I also read somewhere ===>>> ya know.. this is right up there with 'un-named sources' ... lol PM is not an issue of rain .. as much as lack of air movement on warm nights.. when the foliage goes into the dark, dank night already wetted .. these are the conditions that increase PM ... not rain .. or wet soil ..per se ... i am impressed with your drive.. and your quest for knowledge.. and i encourage it.. but i fear you get to wrapped up in all the 'potential' problems.. that may never happen ... you said: I just don't want to plant something that I will regret later. ===>>> and i might suggest that you will end up with a selection of the most boring plants known to gardeners.. on the simple fact that you fear every 'possibility' of what might happen ... ID something you cannot live without.. and makes your toes curl.. and plant it ... and IF... key word 'IF" problems happen .. then deal with it then .. but dont end up with a bunch of boring plants.. that are bullet proof to every know 'possible' problem ... also.. in my world.. i go small.. so it costs substantailly less money for the plant.. so that if i ever have to cross the road of removal ... it doesnt hurt as bad ... in other words.. i will pay $20 and kill it in 5 years.. if it bugs me... rather than spend $250 for a large specimen.. and then never have the ability to kill it.. due to the excessive investment ... [and i could have 12 plants for the same $250 investment.. and if two become problems.. i am still 10 plants ahead ... i have spread the risk over more plants] ... and that is a long story to say that instant gratification might be why you fear failure ... good luck on your quest ... i am impressed with your research ... ken

I have found water works wonders on aphids. I used to use insecticidal soap but water seems to get the same results. The only time I use soap now is if the ground is rain soaked and I think more water could harm the plant. I spray the water on the growing tips where leaves are just developing. The aphids especially like the soft new growth. I also spray under the leaves where aphids also cluster. I have viburnums that have terrible infestations of aphids. The leaves just curl up into balls if I don't "treat" them regularly. I have found that it helps to spray them with water even when I am not seeing the mature aphids. I spray them with water on the growing tips and under the leaves. I think I must be knocking off very tiny young aphids because once I knock off the first visible aphids of the season they I pretty much don't see any again unless I stop spraying them about every five days. Lots of luck to you.

I'm in zone 5, Milwaukee area, the biggest one I've seen was about 7 X 6. I wouldn't worry about the size as its pruned easily. Its actually tolerates light shade, just might not be as purple.

After posting the above, I did a web search on the subject and came up with the following paragraph in a Nursery and Landscape Report out of Ontario. When I did a search last summer, I came up with very little, but now there seems to be a lot of talk on Ninebark and powdery mildew. Too bad. Sounds like a lot of effort must be put into controlling it. Look for thick, white, powdery fungal growth on the newest leaves of Physocarpus opulifolius (especially Diablo). This is powdery mildew (likely Sphaerotheca sp.) that has been reported widely on our ornamental ninebark. This fungus sporulates quite profusely on Physocarpus and is difficult to control with fungicides once heavy sporulation is evident. Remove and destroy infested tips and continue to do so throughout the growing season while protecting new shoots with fungicides (where necessary). Here is a link that might be useful: The report