Module 4. Compartmentalization of decay. Penetration of boundaries. Invasiveness of decay fungi. Prognosis of decay

Transcription

1 Module 4 Compartmentalization of decay Penetration of boundaries Invasiveness of decay fungi Prognosis of decay

2 OMPARTMENTALIZATION F ECAY N REES Shigo & Marx (1977)

3 CODIT-Model

4 Hyphal colonization of wood Within the heart- and ripewood of trees, hyphae grow along the path of least resistance.

5 Active response occurs only within the living sapwood Ring porous trees r. t:r >. 0,3 t Diffuse porous trees!.

6 `Wall 1 of the CODIT model Tyloses Polyphenols Trees can resist longitudinal spread of decay by the occlusions of cells with polyphenolic deposits and via tyloses.

7 Determination of starch in wood with Lugol s Iodine Reagent High energy reserves Low energy reserves

8 Aspiration of bordered pits Margo Sapwood Torus Heartwood Occlusion of tracheids, in conifers (Pinaceae) via aspiration of bordered pits.

9 Temp.-minimum Moulds Temp.-minimum Wood decay fungi Temperature Temp.-optimum Wood decay fungi ±0 Celsius Temp.-minimum Blue stain Temp.-maximum Wood decay fungi

10 `Wall 2 of the CODIT model Latewood cells resist inward and outward spread of decay in the radial direction. Latewood cells are often thick walled and stronger lignified.

11 `Wall 3 of the CODIT model The living cells of the xylem ray parenchyma resist tangential spread of decay by producing abundant polyphenolic deposits.

12 Macro- and microscopic appearance of reaction zones `Walls 1-3 = Reactionzone `Wall 1 `Wall 2 `Wall 3 Schwarze & Baum (2001). New Phytol. 146,

13 Computer tomography maple / Kretzschmaria deusta A high moisture content can be measured within reaction zones of hardwoods eg. maple and beech.

14 Zone lines Enhanced activity of phenoloxidases Host or fungal substances are converted into melanin.

15 Reaction zones - chemical and physical modification of the wood Schwarze & Baum (2001). New Phytol. 146,

16 Reaction zones vs. Barrier zones

17 Development of decay advancing outwards from the centre of a tree As no stem injury is present, only the reaction zone is counteracting decay. Only reaction zones develop within the living sapwood.

18 Wood decay advancing after an injury to a stem Both reaction zones and barrier zones are counteracting decay. The barrier zone sharply demarcates the colonized tissue from the newly formed healthy tissue.

19 Infection courts and host responses to decay in trees Most decay fungi that render trees hazardous become established in the heart- or ripewood of the host. Require exposed heart- or ripewood for infection.

20 Reaction zones and barrier zones

21 Development of decay in living trees Occlusion of cell lumina with polyphenols Anatomy Thylloses Reaction zone? Suberization Moisture content Vitality and season Chemical composition of deposits

22 Inonotus hispidus = dual modes of degradation Meripilus giganteus Ganoderma adspersum Fistulina hepatica Armillaria borealis Armillaria gallica Armillaria cepestipes Armilaria ostoyae Phellinus contiguus Dacrymyces stillatus Simultaneous rot Soft rot Schizophyllum commune

23 Reaction zone penetration by Inonotus hispidus Schwarze & Fink (1997). Mycol. Res. 101,

24 Inonotus hispidus vs. Platanus x hispanica Schwarze & Baum (2001). New Phytol. 146,

25 `Funky Fungi

26 Resistance of xylem rays Schwarze & Fink (1997). Mycol. Res. 101,

27 Inonotus hispidus London plane Ash Strong compartmentalizer Weak compartmentalizer

28 Histological features of barrier zones Barrier zones are chemically and anatomically modified.

29 Kretzschmaria deusta Schwarze et al. (1995). Eur. J. For. Path. 99, Soft rot

30 Schwarze & Baum (2001). New Phytol. 146, Reaction zones in beech are static

31 Beech reaction zone challanged by Kretzschmaria deusta Reaction zones in beech are static boundaries. Schwarze & Baum (2001). New Phytol. 146,

32 Reaction zones in lime are dynamic boundaries Baum & Schwarze (2002). New Phytol. 154:

33 Lime reaction zone challanged by Kretzschmaria deusta Reaction zones in large leaved-lime are dynamic. They progressively migrate into previously functional sapwood. Baum & Schwarze (2002). New Phytol. 154:

34 Characteristics of reaction zones Beech: Large-leaved lime: Dark brown colour 1-2 cm wide Abruptly demarcated from sound wood High amounts of deposits within the cell lumina Vessels with suberised tyloses Static Reddish-brown colour 1-5 cm wide Slow migration of the RZ into the sound wood Deposits mostly in the lumen of parenchyma cells Tyloses absent Dynamic

35 Lignin Substances that inhibit fungal growth in wood Substance Affect Presence Suberin Proanthocyanidin Difficult for fungi to degrade, particular in the presence of high guaiacyl units. Water and air repellent with antifungal properties. Natural resistance against wood decay fungi. Woody cells, particular within the middle-lamella. Tyloses, heartwood, reaction zones, bark. High concentrations within the reaction zone. Catechin Epicatechin Inhibits fungal growth. Involved in the host defence system of plants. High concentrations within the reaction zone of broad-leaved trees.

36 Common features of Ganoderma spp. Basidiomycetes White rot Root- and butt rot Defect symptoms induced by increase in the abnormal bending moment of the stem Selective delignification Simultaneous rot (Soft rot) Annual or perennial fruiting bodies

37 Ganoderma spp. G. adspersum G. lipsiense G. resinaceum Ø2,1μm Ø3,5μm Hyphal strands at the colony margin Hyphal strands absent Chlamydospores Schwarze & Ferner (2003). Arboric. Journal 27.

38 Damage to the reaction zone and its affect on decay development of Ganoderma spp. Schwarze & Baum (2001) New Phytol. 146,

39 London plane wood blocks containing reaction zones challanged by Ganoderma spp. G. lipsiense G. resinaceum G. adspersum Schwarze & Ferner (2003). Arboric. Journal 27.

40 Mass loss in wood blocks containing reaction zones by Ganoderma spp weeks 8 weeks Dry weight loss in % G. lipsiense I G. lipsiense II G. resinaceum I G. resinaceum II G. adspersum I G. adspersum II Fungal species Schwarze & Ferner (2003). Arboric. Journal 27.

41 London plane wood blocks containing reaction zones incubated with Ganoderma adspersum Xylem ray prior to incubation with G. adspersum Xylem ray after incubation with G. adspersum Schwarze & Ferner (2003). Arboric. Journal 27.

42 London plane wood blocks containing reaction zones incubated with Ganoderma spp. G. lipsiense (8 weeks) G. adspersum (4 weeks) Schwarze & Ferner (2003). Arboric. Journal 27.

43 Beech reaction zone challanged by Ganoderma adspersum Schwarze & Ferner (2003). Arboric. Journal 27.

44 London plane wood blocks without reaction zones challanged by Ganoderma spp. G. lipsiense G. resinaceum G. adspersum Schwarze & Ferner (2003). Arboric. Journal 27.

45 Mass loss in London plane wood blocks without reaction zones by Ganoderma spp. 8 Dry weight loss in % weeks 8 weeks G. lipsiense I G. lipsiense II G. resinaceum I G. resinaceum II G. adspersum I G. adspesum II Fungal species Schwarze & Ferner (2003). Arboric. Journal 27.

46 Features of London plane reaction zones challanged by Ganoderma adspersum Preferential degradation of polyphenols Abundant polyphenols Selective delignification

47 Fomes fomentarius

48 Beech reaction zone challanged by Fomes fomentarius

49 Meripilus giganteus

50 Beech reaction zone and Meripilus giganteus

51 London plane reaction zone challanged by brown-rot fungi Brown rot

52 Classification of the invasiveness of decay fungi in beech, maple and London plane Invasiveness Fungus weak moderate strong Laetiporus sulphureus Fomitopsis pinicola Ganoderma lipsiense Kretzschmaria deusta * Inonotus hispidus * Ganoderma resinaceum Ganoderma adspersum * * R.B. Pearce (1996) Schwarze & Baum (2000)

53 Interactions at the host-fungus interface Occlusion of parenchyma and fibre cells Tylosis Enhancement of moisture content Reaction zone Enzymatic ability Penetration via cracks Soft-rot mode Wood decay fungus Anatomy Season Chemical composition of deposits Vitality Suberin layers Dual modes of degradation Adaptation to wood substrate Inoculum potential

54 CODIT- Model

55 Host responses in the tree after wounding of the stem Wound periderm Sound Phloem Discoloured phloem Bark Callus periderm Callus Surface callus Barrier zone Wound surface Reaction zone Discoloured sapwood Sound sapwood (Liese & Dujesiefken, 1988)

56 Host responses in the tree after wounding of the stem Callus Wound periderm Surface callus Barrier zone Dysfunctional wood = Potential substrate for decay fungi! Reaction zone

57 Research requirements: barrier zone and wood decay fungi Is there a correlation between size of the wound and spatial spread of the barrier zone? Are tree spp. such as Tilia correctly classified as effective compartmentalizers? Are stem wounds potential infection courts for decay fungi? Does the barrier zone stop spread of decay in trees?

58 Host response after stem damage to Fraxinus excelsior and Tilia platyphyllos Material & methods 20 year-old trees May 2000 October 2001 Objectives Spatial spread of the barrier zone Histology Durability against wood decay fungi Chainsaw Increment borer Schwarze at al. (2007). Arboric Journal

59 Axial extent of wood discolouration after wounding with the chainsaw Ash Lime

60 Axial extent of wood discoloration after damage with the increment borer 5 cm 5 cm

61 Spatial formation of the barrier zone Tilia platyphyllos Transverse Radial Radial

62 Demonstrating Koch s Postulates Describe and record the symptoms shown Isolate the suspected pathogen from the infected plant material and establish a pure culture Use the pure culture to infect new plant material Describe and record the symptoms shown by the new plant Check that these are the same as your original observations Re-isolate the organism. Check that this is the same as that isolated previously.

63 Isolations from ash and lime resulting from stem wounds with the chainsaw nicht identifiziert Alternaria alternata Aspergillus sp. Aureobasidium pullulans Bakterien Fusarium oxysporum Geotrichum candidum Mucor sp. Penicillium sp. Polyporus squam osus Esche Linde Anzahl der Isolierungen Cladosporium sp. Paecilom yces sp. Heterobasidion annosum Schwarze at al. (2007). Arboric Journal

64 Isolations from ash and lime resulting from stem wounds with the increment borer nicht identifiziert Alternaria alternata Aspergillus sp. Aureobasidium pullulans Bakterien Fusarium oxysporium Geotrichum candidum Mucor sp Esche Linde Anzahl der isolierungen Penicillium sp. Polyporus squamosus Schwarze at al. (2007). Arboric Journal

65 Anatomy of the barrier zone/ash Ring porous Normal wood Libriform wood fibres Xylem rays 2-5 cell rows Paratracheal-vasicentric Apotracheal-terminal Barriere zone Xylem rays <5 rows Libriform wood fibres Paratracheal-vasicentric Paratracheal-confluent/aliform Apotracheal-terminal

66 Anatomy of normal wood and the barrier zone of ash Late wood vessels Late wood vessels Axial parenchyma Xylem rays Axial parenchyma Xylem rays Early-wood vessels Early-wood vessels Normal wood Barrier zone

67 Anatomy of the barrier zone in ash

68 Anatomy of the barrier zone of lime Diffuse-porous Fibre tracheids Normal wood Xylem rays in 2-5 rows Apotracheal-reticulat and Apotracheal-terminal Barrier zone Diffuse-porous Fibre tracheids Xylem rays in <10 rows Apotracheal-reticulat and Apotracheal-terminal

69 Anatomy of normal wood and the barrier zone of lime Axial parenchyma Axial parenchyma Xylem rays Vessels Xylem rays Vessels Axial parenchyma Normal wood Barrier zone

70 Anatomy of the barrier zone of lime Radial

71 Anatomy of the barrier zone in lime Xylem ray parenchyma Axial parenchyma

72 Xylem ray parenchyma in normal wood and the barrier zone Normal wood Barrier zone

73 Identification of suberin (cork) in wood Autofluorescence Secondary fluorescence Sudan IV Suberin has water repellent and antifungal properties! Schwarze at al. (2007). Arboric Journal

74 Tree spp. with strong and weak barrier zones Suberized Platanus Tilia Quercus Fagus Acer Not suberized Fraxinus Sophora Taxus Thuja Populus Robinia

75 Anatomical differences of xylem ray parenchyma in lime Reaction zone Barrier zone

76 Anatomical differences within the xylem ray parenchyma of lime Normal wood Reaction zone Barrier zone

77 Wood blocks containing barrier zones challanged with decay fungi Polyporus squamosus Inonotus hispidus Ganoderma adspersum Ganoderma lipsiense Fomitopsis pinicola Kretzschmaria deusta

78 Re-isolations from ash wood blocks not containing barrier zones after 8 weeks (n=20) Fungal spp. Number of isolations Positive Negative Ganoderma adspersum 18 2 Polyporus squamosus 16 4 Ganoderma lipsiense 12 8 Inonotus hispidus 12 8 Fomitopsis pinicola Kretzschmaria deusta 10 10

79 Re-isolations from lime wood blocks containing barrier zones after 8 weeks (n=20) Decay fungus Number of isolations Positive Negative Ganoderma adspersum 18 2 Polyporus squamosus 12 8 Inonotus hispidus 12 8 Ganoderma lipsiense 4 16 Kretzschmaria deusta 4 16 Fomitopsis pinicola 2 18

80 Are stem wounds potential infection courts for wood decay fungi?? %? %? % Tilia platyphyllos

81 Are stem wounds potential infection courts for wood decay fungi?? %? %? % Aesculus hippocastanum

82 Objectives Our stem wounds potential entry courts for wood decay fungi? Which fungal genera of species can be isolated from stem wounds and do they have the capacity to cause substantial decay? Does the size of the wound correlate with the amount of decay in the tree? Are there differences between strong (Tilia spp.) and weak compartimentalizers (Aesculus spp.)?

83 Aesculus hippocastanum and A. x carnea (32) The Horse chestnut is not endemic to central Europe. It originates from mountain and ravine forests of the Balkans. It was introduced to West-Europe during the late 16. Century. Weak compartimentalizer.

84 Tilia cordata und Tilia platyphyllos (34) Of all endemic deciduous trees in Europe broadleaved lime can reach the highest age (1000 years). As woodland tree it grows preferentially in mountain and ravine forests. Strong compartimentalizer.

85 Materials & Methods Stem damage was of abiotic origin (car damage, damage due to road construction work etc.). Age and degree of wound closure of stem damage was not considered as a defining criteria. Stem wound depth: at least into the sapwood.

86 Data collection Vitality Was determined on the basis of the crown structure. Branching architecture (Roloff, 2001) of the apical shoots - allows differentiation into four different vitality divisions (0,I,II,III). Age (in years) Was estimated. Tree height (in meter) Was estimated. Diameter of dbh (cm) Measured at 1,30 m.

87 Circumference Was measured at dbh. Data collection Surface of wound (in cm) For this purpose the wound-opening was measured in a vertical and horzontal direction. Area of occluded stem wound (in cm) Vertical and horizontal occlusion of wound was measured. Surface callus Assessment of surface callus on the wound-opening.

88 Material & methods Following criteria were defined for the selection of trees: The stem diameter at 1,3 m (BHD) was not thinner than 25 cm, to allow use of a minimum of eight sensors of the PICUS -ultrasonic: This number enables an appropriate resolution quality for the tomograms.

89 Measurement of the wound surface area Wound area (cm) Occluded wound surface Nonoccluded wound surface For this purpose every wound was measured in its vertical and horizontal dimensions. Area of the occluded wound (cm) The occluded wound was measured in its vertical and horizontal dimensions.

90 Computation of the percentage wound area based on a rhombic model Occluded wound area Present wound Red areas represent occluded tissue an blue areas nonoccluded wound tissue that was not considered in the model.

91 Computation of the percentage wound area In the example the length of the illustrated wound is 44 cm and the width 13 cm. The vertical width of the occluded wound is 77 cm, the horizontal width 35,5 cm. The general formula for estimating the area of a rhomboid is: A (cm²) = l (length [cm]) * b (width [cm]) / 2

92 Computation of the percentage wound area based on a rhombic model The larger rhombic area (1366,75 cm²) is defined as 100 % and the smaller non-occluded wound area (286 cm²) is subtracted = 1080,75 cm². With a simple rule of three calculation the present size of the non-occluded wound can be estimated as: 1080,75 cm² * 100 % / 1366,75 cm² 79,07

93 Degree of occlusion (weak) Occluded < 60 %

94 Degree of occlusion (moderate) Occluded %

95 Degree of occlusion (strong) Occluded > 80 %

96 Measurements with stress-wave tomography Stem diameter at 1,3m above ground (dbh): at least 250mm, so as to allow the attachment of least eight sensors of the PICUS - stress-wave timer. This was the minimum number required for an acceptable tomogram quality.

97 Pleurotus osteratus / Horse chestnut Dichte [%] Farbstufen Relationship: Gross density, dry density and colour levels

98 Classification of trees on the basis their Tomograms Category Positive Interpretation Origin of decay is associated with the stem wound. Doubtful Origin of decay cannot be clearly determined. Negative No decay or origin of decay is not associated with the stem wound. Decay originates either from decay present in the root or stem, or cracks and ring shake.

99 Overview: Tomograms Tilia cordata and T. platyphyllos Colour code Brown = sound wood Green = incipient decay (+) Violet = moderate decay (++) Blue = strong decay or hollow +++

100 Overview: Tomograms A. x carnea and A. hippocastanum Colour code Brown = sound wood Green = incipient decay (+) Violet = moderate decay (++) Blue = strong decay or hollow +++

101 Example for a negative classification (Tilia platyphyllos) Features: Age [estimated]: 100 years Length of damage: 800 cm Dbh: 67 cm Width of wound: 48 cm Circumference: 229 cm Length occlusion: 51 cm Tree height: 24 m Width occlusion: 79,5 cm Total occlusion: 40 % Vitality [Roloff]: II - III

102 Example for a negative classification (Aesculus x carnea) Features: Age [estimated]: 70 years Length of wound: 73 cm Dbh: 50 cm Width of wound: 10 cm Circumference: 168 cm Length of wound: 116 cm Tree height: 12 m Width occlusion: 33,5 cm Total occlusion: 81 % Vitality [Roloff]: III

103 Example for a negative classification (Aesculus hippocastanum) Features: Age [estimated]: 80 years Length of wound: 350 cm Dbh: 59 cm Width of wound: 24 cm Stem circumference: 192 cm Length occlusion: 160 cm Tree height: 12 m Width occlusion: 40 cm Total occlusion: 40 % Vitality [Roloff]: II

104 Example for a negative classification (Aesculus x carnea) Features: Age [estimated]: 70 years Wound length: 66 cm Dbh: 56 cm Width of wound: 33,5 cm Circumference: 180 cm Length occlusion: 75 cm Tree height: 18,0 m Width occlusion: 60,5 cm Total occlusion: 51 % Vitality [Roloff]: II

105 Example for a positive classification (Aesculus hippocastanum) Features: Age [estimated]: 70 years Dbh: 52,0 cm Length of wound: 41 cm Width of wound: 18 cm Circumference: 168 cm Length occlusion: 51cm Tree height: 16 m Width occlusion: 30 cm Total occlusion: 52 % Vitality [Roloff]: II - III

106 Classification of investigated tress into different categories on the basis of the tomograms Tilia spp. Aesculus spp Tomogramm auffällig ["positive"] Tomogramm auffällig ["doubtful"] Tomogramm showing decay ["negativ"] Tomogramm without decay ["negative"] Total Examined trees [n] In the case of 87 % of the 32 investigated Aesculus spp. and 85 % of the 34 investigated Tilia spp. No corelation was determined between stem wound and decay!

107 Size of stem wound and extent of decay Amount of decay [%] Tilia spp. Aesculus spp Size of wound [%]

108 Growth media used for the isolation of wood inhabiting fungi Growth media 2% MEA 2 % MEA with 0,2 % Thiabendazole (0,46 mg dissolved in 2ml acetic acid) including 0,1 % Penicillin, Streptomycin and Tetracyclin 2 % MEA with 0,4 % Thiabendazole (0,46 mg dissolved in 2ml acetic acid) including 0,1 % Penicillin, Streptomycin and Tetracyclin 2 % water agar with 0,1 % Penicillin, Streptomycin and Tetracyclin 4 % MEA with Chloramphenicol (100 mg/l, Benomyl 20 mg/l)

109 Identification of wood inhabiting fungi in pure culture Laccase (α-naphthol) Staghorn hyphae Oidia KOH Peroxidase (Pyrogallol & H 2 O 2 ) Tyrosinase (p-cresol) Condia

110 Wood inhabiting fungi isolated from stem wounds of Aesculus spp. Trichoderma spp. Mucor spp. Mortierella spp. Bohrkern Wundfläche Fusarium spp. Diplosporium spp. Cephalosporium spp. Aspergillus spp. Amerosporium spp. Alternaria spp. Pycnoporus cinnabarinus Bakterien nicht identifiziert kein Wachstum Anzahl isolierter Pilze [n]

111 Wood inhabiting fungi isolated from setm wounds of Tilia spp. Trichoderma spp. Tieghemiomyces spp. Penicillium spp. Fusarium spp. Diplosporium spp. Chalaropsis spp. Aureobasidum spp. Aspergillus spp Alternaria spp. Kretzschmaria deusta Yeasts Bacteria Unidentified Sterile Stem section Increment borer Wound surface Isolate fungi [n]

112 Summary In most trees a correlation between stem wounds and wood decay could not be established No differences were found between weak (Aesculus spp.) and strong compartmentalizers (Tilia spp). The size of the wound did not correlate with the extent of decay in the examined trees. Imperfect fungi were mostly isolated from wood samples extracted from the wound surface, increment cores or stem segments.

113 Are stem wounds potential infection courts for wood decay fungi?? %? %? % Tilia platyphyllos

114 Susceptibility Both above and below ground-level, trees are continually exposed to inoculum of wood decay fungi, but they become colonized only under certain conditions, which can be summarized as follows:

115 Conditions contributing to infection The host must be susceptible by lacking barriers, or the ability to form barriers that would be needed to prevent or restrict fungal ingress into the potentially available i.e.: woody tissue. There must be enough spores or inoculum of the fungus. The environmental conditions within the potentially available woody tissue must be conducive to fungal development.

116 Decay triangle DECAY FUGUS Inoculum potential Amount of wood decay Microbial growth-conditions ENVIRONMENT Susceptibility of tissues HOST Agrios (1988) The length of each side represents the influence of each of the three types of factors influencing the interaction between the host tree and a decay fungus. With conditions conducive to colonization (type and size of wound), high spore load of the fungus, wood decay will be extensive in susceptible tree Amount of wood decay With less conducive conditions (e.g. low amount of inoculum), the extent of decay will be small.

117 Pathogens that have been classified as wound parasites on the basis of Koch s postulates Pathogen Symptoms Host Chondrostereum pupureum Nectria galligena Silver leaf, cankers, white rot Cankers Prunus spp. Rosaceen Stereum rugosum Stereum sanguinolentum Cankers, white rot Cankers, white rot Quercus rubra Picea spp. Larix spp.

118 Fire scars Bark stripping Lightning damage Extraction damage

119 There must be enough spores or inoculum of the fungus. Inoculum Inoculum is a general term for infectious material such as sexual and asexual spores or rhizomorphes.

120 Inoculum potential One cell of the bacteria Erwinia amylovora and Agrobacterium tumefaciens can lead to host infection under favourable conditions. One to two microsclerotia of Verticillium dahliae per gram soil suffice, to induce a vascular disease. The amount of the infection source required is determined by fluctuating environmental conditions!

121 Inoculum potential Low amount of dysfunctional wood High amount of dysfunctional wood

122 Host responses in the tree after wounding of the stem Callus Wound periderm Surface callus Barrier zone Dysfunctional wood = potential substrate for decay fungi! Reaction zone

123 Wound parasites The environmental conditions within the potentially available woody tissue must be conducive to fungal development. Inonotus hispidus Polyporus squamosus McCracken & Toole (1969) McCracken & Toole (1974) Kersten & Schwarze (2005)

124 Inoculation trials with wood decay fungi on trees Fomitopsis pinicola Ganoderma lipsiense Ganoderma adspersum Ganoderma resinaceum Trametes versicolor Kretzschmaria deusta Deflorio (2005)

125 Inoculation trials with wood decay fungi on living trees Saprophytes Facultative parasites Deflorio et al. (2008)

126 Biological control of wood decay fungi with Trichoderma spp. Jun Mai Ap Mä Fe Jan Jul Au Se Ok Nov De Sporulationszeit

127 Growth rates of Trichoderma and wood decay fungi Trichoderma spp. Wood decay fungi 24 hrs. 0 hrs. 48 hrs. 5043,2mm 1134,2mm 2 890,5mm 415,3mm 2 Ø 5fold stronger growth rate! Schubert et al. (2006) ISA Inaugural Asia Pacific Conference, Brisbane, Australia Materials Sci ence & Technolog y

128 Decay triangle DECAY FUGUS Inoculum potential Amount of wood decay Microbial growth-conditions ENVIRONMENT Susceptibility of tissues HOST Agrios (1988) The length of each side represents the influence of each of the three types of factors influencing the interaction between the host tree and a decay fungus. With conditions conducive to colonization (type and size of wound), high spore load of the fungus, wood decay will be extensive in susceptible tree Amount of wood decay With less conducive conditions (e.g. low amount of inoculum), the extent of decay will be small.

129 Effective compartmentalization of stem wounds COMPARTMENTALIZATION Stem wounds SAPWOOD DYSFUNCTION! Response against ingress of air and infection by deuteromycetes and wound parasites Effective compartmentalization

130 Effective compartmentalization of stem wounds COMPARTMENTALIZATION Stem wounds SAPWOOD DYSFUNCTION! Response against ingress of air and infection by deuteromycetes and wound parasites Effective compartmentalization

131 Stem injections for control of the horse chestnut moth (Cameraria ohridella) ENVIRONMENT DECAY FUGUS Inoculum potential Pleurotus osteratus Amount of wood decay Microbial growth-conditions Susceptibility of tissues HOST Siewniak & Siewniak (2005)

132 INTERACTIONS IN THE XYLEM OF TREES COMPARTMENTALIZATION 10-20% 80-90% COMPARTMENTALIZATION Stem wounds Wounds to large branches and roots SAPWOOD HEART- & RIPEWOOD DYSFUNCTION! Response against ingress of air and infection by deuteromycetes and wound parasites Occlusion of cells Composition of polyphenols DECAY! Response against infection by wood decay fungi Enzymatic Potential Soft rot mode Anatomy Host response Fungal invasiveness Wood moisture Suberin layers Vitality and season Effective compartmentalization Dual degradation modes Inoculum potential Adaptation to substratum Weak compartimentalization