London Planes turning brown, American Sycamores not
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?