Western Azalea
Rhododendron occidentale
Ericaceae · broadleaf deciduous shrub · native
Last updated
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Western azalea (Rhododendron occidentale) is a deciduous broadleaf shrub in the Ericaceae family native to western North America west of the Rocky Mountains. It reaches 10 ft tall and produces white to salmon-pink flowers with orange-red buds. It blooms on previous season's wood and displays scarlet and yellow fall color.
Western azalea has 35 diseases and 21 pests documented in managed landscapes. One cultivar is available in the trade. All parts are poisonous to humans, cats, dogs, and horses. The striking fall color and bicolored flower buds distinguish it from other native azaleas.
Quick Facts
Height
10 ft
Fall Color
Crimson, scarlet, yellow
Origin
Pacific Northwest native
Diseases (28)
Phytophthora spp. Root Rot (Phytophthora spp.) Podosphaera aphanis var. aphanis Powdery Mildew Ovulinia azaleae Ovulinia Petal Blight Non-pathogenic (iron deficiency) Lime-induced Chlorosis Symptom category — not a single disease Leaf Spot Exobasidium vaccinii Leaf and Flower Gall Cylindrocladium scoparium Cylindrocladium Blight and Root Rot Botrytis cinerea Botrytis Petal Blight Xylella fastidiosa or abiotic Marginal leaf necrosis Rhododendron and Cutting Rots Non-pathogenic (abiotic stress) Leaf Burn abiotic (drought, heat stress) or bacterial (Xylella fast... Leaf Scorch Phytophthora spp. Phytophthora Root Rot and Wilt Phytophthora ramorum Ramorum Leaf Blight Botryosphaeria dothidea Botryosphaeria Dieback Seifertia azaleae Bud Blight Rhododendron necrotic ringspot virus Necrotic Ringspot Many different Phytophthora Blight and Dieback Phytophthora ramorum"filthy five\" genera are inc Ramorum Leaf Blight and Shoot Dieback Thekopsora minima and Naohidemyces vaccinii Rust Taphrina wiesneri Witches' Broom Armillaria ostoyae Armillaria Root Rot Botrytis cinerea Botrytis Shoot Blight Pestalotiopsis sydowiana Gray Blight Non-pathogenic (physiological disorder) Physiological leaf spot Phytophthora spp. Phytophthora Blight Phytophthora spp. (P Phytophthora Root Rot Phytophthora ramorum Ramorum leaf and shoot blight (Sudden oak death)
Pests (21)
Tetranychidae Spider mite Otiorhynchus spp. Root weevil Choristoneura rosaceana Obliquebanded Leafroller Caloptilia azaleella Azalea leafminer Stephanitis pyrioides Azalea Lace Bug Acanthococcus azaleae Azalea bark scale Salt injury Sunburn Tissue Proliferation Aphidoidea Aphid Lepidoptera Caterpillars Parthenolecanium spp. Lecanium scale Stephanitis rhododendri Rhododendron lace bug Dialeurodes chittendeni Rhododendron whitefly Nematus lipovskyi Azalea sawfly Tingidae Lace bug Stephanitis spp. Azalea and rhododendron lace bug Cacoecimorpha pronubana Carnation tortrix Icerya purchasi Cottony cushion scale Coleotechnites huntella Rhododendron bud moth Nematode, Stunt
Cultivars (1)
'Irene Koster'
Common name: Irene Koster (Western) Azalea; Mature height: 4–6 ft