Azalea: Cylindrocladium blight and root rot Categories: Azalea Azalea Diseases Ornamentals Shrubs Last review date: 2026-02-13 10:02 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 sudden general wilting […]
Azalea: Botrytis petal blight Categories: Azalea Azalea Diseases Ornamentals Shrubs Last review date: 2026-02-13 09:43 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 on infected tissues. […]
Azalea: Leaf and flower gall Categories: Azalea Azalea Diseases Ornamentals Shrubs Last review date: 2026-02-13 10:07 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. Leaves may thicken […]
Azalea: Leaf spot Categories: Azalea Azalea Diseases Ornamentals Shrubs Last review date: 2026-02-13 10:16 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 lighter brown, while […]
Azalea: Lime-induced chlorosis Categories: Azalea Azalea Diseases Ornamentals Shrubs Last review date: 2026-02-13 10:23 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 yellow leaves, particularly […]
Azalea: Marginal leaf necrosis Categories: Azalea Azalea Diseases Ornamentals Shrubs Last review date: 2025-05-15 05:43 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 or stem damage, […]
Azalea: Nematode (stunt) Categories: Azalea Azalea Diseases Ornamentals Shrubs Last review date: 2026-02-13 10:38 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 show signs of […]
Azalea: Ovulinia petal blight Categories: Azalea Azalea Diseases Ornamentals Shrubs Last review date: 2026-02-13 10:58 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 become slimy and […]
Azalea: Powdery mildew Categories: Azalea Azalea Diseases Ornamentals Shrubs Last review date: 2026-02-13 11:13 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 be found in […]
Azalea: Root rot (Phytophthora) Categories: Azalea Azalea Diseases Ornamentals Shrubs Last review date: 2026-02-13 11:22 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 leaves, branch dieback, […]