Question
Attempting to rejuvenate old privets.  Cut them to 0ne foot in 2006.  Stumps sent up shoots which I let grow to about four feet before  pruning. Now they're about seven feet tall and some of them are dropping their  leaves after a period o vigorous growth this spring.  Are they sick? Or am I not pruning  properly?

Answer
Cheak your soil for excessive moisture.  
It sounds to me like the trimming may be a problem as the openings are a great way for bacteria to enter and manifest.  
Also could be overfertilizing.  Typically when this occurs we see a explosion of great growth and then a crash.  When the leaves of any plant fall off the plant is saying it cannot support the growth systemically.

I would suggest a new all natural product (Atomic Grow) on the market that will balance the plants systemically and will de-tox them at the same time.

I have worked with it for about 7 years now and it works.

I buy mine from www.crowleynursery.net.  Kathy will take good care of you.  She has 22 acres of organic botanicals.

Good Luck

James