Question

Elm 1  

Elm 2   Hi there,
We have what I believe is an American Elm tree in our back yard (St. Louis). There were some invasive vines growing up the tree last fall so we removed them. They seemed to be growing out of the center of the base of the tree. After removing the vines, we noticed some areas around the base of the tree where the bark could be easily removed due to cracking/flaking (I guess). Under these areas is soft, white/powdery stuff. See elm 1 photo. So we sprayed a couple of these areas with pruning seal. See elm 2 photo. So here are my questions:
1. I've since learned that pruning seals is bad for trees. Have we caused irreversible damage to the tree by spraying a couple areas with pruning seal? Or will it be OK?
2. Is this stuff under the bark just a natural occurrence or is it some kind of disease that is going to destroy the tree?

The tree canopy is large and appears to be otherwise healthy without any signs of leaf discoloration.

Thank you!!!

Answer
More than likely the tree has a decay fungi that has entered the tree trunk through an old wound. Decay fungi enter the tree trunk through wounds and will over time eat away at the woody center part of the tree. They do not infect living cells so they are not really a health problem with the tree.
There is not really anything that can be done about the fungi growing in the trunk. It is not a problem unless you start to have the large limbs break and these are hollow. This would mean the decay has grown up into the trunk and maybe come a problem of breakage of large limbs and the trunk.  This will not be a real problem for many many years and may not ever be a problem.

I would recommend that you fertilize the tree with 10-10-10 fertilizer at the rate of 1 lb of fertilizer per inch of trunk diameter scattered around the tree and watered in good. Apply just before a rain storm and you will not have to water. I would fertilize this Fall and again in the early spring.
The wound dressing is usually not recommended for open wound like a pruning stub because it slows down the natural healing over of the wound. Using the sealer will not effect the overall health of the tree. It neither hurt or helped the wound area. I would not worry about this problem.