black spot fungus on Rose
Quick answer
If your Rose has black spot fungus, the most likely cause is: Diplocarpon rosae fungus thrives in warm, wet conditions (75°F/24°C). Spores splash from infected fallen leaves onto lower foliage during rain or overhead watering, causing circular black spots with fringed edges followed by rapid yellowing and leaf drop.
Start here:
- 1. Remove and destroy all infected leaves immediately (do not compost)
- 2. Rake up and dispose of fallen leaves around the base
Why Rose gets black spot fungus
Rosa spp.
Diplocarpon rosae fungus thrives in warm, wet conditions (75°F/24°C). Spores splash from infected fallen leaves onto lower foliage during rain or overhead watering, causing circular black spots with fringed edges followed by rapid yellowing and leaf drop.
How to reverse black spot fungus on Rose
- 1
Remove and destroy all infected leaves immediately (do not compost)
- 2
Rake up and dispose of fallen leaves around the base
- 3
Apply a fungicide containing chlorothalonil, copper soap, or neem oil every 7-14 days
- 4
Prune to open the center of the bush for better air circulation
Keep black spot fungus off this Rose
Water at the base of the plant only, keeping foliage dry. Apply fresh mulch in early spring to prevent soil-borne spores from splashing up. Choose disease-resistant varieties.