Problem with leaves on Hot Wings Maple

Asked July 3, 2013, 8:29 AM EDT

We have 4 Hot Wings Maple trees planted along the street in the front of our house. They are very pretty this year with lots of hot wings in bright red coloring. Our problem is one tree is showing rust like spots on the leaves and tips are curling up, are dry, and will crumble when rubbed with your finger. This tree is in between 2 others and I would expect it will soon show up in others. What is happening with the tree and is there a recommended treatment? The trees are 12 to 15 feet tall, are stunningly beautiful, but no one told us that each of the Hot Wings seed will root almost any where. Thank you for any help you can give us.

McLean County North Dakota

1 Response

This species of maple is subject to many leaf spot diseases, including anthracnose. I've seen anthracnose on some maples in my office during the past 10 days.

We are seeing lots of leaf spot diseases now due to the wet spring weather.

Symptoms begin as brown leaf spots. Infected leaves later curl, dry, and drop to the ground. Typically the leaves in the shadier portions of the tree/shrub and in the inner canopy are affected first. Leaves on the top of the tree/shrub receive more sunlight and air movement and so are less subject to this fungus.

Well-established trees can tolerate some defoliation. Young plants are more sensitive and we generally recommend applying a fungicide to slow the spread of the disease within the tree or shrub. You need to use a fungicide. Products containing chlorothalonil are often available at garden centers. It's best to apply a day or two before rainy weather strikes so we can put a shield of protection over the leaves. Two sprays spaced 10-14 days apart can be helpful; again we typically only do this for young plants, but it doesn't hurt to spray established plants..

This disease can spread to your other maples.

Rake the fallen leaves. We need to get this disease out of the area. This sanitation will be especially beneficial next spring when infection can occur again (especially if we get a wet spring again). You could consider pruning the maples next March to open up the shrubs and allow more air and sunlight within the canopy. Avoid overhead irrigation on these plants.

Let me know if you have any questions.

Tom Kalb, Extension Horticulturist, NDSU