Honestly, not looking good. My guess would be a watering issue either too much or too little. Describing your native soil, watering regime and planting technique might help people figure out what went wrong. Stick your finger in right now and what is the soil like? Dry, moist, swampy?

Soil is part clay but not overly so. I’ve dug up beside the rootball to check for drainage and it drained well. I’ve been digging into the rootball to check this whole summer to make sure not over watering and usually it’s just moist. It’s not swampy except the day I give it a heavier watering every 5-7 days (which I skip if there’s any rain). its Certainly not swamp like constantly. Usually when I water I would give it about 7 gallons slowly over an hr from the hose and rarely was there any pooling.

I planted at a bit of an elevation with a layer of rocks underneath (not sure if that helps or harms).

Read this to see if it could have any applicability to your situation:

https://pnwhandbooks.org/plantdisease/host-disease/maple-acer-spp-verticillium-wilt

Too much water - rocks underneath where you planted in clay = disaster. All the water will pull into this location.

Whaas5a. If you have a Korean maple how much did you water it usually in the first couple of seasons. Do you think I should try planting a new one or wait till next spring to see if it survives.

The rocks at the bottom of the planting hole are not really an issue, especially if the site is raised or elevated. And if the soil is just moist to the touch, I doubt it is overwatering. And root rots that may arise as the result of overwatering do not manifest overnight.

With that rapid a decline, I'd look first to verticillium wilt, to which maples are highly susceptible. Or to a period of allowing the tree to dry out excessively. But even that rarely will show up as a complete wilt and drying in just 2 days.

Yep!

Yep it’s a disease or I should wait till next spring to see if it bounces back?

Yep to her entire post - look at the page I linked to to see how to tell for yourself if your tree has verticillium. Because nobody looking in here is going to be able to tell you using just your two pictures.

Yes if you look at the sapwood you may be able to tell if you have VW.

What you show is either too little water, too much water, VW or some other enviromental stress.

Your details indicate too much water.

7 gallons of water every 5-7 days with rocks on the bottom. You also said curling leaves all summer.

VW and under watering where my last choices. Personally I haven’t heard of VW effecting the entire crown of a tree that was planted a couple months ago.

GG and Ron - have you?

You bet!! In fact, VW is faster and probably more deadly with younger, not fully established trees than it is with those who have been around a few seasons. The VW pathogen is present in most soils but in an inactive or dormant state and the root disturbance involved with just the act of planting is enough of an inroad for the disease to become active and established.....same with any other possible stressors. IME, neither under nor overwatering will result in that fast a wilted appearance. I have only ever seen VW produce that fast - almost overnight - a decline.

Thanks for your input.

i scratched the branches and all still green and it did bud set for next season when I took off a few leaves which is good I guess. Is there anything I can do except wait and see?

in Terms of watering I guess I may have been heavy handed. that being said the tree was getting about 12-14 hrs of sunshine daily in July and there was a couple weeks where it was close to 30 degrees C and when I dug the rootball it was dry enough I felt To rewater

whaas- if I take A chance and replant a korean maple there next year (hopinh it’s not v wilt) what would be a more appropriate amount to water?

If you are saying you dug it up since it shriveled and found an original, undisturbed potting soil root mass to be dust then that implies the problem is the plant dried out.

Horticultural techniques for successful plant establishment

http://pnwmg.org/wp-content/uploads/2015/03/PlantingFS-2015.pdf

I don’t see any wilting / discoloring in the shoots either. Wouldn‘t you see this with VW?

Again wilting leaves ALL summer long so it’s been stressed all along.

You may have high reflective heat in this location as well - and thats a lot of sun in that type of location as it traps the heat.

I am still sticking with highexcessive sun with minimal air movement topped with overwatering.