something might be boring into my maple tree

Asked October 3, 2018, 10:41 AM EDT

Hi, experts. For the past several months, I've been noticing some black semi-weeping areas on my swamp maple tree. The areas are only on the side facing my house, not on any other area of the tree trunk. It almost looks like something (insect?) is boring into the trunk of the tree. The canopy looks fine and all other aspects of the tree look fine to my amateur eye. But I'm wondering if there may be a problem here that I need to address. The tree provides wonderful shade in my yard and helps me conserve energy by its shade in the summer. The attached image should be rotated so that the trunk is shown vertically.

Prince George's County Maryland slime flux trees

7 Responses

This is not uncommon and looks like slime flux.
Here is our page on it:

If the tree looks good there is nothing that you need to do. Just keep an eye on it.


Thanks. The description in the text of your information page sounds EXACTLY like what I've observed. The pictures don't look quite like what I have but the description is right on target. The information page says "follow optimal cultural practices that minimize stress". The tree is in ground that is part of a retaining wall, on a west facing side of my townhouse in the old section of Greenbelt. That area has certainly been well watered this year due to high rainfall. Is there anything you would specifically mention as an "optimal cultural practice" to minimize any stress the tree may be experiencing? I'm just trying to put my finger on anything I can do to continue to make this a good environment for that tree, or enhance that environment if it would decrease any stress that may be happening.

One of the biggest stressors here is when we go into a period of drought- and you could offer supplemental water. NOT an issue this year!

It likely already is, but a 2-3 inch mulch layer is a good idea(no more than this and keep it from contact with the trunk of the tree.).
It helps regulate temperature and moisture, and also tends to keep injuries from string trimmers or mowers, etc. from damaging bark.
If you don't have any there now, wait until after the leaves fall to apply. (Mown leaves make a good mulch, but commercial ones are fine too).


Thanks. Right now the lawn goes right up to the base of the tree. I guess now I know that there IS a reason for those mulch circles around trees. I guess I kind of thought of the circles as landscaper fashion choices, associated more with the visual aspect than the health aspect of a tree!

If the "circles of mulch" help, I'll make one after the leaves have fallen. I'll be careful not to heap the mulch too high. And the City of Greenbelt has a mulch pile from which any resident can keep their individual garden supplied. I'll just add the "tree circle" to the areas I usually mulch. Thanks!

If it's part of a bed, it doesn't have to be circle-shaped.
The tree will actually do a bit better without the competition from the grass for water and soil nutrients.


Thanks. Decreasing the competition from the grass makes perfect sense. Appreciate your expertise. Until next time......