The leaves of my maple trees
[bloodgood] experienced the same thing. During the two-week period in July when the temperature ranged from 93*F to 103*F, the leaves just dried up, turned brown and started falling off. I continued watering to keep the soil moist but not soggy. Two weeks ago, new leaves started out and the trees
are now full of red leaves again.
Try to protect the tree
as BFVision said from hot sunlight. A 5-ft. canopy probably means that the tree
is about 5-9ft. high. A 9-ft. market umbrella placed near the tree
might be able to offer some shade from direct sunlight .