PDC, University of Missouri


	PDC Fact Sheet *Wood Rots*

Cause: 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 / 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 (figure 1). An arborist may be able to evaluate the tree and extend the useful life of the tree by bracing branches with cables.

Photo of tree structurally compromised because of an internal wood rot.

Figure 1. Tree structurally compromised because of an internal wood rot.

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Email: plantclinic@missouri.edu

Cause:	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 / 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 (figure 1). An arborist may be able to evaluate the tree and extend the useful life of the tree by bracing branches with cables.

[ Top of Page ] [ Back to Index ]
	Email: plantclinic@missouri.edu