Another pic.

And another

The soil looks dry and bare. A moisture meter will eliminate guessing on when to water. Mulch out around the drip line but not against the trunk. Bare and dry soil is an invitation to mites and other pests that thrive in such an environment. Deep watering as needed is best for trees.

It does indeed look like heat damage, and it's not unusual to see a few of these type of leaves, especially at the onset of the high heat as the tree "hardens off" to it. Pink Lady does tolerate high temps and does fine in Phoenix and Las Vegas. If this tree is killed by it despite plenty of water, I would look to a root problem, such as gophers, cotton root rot, or wooly aphid. This usually affects the whole tree though, and the new growth would hang limp.

That being said I have 100+ apple varieties and all the trees themselves seem impervious to high heat (113F); however the apples have very mixed reactions to it, some baking to mush, some staying crisp and juicy. Heat alone should not be killing your apple trees.

Thanks for the suggestions. The tree is mulched, and the ground underneath the mulch generally feels moist, but I may not be watering deep enough. I'll try to do some deeper watering, and maybe a pesticide to see if I can get it through this summer.

I would not spray, it might send it over the edge, just water then water some more and watch