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London Planes turning brown, American Sycamores not

Posted by hairmetal4ever Z7 MD (My Page) on
Sun, Sep 1, 13 at 22:59

There are a lot of Platanus x acerifolia (London Plane) & also a fair number of what I believe are P. occidentalis as well.

The springtime anthracnose causes the P. occidentalis to not come fully into leaf until sometime around mid to late June. Usually the P. x acerifolias are affected to a much lesser degree & leaf out by early May.

However, after that point, the London Planes have much less attractive foliage than the American Sycamores do - the LPs have a rusty, brownish-green foliage, while most of the American Sycamores have a nice medium green, much healthier looking leaf.

As of right now (& most past summers come to think of it), most of the London Planes are turning yellow-brown & have dropped a fair number of crispy brown leaves already. If years past prove true they'll slowly do this through October until bare.

Meanwhile, the trees I believe are American Sycamore (a few larger planted trees plus those growing wild) have generally nice looking, green, healthy foliage for the most part (with some mild anthracnose damage & mild pest damage, etc). They will probably hold their leaves until early Nov. then turn brownish & drop.

What is it that causes the London Plane, well regarded because of its resistance to anthracnose, to look so haggard by this time of year?


Follow-Up Postings:

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RE: London Planes turning brown, American Sycamores not

  • Posted by beng z6 western MD (My Page) on
    Mon, Sep 2, 13 at 9:24

Seen it before sometimes -- it's some kind of late-summer leaf-blight that London planes get & pure Amer sycamores don't.


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RE: London Planes turning brown, American Sycamores not

Would be nice to find a Platanus that is resistant to both diseases.


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RE: London Planes turning brown, American Sycamores not

I have 2 London Plane trees with similar disease. From a distance, tree looks like it's coated with a dull gray/white film - it looks dry. Up close, see photo. The bark also looks dry & dead, and there are small flying insects (new this year). The trees have steadily gotten worse over several years. Everyone I've spoken to locally thinks it's anthracnose, but it doesn't look like any of the photos online. Also new this year, plants below tree are also looking similar. I would love to know how to treat these poor trees!


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RE: London Planes turning brown, American Sycamores not

I think that's powdery mildew, and I think that's part of the problem here, too.


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RE: London Planes turning brown, American Sycamores not

I get the gist that it is nothing life or death? my London plane looks ok. I guess there is no need to spass out yet.


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RE: London Planes turning brown, American Sycamores not

There has been hybrid London Planes that are far superior than the existing species, including American Sycamoures.


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RE: London Planes turning brown, American Sycamores not

Platanus mexicana is very resistant to foliar diseases. They look flawless all year here.


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RE: London Planes turning brown, American Sycamores not

Thanks for the ideas. Powdery mildew photos online don't really look the same, but could just be difference in location, etc. Does anyone have comments on efficacy of standard treatments for powdery mildew?


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RE: London Planes turning brown, American Sycamores not

There's also the lace bug.


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RE: London Planes turning brown, American Sycamores not

Same thing happening this year. I'll post some pics soon.

I think the LP's suffer from a combo of sycamore lace bug and powdery mildew damage.


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RE: London Planes turning brown, American Sycamores not

From a local park. Most London Plane look more or less like this around here.


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RE: London Planes turning brown, American Sycamores not

Leaf:


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RE: London Planes turning brown, American Sycamores not

At least they have attractive bark for the winter or when they are defoliated.

I just can't beliebe after losing ALL their Ash trees the Gateway Arch ground folks decided to plant ALL of one kind of tree again. The planetree in this case.


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RE: London Planes turning brown, American Sycamores not

I do wonder if some of the newer cultivars like 'Exclamation' and 'Columbia' fare any better in this regard. Seems like nobody plants anything but 'Bloodgood' and unnamed seedgrown LP here.


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RE: London Planes turning brown, American Sycamores not

I wonder if it isn't the moisture in the air, the weather etc. My London plane has a few leaves turning burnt orange, but the Sycamores are more affected, getting brown leaves. But this is late summer, if it is just a matter of "ugly leaves" who cares? Next season it may not be a problem. If it is humidity, and is showing up in August especially middle to late August, I could live with it. I am in the country though. There are lots of other trees around, in the city I guess, if you have a specimen tree, and it looks like crap, I might be sqwauking too.


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