Is this fungus/mushroom harmful for our maple? - Ask Extension
We recently noticed this fungus/mushroom growing on a large silver maple. I believe it appeared or grew to this size sometime in the past few weeks. W...
Is this fungus/mushroom harmful for our maple? #816950
Asked November 27, 2022, 2:39 PM EST
We recently noticed this fungus/mushroom growing on a large silver maple. I believe it appeared or grew to this size sometime in the past few weeks. We hoping to find out what this is, if it is harmful to our maple, and if it should be removed. Thank you!
That is a type of mushroom referred to as a 'bears head' or 'lions mane'. Unfortunately, it is a sign of heart rot within the tree. You can see a large area to the right in your first two photos that looks like a deep split. We think that it's a good idea to contact a tree health expert, a.k.a. an ISA-certified arborist to do an on-site evaluation of the tree and its structural integrity. You should do this sooner rather than later if its fall would threaten people or homes. This page from our website can help you to find an arborist and learn signs of a tree's decline: https://extension.umd.edu/resource/how-do-you-decide-when-remove-tree
Arborists are usually on staff at larger tree companies or you can search for one at the credentialing agency at http://www.treesaregood.org .
Thank you Christine. We really appreciate the feedback, we just had an arborist out to assess the tree and plan for trimming branches which may be at risk of falling toward our roof. We also removed the lions mane from trunk. The mushroom was just massive - the pictures didn’t do justice and I weighed it out of curiosity… 19.2lbs!
You're welcome. Wow, that is an impressive mushroom! The fungus that produced it is still growing within the tree (mushrooms for fungi are like flowers for plants...they can be removed without killing the whole organism, which in the case of fungi is a network of tissues inside what it's feeding on) so you might see more when the fungus is ready to produce them and the weather conditions are suitable.
This work is supported in part by New Technologies for Ag Extension grant no. 2020-41595-30123 from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.