Hello Karen,

This is some sort of rot, with the fungi being the fruiting bodies of the rot fungi pushing out through the bark. The hilled up soil and plants growing against the trunk can cause the bark of the trunk to rot and allow fungi to grow.

Also, rots can penetrate the tree bark when it is injured by frost cracks, sun scald, or injuries from mowers or weed whips. Once rot is inside the trunk, there is no cure or way to stop its growth.

Some trees can live with rot for many years, if the type of fungi are slow growing. Or, the rot may be  a  fast growing type and this can cause the tree to fall in a storm.  A certified arborist can assess the tree and give you advice on whether the tree should be removed.

The tree may also have a girdling root that is slowly cutting off water and sap flows, which cause dieback in the crown of the tree. The arborist can determine whether this is the case.

Find certified arborists by zip code here-

www.treesaregood.org

If/when the tree is replaced, follow good planting and care practices that encourage healthy, long living trees:

-Plant at the correct depth, leaving root collar exposed.( pg 2 of link below)

-Mulch leaving a bare space all around the trunk so that mulch and soil do not touch bark or root collar. ( pg 11 in link below)

-Water deeply during droughts

-In winter, protect bark on trunk from frost cracks and sunscald, using tree wrap. Remove each spring. Do this the first 3-4 years after transplanting.

Here is a tree owner’s manual that explains these points in detail-

https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5368392.pdf

Would it be of benefit to remove the plants beneath the tree to extend it’s life?  Would trimming the branches extend its life?  What suggestions would you have besides cutting the tree down?  There are about 3other trees in the subdivision with similar conditions, all the same maple, all planted at the same time 

Removing the soil and plants down to where the root collar begins( where the trunk flares out into the main roots), may help. However, you might find many fine fibrous roots in the soil that are helping the plant. So, if you do this, wait until next spring when the tree is actively trying to put on new growth, since these fibrous roots will be lost. Do not try to paint or seal the bark with anything.
Keep the tree watered anytime the rainfall is less than an inch every 7-10 days.
Mulch in a circle( or a square shape if you prefer), around the toot zone at least a couple feet out. Leave a donut hole shaped bare area around the trunk, as is shown on page 11 in the Tree Owners Manual.An arborist need to be consulted for at least two things- how extensive the rot is( the tree may be structurally unsound and in danger of falling); and if the tree is able to be saved then the arborist has the training  and tools to correctly remove a girdling root.

If the other trees are nearby, you might be able to share the expense with those neighbors and have the arborist address all the trees in one visit.

Hello Karen
We ask that you open a new question each time, u less it is a followup for the same plant. This helps us properly account for how many questions we receive each season.
So, in future, please do open a new question each time.

For this tree, it isn’t as deeply buried as the first one was.  I can see the root collar just beginning to glare out at the base of the trunk, so this tree is actually in pretty good position.

When the collar and the roots are buried more than a 2-3 inches by soil or mulch it restricts oxygen from getting to the roots. (Yes roots need oxygen, too).