While cotinus is known to be susceptible to verticillium, neither the Stewartia or crape myrtles are recognized as being prone to this pathogen. That doesn't mean it can be eliminated as an issue, only that it is rather unlikely. There are other problems that can present similar symptoms of wilting or premature leaf drop but if this is just something that has come about in the past few weeks, I'd be more inclined to attribute it to a poor and wet growing season. Verticillium usually becomes evident in midseason, typically in the height of summer.

If you have concerns about the cotinus, I'd look to your extension service for a diagnosis. The staining often associated with VW is not necessarily always present or uniform -- sometimes tissue testing is required.

How is your drainage overall? If your soil drainage is generally good (wet summer aside), then I'd recommend waiting to see how these plants emerge in spring before I made any hasty moves. If it is VW, there's not much you can do about it now anyway but I'm leaning more towards just the effects of a poor, wet growing season.

Thanks, gardengal. Drainage here isn't much of an issue, especially for the cotinus, which is at the top of a stone retaining wall. Our soil's glacial outwash, so there are layers of sand, clay and silt, with sand being the most prevalent. I've got 20 years worth of compost worked in to most of the beds as well, and being a compulsive digger, most of the clayey subsoil has been removed over the years.

My garden is probably too tightly packed with plants, however, so it's possible that another fungus is responsible - something that has hit the leaves directly. An airborn fungus seems like it would have a better prognosis, so I'm really hoping this isn't VW! I'll take your advice and see what happens next spring (I can't wait).
Thanks again -DtD.

can you tell the diff between mildew and fungus...

powdery mildew is the first thing that came to my mind.. and is prevalent wit a lack of air circulation.. in an over-stuffed garden ...

words just arent going to get you very far here.. you either need to post some pix... or head to the extension agent

good luck

ken

With the clayey subsoil, do you tend to get puddling after heavy rains? I have a swamp at the bottom of my yard. Because of the wet weather, the squish has seeped into more of the yard than usual, and areas that are usually fine aren't. This is what I'm attributing the sudden browning/leaf drop of a volunteer maple near the top of the swamp to.

No puddling here, especially (now that I think about it) in any of the 3 locations where these shrubs are: top of the wall, my old vegetable garden, and a double-dug mixed bed that has never gotten any kind of compaction (because there's a low "dog fence" around it).

I have photos of the stewartia and crape myrtle in this album; actually 2 specimens of each, before and after, to show that one is completely brown and the other is still in color. Maybe this is overkill ... and I should just wait and see what happens in spring.
{{gwi:282903}}wilt_fall_2009

frankly.. the pics look like my garden.. after the first hard frost ...

i do NOT grow most of the plants you ask about... but i do have a smokebush .. it is deciduous up here.. so browning leaves in november.. isnt all that surprising...

frost is a weird creature.. able to hit a whole plant.. or just parts of the plants.. especially in an over-stuffed garden ....

frost would also answer why otherwise evergreen plants for your zone might be affected ....

there is a website that tracks temps by zip code ... but i dont have the link .... see link

but i think you are on the right track ... its november... its not really time to be FIXING things with chemicals.. or jumping to conclusions about removal .. personally i would wait until spring and see what develops ....

one other oddity.. is that in your otherwise.. presumably healthy garden.. a bunch of diverse plants.. get a weird malady.. overnight.. again.. bringing me back to frost .... the odds of such is astronomical ... but for wild temp swings ....

good luck

ken

Here is a link that might be useful: it popped into my head