Mountain Ash

Sorbus poteriifolia

Rosaceae · broadleaf deciduous shrub · introduced

Last updated May 11, 2026

Plant Profile

Size & Form

Height

9 ft

Site Requirements

Light

Full Sun to Part Shade

Hardiness

Zones 3a–8b

Ornamental Interest

Fall Color

Red

Origin

stony slopes

Cytospora CankerHigh

Peak Spore Production and Dispersal

Fire BlightHigh

Bloom Infection Window

RustHigh

Uredinial Stage (Summer)

Peak Population & Dispersal

+ 2 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 Ash borer Enarmonia formosana Cherry bark tortrix Leaf blister mite Pristiphora geniculata Mountain ash sawfly Pear sawfly (pear slug) Otiorhynchus spp. Root weevil Malacosoma spp. Tent caterpillar

Data Maturity

Structured Multiple sources. Expert review underway.