treating black spot on roses

Asked May 14, 2018, 12:32 PM EDT

If my rose bushes have black spot on them and are already budding, can I use the copper fungicide on them now?

Yamhill County Oregon roses

1 Response

Thanks for sending us your questions,

First consider these non-chemical options,
  • 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.
  • Read more here: Black Spot
Are you sure it is not downy mildew which can ressemble black spot? To be sure drop off samples at your local extension office.

The black spots made by downy mildew spores are not as dark and can have an angular appearance, look for downy growth on undersides of the diseased leaves. read more here: Rose diseases

It is recommended to use dormant sprays of lime sulfur or copper fungicide on roses in January before new growth appears, or, plan to replace susceptible varieties with resistant cultivars in February. If you apply now it will less effective and will discolor the blooms, read more here: Garden calendar
Please be sure to always follow product instructions for your safety and protect the environment.

Enjoy those roses!