This tree looks severely dehydrated, not surprising since we're in record-breaking drought. We'd recommend watering it immediately. Water slowly (a long-lasting slow stream from a hose, moved periodically around the entire root zone ) and deeply.
These leaves are drooping and turning brown, which means the roots are in crisis. Do not allow it to go into the winter in dry soil. That will probably kill it entirely.
If watered well now, it may have enough root system left alive to put out leaves in the spring. Water well during dry spells (anytime there is less than 1" of rain a week, spring through fall) for the next 2 years.