WSU Extension

Hortsense

Rose : Black spot
(revision date: 4/11/2018)


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 by leaf yellowing and leaf drop in susceptible varieties. Canes often display small reddish-purple to black spots. High humidity, rain, and overhead watering contribute to the development of this disease. Black spot is spread by splashing water.
Management Options

Non-Chemical Management
  • Avoid overhead watering. If overhead watering is necessary, water during the morning hours so leaves can dry quickly.
  • Space plantings and prune to improve air circulation. Good air circulation limits disease development.
  • Prune and destroy diseased leaves and canes. Do not compost diseased material.
  • Rake and destroy all fallen leaves from under plants.
  • Plant resistant varieties. Your county extension agent or WSU Master Gardeners can make recommendations.
Select non-chemical management options as your first choice!

Chemical Management

Apply frequently in wet spring weather and occasionally in summer. Copper fungicides may cause some discoloration of foliage or blooms.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • Bayer Advanced Garden Disease Control/Roses, Flowers & Shrubs Conc
    Active ingredient: tebuconazole  |  EPA reg no: 72155-14
  • Bonide Copper Fungicide Spray or Dust RTU [Organic]
    Active ingredient: basic copper sulfate  |  EPA reg no: 4-58
  • Bonide Fung-onil Multi-Purpose Fungicide Conc
    Active ingredient: chlorothalonil  |  EPA reg no: 60063-9-4
  • Bonide Infuse Systemic Disease Control Lawn & Landscape
    Active ingredient: thiophanate methyl  |  EPA reg no: 53883-183-4
  • GardenTech Daconil Fungicide Conc
    Active ingredient: chlorothalonil  |  EPA reg no: 67572-82-71004
  • Monterey Horticultural Oil [Organic]
    Active ingredient: mineral oil/pet distillate light  |  EPA reg no: 48813-1-54705
  • Monterey Liqui-Cop Copper Fungicidal Garden Spray
    Active ingredient: copper-ammonia complex  |  EPA reg no: 54705-7
  • Ortho Max Garden Disease Control Conc
    Active ingredient: chlorothalonil  |  EPA reg no: 239-2522
  • Spectracide IMMUNOX Multi-Purpose Fungicide Spray Conc
    Active ingredient: myclobutanil  |  EPA reg no: 9688-123-8845
  • This list may not include all products registered for this use.
Images
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Caption: Rose black spot on leaves
Photo by: R.S. Byther
Caption: Rose black spot on leaves
Photo by: R.S. Byther
Caption: Rose black spot stem infection
Photo by: R.S. Byther