To top it off the last two seasons had cool wet springs followed by hot dry summers.

Two questions:
1) Is the black foilage (which was infected) retained by the plant able to infect new foilage in the spring?

2) If yes should I just cut the plant down within 12" of the ground? Some of the ninebarks only have 3-4 major stems coming from the ground.

I'm beggining to think this is a lost cause and may have to replant.

and i cant see the leaves with any clarity to come to any conclusions...

can you edit out some leaf closeups from the original???

ken

My title is wrong too...I know the foliage is infected. I really posted the pics so you could see the size of the plant and the amount of foilage retained.

I just don't know if I should selectively prune out all the limbs with the foliage, cut it back to 12" of the ground or just leave it assuming the dried infected foilage (from last growing season) will NOT infect the new growth. I don't know how the disease overwinters.

I have 3 weeks to make a decision, help me out folks!lol!

You could cut it back now, but there is no guarantee you will be removing all the sources of reinfection (spores can also overwinter on the bark and stems). A hort oil spray (or neem oil) applied ASAP - before it leafs out - could serve to smother any fungal spores remaining on the plant itself. And you will need to be diligent in treatment during the growing season, applying the PM fungicide of your choice periodically before you see signs of the disease (you will need to repeat applications, especially after heavy rains). Check out the recent thread discussing PM on lilacs for some "organic"/low toxicity PM treatments.

We do encounter PM on ninebarks from time to time in the nursery but I have never contracted this problem on my own growing in the garden. Not at all sure why, since if there is a fungal disease floating around, the PNW is pretty much guaranteed to have it :-)

How far down would you cut them down? 3" of the ground?

It was much worse than originally thought. I could see the mildew on many of the younger stems. There were crushed leaves all over the place so I can't tell what is what.

On top of everything my sprayer was broke. I didn't realize I left some liquid in it over winter...I just bought the thing too.

So even if I am deligent with getting rid of or at least controlling the PM is it even worth the headache?

I've been considering replacing these plants with Viburnum rhytidophylloides 'Allegheny', Picea pungen 'Fat Albert' or a V. dentatum cultivar.

Would one of these be a better plant in a well drained dry location? Or is there a dogwood cultivar you'd recommend?

Thanks for dealing with all the questions! I feel like I lost 2 years of my life trying to establish a hedge to block the one most important thing...my neighbors patio!

i dont see that your plant is actually listed on the label ... no clue if that makes it an inappropriate use???

though surely it is for mildew ... though it does not specifically mention POWDERY mildew ...

we often say 'use according to instructions/label' ... where does this fact scenario fit????

all that said... WHY ARE YOU MESSING WITH THIS???

re-cut at ground level.. and apply the chemical that will solve the problem .. generic roundup ... or stump killer

there.. problem solved.. and you wont spend the rest of your life exposing yourself to mildew-cides ...

always ask yourself if your own exposure is worth the plant you are trying to save ....

ken

ps: BTW... any host plants in the area.. like lilac.. monarda??? you may be attacking the 'result' .. instead of the 'host or cause' .. is there any other plant in the area that could be the cause???? .. get rid of those also ...

PM has thousands of host plants, depending on strain (there are many different strains of PM and each affects a different set of plants) and since it is an airborn fungus, eliminating other host plants in your garden will not guarantee avoidance. It is also very climate related, encouraged by high humidity and close air circulation. Some plants are indeed more prone to the problem than others and in some growing seasons, the incidence of PM will be more pronounced than others.

Personally, I'd be inclined to give the ninebarks another season or two to see how well they do before ripping them out. If the issue persists, it may be most practical for you to select another shrub that will have fewer problems. FWIW, in the vast majority of woody plants, PM is only a cosmetic concern, causing no real permanent damage to the plant, although repeated severe infestations can weaken the plant and reduce growth.

you said: a little extreme but it does make a point (if you look for it :-))

====>> yep.. just playing devils advocate ...

you said: (and it IS labeled for powdery mildew on ornamentals, Ken)

====>>>> so that is the catchall ....?? ... so what is the point of specifically listing certain plants...

EVERYTHING.. including the weeds are ornamental in my garden ... lol.... again.. just being the advocate ... so in theory i can air bomb my garden ... nature be darned ....

and finally .... i clarified in my head what i meant... you can spray your brains out on the diablo .. but if here is a plant upwind that is the host.. you will never FIX the diablo .... so .. the point.. if i have one [as noted by gal] .... cast about for the cause.. you might solve your problem elsewhere ... like removing a horribly mildew diseased old fashioned lilac upwind .... and then your problem on the diablo mysteriously disappears.. go figure on that potential ....

whaas ... you buy big.. and you bought multiples ... and i fully understand you have an immense $$$ investment here ... and i wish you all the luck in TRYING to solve your problem ... just keep that brain cell in the back of your head viable.. about just fixing the mistake at its inception ...

as always.. continued luck

ken

The ninebarks are the only infected plant "in my yard". And they are HEAVILY infected on some branches.

I have a 'Summer Wine' about 50' away and it had small traces of PM one year (because of the weather). The diablos are also in close proximity to other PM susecptible plants, lilac, vibrunum, maple, etc. All are looking good.

In the end I'll see how the Diablos respond to the pruning and how bad a return infestation is. That will determine if I replace them or not.

The only reason I am keeping them there is I CAN'T find a GOOD replacement.

Full Sun now, partial shade in ~7 years
Poor soil, dry, gravely
Plant needs to be between 8-12'T X 6-12'W
Limited variability in shape and growth rate as it will be used as a screen.
Good multi-seasonal interest...its right of the patio and its the focal point out the bay window on the side of my house.
NOT susecptible to PM

=====>>>> check my latest posts at the tree forum .. couple small trees ...

ken

The other 3 are being replaced with Summer Reflection Viburnum...hopefully I'll have better luck with these.

Its funny how many posts there are with Diablo ninebark and PM. I think its great for a 1 off speciman but it should be banned in quantities greater than one.

I make it a policy to never bring home a plant species that is known for certain problems. Or, at least, I'll know enough to be prepared so that I can grow such a plant with extra observation and care.

But like you said, with some good detective work you sort through to find the true problem child.

Originally when I pruchased these the nursery said it was a good choice...plus I did a little research (didn't find the GW at the time). Since then I've accuired a bit more knowledge and access to additional resources.

It kills me the nusery industry continues to sell plants that are disatrous to the landscape, whether its invasises or problem plants.

tj

Excactly...you never know, you lose some, you win some...hopefully more wins though!