Rhododendron: Armillaria root rot Categories: Ornamentals Rhododendron Rhododendron Diseases Shrubs Last review date: 2025-06-27 10:25 Last edit date: White fungal mat of Armillaria root rot infecting trunk Photo by: C.R. Foss Biology Armillaria root rot is a fungal disease transmitted between plants by root contact. Armillaria is often found in newly cleared soils or soils […]
Rhododendron: Botrytis shoot blight Categories: Ornamentals Rhododendron Rhododendron Diseases Shrubs Last review date: 2025-06-27 11:10 Last edit date: Botrytis shoot blight Photo by: R.S. Byther Biology Botrytis shoot blight is a fungal disease found on shoots in early spring. Symptoms of infection include brown, water-soaked spots on the shoots and masses of gray spores which […]
Rhododendron: Gray blight Categories: Ornamentals Rhododendron Rhododendron Diseases Shrubs Last review date: 2025-06-27 11:13 Last edit date: Rhododendron gray blight Photo by: R.S. Byther Biology Gray blight is a fungal infection of the leaves. It usually becomes established after an injury to the leaf, such as sunscald, frost damage, or some mechanical injury. White spots […]
Rhododendron: Leaf spot Categories: Ornamentals Rhododendron Rhododendron Diseases Shrubs Last review date: 2026-08-28 02:29 Last edit date: Rhododendron fungal leaf spot Photo by: R.S. Byther Biology Several fungi cause leaf spots on rhododendron. They often infect through wounds. Infected leaves display dark brown spots which may cover up to half of the leaf surface. These […]
Rhododendron: Lime-induced chlorosis Categories: Ornamentals Rhododendron Rhododendron Diseases Shrubs Last review date: 2025-06-27 11:15 Last edit date: Lime-induced chlorosis on rhododendron Photo by: R.S. Byther Biology Lime-induced chlorosis, or leaf yellowing, is caused by alkaline soil conditions. High alkalinity of soils can make iron or manganese unavailable to plants, causing leaf chlorosis. Pale to bright […]
Rhododendron: Marginal leaf necrosis Categories: Ornamentals Rhododendron Rhododendron Diseases Shrubs Last review date: 2025-06-27 11:16 Last edit date: Rhododendron marginal leaf necrosis Photo by: R.S. Byther Biology Leaf scorch on rhododendrons is a response to stress. Symptoms include browning of tips or margins of leaves, with the damage sometimes spreading to the center of the […]
Rhododendron: Physiological leaf spot Categories: Ornamentals Rhododendron Rhododendron Diseases Shrubs Last review date: 2025-06-27 11:18 Last edit date: Rhododendron physiological leaf spot Photo by: R.S. Byther Biology Rhododendron leaves sometimes develop variously sized and shaped spots. These are usually dark purple in color. The exact cause is unknown, but cultural or environmental stress may result […]
Rhododendron: Phytophthora blight Categories: Ornamentals Rhododendron Rhododendron Diseases Shrubs Last review date: 2025-08-20 07:14 Last edit date: Rhododendron Phytophthora blight Photo by: J.W. Pscheidt Biology Phytophthora blight is a fungal disease whose symptoms are often confused with chemical or mechanical injury or leaf scorch. Irregular dead spots on the tips or margins of leaves, shiny […]
Rhododendron: Phytophthora root rot Categories: Ornamentals Rhododendron Rhododendron Diseases Shrubs Last review date: 2025-06-27 11:21 Last edit date: Phytophthora root rot on rhododendron Photo by: R.S. Byther Biology The symptoms produced by Phytophthora root rot are often confused with those caused by environmental or cultural problems. Above ground, infected plants may show stunting, yellowish-green leaves, […]
Rhododendron: Powdery mildew Categories: Ornamentals Rhododendron Rhododendron Diseases Shrubs Last review date: 2025-06-27 09:44 Last edit date: Powdery mildew causing yellow spots on rhododendron Photo by: C.R. Foss Biology Powdery mildew on rhododendrons is a fungal infection of the leaves. On rhododendrons, the disease often fails to develop the distinctive powdery white growth normally associated […]