I have tried 3 different Japanese maples in a specific location (inside a circular raised bed in my herb garden) and all have done OK initially then just up and died. My son recently informed me it is likely that the soil is infected with verticillium wilt. I've read up on the wilt, and it does appear that this is what I have and that there is not much to be done. Before I dig is up - has anyone had any sort of success combating this wilt, or should I just resign myself to this tree dying as well and try to come up with another focal point. On another note, does anyone know of a way to 'save' the existing tree - dig it up, wash off all soil, perhaps soak in something to kill off the wilt. I do have lots of field space and could isolate the infected J. maple well away from other maples (I have several J. maples as well as native vine and big leaf maples). I am currently doing online research but wanted to see if others have experienced this and their thoughts.

If it is verticillium wilt it is inside the plant so digging it up and washing it off won't help. If it's not too far gone (is it currently looking like the picture?) you can maybe keep it going a bit longer by keeping it watered and fertilized, and also mulched. If you decide to replace it you'll need to look for something that is not susceptible to the disease because it will still be in the soil in that spot. There are lists online of susceptible and resistant plants. You don't want to move any of the soil to another part of the garden either. Very disappointing for you

For the past few years, it looks fine until about mid-August or so. Then the outer leaves begin to discolor and wilt. It appears from my reading that the wilt can stay in the soil for 10+ years, so looks like I'll need to figure out something else for that spot. On the plus side, perhaps it is contained within the rock circle and has not spread into the adjacent beds. I have a dahlia close by which is also susceptible to this fungus, and will keep a close eye on it this season.

Yes, it's disappointing, but on the other hand, after three maple failures at least I can pin down the underlying issue.

Any suggestions on a smallish focal point tree/shrub for this spot?

Does it wilt all over, or is it just on some branches, or one side? Verticillium often affects one side or branch. To know for sure it's verticillium would need a lab diagnosis which you may not want to bother with. You could look inside a dead branch to see if there is internal staining. I would try mulching it because being raised is likely making the soil around the roots hotter.

I don't know what would do well in your area, you probably have a lot more choices than I do here in Zone 4, but one list says willows are not susceptible so what about the Japanese variegated willow (Salix integra 'Hakuro-nishiki')?

Since conifers are resistant I'll give a shout out to Hinoki Cypress, Chamaecyparis obtusa. There are plenty of dwarf growers to choose from.
http://garden.org/plants/searc...

Sooty, since this is the 3rd J. maple to fail in one specific site, I think I'll just ditch it (it was a free tree) and not bother trying to pinpoint exactly what the issue is/was. As I recall, it was a bit of a spotty response - one limb would be infested, another was fine, which is in line with your thoughts. Thanks for replacement suggestions. I'm also thinking perhaps a sumac for the fall color and interesting form.

Perhaps other sumac's are better behaved than the Rhus typhina that grows wild around here? That one spreads, and is also susceptible to Verticillium. How about a small weeping crabapple?

There's a list of susceptible and resistant plants here that might help:

http://depts.washington.edu/ho...