I had a bit of dieback on mine, but I attribute it more to the extreme heat we saw last summer.
I moved mine to an area a bit easier to reach with a hose, trimmed off the dead parts, and it seems to be bouncing right back.
I will always try and save a tree.
I haven't lost a JM yet and I'm not about to start, lol.

Unfortunately, that tree is quite beyond saving :-(

I'd investigate the possibility of verticillium wilt (take a sample to your extension service for a proper diagnosis). This is an opportunistic, soil-borne pathgogen that is particularly devastating to Japanese and other Asian maples. It tends to be a very rapid onset and often right as the tree is leafing out after winter. It can also happen midseason. Often it is the aftermath of some sort of stressor but it can also be the result of mechanical damage to the roots or via pruning cuts.

If it tests out positive, you won't want to replant with another maple. Pick a disease resistant species.

hmmm....maybe the roots were affected. Last fall I was digging around to remove those two yellow Hosta Kabitans that were getting swallowed up by the Ajuga 'chocolate chip'. I was also digging the choc chip just to keep it out of the lawn. That choc chip nearly doubles in size each year. A real pest ... but awesome when in bloom.

Are JM roots shallow, where that activity could have damaged it?

Very definitely! I always recommend underplanting JM's with something that will not require division or frequent cultivation or anything that would easily outgrow the space and need to be moved. Groundcovers are ideal. Japanese maple roots are extremely sensitive to disturbance and even minor damage to the root system can vector in the pathogen.

Thanks GG. I wish I could remember just what I did last fall. I just took a closer look at the groundcover area and I see that the hosta I removed is a good 3' away. I think the closer hosta was removed the year before.

Could the groundcover itself be too strong for a JM? Would thinning/pulling out the groundcover have done damage?

In any case, I am certainly going to be careful of JM underplantings in the future!!! Thanks.

Well, when I got close up to cut it down, I just couldn't bear to. The pathetic amount of foliage had filled out and some sprouts looked promising, so I decided to give it a try. One thing I noticed is that the surviving branch and even the sprouts along the trunk were all south-facing. Not sure if that's pertinent but it did catch my eye.

Here it is before I pruned:

Here it is after:

Maybe next year if those sprouts turn into branches and if I get more good sprouts, I will top off the tree to attempt to balance things. (that is, if I don't move. The house is up for sale again so it may no longer be my problem!).

Wendy,

I can understand your reluctance to take it down completely. If it were mine, I would consider chip budding 'Aureum' onto the trunk in the summer to create some lower branches, even knowing it might be beyond rehabilitating.

Chip budding is not too hard for a novice to accomplish. If you are interested, read up on it and let me know. I'd be happy to send you 'Aureum' buds at the right time for you to try it. I have one that need pruning

Keith

Keith, That's a cool idea. Actually I think I learned that in hort school one time. Is it the same as grafting? It was kinda tricky.

Couldn't I take the scion from the new growth of my 'Aureum'?

You could use buds from your plant, but you don't have a lot of leaf mass currently. I have some branches that are headed toward my deck and will be taking them off eventually, so could certainly send to you.

Chip budding is a type of grafting. You wouldn't need much to try it. Just a single blade razor and parafilm grafting tape

Thanks for the offer. The Open House is today. I think the house will sell this time around, but if not, I will give it a try!

Maybe if its a smooth transaction and the buyers are into gardening, we could try it together! Anyone who buys this place ought to be into gardening. It's loaded!

One side of my tree has died completely. I have been digging around in the root area but just above on the main stem where there was the original but dead trunk. Inside I found these...which coincidentaly we found in our poorly Money Tree...they are millipedes. Google them and you may find that these got into the root of the above tree.