Formosum Rhododendron
Rhododendron formosum var. formosum
Ericaceae · broadleaf evergreen shrub · introduced
Last updated
An evergreen shrub native to Assam and northwest Burma (Himalaya), reaching 4 feet. Fragrant funnel-shaped flowers, white or white tinged with pink, with a yellow blotch at the base.
Fragrance and white flowers make this a useful species for sheltered woodland settings. Acidic, well-drained soil. Twenty-one diseases and 15 pests documented at the genus level. All parts contain grayanotoxins and are toxic if ingested.
Plant Profile
Size & Form
Height
4 ft
Ornamental Interest
Origin
Assam and northwest Burma (Himalaya)
Watch for this season
Root Colonization (Spring–Fall)
Gall Development & Sporulation
Powdery MildewHigh
Active Conidial Spread
RustHigh
Uredinial Stage (Summer)
+ 13 more — see full disease and pest lists below
Diseases: Regionally Documented (21)
Root Rot (Phytophthora spp.) Multiple obligate biotrophic fungi (Erysiphales: Erysipha... Powdery Mildew Ovulinia azaleae Ovulinia Petal Blight 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 Petal Blight Multiple soilborne and waterborne pathogens cause cutting... Cutting Rots Leaf Burn Ramorum Blight (Sudden Oak Death) Botryosphaeria dothidea Botryosphaeria Dieback Seifertia azaleae Bud Blight Rhododendron necrotic ringspot virus Necrotic Ringspot Multiple genera (Melampsoridium, Thekopsora, Naohidemyces... Rust Taphrina wiesneri Witches' Broom Armillaria spp. — primarily A Armillaria Root Rot Pestalotiopsis sydowiana Gray Blight Physiological leaf spot Phytophthora Blight Tylenchorhynchus claytoni Nematode, Stunt
Pests: Regionally Documented (15)
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 Aphidoidea Aphid Lepidoptera Caterpillars Parthenolecanium spp. Lecanium scale Stephanitis rhododendri Rhododendron lace bug Dialeurodes chittendeni Rhododendron whitefly Nematus lipovskyi Azalea sawfly Cacoecimorpha pronubana Carnation tortrix Icerya purchasi Cottony cushion scale Coleotechnites huntella Rhododendron bud moth
Data Maturity Structured Multiple sources. Expert review underway.