Azalea: Cylindrocladium blight and root rot Categories: Azalea Azalea Diseases Ornamentals Shrubs Last review date: 2026-02-13 10:02 Last edit date: Nursery plants dying from Cylindrocladium root rot Photo by: R.S. Byther Biology This fungal disease may infect plants through the roots or stems and cause diverse symptoms. Leaf spots, cankers on stems, root rot, and/or […]
Azalea: Botrytis petal blight Categories: Azalea Azalea Diseases Ornamentals Shrubs Last review date: 2026-08-28 02:15 Last edit date: Botrytis shoot blight Photo by: R.S. Byther Biology Botrytis petal blight is a fungal disease typically found in early spring. Symptoms of infection include brown, water-soaked spots on the leaves, and masses of gray-brown spores which form […]
Azalea: Leaf and flower gall Categories: Azalea Azalea Diseases Ornamentals Shrubs Last review date: 2026-08-28 02:29 Last edit date: Azalea leaf and flower galls Photo by: R.S. Byther Biology The leaf and flower gall fungus attacks expanding leaf and flower buds. Initially, the affected plant part shows a thickening and gradually assumes a fleshy appearance. […]
Azalea: Leaf spot Categories: Azalea Azalea Diseases Ornamentals Shrubs Last review date: 2026-02-13 10:16 Last edit date: Rhododendron fungal leaf spot Photo by: R.S. Byther Biology Leaf spot or leaf scorch on azaleas is caused by a fungus. At first, dark red to brown spots appear on leaves in early summer. Later these spots turn […]
Azalea: Lime-induced chlorosis Categories: Azalea Azalea Diseases Ornamentals Shrubs Last review date: 2026-02-13 10:23 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 […]
Azalea: Marginal leaf necrosis Categories: Azalea Azalea Diseases Ornamentals Shrubs Last review date: 2025-05-15 05:43 Last edit date: Rhododendron marginal leaf necrosis Photo by: R.S. Byther Biology Leaf burn on azalea is a response to stress. Leaves turn brown, especially at the tips and along the edges. Water stress (too much or too little), root […]
Azalea: Nematode (stunt) Categories: Azalea Azalea Diseases Ornamentals Shrubs Last review date: 2026-02-13 10:38 Last edit date: Biology Nematode problems are most common in nursery plantings. Nematodes are tiny, worm-like parasites found only in the soil that feed on the roots. The root damage causes an overall stunting of affected plants, and plants may also […]
Azalea: Ovulinia petal blight Categories: Azalea Azalea Diseases Ornamentals Shrubs Last review date: 2026-08-28 02:15 Last edit date: Azalea Ovulinia petal blight Photo by: R.C. Linderman Biology Ovulinia petal blight affects the flowers only (not leaves or shoots) of azaleas and rhododendrons. Infected flowers first display small, water-soaked spots which enlarge quickly. The petals quickly […]
Azalea: Powdery mildew Categories: Azalea Azalea Diseases Ornamentals Shrubs Last review date: 2026-02-13 11:13 Last edit date: Azalea powdery mildew Photo by: R.S. Byther Biology Powdery mildew on azalea forms a characteristic fuzzy white growth on upper or lower leaf surfaces. Entire leaves can be covered. In late summer and fall, small black specks may […]
Azalea: Root rot (Phytophthora) Categories: Azalea Azalea Diseases Ornamentals Shrubs Last review date: 2026-02-13 11:22 Last edit date: Phytophthora root rot damage to trunk 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 […]