Integrated Pest Management

Wood Decay Fungi

Many fungal species

brown rot

Brown rot (Mates, Wikimedia Commons)

white rot

White rotĀ (Ryan Davis, Utah State University Extension)


Ganoderma conkĀ (Claudia Nischwitz, Utah State University Extension)

Hosts, Symptoms & Signs

  • all trees and shrubs
  • wood decay fungi may form fruiting structures called conks on affected branches and trunks, but not always
  • presence or absence of conks is not an indication of wood decay
  • wood decay fungi can degrade wood strength leading to stem or branch failure

White Rot

  • caused by fungi that decompose most of the wood components
  • the leftover material is very light

Brown Rot

  • fungi causing a brown rot cannot decompose lignin, giving it a reddish-brown color
  • limbs can die back, but in some cases wood decay fungi can hollow out branches and tree trunks and the tree will show no symptoms; these trees are prone to sudden breakage in storms

Disease Cycle

  • spores of wood decay fungi enter through wounds caused by winter injury, lawn mowers, incorrect pruning or insect feeding, and start colonizing and decomposing the wood; this process can go unnoticed for years

IPM Recommendations

  • Remove affected branches. If the trunk is affected, remove the tree.
  • If unsure about the presence of wood decay, have a certified arborist evalutate the tree.