Mountain Ash: Beautiful but Short-Lived Tree

Mountain ashes (Sorbus spp.) are beautiful small trees with many good features: decorative bark, masses of white flowers in spring, dense clusters of orange-red fruits in fall that persist part of winter and that attract birds, etc. But they also have a major flaw: they are incredibly susceptible to diseases including fire blight, a deadly disease that always seems to hit just when the tree begins to reach its most beautiful. The symptoms? A branch suddenly turns black in mid-summer, retaining its brown leaves, as if it had been scorched. Over time, the disease spreads, causing cankers on the trunk. The next thing you know the tree is half dead (literally, because often the disease affects one half of the tree before the other) and you have little choice but to remove it.

Yes, I know: theoretically you can prune off the blighted sections, sterilizing your shears between each cut. But this seems to be a strictly aesthetic measure, as once the tree is struck by fire blight, it inevitably comes back year after year, eventually killing the tree

And fire blight is just one of the diseases that can strike mountain ashes: there is also rust, scab and a long list of insects, from scale to borers. If you want to grow a mountain ash, calculate you’ll have to remove it in as little as 15 years… and that is very, very little time for a tree.