How to kill slime mold on tree trunk?

HI there, it sounds like it won't arm your tree and is probably due to lack of sunlight but I was looking up oaks because the bark on your tree reminded me of the bark on our own oak trees. I hope this helps! https://www.gardenguides.com/127849-rid-oak-trees-green-fungus.html

That mold is formed from a wound in the tree. Moisture and sap is oozing out causing the growth. Basically it isn't harmful to the tree.

https://www.gardenguides.com/125320-kill-tree-mold.html

While slime molds are definitely unattractive, they are not harmful. Slime molds often appear in the spring due to the fact that they get their moisture from the air and feed on the nutrients from whatever it is growing on, which is commonly your mulch beds.

You can knock it off the tree and hose it away. If you're really concerned slime mold, as well as any mushrooms or toadstools, can be knocked out with baking soda, potassium bicarbonate, cornmeal, cornmeal tea, or hydrogen peroxide.

IF the tree has a wound, please just allow the tree to heal itself. Applying things like tar or paint doesn't stop any decay and may actually increase the chances of larger problems developing. https://www.gardeningknowhow.com/ornamental/trees/tgen/wound-dressing-on-trees.htm

the tree is oozing out the slime to protect the inside - I would leave it alone for now

here is another idea if yo want to remove it

https://www.youtube.com/watch?v=lGKZ6XriF3c

We use our power washer on our trees every few years. to remove any moss or other growth. Just be gentle.

This will help: https://www.youtube.com/watch?v=zUEIG1gCMBU

No need to remove it. It's harmless as already mentioned. No need to use any chemicals, which will not kill it anyway and may harm other things.

I would hit the tree with a hose and get off what comes off, but this is not harmful to the tree, so do not worry about it.

Hello. Here’s a helpful link.

Your slime mold up eventually dry and disappear. It may be best just to leave it alone. You could potentially damage the tree bark further by applying chemicals or using a forceful water spray.

https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/diseases/slime-molds.aspx

Try this https://www.youtube.com/watch?v=8YC_CQcQ62A

Thanks everyone!

I talked to the County Extension Office today and they say it’s a White Wood Rot Mold, not Slime Mold

and they suggested getting an arborist out there, because the trunk has more splitting on the back side.

They also suggested the bleach water method after scraping off the obvious parts of the mold.

I'm happy you spoke to your county extension but from my reading, I'm not certain they've diagnosed the issue properly. Here are articles on white rot, none mention using bleach and water! Most state that the tree won't survive, others recommend using a good fungicide on a routine schedule. AND, this mostly affects apple/fruit trees.

https://www.gardeningknowhow.com/edible/fruits/apples/managing-bot-rot-of-apple.htm

https://extension.psu.edu/apple-disease-white-rot

https://en.wikipedia.org/wiki/Botryosphaeria_obtusa

https://www.phillyorchards.org/2015/08/31/black-rot-of-apples-and-other-pome-fruits/

https://mrtreeservices.com/blog/tree-rot-101/

Apparently if you just aim your garden hose at it, you can blast it off the tree: https://homeguides.sfgate.com/kill-slime-mold-37461.html

This can be disinfected using rubbing alcohol or any household bleach solution of one part bleach to nine parts water. The excess sap should be wiped from the tree to discourage hungry insects. However there is no cure, but the bark of a tree is like skin.

Slime mold, as well as any mushrooms or toadstools, can be knocked out with baking soda, potassium bicarbonate, cornmeal, cornmeal tea, hydrogen peroxide or commercial products like BioSafe Disease Control. Physical disturbance such as mowing the grass or scratching the slime mold in beds are also effective