Question
2 years ago, I bought a house with a maple tree, which I guess is approx. 35-40 years old.  Although there are lots of leaves on the outer branches, there are no leaves at all on the inner branches.  Therefore, the tree looks like an umbrella.  What can I do to encourage growth on the inner branches?  I live in Toronto.  My neighbours have the same maple tree, but they don't have this problem.  I did notice that there are tar spots on some of the leaves in the fall.

Answer
The leaves on the inner part of the trees crown will die due to the shading effect. The leaves can not get enough sunlight to produce. About the only thing that could be done is to thin the branches so sunlight will reach the trunk. As long as the leaves are green and full and healthy looking the tree is doing fine without the inner leaves.
Fertilizer will also help--fertilize with 10-10-10 fertilizer at the rate of 1 lb per inch of trunk diameter scattered around the tree and watered in good.