Knowledgebase

Bright yellow mass at base of a tree stump #876895

Asked July 11, 2024, 9:15 PM EDT

I found a very bright yellow mass with a bumpy surface at the base of a tree stump teaching the soil.  A few days later it had turned tannish color with a smooth surface. I poked it a bit and it was black inside. There was also some white lines going up the stump. I saw the same thing on dirt in a street. Can you tell me if it is toxic to humans or trees and vegetation. What is it? Thank you. 

Lane County Oregon

Expert Response

That looks like a slime mold, which are fungus-like organisms. Slime molds are initially yellow to red but fade to a tan or brown as they dry out. They are not known to be a danger to humans or animals. The slime mold in the photo is possibly dog’s vomit slime mold (Fuligo septica), which is very common in this region. For more on slime molds, refer to https://www.nps.gov/articles/000/slime-molds.htm.


Erica Chernoh Assistant Professor of Practice Community and Commercial Horticulture OSU Extension Lane County Replied July 12, 2024, 1:22 PM EDT
Thank you for your answer. But you are not answering my question: is it toxic to trees and vegetation? 
Thank you. 

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On Fri, Jul 12, 2024 at 10:22, Ask Extension <<personal data hidden>> wrote:
The Question Asker Replied July 12, 2024, 1:52 PM EDT
No, slime molds are not toxic to plants. 
Erica Chernoh Assistant Professor of Practice Community and Commercial Horticulture OSU Extension Lane County Replied July 12, 2024, 1:59 PM EDT
Thank you very much. 
Michele 

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On Fri, Jul 12, 2024 at 10:59, Ask Extension <<personal data hidden>> wrote:
The Question Asker Replied July 12, 2024, 2:26 PM EDT
Hello again. 

 I am sending you the actual picture of the bright yellow “slime mold” on my tree stump. Taken 3-4 weeks ago. 
And the picture of how it is looking today. It’s been looking like this for about 2 weeks. 
You would say it’s still slime mold? Do they change color and become firm with all that white stuff ?
Thank you. 
image

image

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On Fri, Jul 12, 2024 at 11:25, <<personal data hidden>> wrote:
Thank you very much. 
Michele 

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On Fri, Jul 12, 2024 at 10:59, Ask Extension <<personal data hidden>> wrote:
The Question Asker Replied July 14, 2024, 3:54 PM EDT
Yes, slime molds turn tan/brown and harden as they dry out. 
Erica Chernoh Assistant Professor of Practice Community and Commercial Horticulture OSU Extension Lane County Replied July 15, 2024, 2:31 PM EDT
Thank you. It’s good to hear. 
But what is the white stuff a bit fuzzy at the bottom and looking like white paint going up the stump?

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On Mon, Jul 15, 2024 at 11:31, Ask Extension <<personal data hidden>> wrote:
The Question Asker Replied July 15, 2024, 2:50 PM EDT
The white stuff under the slime mold is just a part of the slime mold. They do move and leave behind trails of slime. Further up the trunk it looks like there are different types of algae and lichen growing on the trunk. I am not sure what the white "paint"-like substance is. It could be related to the slime mold, algae or lichen, or perhaps it is a sign of decay. It is hard to tell from the photo.
Erica Chernoh Assistant Professor of Practice Community and Commercial Horticulture OSU Extension Lane County Replied July 22, 2024, 6:22 PM EDT
Thank you. You have been very helpful and patient. 

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On Mon, Jul 22, 2024 at 15:22, Ask Extension <<personal data hidden>> wrote:
The Question Asker Replied July 22, 2024, 6:55 PM EDT

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