Wood decay fungi on trees: what the sources record
A comparison of the wood decay fungi that tree-care and forestry sources describe: the rot each causes, the hosts, where the fruiting body shows, and what the sources say a conk can indicate. One page each for the fungi with enough sourced facts.
Checked against the sources at the bottom of this page on October 8, 2026. Rules, fees and pay change: the source has the last word.
This page compares what published sources say about wood decay fungi on trees. It does not identify a fungus from a photo and says nothing about any single tree. The sources are from the United States and the United Kingdom, and they use different common names, so each fungus has its own page below with its sources.
What the sources say about conks in general
The Washington State University extension sheet says the presence of a conk generally means rot several feet below and above it, and that the absence of fruiting bodies does not mean a tree is free of decay, because some fungi fruit only after extensive decay. The University of California integrated pest management program says a visible fruiting body is usually associated with advanced decay and that the extent of decay may be far above or below it. The page on white, brown and soft rot compared sets out how the sources define the rot types.
The fungi side by side
| Fungus | Rot type, place and hosts, as sources give them | Page |
|---|---|---|
| Brittle cinder fungus | Soft rot at the lower trunk and buttress. Hosts: Beech, maple, linden, hackberry, oak, elm, ash | Full page on Brittle cinder fungus |
| Ganoderma conks | White rot at the base and roots. Hosts: Oaks, honeylocusts, maples | Full page on Ganoderma conks |
| Chicken of the woods | Brown rot of heartwood. Hosts: Oak, yew, cherry, sweet chestnut, willow | Full page on Chicken of the woods |
| Weeping conk | White rot of butt and roots. Hosts: Oak, also beech, birch, alder | Full page on Weeping conk |
| Beefsteak fungus | Brown rot, low on the trunk. Hosts: Oak and chestnut, rarely maple, birch, hazel, beech | Full page on Beefsteak fungus |
| Conifer root and butt rot | Root and butt decay at the base of conifers and on stumps. Hosts: Conifers, a few broadleaves rarely | Full page on Heterobasidion root and butt rot |
| Elbow-patch crust of plane | White rot of sapwood and heartwood after a canker; notifiable in the UK. Hosts: London plane | Full page on Elbow-patch crust of plane |
| Massaria disease | Soft rot of branches; notifiable in the UK. Hosts: London plane and its parents | Full page on Massaria disease |
Other fungi the sources describe briefly
- Armillaria: UC IPM lists a white butt and root rot.
Who examines trees
For the methods and the credentials, see tree risk assessment methods and consulting arborist credentials. For who may apply pesticides to trees, see pesticide licences by country. For how wood resists decay, see tree biology.
Decay fungi, one page each
Sources
- UC IPM, Pest Note 74109, Wood Decay Fungi in Landscape Trees (revised August 2019), read October 8, 2026
- Washington State University Extension, Wood Decay: Common Disease in Trees, read October 8, 2026
- TCI Magazine, Wood-Decay Fungi, Part 2: Identifying Important Species (October 7, 2024), read October 8, 2026
- Woodland Trust, Beefsteak fungus, read October 8, 2026
- Forest Research, Conifer root and butt rot (Heterobasidion annosum), read October 8, 2026
- Forest Research, Elbow patch crust of plane (Fomitiporia punctata), read October 8, 2026