I have two Ninebark Diablo shrubs about 3 yrs. old. They have grown well and always appeared very healthy. They are in a small shrubbery about 12ft. apart from each other. I garden in zone 5b. A few days ago I noticed that most of the leaves were covered with what might be mildew and most of the lower branches were dead. I immediately pruned out all the affected branches, which turned out to be most of them, as I didn't want, whatever it was, to affect anything else. I have always thought Ninebarks were easy care and have not been able to find any reference to them being prone to any disease. I have gardened for decades and have a very extensive garden but have never had a diseased plant before. I am at a loss to know what this is and wonder if I should prune the shrubs to the ground or even remove them. I would be grateful if anyone can enlighten me as to what this disease might be and how I should deal with it. Diane W. Ontario
I just joined this forum when I 'googled', searching for an answer about our ninebark. Your question popped up as a result but I was dissapoointed to find that no one had replied to your post. I have exactly the same problem this year with our diablo ninebark. Is there anyone out there who can suggest what to do?
Unfortunately I don't know what has infected your shrubs. I just note that you are in two distinct locations having a similar (same?) problem. I know the weather has been unseasonably warm (and humid?) in the East, wondered if Manitoba was having warm and humid weather that may be promoting some pest. Any chance of photos?
Sorry, can't provide photos but am sure it's mildew. After cutting back my shrubs by about half (thereby losing all this year's bracts!) they are growing like crazy but the new leaves are still getting the mildew. I have been using fungicide about every five days for three weeks but it has had no effect. As no other plants are being affected, I think I will just leave the ninebarks alone and hope they "sort themselves out" by next year. Thanks for trying to help. Diane.
To all you Ninebark lovers, I just found you by Googling "problems with Ninebark" - I'm in zone 6, and we have had predominantly draught with some intermittant torrential rain this spring. I'm having the same (what appears to be) mildew issue. Diane said it best - for the past 3 years, I've had four Ninebarks, each about 4ft apart, framing out a patio - always were healthy and prolific...true conversation pieces with their white flowers. This year, I noticed one had a downy/powdery white mildew-like look to it's leaves. I trimmed it down and used a fungicide on it . . . by the next week, the same look was on the other 3 shrubs, each one to a lesser degree, with the first (treated) shrub looking the worst. Would this imply that the first shrub "spread" something? I took a sample to the nursery and they suggested the fungicide, now I'm lost as to how to correct the condition. Hearing that Diane cut her shrubs down and they returned with the same mildew problem, I won't try that. It's been a year since "Diane's" postings, just wondering how/if the problem was resolved. I would HATE to lose my Ninebarks. Thanks for any comments. Marilyn Westfield, NJ, USA
Physocarpus opulifolius Diabolo® (a.k.a. 'Monlo') was introduced by Monrovia Growers in 1999. Consider using Monrovia's Ask the Experts website feature to address this question: http://azdomino.monrovia.com/monroviaweb.nsf/NGAFrameQ!OpenFrameSet. I acquired 'Monlo' last year and 'Luteus' this year, neither of which has shown any signs of mildew. I will cross my fingers that this remains true, otherwise they will find a new home at my mom's windy garden in zone 6, where I never see powdery mildew.