6 Wood Discoloration

188 8 Habitat of Wood Fungi
Fruit body (Fig. 8.12c): central stipe (to 15 cm), cap 5–15 cm in diameter;
annual, in groups on stumps and at the root collar in late autumn; upper
surface (A. mellea): small, yellow-brown scales on honey-yellow ground (Honey
fungus); gill surface: cream-white to brownish-red gills; monomitic; clamps
only at the basidium basis; pileus with white ring; young edible, danger of
sickness when insufficiently cooked or overmatured;
Significance: The Armillaria fungi, which are feared by the foresters, belong
to the most important and cosmopolitan pathogens inside and outside
the forest. They can attack almost all species of hardwoods and conifers of
all ages (Hartig 1874; Schönhar 1989; Livingston 1990; Klein-Gebbinck and
Blenis 1991; Gibbs et al. 2002). They live as saprobes in the soil on dead wood
remainders and on stumps. The transition to the parasitic phase occurs, if the
tree is weakened by stress (other parasites, wetness, dryness, pollution), so that
forest damage sites showed increased occurrence of Armillaria. The infection
occurs by rhizomorphs (Fig. 8.13). Solla et al. (2002) showed that A. mellea
Fig.8.13. Development and transmission of Armillaria root disease (translated from
Nierhaus-Wunderwald 1994, with permission of Swiss Federal Institute for Forest, Snow
and Landscape Research)
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