Timber decay
Characteristics
There are 4 key characteristics that can be used in the identification of fungal growths:
- mycelium;
- appearance of decaying wood;
- rhizomorphs or strands; and
- sporophores or fruiting bodies.
Other optical and microscopic characteristics, e.g. size and shape of spores and mycelia, different physiological and morphological and dying characteristics, can be used in the laboratory.
Figure 1: Typical cuboidal cracking caused by dry rot (Serpula lacrymans)
| Comparison of characteristics for dry rot (Serpula lacrymans) with those of wet rot | ||
|---|---|---|
| Charasteristics | Dry rot (Serpula lacrymans) | Wet rot (Coniophora puteana) |
|
Mycelium |
Damp conditions: masses of tears on silky white surface, with bright lemon patches. Drier conditions: thin skin of silver grey in colour, with deep lilac tinges. |
High humidity: yellow to brownish in colour. |
| Decaying wood | Deep cuboidal cracking associated with differential drying shrinkage. Reduction in weight. Dull brown in colour. Resinous smell gone. | Cuboidal cracking on smaller scale. Thin skin of sound wood. Weight loss. Localised infection. |
| Strands (rhizomorphs) | 3mm in diameter. Brittle when dry. Off-white/dark grey in colour. | Thinner than dry rot. Flexible when dry. Creamy white in colour. |
| Sporophores (fruiting bodies) | Tough, fleshy pancake or bracket-shaped, varying from a few centimetres to a metre across. Ridged centre: yellow-ochre when young, darkening to rusty red when mature. Lilac/white edged. Distinct mushroom smell. | Not very common in buildings. Musty smell, rather than mushroom smell associated with an active growth of dry rot. |
For detailed information on timber decay caused by wood decay fungi, see Review : Dry Rot and Other Wood-Destroying Fungi: Their Occurrence, Biology, Pathology and Control