Articles

Rose Diseases (Greenhouse)

Name: Rose Diseases (Greenhouse)
SKU: ART-3964

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

Save for later Print

Updated:

April 3, 2023

Skip to the end of the images gallery

Skip to the beginning of the images gallery

Disease	Symptoms	Pathogen/Cause	Management
Anthracnose	Dark purple to black spots are bordered by a narrow, dull brown band. Centers of spots turn grey and fall out. Spots form on canes, similar to leaf spots.	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 and provide ventilation to avoid excessively high humidity. Remove fading flowers and yellowing leaves. Apply a fungicide to protect healthy tissue. Heat and ventilate to maintain low humidity.
Cankers	Reddish-brown spots on canes turn light to dark brown and become covered with tiny black dots. Cankers girdle and kill the cane.	Coniothyrium fuckelii, Cryptosporella umbrina, Coniothyrium wernsdorffiae, Cylindrocladium scoparium	Do not plant stock with cankers. Removed infected canes making the cut immediately above a bud. Apply a fungicide after pruning. Sterilize the shears with disinfectant between cuts. Maintain even soil moisture and fertilization.
Crown Gall	Small white to cream-colored galls form on stems. Galls may enlarge to 6 inches in diameter. Galls can form on roots or stems.	Agrobacterium tumefaciens	Do not plant infected material. Steam sterilized beds where infected plants were grown. Remove and destroy infected plants. Apply Agrobacterium radiobacter K-84 to protect healthy plants.
Damping-off	Cuttings fail to root, defoliate and die. Roots are killed.	Pythium	Pot and propagate in pasteurized media. Use clean, disinfested tools. Discard infected plants. Do not leave cuttings in mist beds for excessive periods. Pot as soon as rooted.
Downy Mildew	Purplish-brown spots form on leaves. Leaves yellow and fall. Small spots or long purplish areas may form on canes and may kill twigs.	Peronospora sparsa	Heat and ventilate to maintain low humidity. Water in a manner that keeps leaf surfaces dry. Apply a fungicide to protect plants.
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	Remove and destroy fallen leaves. Apply a fungicide to protect plants.
Viruses	Leaves may exhibit mosaic, mottling, yellow line or ring patterns. Veins may turn yellow.	Rose mosaic, mottle, yellow mosaic, ring pattern, tobacco streak, rose rosette, rose wilt, spring dwarf, color break or strawberry latent ringspot virus	Destroy infected plants. Plant only healthy, virus-free plants. Maintain good insect and mite control.