Rhododendron: Armillaria root rot categories: Ornamentals Rhododendron Rhododendron Diseases Shrubs revision date: 2022-12-05 12:00 White fungal mat of Armillaria root rot infecting trunkPhoto 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 which have been flooded. Symptoms […]
Rhododendron: Botrytis shoot blight categories: Ornamentals Rhododendron Rhododendron Diseases Shrubs revision date: 2022-12-05 12:00 Botrytis shoot blightPhoto 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 may be formed on infected […]
Rhododendron: Gray blight categories: Ornamentals Rhododendron Rhododendron Diseases Shrubs revision date: 2022-12-05 12:00 Rhododendron gray blightPhoto 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 or blotches with dark margins […]
Rhododendron: Leaf spot categories: Ornamentals Rhododendron Rhododendron Diseases Shrubs revision date: 2022-12-05 12:00 Rhododendron fungal leaf spotPhoto 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 spots may feel bumpy on […]
Rhododendron: Lime-induced chlorosis categories: Ornamentals Rhododendron Rhododendron Diseases Shrubs revision date: 2022-12-05 12:00 Lime-induced chlorosis on rhododendronPhoto 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 yellow leaves, particularly on the […]
Rhododendron: Marginal leaf necrosis categories: Ornamentals Rhododendron Rhododendron Diseases Shrubs revision date: 2022-12-05 12:00 Rhododendron marginal leaf necrosisPhoto 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 leaf. Water stress (too much […]
Rhododendron: Physiological leaf spot categories: Ornamentals Rhododendron Rhododendron Diseases Shrubs revision date: 2022-12-05 12:00 Rhododendron physiological leaf spotPhoto 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 in physiological leaf spot. One particularly […]
Rhododendron: Phytophthora blight categories: Ornamentals Rhododendron Rhododendron Diseases Shrubs revision date: 2022-12-05 12:00 Rhododendron Phytophthora blightPhoto 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 black cankers on shoots, and […]
Rhododendron: Phytophthora root rot categories: Ornamentals Rhododendron Rhododendron Diseases Shrubs revision date: 2022-12-05 12:00 Phytophthora root rot on rhododendronPhoto 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, branch dieback, wilt, and even […]
Rhododendron: Powdery mildew categories: Ornamentals Rhododendron Rhododendron Diseases Shrubs revision date: 2022-12-05 12:00 Powdery mildew causing yellow spots on rhododendronPhoto 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 with powdery mildews. Leaves may […]