Knockout rose bushes
Put in some Knockout rose bushes last year. They did great. Husband trimmed them back this spring and they seemed slow to grow, but have come back okay. My problem is about a month ago I noticed RED spots on the leaves. On top of the leaves, not underneath. Then noticed they weren't blooming as much as they did last year and when they do bloom, the flowers are very small, like their growth has been severely stunted and the color is no longer a nice red but more of an ugly pink. So now the red spots are gone but now have black spots and the flowers are few and far between with tiny blooms. What happened?? Thanks!
Certified GKH Gardening Expert
It sounds like a possible fungus attack. Also in the hotter months of the year the color is not as vibrant as in the early spring and then again later in the year when temps cool down. Spray all of the roses with a good fungicide such as Green Cure or if you cannot find the Green Cure locally or on-line try Immunox as directed on the label. There is also a product by Bayer called Tree and Shrub granules. Giving all the rosebushes some of that product will typically handle the problem as well.