Stem Decay

Stem decay in conifers like pine, western redcedar, and Sitka spruce shows up as heartwood rot that may be invisible until a tree breaks in a windstorm or you spot a fungal fruiting body on the trunk. Different decay fungi produce different signs: some create white pockets in the wood, others cause stringy white rot, and some produce bracket-like conks. Once established, decay can extend several feet up or down the tree.

The critical thing to understand is that trees can't be cured of stem decay, but you can prevent it by avoiding wounding trees during vulnerable periods. Trees compartmentalize decay on their own, so the presence of a conk doesn't mean the entire tree is worthless. For landscape trees, remove any standing hazards near structures or roads, and remember that dead trees with decay columns provide important wildlife habitat if they're in safe locations.