Altaglow [ornamental] Saskatoon?
It's a rare species, white-fruited...if you're growing this one I would like to hear more about it, overall performance etc. link below.
from the web...
Another selection from the Peace River country, Altaglow was introduced in 1935 by Brooks Research Station in Alberta. It was released in 1960. It is considered an ornamental rather than a fruiting variety. It has an erect columnar form and brilliant fall color. With a height of eight feet, its foliage is retained into fall, changing from dark green to deep purple, bright red, and yellow. It is self-sterile and white-fruited. But is readily pollinated by blue-fruited saskatoons.
Here is a link that might be useful: Altaglow