1. Plant Disease
  2. Host and Disease Descriptions

Rose (Rosa spp.) and hybrids-Leaf Spots, Miscellaneous

  • Facebook logo
Latest revision: 
March 2025

See:

Rose (Rosa spp.) and hybrids - Black Spot

Rose (Rosa spp.) and hybrids - Rust

Cause Several fungal leaf spots have been reported from the PNW. Cercospora leaf spot caused by Rosisphaerella rosicola (formerly Mycosphaerella rosicola or Cercospora rosicola) has been reported in Washington. It has become more important in the Southeastern United States as black spot resistant but Cercospora-susceptible roses become more widely planted. Damage appears to be greater on shrub and ground cover roses compared with hybrid tea and grandiflora roses. Spores produced in the spots are rain splashed to healthy foliage. Rainy weather favors the disease.

Spot anthracnose caused by Elsinoe rosarum has been reported from both Oregon and Washington. The fungus overwinters on infected leaves and stems with conidia continuously being formed in spring and early summer. Spore dispersal primarily occurs with the aid of water through rain and irrigation. There were 5 races of the fungus identified in Germany.

Cladosporium herbarum has also been reported from leaf spots in Washington.

Abiotic leaf spots due to many different situations, including chemicals, are a common problem sent into the OSU Plant Clinic. Some chemicals used to manage common disease, such as black spot, powdery mildew, or rust, may cause various leaf or petal spots or discoloration. Always watch for warnings on labels of various products.

Symptoms Cercospora leaf spot - Numerous tiny maroon-to-purple oval lesions develop randomly across the leaf surface. The center of these spots then turn tan-to-gray while the margin of the spot remains maroon-to-dark-purple. Heavily spotted leaves turn yellow and are prematurely shed. Typically, leaf loss begins at the base of the canes and gradually spreads upwards through the plant canopy towards the shoot tips. Leaves are most often infected but stems, pedicels, fruits, and bracts can also have symptoms.

Spot anthracnose - at first, the appearance of red spots that vary from brown or dark-purple on the upper leaf surfaces occurs. Small spots may be scattered or grouped and sometimes overlapping. Chlorosis or yellowing of the leaves may also occur. Later, spots become ashen-white with a dark-red margin. This tissue may fall off of the lower leaf surface, leaving a thin papery membrane or fall out entirely resulting in a shothole symptom. Symptoms occur on stems, hips, and pedicels as well as leaves.

Cultural control In general, tactics used to manage black spot, powdery mildew, and/or rust will be effective on many leaf spotting fungi.

  • Space or prune bushes to allow for good airflow. Avoid dense plantings and shaded areas.
  • Avoid overhead watering that keeps plants wet for extended periods of time.
  • Rake up and burn all leaves at season's end.
  • Remove and destroy infected plant parts.

Chemical control In general, tactics used to manage black spot, powdery mildew, and/or rust will be effective on many leaf spotting fungi. Always watch for warnings on labels of various products.

Products available in home packaging:

  • BioAdvanced Disease Control at 0.75 fl oz/gal water. Group 3 fungicide. H
  • Bonide Captan 50 WP at 2 Tbsp/gal water can be used in home gardens. Washington only. Group M4 fungicide. H
  • Bonide Fung-onil Multi-purpose Fungicide at 2.25 teaspoons/gal water. Group M5 fungicide. H
  • Bonide Copper Fungicide at 8 oz/3 gal water. Group M1 fungicide. H
  • Ferti-lome Liquid Systemic Fungicide II at 1 fl oz/gal water plus another fungicide. Group 3 fungicide. H
  • Infuse Systemic Disease Control at 2 Tbsp/gal water plus another fungicide. Group 3 fungicides. H
  • Monterey Liqui-Cop at 3 Tbsp/gal water. May discolor blooms. Group M1 fungicide. Group M1 fungicide. H
  • Ortho MAX Garden Disease Control at 1.5 Tbsp/4 gal water. Group M5 fungicide. H
  • Ortho Rose & Flower Disease Control at 2 fl oz/gal water. Group 3 fungicide. H
  • Spectracide Immunox Multi-Purpose Fungicide Spray Concentrate for Gardens at 1 oz/gal water. Group 3 fungicide. H

Products available for commercial use. Alternate or tank-mix products from different groups that have different modes of action. Limit the use of any one group during crop production.

  • Armada 50 WDG at 3 to 9 oz/100 gal water. Do not use a silicone-based surfactant. Not for nursery or greenhouse use. Group 3 + 11 fungicide. 12-hr reentry.
  • Avelyo at 3 to 5 fl oz/100 gal water. Group 3 fungicide. 12-hr reentry.
  • Broadform at 4 to 8 fl oz/100 gal water. Group 7 + 11 fungicide. 12-hr reentry.
  • Captan 80 WDG at 1.5 lb/100 gal water. Group M4 fungicide. 48-hr reentry.
  • Compass 50 WDG at 2 to 4 oz/100 gal water. Do not use organosilicate additives. Group 11 fungicide. 12-hr reentry.
  • Concert at 22 to 35 fl oz/100 gal water. May cause injury to buds, blooms or tender new growth especially foliage of "Knock Out" and "Double Delight" roses. Landscape use only. Group 3 + M5 fungicide. 12-hr reentry.
  • Daconil Weather Stik at 1 pint/100 gal water. "Knock Out" and "Double Delight" roses can be sensitive resulting in damaged foliage. Do not use during summer heat. Group M5 fungicide. 12-hr reentry.
  • Disarm 480 SC at 1 to 4 fl oz/100 gal water. Group 11 fungicide. 12-hr reentry.
  • Eagle 20 EW at 6 to 12 fl oz/100 gal water. Group 3 fungicide. 24-hr reentry.
  • Fame SC at 2 to 4 fl oz/100 gal water. Group 11 fungicide. 12-hr reentry.
  • Fixed coppers. Group M1 fungicides. O
    • C-O-C-S WDG at 2 to 3.9 lb/100 gal water. 48-hr reentry general or 24-hr reentry for greenhouse.
    • CuPRO 5000 at 1.5 to 2 lb/A. May discolor foliage or blooms. 48-hr reentry.
    • Grotto at 0.5 to 2 gal/30 to 100 gal water/A. Some cultivars may develop purple spots indicating copper toxicity. 4-hr reentry.
    • Kocide 2000-O at 0.75 to 2 lb/A. Discoloration of foliage or blooms has occurred on some cultivars. 48-hr reentry.
    • Nu-Cop 50 DF at 1 lb/100 gal water. Foliage and/or blooms may become discolored. Greenhouse reentry is 24-hr, all others 48-hr reentry.
  • Heritage at 4 to 8 oz/100 gal water plus a non-silicone-based wetter sticker. Heritage can also be used at 1.6 to 8 oz/A for commercial rose production. Group 11 fungicide. 4-hr reentry.
  • Insignia SC at 6 to 12 fl oz/100 gal water. Do not use with organosilicate-based adjuvants. Use preventively only. Group 11 fungicide. 12-hr reentry.
  • Mancozeb-based products. Group M3 fungicides. 24-hr reentry.
    • Fore 80 WP at 1.5 lb/100 gal water plus a spreader-sticker.
    • Protect DF at 1 to 2 lb/100 gal water plus 2 to 4 oz spreader-sticker.
  • Monsoon Turf at 4 to 10 fl oz/100 gal water. Group 3 fungicide. 12-hr reentry.
  • Mural at 7 oz/100 gal water. Group 7 + 11 fungicide. 12-hr reentry.
  • Myclobutanil 20 EW T&O at 6 to 12 fl oz/100 gal water plus spreading agent. May observe a PGR effect. Group 3 fungicide. 24-hr reentry.
  • Orkestra at 8 fl oz/100 gal water plus a surfactant. Group 7 + 11 fungicide. 12-hr reentry.
  • Pageant at 6 to 12 oz/100 gal water. Do not use with organosilicone-based adjuvants. Group 7 + 11 fungicide. 12-hr reentry.
  • Phyton 27 at 1.5 to 5 oz/10 gal water. Group M1 fungicide. 48-hr reentry.
  • Postiva at 10 to 28 fl oz/100 gal water. Group 3 + 7 fungicide. 12-hr reentry.
  • Previa at 1 pint/100 gal water. Group M5 fungicide. 12-hr reentry.
  • Propiconazole-based products plus another fungicide. Field-grown roses only. Group 3 fungicides.
    • Banner MAXX at 5 to 8 fl oz/100 gal water. 12-hr reentry.
    • Fitness at 1.8 to 3 fl oz/100 gal water. 12-hr reentry.
    • ProCon Z at 5 to 8 oz/100 gal water. 24-hr reentry.
    • Strider at 5 to 8 fl oz/100 gal water. 12-hr reentry.
  • Spectro 90 WDG at 1.53 lb/A. Group 1 + M5 fungicide. 12-hr reentry.
  • Tebuzol 3.6F at 4 to 10 fl oz/100 gal water. Group 3 fungicide. No reentry interval listed.
  • Torque at 4 to 10 fl oz/100 gal water. Group 3 fungicide. 12-hr reentry.
  • Tourney EZ at 1 to 4 oz/100 gal water. Poor control. Group 3 fungicide. 12-hr reentry.
  • Trinity TR at 1 can/3,000 sq ft of greenhouse. Group 3 fungicide. 12-hr reentry without ventilation or 4-hr with ventilation.
  • Wettable sulfur at 3 Tbsp/gal water. May stunt shoots. Group M2 fungicide. O
  • Ziram 76 DF at 1.5 to 2 lb/100 gal water. Group M3 fungicide. 48-hr reentry.

Reference Bagsic, I., Linde, M., and Debener, T. 2015. Genetic diversity and pathogenicity of Sphaceloma rosarum (teleomorph Elsinoë rosarum) causing spot anthracnose on roses. Plant Pathology. DOI: 10.1111/ppa.12478