I have some sort of disease on my Diablo Ninebarks. Last fall I noticed a couple branches that had some sort of white fungus or something on them. The leaves on those branches were stunted and I think they died. Now I have white stuff on almost all the branches on three shrubs that are planted next to each other. Any idea what I should do about it?
Here's a better picture:
One more picture:
I just did some searching and it seems like it's probably powdery mildew. Now the question is, what do I do about it? I read that you can spray a mixture of milk and water on them or a mixture of baking soda and water. That seems to just control it. Is there a way I can prevent it from coming back year after year? Should I pull them out and plant something else? I'm really disappointed because this is their third year in the ground and they were finally going to get to be a decent size.
I have not had to deal with a powdery mildew on Diablo but I am reading of a lot of people being plagued by the same symptoms. Are you in a position to send it out to be cultured? What about calling Monrovia and asking them about this? It's been my experience they are extremely responsive the few times I have had to call. There are too many people having issues with this and they are from across the board. I just called my neighbor and he ditched all of his Physocarpos 'Diablo' last year and replaced them with straight species P. opulifolius because he didn't want to deal with it. I've got three Diablo here and mine are unaffected. I also have about 50 P. opulifolius and those are unaffected but I will check again. I'm not all that thrilled about so many people reporting the same symptoms. I think I'll go poking around for myself on this but I'm no help at all to you because I simply haven't been hit yet.
Here's a contact for Monrovia-
http://www.monrovia.com/monroviaweb.nsf/8c104835579b67e18825685f006acdf8/b3546a017146638188256fdb00648e40!OpenDocument
I called on the phone and spoke to somebody who was really on the ball over there. I suspect if you are persistent, you will have the same success.
Thanks Equilibrium. I'll call tomorrow. Is Diablo the only cultivar that you've heard about that is affected? Are there other dark-leaved cultivars that are disease resistant? Am I out of luck in saving these? Thanks again for your help.
Rob
I have no idea if you are out of luck saving them but, I don't want what you've got that's for sure. If you ever come to visit... leave your plants behind please. Just kidding with you because I get the distinct impression my plants are next.
Also too, I have no idea what is disease resistant and what isn't because I don't even know what you've got on your plants.
I'm really sorry but the only plants I keep hearing about being affected are the Diablo. I am not hearing that the straight species is affected and I don't personally grow any other dark leaved cultivars. Do I want to right about now? This leads me to believe there may exist a possibility there is something being unknowingly shipped out on Diabolo plants. It happens.
I am glad you are calling as opposed to e-mailing. I recall having a dickens of a time finding their phone number. Be prepared to get disconnected. It happened to me quite a few times and I never once got the impression it was intentional. Also be prepared to get passed around a lot. They don't seem to be used to people who call in and they tried their darndest to get me to somebody who could help. I don't recall the name of the man with whom I ended up actually speaking but I believe he may have been a biologist.
One thing, I'd stay away from spraying it with milk or anything else until you know what it is. What about sending this off to Cornell if you aren't comfortable with what you are told by Monrovia. You'll be charged a fee but it might be worth it.
http://plantclinic.cornell.edu/
I just called Monrovia's main office and left a voice mail for a horticulturist. After several hours, I had not gotten a call back, so I called back and ended up getting transferred several times until I was back to the local sales representative. He told me to go to the nursery where I bought the plant. I continued to ask questions, but got only general answers to my questions, such as the obvious recommendation to use a fungicide on it. I'm going to keep trying, but this may be more trouble than it's worth. I don't want a plant in my landscape that I have to continually treat with chemicals to keep it alive.
That's about what happened to me when I called them but I was persistent. I finally got through and was able to talk to someone who was incredibly intelligent and capable of answering all my questions. Did I mention I was disconnected a few times? I was disconnected a few times which does tend to irk me.
Well, I have some bad news. I will send you a d-mail complete with photos for you to take a look at. Give me a few minutes to begin transferring images to you.
At first blush, that looks a lot more like a cottony scale insect than powdery mildew. Have you rubbed any of the blobs to see if they mush?
It's dark out now, but I'll go rub some blobs tomorrow. If it's cottony scale insect, would those be eggs I'm seeing? There are little specks of the stuff on almost all the leaves, but the bottom leaves have a lot of the white stuff on them.
I don't think it's a cottony scale of any type. The egg sacs on cottony scales are quite distinct and should be visible to the naked eye. If you want to look up images of assorted egg sacs; google cottony maple scale, cottony camellia scale, and cottony cushion scale and that might give you an idea of what exactly to be on the look-out for.
Mealybugs present in this fashion, too.
Cooperative extension service offices, affiliated with your land grant university, usually perform plant pathology services for free (since your tax dollars have already paid for it). A call there may yield the answer you are after (good local knowledge).
And here's the hotline:
http://web1.msue.msu.edu/genesee/hort/Plant%20and%20Pest%20Hotline.htm
Mealies present in that fashion? I’ve never seen mealies do that before but anything is possible these days.
Try Microsphaera or Poria but maybe Phyllactinia? There are hundreds and hundreds of fungal pathogens responsible for powdery mildews and without a lab report this is all a stab in the dark. I think this is a double or triple whammy fungal infection and more than one mildew is colonizing thanks to all the nice warm and rainy weather we've had. The high for today is going to be 90. Those are temps we don’t normally see until July or August.
I love the extension offices in Upper Peninsula Michigan. I’ve not known our extension offices to provide free disease diagnostic services though but maybe the extension office near Alpena are different.
