Certainly an attractive tree you've got there. Nurseries used to plant the European ones, but they got fire-blight or something and you don't see them anymore, at least here in z6. I understand they are cool-climate trees.

I had an oak leaf sorbus, but it died. I always get excited when I come across our native mountain ash in the mountains. It’s seemingly rare. Yours is a beaut

I've also got a European Mtn. Ash (S. aucuparia) that has been surprisingly vigorous. Both of my Sorbus were used by Bucks as a rubbing post at a young age and had to overcome that ordeal. The Korean Mtn. Ash reportedly has better disease resistance than the other commonly grown species. Fun fact: S. alnifolia has simple leaf structure, while most (all?) Sorbus have compound leaves.

Lane, are you referring to Sorbus scopulina? I had to look up what Sorbus are native to the western US and had never heard of it. In the upper Midwest, S. decora and S. americana are native, but generally confined to areas ringing the Great Lakes. I have never seen a wild native Sorbus where I'm at.

I had one, bought at the late lamented Arborvillage Nursery in their last year of operation.

Alas, it got fire-blight so bad I decided it had to be deaccessioned. I wasn't going to bother spraying it.

There was what I believe to be a Sorbus Americana growing in the yard when I moved here, It had a noticeable cant from the big storm.

It grew nice for a year or two then became a compelling treat for some sapsuckers. Their regular visits caused considerable damage. Guess I just got sick of seeing it in continual rehab. Now it's gone.

Yeah, it must be sorbus scopulina. I had to look it up, too. I see them near creeks in the riparian zone. If you look at the wikipedia range map I’ve seen them in the farthest dot in the SE of Wyoming in the Snowies and also in the wind river range. They stink in the spring when flowing

IMO, S. alnifolia should be planted more often here in the Great Lakes region, but very few nurseries carry it. We've planted a small number of them, and probably the only criticism I would have is that they are quite slow growers. I haven't noticed any issues with fire blight or borers on trees I've seen in this area. S. aucuparia, OTOH, is susceptible to both borers and FB (as well as sawflies).

Didn't have a chance to get a photo this spring, but here is one of our S alnifolia last May (5/16/23):

Fall color on the same tree a couple years ago:

A nice specimen in a public garden in Flint (9/12/20):

Fall color, same location:

Tree in the backyard that I grew from seed (photo earlier this evening 5/24/24):

Yes, the fall color on KMA (!) can be very nice. It took seven years for mine to take off, so slow-to-establish is apparently a trait. On a positive note, the foliage stays just about perfect throughout summer. Lovely flowers, clean foliage, ornamental fruit, and great fall color makes for a nice medium-size tree in the Great Lakes region.

Arbordave, your one S. alnifolia has a nice thick base. Great fall color too.