Question
On the North side of our house is our problem Crimson king Red maple. A couple of years ago I noticed that the leaves appeared to be turning brown around August. We had a few branches succumb and die in the middle of the crown, this tree is about 12 years old with a healthy trunk, and open garden soil below. Last year at this time I noticed what appears to be a white film on the tops of Southern exposed leaves, with brown edges. The leaves don't appear to have fully opened to a flat natural looking form, and if as it was last year; will shrivel-up and die by months end. Any diagnosis that comes to mind as to what is happening here? We live in the Northeast if it makes a difference. Thanks.

Answer
Sounds like powdery mildew.
Almost all landscapes have plants that become diseased with one of the powdery mildew fungi. Although the fungi that cause powdery mildew are usually different on different plants, all of the powdery mildew diseases are similar in appearance. In most cases, prompt recognition and control actions can prevent severe damage to plants from powdery mildew diseases.

Powdery mildews, as the name implies, often appear as a superficial white or gray powdery growth of fungus over the surface of leaves, stems, flowers, or fruit of affected plants. These patches may enlarge until they cover the entire leaf on one or both sides. Young foliage and shoots may be particularly susceptible. Leaf curling and twisting may be noted before the fungus is noticed. Severe powdery mildew infection will result in yellowed leaves, dried and brown leaves, and disfigured shoots and flowers.

I would spray the foliage with a fungicide for powdery mildew. Fungicides must be used to achieve acceptable control. For best results with fungicides, spray programs must begin as soon as mildews are detected. Spray on a regular schedule, more often during cool, damp weather. Use a good spreader-sticker with the fungicides. Be sure and cover both surfaces of all leaves with the spray. Fungicides generally recommended for powdery mildew control include: Triadimefon (Bayleton, Strike); Triforine (Funginex), Thiophanate-methyl (Cleary's 3336, Domain) and Propiconazole (Banner).