Green, maybe it is my old cell but I am having trouble zooming in on the crack or to see anything wrong with the trunk.

SOMETHING obviously is keeping nutrients from getting to the top of the tree. We had a rough winter here so it could be that for you. Could be physical damage or could be borers.

Where are you? Emerald Ash Borer has me treating my two remaining trees with a terrible poison to they MAYBE won't get killed by the bug. Google EAB zone and if you are near it you may as well cut your losses early.

A shame. I really liked my old white ash trees.

Regardless if there is no top growth by the fourth of July I would cut the top off. Then next year pick the tallest or strongest of the suckers if you decide to keep the tree. If you are near the EAB infection zone (think east of the rockies in the U.S. or Canada) I really recommend sonething else.

see another pic

toronado3800, Thanks for your information.
I live in zone 5.
I gave the details of the base of the trunk please see above pic.

Thanks for your help

Have you used a broadleaf weed killer on your lawn?
The ash trees in the background look OK.
Mike

Oddly I see both the obvious crack and some odd leaf curl like my neighbor's dwarf peach has. That is fungus caused.

Good observation on the trees across the street.

Thanks toronado& Mike, do you think I need to use fungus killer or something else to rescue it? Is it dying?
I did not use a broadleaf weed killer on my lawn, should I use it now? Thanks.

Where do you live?

The curled leaves could be due to ash psyllid.
See this
http://www.bozeman.net/Departments/Park-Rec-Cemetery/Forestry/Insects-and-Diseases/Cottony-Ash-Psyllid

Here is a link that might be useful: damage from ash psyllid

Thanks Jean, I live in Colorado.
The curled leaves are only from the bottom of the trunk.
I wonder if I can cut those leaves off to save the tree. Tks.

EAB could be a culprit (not sure where OP is) but IME, there are several other killers of Ash as well.

I noticed something weird in PA (near the DE line) this weekend - some of the ashes have had such heavy seed crops, that they're nearly bare now that the seeds have dropped - only a few small leaves at the tips.

Is that normal or a sign of EAB or other disease/insect issues?

The ashes in that area that appear to be male have nice deep green canopies.

Sun scald on the trunk, you might have killed it with the weed killer, very easy to do.

Doesn't look like ash borers

not ash borer. EAB would leave very obvious S shaped galleries behind the peeling bark. I don't see that in the photo.

do not try to save it. replace it with a red oak or autumn blaze maple. EAB is present in colorado, so even if you were able to resurrect it, the bug would just kill it soon enough.

If it is a white ash, and I can't quite tell but I think it may be, there is a long-standing issue of graft incompatibility which presents exactly like this. I once had an "Autumn Purple" cultivar of white ash-developed in my own state-suffer miserably until death did us part, out on my terrace. I babied the tree during initial establishment but nothing I did improved anything. Look up graft incompatibility on white ash and see if you don't think that's what you have going on here.

The irony of that situation is that in the woods can be found numerous fine white ash saplings-at least where EAB is not yet raging-any one of which would make a perfectly fine specimen, without the added step of bud or chip grafting. Not sure why that process still remains such a mainstay of amenity tree production. Own-root is the way to go, IMO.

+oM