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Wednesday - June 25, 2008

From: Edmonton, KY
Region: Mid-Atlantic
Topic: Diseases and Disorders, Pruning, Trees
Title: Premature leaf drop on Red Maple in Kentucky
Answered by: Barbara Medford

QUESTION:

I have a ten foot Red Maple tree that has been set out for 4 years. Its leaves have slowly turned colors until it currently looks like fall. The leaves are not falling off nor is there yet any sign that they are dying. There are a few sprouts lower on the trunk that are green. I have three other Red Maples of the same age and size which are doing fine, although none are close to this one in the lawn. What is happening and what should I do. Last spring, the trees around here were already in leaves when a late frost occurred and killed them. The leaves returned and then we had a dry summer. I notice the bark on the trunk is also cracked and peeling. Also, we are experiencing the Cicadas this year. I do not know if any of that is relevant, but I thought I would include it. Thank you.

ANSWER:

Acer rubrum (red maple) is a native of North America and also of Kentucky, so the tree should do well in your area. The fact that you have three others on the property that are showing no similar problems indicates the location of that tree may be the clue. Maples prefer full sun, but can survive in some shade, but insufficient sun exposure shouldn't cause early leaf color change; more likely, it would just cause the tree to grow poorly. The bark of the maple is thin and easily damaged by mowers, weed eaters or just accidental hard contact so, again, the position of the tree on your property might be a clue to the bark problem. Check this Ohio State University Extension Fact Sheet on Verticillium Wilt of Landscape Trees and Shrubs, just in case it's something that serious.

There are two possibilities that we have found so far for the premature color changes on your tree. One is that of chlorosis, which can occur in maples that are in alkaline soils and manganese in the soil is not accessible to the roots. Chlorosis is the absence of chlorophyll (which causes the color green in the leaves) and indicates a plant in distress. Since you have three other red maples on your property, it wouldn't seem that the soil would be all that different around the tree you are concerned about.

The other possibility we found in a USDA Forest Service website on Acer rubrum. Note the references on Page 4, midway down in the right-hand column on girdling roots. This is indeed serious, and can best be prevented by cutting circling roots from being too long in a container, but that has to be done before the tree is planted.

Finally, this Cornell University Extension website on Noninfectious diseases of maples addresses both of the problems, girdling and shortage of manganese. It also has practical suggestions for dealing with the problems. Hopefully, since your tree is still young, you can do what's needed to let it grow to a tall, magnificent maple.

Acer rubrum