I've got an oak tree. Within the last 2-3 weeks I've observed two growths on the base of the tree that started from nothing to what you see below. They're a fungus or mushroom of some sort. They're solid structures, but if you look closely you can see fuzz on the tree itself where they meet.

My plan was to call someone on Monday, but I'm not entirely sure who. An arborist? Before I do call though, I'm trying to get as much information on this as I can, because I know it can range from being treatable to being dangerous.

Any ideas? Thanks!


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  • Hi Steve! Can you post a picture of the rest of the tree? How's it doing? Do you see any areas higher up that look like they might be the beginnings of more of these mushrooms? Is this your only oak? If not, how are the others? If you do need to call someone, an arborist is the right choice. I don't know where you live, or even which country, but I'd start by calling your town. Our town's arborist came out for free to do a diagnostic visit, and he included not just that tree but all the ones in my yard! Commented Oct 14, 2017 at 1:32
  • I will post a picture of the rest of the tree in the morning. There aren't any others around. It's quite tall (>30 ft), so getting useful pictures might be tricky. I'm in south-east Tennessee. I have noticed it's starting to drop quite a few dead branches, but just small stuff.
    – Steve
    Commented Oct 14, 2017 at 2:16
  • I've added additional pictures of the tree. I'm not sure how helpful they are, since they're far away.
    – Steve
    Commented Oct 14, 2017 at 12:45
  • Doesn't make a difference, the prognosis is as I've said below I'm afraid,but if the only shelf fungus is at the base, just means its foot and butt rot, or at least, that's where it started. You still need an arborist...
    – Bamboo
    Commented Oct 14, 2017 at 15:11
  • first-nature.com/fungi/~brackets.php Commented Oct 14, 2017 at 18:04

2 Answers 2


I know a question or three like this been answered before, but I can't locate them, unfortunately.

This is a shelf or bracket fungus (as we call them in the UK) and I'm sorry to say its presence spells death for your tree. It's the fruiting body of mycelium already at work within the tree, and those mycelium will have been there some time before this appears.

An arborist is essential to check if the tree is safe at the moment, though you may have a little time before it becomes a matter of urgency that the tree should be removed.

  • Also "shelf" fungi in US. I would not pay an arborist ; the tree is dead and does not know it yet. That being said, I had an oak about half that size that lost branches for 20 years before it was completely dead ( location of falling branches was not a problem). Commented Nov 4, 2021 at 18:45

Mushrooms or large fungi growing from the sides of trees like this indicate that there may be internal rot which is providing food for the fungus. Healthy trees produce fungicides to inhibit the growth of fungi which is why you normally wait a few weeks after felling an oak tree or cutting off a branch before attempting to inoculate with oyster or shiitake mushroom mycellium.

So, arborist is the right call. And if the tree needs to come down, you're going to be able to grow a heap of mushrooms for years to come!

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