Wood Decay and Forest Disease

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Wood Decay and Forest Disease
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Saprotroph ( saprophyte, saprobe) an organism
that acquires its nutrition from dead and
decaying plant matter, or other organic
non-living substrate Biotroph - an obligate
parasite growing on or in another organism
acquires derived from living cells Necrotroph -
parasite that kills host cells acquires
nutrition from dead cells Pathogen - a parasite
that causes disease
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• Saprotroph substrate groupings
• Sugar fungi rapidly exploit simple organic
  compounds
• Cellulytic fungi degrade cellulose similar
  common polymers
• Lignin-degrading fungi degrade complex polymers
  
• Secondary sugar fungi gain access to simple
  compounds
• via activity of other fungi

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• Behavioral grouping
• Pathogens and weak parasites
• Pioneer saprotrophic fungi
• Polymer-degrading cellulose, hemicellulose,
  starch, lipids,
• proteins
• Degrade recalcitrant compounds
• Secondary saprotrophs

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• The challenge of wood decay
• Consists of complex polymers
• Cellulose 40-50 (beta 1-4 D-glucose)
• Hemicellulose 25-40 (beta 1-4
  D-xylose)
• Lignin - 20-35
• Very low N levels CN is 5001
• Low P levels
• Potentially fungitoxic compounds
• Hardwoods - tanins
• Conifers - phenolics
• Thujaplicins (cedars) - source of
  resistance to decay fungi

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• Soft Rot
• decay of wet wood
• degrade cellulosic material in soil and
  estuaries
• mostly ascomycetes
• degrade cellulose and hemicellulose via
  cellulases
• do not degrade lignin

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• Brown Rot - cubicle brown rot
• 10 of all wood-decay fungi
• 80 of these occur on conifers
• mostly members of the Polyporaceae
• degrade cellulose and hemicellulose but not much
  lignin
• the major component of humus
• degrade cellulose via oxidative process
  involving production
• of H2O2 during breakdown of hemicellulose

fhpr8.srs.fs.fed.us/idotis/diseases/
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• Ecology of brown rot fungi
• humus
• remains in soil for up to 3000 years
• essential for continued renewal of coniferous
  forests
• many conifers germinate in lignin rich - humus
  soils
• brown rot residues increase
• aeration and water holding capacity of soil
• mycorrhizal formation
• N fixation by free living bacteria
• soil cations
• decrease soil pH

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• White rot fungi
• largest group of wood rot fungi Basidiomycota,
  Ascomycota
• degrade cellulose, hemicellulose and lignin at
  equal rates
• produce a white stringy decay of wood
• 3 classes of enzymes for cellulose
  hemicellulose degradation
• Hydrolytic cellulase, glucanases, glucosidases
• Oxidative enzymes cellobiose (hemicellulose)
• Oxidoreductase cellobiose reductase

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• several enzymes involved in what is referred to
  as an
• "enzymatic combustion of lignin,
  nonspecific
• degradation of lignin by phenol oxidases
• Laccase
• Lignin peroxidase
• Mn-peroxidase

lignin
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Some major groups of litter and wood decay
fungi Aphyllophorales (non-gilled) Polyporacea
e (major brown rot group) Hymenochaetaceae Cort
iciaceae (resupinate) Agaricales Agaricaceae En
tolomataceae, Pluteaceae Lepiotaceae,
Tricholomataceae Strophariaceae Jelly
fungi Auriculariales Tremellales Dacrymycetales
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• some wood decay fungi cause disease
• many forest pathogens participate in wood decay
• many wood decay fungi and forest pathogens are
  closely related
• heart rot, butt rot, root rot
• play important role in creating gaps

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• Heart Rot
• may cause canker formation as they grow into
  sapwood
• eventually arrive at heart wood where they can
  weaken tree
• increases susceptibility of wind throws
• some heart-rot and butt rot fungi can eventually
• attack functional vascular tissue

Inonotus
Sparassis
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Phaeolus schweinitzii - butt-rot attacks
the roots of living trees host becomes
more susceptible to wind-throws
www.cfl.scf.rncan.gc.ca/imfoc-idwcf/images/maladie
_full/ea_012_g.jpg
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• Phellinus spp.
• causing agent of laminated root rot
• important in the decline of the Douglas-fir
  stage of
• succession in cedar-hemlock forests
• affects other conifers as well (e.g., Pinus
  spp.)

www.pilzverein.de/galerie/galerie.htm
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• Armillaria spp.
• Armillaria root rot
• enters through roots
• results in damage and death of main roots near
  root collar
• extensive colonization below bark
• mycelial fans and rhizomorphs

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Several heart, butt and root rot fungi are able
to survive as mycelium in dead root systems for
decades provide an inoculum to infect roots
that come into contact with dead fungus-bearing
roots. Fungal rots are also common in houses,
utility poles, pilings, etc. with the most
common resulting in what is referred to as dry
rot.
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• Serpula lacrimans
• dry rot
• major cause of wood decay in homes
• misnomer requires 20 humidity
• produce rhizomorphs that translocate water

www.streetandwalton.co.uk/church/images/timber1.jp
g
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• Importance to animals
• many cavity nesting birds prosper in old growth
  forests
• Red-cockaded Woodpecker the reduction in number
  of birds
• linked to the loss of older southern pines with
• extensive heart rot caused by Phellinus pini
• managed southern stands are harvested on a
  shorter rotation
• than is necessary for substantial heart-rot to
  take place
• the extinction of the Ivory-billed Woodpecker

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• Medicinal and Cultural uses
• the basidiocarps of a large number of species of
  wood decay
• fungi are used medicinally
• Ganoderma lucidum - Ling Chi, Reishi
• up to 12 species of Phellinus have been used in
  herbal medicine

perso.club-internet.fr/sevlauqu/fichiers_html/inde
xspecies.htm
www.mycolog.com/chapter18.htm
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• Fompitopsis officinalis
• used by indigenous peoples of the PNW
• grave guardians
• administered medicinally
• the quinine conch
• treatment of tuberculosis
• Many local edible species
• Sparassis crispa
• Hericium erinaceum
• Laetiporus sulphureus

www.herongroupllc.com/russia/efp/0012m_.htm