Irroratum Rhododendron
Rhododendron irroratum
Ericaceae · broadleaf evergreen shrub · introduced
Last updated
An evergreen shrub native to Yunnan and Sichuan, China, at 9,000 to 11,500 feet elevation, reaching 5 feet. Flowers range from white or cream to violet-pink with green or purple spots.
Flower color is variable among populations and clones. A high-elevation Chinese species suited to cool, moist conditions. Acidic, well-drained soil. Twenty-one diseases and 15 pests documented at the genus level. All parts contain grayanotoxins and are toxic if ingested.
Quick Facts
Height
5 ft
Origin
China (Yunnan, Szechwan, 9,000-11,000 ft elevation)
Watch for this season
Root Colonization (Spring–Fall)
Infection at Bud Break
Apothecia Formation & Spore Release
RustHigh
Aecial Stage (Alternate Host)
+ 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.