Question

Bark Damage   Greetings from the North Carolina piedmont.

I'm looking for help assessing damage that seems to be progressing with an Autumn Blaze Maple.

I had 8 of these trees installed in September, 2009 so they've been in the ground at my house for almost three years. All 8 trees were approximately 5-to-6 inches in diameter when installed - I'm not sure how old that makes them.

This summer I have noticed that one of the trees appears decidedly less healthy than the others. The foliage just isn't as full and generally speaking it just looks weak.

I took a closer look at the tree yesterday and I'm seeing damage to the bark that I don't understand. I have attached an image to illustrate what I see. I'm seeing insect activity in the areas where the bark is cracking and revealing the inner wood. There appears to be a couple of different ants - I'm not sure what else is living in there. I don't recall seeing this bark damage last season; my impression is that it is something that is progressing rather quickly.

The only difference in this tree, compared to the other 7, that I would note is that it's bark got damaged by the installers as it was being set into the ground. The third photo from the left shows that area.

I would greatly appreciate any ideas you have.

Best regards,

Kevin

Answer
The damage from the planting has allowed an insect called a borer to enter the tree trunk. These insects over time can kill a maple tree especially if it is young. There is also a decay fungi that has entered the wound and this will cause the tree to become hollow over many years, There is not really anything that can be done for the decay fungi. It is very slow growing and more than likely not cause the tree to die. You can remove the loose bark and this will help the wound heal better.

For the borer, the trees can be sprayed with an insecticide called Onyx or Merit. The trunk as far up as possible will need to be sprayed. A newer insecticide called Bayer Advanced Tree an Shrub Insect control can be used on large trees. This is a applied to the soil around the tree and the roots will carry it to the trunk branches an when an insect borers in to or feeds on the tree it is killed. This soil applied insecticide will protect the tree form other attacks for the season. Here is a web link to this product. Check with your local nursery for this. BUT the chances of spreading from one tee is slight. I would monitor the other trees and look for signs of borers-boring dust, single holes in the bark. wet places on the bark. IF these are found then treat the tree.
Usually tree attacked by borers are under stress __in this case the wound_. I would recommend that the tree be fertilized with 10-10-10 fertilizer at the rate of 1 lb per inch of trunk diameter scattered around the tree and watered in good. Apply the fertilizer just before a rain storm and you will not need to water. I would wait until this Fall to fertilize the trees.And repeat in the spring.  This will increase the health of the root system.          
http://www.bayeradvanced.com/tree-shrub-care/products/12-month-tree-shrub-insect