Rose: Black mold Categories: Flowers Ornamentals Rose Rose Diseases Last review date: 2025-07-28 10:52 Last edit date: Biology Black mold primarily affects material used for propagation. The fungus grows on cut surfaces, such as at the contact points between rootstocks and scions and rootstocks and bud shields. This causes graft failures. A gray-white fungus growth […]
Rose: Black spot Categories: Flowers Ornamentals Rose Rose Diseases Last review date: 2026-08-28 02:29 Last edit date: Rose black spot on leaves Photo by: R.S. Byther Biology Black spot is a very common fungal infection of the leaves and canes of roses. Round black leaf spots (sometimes with fringed or feathery edges) may be accompanied […]
Rose: Botrytis bud and twig blight Categories: Flowers Ornamentals Rose Rose Diseases Last review date: 2026-08-28 02:15 Last edit date: Botrytis on rose canes Photo by: R.S. Byther Biology Botrytis can infect stems and flowers, including stubs left from pruning or flower removal. Infected tissues are usually covered with a fuzzy, gray-brown growth. Infected flower […]
Rose: Brand canker Categories: Flowers Ornamentals Rose Rose Diseases Last review date: 2025-07-28 10:56 Last edit date: Rose brand canker Photo by: R.S. Byther Biology Brand canker is a fungal disease that often infects plants in the winter, especially when winter protection of roses keeps the canes moist. Initial symptoms of infection are small dark […]
Rose: Bullheading (cold damage) Categories: Flowers Ornamentals Rose Rose Diseases Last review date: 2025-07-28 10:58 Last edit date: Rose bullhead Photo by: R.S. Byther Biology Bullheads are the most prevalent when temperatures dip to 53-59 degrees Fahrenheit during early flower development. Low temperatures appear to alter metabolic activity, which results in the abnormal appearance of […]
Rose: Common canker Categories: Flowers Ornamentals Rose Rose Diseases Last review date: 2025-07-28 10:59 Last edit date: Rose common canker Photo by: R.S. Byther Biology Common canker is a fungal disease that infects plants through long stubs left by improper pruning or through other wound sites. Small yellow or reddish spots appear on canes and […]
Rose: Crown gall Categories: Flowers Ornamentals Rose Rose Diseases Last review date: 2025-07-28 11:00 Last edit date: Crown gall on crown of rose. Photo by: R.S. Byther Biology Crown gall on roses usually occurs at or just beneath the soil surface. It may also be found on stems and roots. Young galls appear as a […]
Rose: Downy mildew Categories: Flowers Ornamentals Rose Rose Diseases Last review date: 2026-08-28 01:39 Last edit date: Downy mildew on rose Photo by: R.S. Byther Biology Downy mildew can affect leaves, stems, flower stems, and flower parts. The infection is usually found only on young growth. On leaves, symptoms include purplish or brown spots, usually […]
Rose: Powdery mildew Categories: Flowers Ornamentals Rose Rose Diseases Last review date: 2026-08-28 01:56 Last edit date: Powdery mildew on rose Photo by: R.S. Byther Biology Powdery mildew is a fungus attacking leaves, stems, and flower parts. Usually, young growth is most severely affected. Reddish, blister-like areas on the upper side of leaves are followed […]
Rose: Rust Categories: Flowers Ornamentals Rose Rose Diseases Last review date: 2025-07-28 11:06 Last edit date: Rust on rose leaves Photo by: R.S. Byther Biology Rust usually is first noticed as clumps or pustules of red to orange powder on the lower surfaces of leaves. The upper surface may also show yellow, orange, or brown […]