Korean Mountain Ash

Sorbus alnifolia

Rosaceae · broadleaf deciduous tree · introduced

Last updated May 11, 2026

Quick Facts

Height

40–50 ft

Spread

26 ft

Growth Rate

Fast

Light

Full Sun to Part Shade

Soil

Moist

Water

Moderate

Hardiness

Zone Zones 4a–8b

Bloom Time

May

Fall Color

Brown

Origin

central China, Korea and Japan

Cytospora CankerHigh

Spring Canker Activation

Fire BlightHigh

Bloom Infection Window

Nectria CankerHigh

Spore Release (Fall & Spring Rains)

RustHigh

Aecial Stage (Alternate Host)

+ 4 more — see full disease and pest lists below

Diseases: Regionally Documented (5)

Cytospora spp. (Valsa spp., Leucostoma spp.) Cytospora Canker Erwinia amylovora Fire Blight Symptom category — not a single disease Leaf Spot Neonectria ditissima Nectria Canker Multiple genera (Melampsoridium, Thekopsora, Naohidemyces... Rust

Pests: Regionally Documented (9)

Aphidoidea Aphid Choreutis pariana Apple-and-thorn skeletonizer Enarmonia formosana Cherry bark tortrix Pristiphora geniculata Mountain ash sawfly Pear sawfly (pear slug) Leaf blister mite Otiorhynchus spp. Root weevil Malacosoma spp. Tent caterpillar Ash borer

Data Maturity

Structured Multiple sources. Expert review underway.