6 Wood Discoloration

8.3 Tree Rots by Macrofungi 191
single cases up to 55 m; maximum age of an individual genet around 200 years
(Queloz and Holdenrieder 2005);
Physiology: white rot, root rot, butt rot, so-called red rot due to reddish
discoloration of the wood; at initial decay preferential lignin degradation, later
simultaneous white rot (Peek and Liese 1976); parasite and saprobe;
Characteristics: anamorph Spiniger meineckellus (A.J. Olson) Stalp.
(Fig. 8.14C) on agar and fresh wood samples at high relative humidity: clubshaped
thickened conidiophore after spore dispersal like a morning star
(“Brefeld conidia” as identification feature: Brefeld 1889); flask-shaped increase
of the stem basis of spruce by cambial irritation; resin excretion;
Fruit body (Fig. 8.14A): annual to enduring crusty brackets in autumn,
often resupinate (1 cm thick, 3–20 cm wide) in rows and roofing tile-similar,
usually fused, at the stem basis and on flat-running roots, frequently covered
by needle litter; yearly a new pore layer; fresh: tough, old: hard and woody;
upper surface: bumpy-wrinkled, brown, often zonate, leathery-crusty, whiteyellowish
margin; pore surface: white-cream with circular-angular pores (4–
5/mm); dimitic; bipolar.
Significance: The fungus is one of the most important pathogens in coniferous
forests of temperate regions (Hartig 1874, 1878; Rishbeth 1950, 1951;
Zycha et al. 1976; Hallaksela 1984; Tamminen 1985; Benizry et al. 1988; Schönhar
1990; Woodward 1992a, 1992b; LaFlamme 1994; Woodward et al. 1998;
Heydeck 2000; Greig et al. 2001; Gibbs et al. 2002; Korhonen and Holdenrieder
2005), which causes substantial damage particularly in older forests. The infection
occurs by germinating spores or by mycelium that is already present
in roots or soil. Several infection ways are possible: by basidiospores (also
conidia) via stump infection (Redfern et al. 1997), by mycelial growth through
root graft transmission from diseased to healthy roots (Hartig 1878; Schönhar
2001), or via spores [germinable about 1 year: Brefeld (1889)], which are
washed into the soil by rain and germinate on the roots. The fungus penetrates
into older roots through wounds and into young uninjured roots through the
thin bark (Rishbeth 1951; Peek et al. 1972a, 1972b; Lindberg and Johansson
1991; Lindberg 1992; Solla et al. 2002). The hyphae penetrate into sound spruce
roots via the pit channels of the thick-walled stone cork cells. The walls of the
following thin-walled stone cork cells and the sponge cork cells are degraded.
The fungus colonizes the tracheids from the bark rays via the wood rays. The
tracheids are degraded by enzymes and perforated by microhyphae (Peek and
Liese 1976). Embryos of Pinus spp. showed three days after artificial inoculation
intercellular penetration of hyphae through the epidermis and into the cortex
(Nsolomo and Woodward 1997). Infection of spruce seeds of 4–7 days of age
showed that infective structures on the root surfaces were evident 24 h after
inoculation. Internal colonization of cortical tissues started after 24–48 h and
reached the endodermis within 72 h. Severe destruction of stelar cells occurred
12–15 days postinfection (Asiegbu et al. 1993). Infection of nonsuberized and
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