The tree is deteriorating. It's losing its needles, and some branches
are completely free of needles.

That's common and natural on a maturing pine tree. Pines in our area have
been shedding needles for over a month. That's not a problem. As trees
mature such as pines, often, some branches cannot manufacture enough food
for the branch and the branch becomes symplastless, sheds its needles and is
then shed. Shedding woody and non-woody parts is common and good for the
survival of the tree. Very common and natural. We do not spray anything on
the pines we care for.

--
Sincerely,
John A. Keslick, Jr.
Consulting Arborist
http://home.ccil.org/~treeman
and www.treedictionary.com
Beware of so-called tree experts who do not understand tree biology.
Storms, fires, floods, earthquakes, and volcanic eruptions keep reminding us
that we are not the boss.