Black Spot

Photo courtesy OSU Extension
  • A fungus (Diplocarpon rosa) that occurs in spring and fall that causes brown to black spots with diffuse edges on leaves and stems
  • Spores are spread by water during rainy periods
  • Purchase black spot resistant cultivars
  • Remove leaves, stems, and flowers that show disease
  • Water early in the day and avoid overhead watering
  • Fungicides effectively control black spot when used according to label directions

Rose Cultivar Resistance: https://pnwhandbooks.org/plantdisease/cultivar-tables/rose-cultivar-resistance

How To Get Rid of Rose Black Spot: https://solvepestproblems.oregonstate.edu/plant-problems/roses/black-spot

Powdery Mildew

Photo courtesy of Northwest Center for Alternatives to Pesticides
  • A fungus (Sphaerotheca pannosa) that covers the leaf and bud parts of the rose with a mat of white, powdery looking fungal filaments
  • Prevalent during summer’s driest time when nighttime humidity is high
  • Select disease resistant varieties
  • Avoid overhead watering
  • Remove any fallen leaves from the ground to prevent the spread of spores
  • Provide roses with adequate air circulation

Controlling Diseases and Aphids on Your Roses: https://extension.oregonstate.edu/catalog/pub/ec-1520-controlling-diseases-aphids-your-roses

Rust

Photo courtesy of Northwest Center for Alternatives to Pesticides
  • Rust is a fungal disease of the genus Phragmidium which begins in spring and peaks in early summer
  • Appears as orange pustules on foliage
  • Spores are carried by air and water onto new growth
  • Remove all infected plant tissue throughout the season
  • Prune roses to provide adequate air circulation
  • Select disease resistant cultivars

Controlling Diseases and Aphids on Your Roses: https://extension.oregonstate.edu/catalog/pub/ec-1520-controlling-diseases-aphids-your-roses

Aphids

Photo courtesy OSU Extension Solve Pest Problems
  • Aphids feed by piercing and sucking the liquid from the leaves
  • Aphids produce unattractive sticky black honeydew on leaves
  • Monitor your roses frequently for early detection
  • Hand pick or squish the aphids
  • Hose aphids off the plant with a strong spray of water
  • Apply Neem, horticultural oil, or Insecticidal Soaps
  • Use a dormant season spray of horticultural soap to suffocate overwintering aphid eggs.

Rose Aphids: https://solvepestproblems.oregonstate.edu/plant-problems/rose/aphid

Click here for a printable pdf version of this article. Written by Cheryl Borden, June 2024