6 Wood Discoloration

180 8 Habitat of Wood Fungi
Fig.8.11. Use of a plastic wrap to improve
the development of a surface callus.
a Fresh, cleaned wound. b Wound
covered with a black plastic wrap.
c After9weeksnearlyhalfofthewound
coveredwithabrightsurfacecallus
tissue (from Stobbe et al. 2002b)
niques, and some of the latter are capable to identify the causal agent. Due
to some overlapping in their use, the methods are listed together in Table 8.4.
Limits of ultrasonic evaluation of wood defects have been shown by v. Dyk and
Rice (2005). There is a great bulk of references on the various techniques; thus,
only examples are given in Table 8.4.
The earliest nondestructive evaluation of trees is the visual inspection of
the tree condition (growth, foliation, wilt) and occurrence of wounds, resin
excretion, necrosis, canker, or fruit bodies. Visual inspection is also applied
for lumber, poles, and wood in indoor use. Fruit bodies might serve to identify
the causal agent. This visual inspection is by definition neither objective nor
sure. Olfactory detection is done by the use of sniffer dogs that detect dry rot
(Koch 1991), molds, or termites (Zabel and Morrell 1992).
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