White rot, brown rot and soft rot compared: what the sources say
How a California pest note, a Washington State extension sheet, a botanical garden and Forest Research define white, brown and soft rot in trees, and what each source says about strength loss.
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 how published sources define the three main types of wood decay. It does not identify a decay type in any single tree. The sources are from the United States and the United Kingdom.
The three types side by side
| Type | What the sources say | Examples with pages here |
|---|---|---|
| White rot | The Washington State University sheet says the majority of decay fungi on deciduous trees cause it and that wood strength declines gradually; UC IPM says white rots usually form in flowering trees and less often in conifers | Full pages on Ganoderma, weeping conk |
| Brown rot | The Washington sheet says under 10 per cent of wood decay fungi cause it, mostly on conifers, and that large amounts of strength are lost early in the decay | Full pages on Chicken of the woods |
| Soft rot | The Missouri Botanical Garden says the fungus mostly breaks down cellulose, leaving wood brittle; Forest Research uses it for Massaria | Full pages on Brittle cinder fungus, Massaria |
Strength loss, as the sources describe it
The Washington State University sheet says that in white rot wood strength declines gradually over time, while in brown rot large amounts of strength are lost early in the decay process. UC IPM says a 10 per cent loss of wood weight can result in a 70 to 90 per cent loss in wood strength, and that decay can be hidden, affecting strength without any outward sign. The Missouri Botanical Garden describes the soft rot of brittle cinder fungus as making wood brittle. The sources do not measure any particular tree.
How the sources use the terms
The Missouri Botanical Garden and the TCI Magazine article name the rot type next to each fungus, so a reader can see the same labels used across species: soft rot for brittle cinder fungus, white rot for Ganoderma and weeping conk, brown rot for chicken of the woods. Forest Research applies the label soft rot to the branch decay in Massaria disease of plane. Where a source gives a different label for the same fungus, the fungus page notes it.
The UC IPM pest note and the Washington sheet also describe where in the tree each rot is found, for example heartwood, sapwood, or butt and roots, and note that a conk is usually a late sign. That point is why they separate the type of rot from the visible fruiting body.
Where the sources stop
The sources agree that a type of rot is identified by sampling and expert examination, not by one sign alone. For the methods used to judge decay, see tree risk assessment methods. The way trees wall off decay is covered in tree biology. Each fungus has its own page, listed on wood decay fungi on trees.
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
- Missouri Botanical Garden, Brittle Cinder Fungus plant problem page, read October 8, 2026
- Forest Research, Massaria disease (Splanchnonema platani), read October 8, 2026