Sorbus aucuparia

Sorbus aucuparia, or European Mountain Ash, is a small, deciduous tree, often multi-trunked and low-branching, that grows to 40 feet. It has an erect, oval form when young, becoming a slender trunk with branches curving upwards as the tree ages. It is often short-lived; is not heat tolerant; and dislikes compacted soil. As the common name suggests, this is a tree of cool mountain climates that dislikes hot and humid summers, and will not grow well south of USDA Zones 5-6. On the plus side, however, it does flower in late May and fruits in late summer to early fall. The fruits are a good food source for birds and the fall foliage of yellow to reddish-purple leaves adds to the attractiveness of the tree.. 

The European Mountain Ash grows best in moist, acidic, well-drained soils in full sun. It is widely planted in northern North America as an ornamental and has naturalized in some parts of Canada and the northern U.S. Mountain ashes have ash-like leaves, but are members of the rose family, and are not related to true ashes (Fraxinus), which are in the olive family.

Insects, Diseases, and Other Plant Problems

Bacterial fireblight can be a severe problem, causing scorched leaves at the branch ends. Scab can cause significant defoliation. Cankers, crown gall, powdery mildew and rust may also occur. Insect visitors include aphids, sawfly, scale and borers. Stressed trees are particularly vulnerable to borers and cankers.