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Rose Diseases (Outdoors)

Name: Rose Diseases (Outdoors)
SKU: ART-4093

Informational table showing disease name, symptoms, pathogen/cause, and management of Rose Diseases (Outdoors) diseases.

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Updated:

November 15, 2023

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Disease	Symptoms	Pathogen/Cause	Management
Anthracnose	Dark-purple to black spots are bordered by a narrow, dull-brown band. Centers of spots turn gray and fall out. Spots similar to leaf spots form on canes.	Sphaceloma rosarum	Maintain good sanitation. Black spot control procedures (below) also control anthracnose.
Black spot	Brown to black round spots with feathery edges form on leaves. Leaves yellow and fall. Small, purplish spots form on canes.	Diplocarpon rosae	Remove infected canes. Remove and destroy fallen leaves. Water in a manner that keeps foliage surfaces dry. Apply a fungicide to protect new foliage.
Botrytis blight	Small, water-soaked lesions form on petals. Gray fungal growth covers infected petals. Stubs left after harvest become infected. The fungus then moves down to girdle the cane.	Botrytis cinerea	Space plants to ensure good air circulation. Remove fading flowers and yellowing leaves. Apply a fungicide protect healthy tissue.
Cankers	Reddish-brown spots on canes turn light to dark brown and become covered with tiny, black dots (fungal fruiting structures). Cankers girdle and kill the cane.	Coniothyrium, fuckelii, Cryptosporella umbrina, Coniothyrium wernsdorffiae, Cylindrocladium scoparium	Do not plant stock with cankers. Remove infected canes, making the cut immediately above a bud. Apply a fungicide after pruning. Sterilize the shears with a disinfestant between cuts. Maintain even soil moisture and moderate fertilization.
Crown gall	Small white to cream-colored galls that form on stems may enlarge to 6 inches in diameter. Galls can form on roots or stems.	Agrobacterium tumefaciens	Do not plant infected material. Apply Agrobacterium radiobacter to protect healthy plants at transplant.
Downy mildew	Purplish-brown spots form on leaves during cool, damp spring weather. Leaves yellow and fall. Small spots or long, purplish areas may form on and kill twigs.	Peronospora sparsa	Water in a manner that keeps leaf surfaces dry. Apply a fungicide.
Powdery mildew	Spots on leaves, stems, and flower parts expand and become covered with white fungal growth. Small dead spots form on some cultivars.	Sphaerotheca pannosa	Apply a fungicide.
Rose Rosette	Leaves are distorted and often bright red. Canes are excessively thorny and mature very slowly. Plants may branch excessively (witches'-broom).	Rose rosette virus vectored by eriophyid mites.	Destroy infected plants. Eliminate multiflora roses in a 100' radius of desired roses.
Rust	Lower leaves and cane tissue in the spring and summer have masses of orange powdery spores. Black spores form on the leaves and other parts in autumn.	Phragmidium	Infected plants should be immediately destroyed since this disease is not common in the U.S. and poses a serious threat to roses. Bury infected plant material or seal in a plastic bag and send it to a landfill. Only roses are susceptible. The fungus will die quickly if no roses are available for infection.
Viruses	Leaves may exhibit mosaic, mottling, yellow line, or ring patterns. Veins may turn yellow.	Rose mosaic, mottle, yellow mosaic, ring pattern, or streak virus. Tobacco streak. Rose rosette, rose wilt, spring dwarf, or color break virus. Strawberry latent ring spot.	Destroy infected plants. Plant only healthy, virus-free plants. Maintain good insect and mite control.