I've grown several of the half high U of M hybrids; Northsky, Northblue, Northcountry, Polaris; and one high bush: Northland. Northblue is my favorite. Of course, nothing beats the flavor of wild blueberries, and the black berried type is the most flavorful, IMO, but they are so darn tiny. If you had an excessive amount of rain (as I did in Minnesota) with the yellow leaves, I'll bet that is the reason. Waterlogged soil can change the way iron, magnesium, manganese and copper are available to the plant, even if the pH is correct. But there should be good root systems.
You're not tied to using only the Amelanchier alnifolia species of June berries, which is what Dora's link is. There are many other good cultivars out there.
