Wood rots
Various fungi can invade trees to cause a decay of the heartwood or sapwood.
Primary hosts in Missouri
No host is immune to wood rots caused by opportunistic pathogens that invade
stressed or damaged tissue.
Symptoms
and diagnosis
Decay of heartwood is very common especially with older trees. With this type
of decay there are two types of general rots. White rots cause affected wood to
become pale, soft and punky. Brown rots cause affected wood to become dark, firm
and chunky. Hollow trees may result of successive wood rots over several years.
The sporocarps or fruiting bodies of the fungi that cause these rots usually are
shelf fungi or mushrooms. If is very difficult to determine the identity of a
fungus causing a wood rot unless a sporocarp is present. Wood rots do not reduce
the vigor of the tree, but do reduce the strength of the wood.
Sapwood rots are far less common. They affect the wood that is actively conducting
water. These rots lead to decreased vigor and often kill their host.
Integrated
management strategies
There are no controls for wood rots after an infection has occurred. Since
wood rots usually infect through wounds, avoiding unnecessary wounding is important
and proper pruning techniques are important. Because wood rots can affect the
strength of the wood, this may lead to increased storm damage or become a potential
hazard. See figure 1. An arborist may be able to evaluate the
tree and extend the useful life of the tree by bracing branches with cables.
Figure
1
Tree structurally compromised because of an internal wood rot.
Updated 6/9/09