Some Variations and Exceptions

Figure 78.  Innotus obliquus on white birch.
Figure 78

Canker rots have yet another pattern of decay. After the canker rot fungus becomes established, it forms a pressure pad that kills the cambium, thus enlarging the wound. The tree responds by compartmentalizing each new wound. These fungi may kill a tree by girdling. (figs. 78-79)

Figure 79 Figure 79. Fomes chyrsoloma on white fir.

Figure 80.  Fomitopsis annosa on white pine.
figure 80
Some decay-causing fungi can attack and kill roots that have not been wounded. But, these fungi may be compartmentalized as they grow from the roots upward into the trunk. The trees attacked by these fungi are often stressed or weakened by other factors first. (figs 80-81)

figure81 Figure 81. Armillariella mellea on red oak.
1.Fruit body
2.Rhizomorphs

Figure 82
figure 82
Other species of decay-causing fungi usually attack wood after the tree has been made into a product. In some cases the patterns of decays in the product will still follow the patterns set while the tree was alive. (figs. 82-83)
  1. Hot spot for decay in poles, 6 inches above and 18 inches below ground.
  2. Typical patterns of internal decay in poles: A, shell; B, wedge; C, in-between; D, central; E, complete.
  3. Typical patterns of external decay in poles: A, surface rot; B, soft rot.


Figure 83
figure 83
1. Lentinus Iepidius, a destructive fungus.
2. Color change associated with stub.
3. Ring shake associated with wound.
4. Decay starting above and below stub-typicaI in-between pattern common in southern yellow pine.

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