Question
I have a white birch tree that is over 20 years old.  It has always been pretty all summer.  Last spring, 2007, the tree was starting to bud and we had a late frost, and the top of the tree did not do well and looked like it was dying.  My husband said it was the frost, and would be ok in 2008.  Well this year it is not better.  The top portion of the tree looks dead,  there are leaves on some of the bottom but it is not all over.  What can I do to bring this tree back to life or is it to late.  I am not sure it was the frost last year that caused the problem, but it did happen.

Answer
To determine if the tree is still alive or what part is still alive--start near the highest branch you can reach and scrape a small bit of bar off the twig if the color under the bark is green the branch is still alive and should leaf out. If the color under the bark is not green (brown) then the branch is dead at this point on the branch. If brown continue down the branch scraping at intervals until you find green or reach the trunk. Do this on other branch to determine if they are dead. The dead branches can be pruned off but this may leave a stubby tree. If you have enough foliage left the tree will grow but will take some time to regain a tree like appearance. If you can not reach the limbs to test you can just wait and see what happens but expect the top to be dead and that you may have to cut the top off.
There is not anything that can bring the dead part of the tree back to life and new limbs will not sprout from the area. Depending on what is left it maybe best to just remove the tree and replant another one.