he asked if I could find out why sections of our Maple trees seem to "burn
out."
This year we're having a particular spotty problem

By "burn-out" I assume you mean leaf scorch, that is the edges of the leaves
turn brown & the leaves get raher dry. You don't mention where you live or
which species of maples. In general, most maples are from cool forest areas.
Some of them are not suited to growing alone in the sun in a climate with hot
dry summers. Their thin leaves get scorched. Usually, it is a cosmetic problem
and the trees themselves survive, as long as the roots get enough water. If
these are adult trees, there is nothing you can do about it, unless you want to
stand there every hot sunny day and spray the entire tree with water. The other
thing you can do is make a note of which trees are affected and don't plant
that species when you own your own home.
The leaf spotting is a fungus disease caused by our unusually rainy summer. It
is also basically a cosmetic problem. It is too late this year to do anything,
but in the fall, be sure you clean up all the infected leaves and get rid of
them. In the spring, any time they are predicting a lot of rain, have the most
sensitive trees sprayed with a fungicide by a certified arborist.
Iris,
Central NY, Zone 5a, Sunset Zone 40
"If we see light at the end of the tunnel, It's the light of the oncoming
train."
Robert Lowell (1917-1977)