Question
I'd been noticing branches failing to grow leaves on my white oaks - mostly the lower branches.  I assumed it was due to lack of sun light, and the trees simply no longer needed them.  However, the leafless branches began to appear higher and higher, including entire branches.  I've noticed the same problem on many other white oaks.  Said branches appear to be dead.  What causes this, is it reversible, and can the trees be saved?  They are 20-30 years old.  Thanks!

Answer
I agree with you. As a tree especially oaks mature they will shed the lower branches which is normal. The shading from the other branch brings this self pruning on.  Some of the upper branches may also shed due to interior shading. As long as the foliage looks green and healthy it is ok. If you want to help increase the foliage growth you can fertilize the tree 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 it in. Do this now and maybe every other year or third tear or so. Trees do not need a lot of added fertilizer but every once in a while it helps.