In May 2015 I wrote about a new landscape bed which I put in that contained 2 Coppertina Ninebark plants. The first year I really liked them. The changing copper colors were quite attractive. But as the year went on I began to notice a problem with powdery mildew. I cut out the affected leaves then sprayed with a fungicide. As time went on the fungicide seemed to have no effect, so I sprayed again when we would have several rain-free days. Still no control of the mildew.
This spring the powdery mildew came back with a vengeance. I checked Google to see if there was a known problem for this type of plant and found several articles on the subject. It seems powdery mildew and Witch’s Brooms are a genetic problem with Ninebarks although some varieties are less damaged by the disease. None of the suggestions for control were very effective. The stems where the Witch’s Broom occur soon turn black as do the leaves.
One of the two plants was smaller and less attractive since it has had more powdery mildew problems than the other one. I don’t want to have to mess with pruning off the affected leaves and black stems every couple weeks OR have to weekly spray a fungicide that really doesn’t work, so I removed the smaller plant. I’m really disappointed since the plant is or could be very attractive but this genetic issue makes them a questionable purchase. Be advised!