Looks like I've lost another three oak trees this year.

Three of them (about 12-14" diameter) died last year, along with a dogwood.
Common wisdom at the time seemed to be the draught had taken it's toll. I
cut them down and mulched the area last fall. As a matter of fact, there was
one that died the year before that.

Now, I see that two more oaks with trunks 2'-3' wide have been leafless for
most (if not all) of the summer. A third one about (18" diameter trunk) has
some leaves, but the highest branches are barren with no growth.

I have no idea what is going on. The pines in the same area show no
indication of distress. Other than mulching, I don't do any special care
like watering, spraying or pruning. They are basically trees in the 'woods'.
They are within about 50-75 ft of each other.

These are big old trees - maybe a hundred years, and it is a terrible shame
they are dying. But I don't know what to do to prevent it from spreading.
Any advice appreciated.

Robert