Black spot is a common fungal disease that most often affects Roses. Black spot start as dark blotches on the tops of leaves and eventually causes the leaves to yellow and begin to drop from the plant. Leaves will drop from the bottom of the plant and progress upwards. Once black spot disease begins attacking your roses, it can be very difficult to control and manage. If left untreated, the plant can become weak and perform poorly. Similar to powdery mildew, blackspot is caused by a fugus that typically occures in early summer when the days are hot and the nights are cool.
Prevention is best – here a few things you can do to help prevent black spot:
- Water earlier in the morning and avoid watering in the evening to foliage has time to dry before dark. Water at soil level instead of overhead watering.
- Prune inner canes that cross over to allow airflow into the plant
- Make sure roses get 6-8 hours of sunlight
- Use fungal sprays as a preventative such as Dusting Sulfur or Neem oil.
If your roses do become infected, remove the diseased leaves and canes and dispose of them. Do not compost or pile near existing shrubbery to prevent spread.
Black spot can’t be revesed on infected canes and leaves but you can stop the fugus from spreading to other leaves. You can use fungicides with Sulfur or Neem Oil and Neem Oil. Make sure to coat both the tops and bottoms of leaves thoroughly as well as the canes.
We also recommend spraying Dormant Oil before winter hits and making sure to clean up all leaves and dead debris from under roses. Dead leaves can provide a great environment for black spot to overwinter.