several plants may have black spot

Asked July 5, 2017, 9:29 PM EDT

I have roses with brown/black spots on them that a friend told me is a black spot mold issue. I also have spotted this on other plants. A monarda clump is showing some spots now and my 4' delphinium have many leaves that have a gray mildew look with edges curling up and black spots visible. I wonder if there is something I can do to help them. I did take Photos but I do not know how to upload them.

Ramsey County Minnesota

1 Response

The problem with your roses may not be the same problem your monarda and delphinium have. If your roses have black spot you will need to treat them with a fungicide. Here is a link with photos to compare to yours. http://www.extension.umn.edu/garden/diagnose/plant/annualperennial/roses/leavesspots.html .

Here is a link to info about treating problems. http://www.extension.umn.edu/garden/yard-garden/flowers/rose-diseases/ .

Good air circulation during wet weather is important in dealing with fungal problems. Powdery mildew is common during wet, humid weather. Clean up the foliage good in the fall and consider dividing perennials that have become large and grown together to help air circulation. Don't water in the evening and don't wet the whole plant.