I have a five year old amelanchier in a huge container (which has rooted down into the soil below). Every year it leafs up and blossoms well, with a good set of berries. By late July, all the leaves start to shrivel and the berries go black. The soil is always kept fed and well watered (without being soggy). If the tree starts off the year well, why does it fail like this (regardless of what sort of summer it has been). The condition looks rather like fireblight on pyracanthus.