White fungus? around base of cedars and yews


I just noticed this around the base of some, not all, of the cedars and yews at the back of my yard.
It seems to be localized in one small area.
What is unusual is that there is a log/stump (dead chunk of tree that I brought into the yard to act as a stool) and it has it also… so the live trees have it and the dead chunk of tree has it.
Last year I applied a mulch of composted seaweed and fish meal to the entire area ( the reco from the owner of a reliable nursery.
The compost is only a few inches deep and is not close to the base of any of the trees at all.
When I scratched the white stuff at the base of the trees it had a bit of a fungus/mushroom kind of smell.
Do you think it had something to do with the compost.
Or maybe it arrived with the stump that I brought in (found it out for garbage at someone’s home)… maybe it was holding the fungus and now spores are loose.
Any idea what this is?
If so how harmful is it and how do I get rid of it.
Thanks for your time.


Thank you for contacting Toronto Master Gardeners with your concern about the white coating at the base of your cedars & yews.

It appears this is a fungal decay organism commonly called white rot.  According to ScienceDirect.com,   https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/white-rot-fungi  white rot fungi (WRF) are able to degrade lignin most effectively due to the production of ligninolytic extracellular oxidative enzymes.   Lignin is a oxygen containing organic polymer that combines with cellulose to form cell walls in wood & bark. WRF tends to grow on woody surfaces, decompose the wood, leaving wood residues that are usually whitish in color and fibrous in texture.  WRF can degrade both hardwod and coniferous wood.

We suggest consulting an arborist or the reliable nursery where you purchased the trees for treatment of this fungus.

Landscape Ontario is a good resource for finding reliable arborists or nurseries in your area.