Kretzschmaria deusta

January 11, 2021

Good afternoon team.

I could feel everyone chomping at the bit this morning for their weekly mushroom, and I appreciate you bearing with me as my colleagues and I participated in Day 1 of the First Annual Natural Areas Winter Togetherness Week (FANAWTW). Without further ado, this week’s mushroom is Kretzschmaria deusta, commonly known as brittle cinder. K. deusta can be found across the northern hemisphere. It is a pathogenic fungus that causes a soft rot in hardwoods by consuming the cellulose, and later the lignin, in the plant cells at the base of trees. Cellulose and lignin are two of the main components of plant cell walls so when degraded this creates root rot/butt rot in afflicted trees. I have to imagine the tree crew has encountered this fungus in their myriad inspections throughout the park. It can infect a tree through open injuries in the bark or through root contact with infected trees. 

Another interesting feature of this parasitic fungus is that it has both an asexual body morph and a reproductive body morph. In the spring it produces the asexual body which is whitish gray but it turns to its namesake brittle black crust (spore producing morph) in the summer. I’ve attached pictures of both body morphs. The picture of the asexual morph is courtesy of Michael Kuo from while the pictures of the spore producing black crust are my own taken on 12/31/2020. 

Hope it was worth the wait,