Looks like murphy is dead.
That's the trouble with growing trees in pots. It's a lot of work. You have to water daily or multiple times a day in hot dry weather. You can't forget or go out of town and hope that mother nature will give you a second chance. It doesn't work that way. And no, there is no miracle fertilizer that will make a tree come back from the dead. Trees like red maple don't make good potted plants. Murpy would have been much happier living in the ground.

You appreciated something that most of us take for granted. A lot of us spend countless hours pulling maple volunteers out of unwanted places. Put a few bare pots out there in february and you're probably get murphy 3.0 and this time, get murphy v3 in the ground by may 1st. Mulch well and water until established.

The first thing trees do when stressed is to loose leaves. They dry and fall off. There is a chance that it is still alive. Scratch the bark with your finger nail, if you see a green under the bark, there is hope. Forget the fertilizer, water well then allow to dry, watch everyday. Stick your finger in soil, when it is dry water. It looks like it was planted in a pot that was too small. It should have been transplanted long ago. The small pot easily dried out esp. if it was hot for a long time. I will also say that if it does live, to go to the container forum and read about making some potting soil that will last a long time. The stuff in the bags at the garden centers is ok for a shirt time, but will not do well over a long period of time.

At some point if you do fertilize do not give it the does recommended on the bag, make a weak version and use it regularly. Use 1/4 strength, - on regular basis. Wait until you see new growth before you fertilize.

LOL - Mike

Thanks to both for a response.
I have 2 questions.
I did the fingernail scratch bark test, and discovered a very light yellow green. Kinda close to the color of lima beans or alfalfa sprouts... is this green enough to have hope that Murph might still indeed be alive?

And if he is, at what point should I replant in better potting soil?

Keep it watered and see if it sends out some new leaves.

if its still alive its in hibernation mode. keep it in the shade, add some mulch or extra soil. too much exposed roots.

repotting should be done in late winter, early spring, when the tree is dormant.

jveirs,

I've had this happen to a number of potted maples over the years. If the plant doesn't recieve water when the leaves dry up and die, the next stage is that the branches die, and the last part to die is the trunk/stem/base. From your pictures, the little branches look dead, however, the "trunk" might still be alive so keep watered and hope for the best.