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Diseased Functions

• Impact on Forest
• dependent on climate, forest composition, site
• loss of dominant and co-dominant fir component
• change in species composition and age structure

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Impact on Forest Maritime vs. Continental N.B.
Characteristic Maritime Continental

• All trees crown and stem infestations
• Crown infestations persist w/ new growth

• Small, isolated patches
• Stem infestations on lower bole
• Crown infestations checked by cold winters

Infestation Pattern

• Some large diameter trees killed by stem
  infestation
• Low tree mortality

• Most overstory trees killed or have dead tops

Tree Mortality
Regeneration

• Some severely gouted and killed

• Regeneration by stem infested trees gouted

Source Greenbank, D.O. 1970. Climate and
ecology of the balsam woolly aphid. Can. Ent.
102 546-578.
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Diseased FunctionsImpact on Forest
BALSAM WOOLY ADELGID INFESTATION SALVAGE
HARVEST. . .
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Primary Stress Agent

• Balsam Woolly Adelgid -- Adelges piceae
• Introduced from Europe ca. 1900 on nursery stock
  to Maine and Nova Scotia
• On native silver fir does not cause significant
  damage
• North American host trees Abies spp.

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Pathogen

• Signs
• Eggs--up to 248 yellow eggs laid in waxy
  wool-like extrusions
• Larvae--3 larval instars
• Adult-- approximately .8 mm long, covered in waxy
  wool-like material

Photo Jerald E. Dewey, USDA Forest Service,
www.forestryimages.org
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Environment

• Host True firs
• balsam and Fraser in the east sub-alpine,
  Pacific silver and grand in the west

Native range of balsam fir (from silvics)
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Environment
East Coast West to east prevailing winds limit
inland spread

• Distribution of Balsam Woolly Adelgid
• From BWA FIDL 1970

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Environment

• Moderate winters
• Do not survive below -30º F
• Snow and tree structures afford some protection
  from cold

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Predisposing FactorsTree Adaptations

• Introduced Pest
• North American firs highly susceptible
• Site
• Productive
• Washington State, Pacific silver fir
• Johnson et al. 1963
• Well drained to dry
• Newfoundland
• Page 1975
• Poorly drained
• Maine
• Brower 1947

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Predisposing FactorsTree Adaptations

• Age Related Factors
• Initial infestations on larger trees
• Taller
• Deeper Crowns
• Larger Diameter
• More likely to have stem infestations
• Ideal size around 30-40 years old
• Rough barked trees more susceptible (more
  protected locations)
• Younger, denser stands less susceptible

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Predisposing FactorsDegree of Stress

• Life Cycle Components
• Impacting Degree of Stress
• Eggsaverage 100 eggs/female 1st gen (50, 2nd
  gen), some dispersal
• Larvae Crawlers mobile stage, dispersal,
  overwintering
• Adults High reproductive capacity
• Reproduction parthenogenetic, no males
  necessary, no need for mate finding or successful
  mating
• Multivoltinism

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Predisposing Factors Degree of StressLife Cycle
(Maine 2 generations/year)
Overwintering Neosistens
2nd, 3rd instars and adult
1st Instar (Crawler)
Neosistens
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Predisposing Factors Degree of StressMechanism
of Disruption

• Stem Infestation
• change in water transport structures
• development of rotholz
• Reaction to chemicals in the insects saliva
• Thick walled cells, wide rings
• Similar to compression wood/heartwood
• poor water conduction
• physiological drought

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Predisposing Factors Degree of StressMechanism
of Disruption

• Crown Infestation
• change in wood structure (rotholz)
• old needles not replaced
• buds inhibited
• loss of photosynthesizing capacity
• gradual starvation

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Predisposing Factors Degree of
StressPopulation Controls

• Weather
• Early or late freezing temperature
• 100 mortality of overwintering stage at -30ºF,
• NB study, 40 died w/ low T of -22 º F (80
  after 5 days of -22 ºF)
• All other life stages die w/ prolonged temps lt32
  ºF, killed instantly _at_ -5 ºF
• Cold winters with little snow cover
• Warmer climates see more generations/yr.

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Predisposing Factors Degree of
StressPopulation Controls

• Native Predatory Invertebrates/Introduced
  Predators
• Native natural enemies
• Predatory mites
• Lacewings (occasional)
• Plant bugs (Mirids)
• Coccinellids
• Syrphids
• Most important natural enemy
• Success limited by high level of parasitism
• Introduced biological control
• 3 Coleoptera
• 3 Diptera

http//photo.dipterologic.com/data/media/1/ skuzne
tzov_syrphus_torvus_DSC072345.jpg
http//www.rutkies.de/kaefer/Aphidecta20obliterat
a 20-20Gebirgsmarienkaefer2001.html
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Predisposing Factors Degree of
StressPopulation Controls

• Native Predatory Invertebrates/Introduced
  Predators
• Issues
• Generalist predators
• Univoltine predators, multivoltine target
• Do not feed on important life stages
• Controls dependent on high adelgid populations
• Cold tolerance of introduced controls
• Introduced predators all adapted to feeding on
  stem infestations
• Ideal
• Specialist Predator
• Capable of surviving on low densities (and
  keeping densities low)
• Capable of responding through increased fecundity
  or increased feeding rate to growth of prey
  populations
• Capable of active searching and feeding
• In diverse habitats (stem and twig)
• On several life stages (esp. egg crawler)
• Parasitoid (no known on Adelginae)

http//cedarcreek.umn.edu/insects/ album/029083009
ap.html
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Predisposing Factors Degree of
StressPopulation Controls

• Food availability and quality
• After several years of infestation, changes in
  the bark structure can make individual trees
  temporarily unsuitable
• Leads to decreased adelgid population
• As cracks form, parenchyma is near surface
• Again suitable for adelgid
• Possible for insects to build up from low level
  populations on understory fir

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Inciting Factors

• Arrival of crawler on suitable feeding site
• Insertion of stylet and change to neosistens
  (rotholz develops at this stage regardless of
  further survival of the insect)

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Contributing Factors

• Drought
• Ice and wind damage
• irregular crown shape contributes to
  predisposition to damage
• Fungal Infection
• root rots (which further predispose to windthrow)

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• Questions?

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Your Questions

• Based on your knowledge of the balsam woolly
  adelgid and of balsam fir
• describe preemptive control measures.
• Describe reactive control options
• Justify your answers with supporting biological
  and ecological characteristics of the species