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Thursday - June 09, 2011

From: Denver, CO
Region: Rocky Mountain
Topic: Diseases and Disorders
Title: Problems with maple in Denver
Answered by: Barbara Medford

QUESTION:

I live in Denver, CO and planted an Autumn Blaze maple three years ago. It has done very well until about a week ago. The leaves are drying out and falling off and earlier today I noticed some bugs on the trunk, which I believe are red-headed ash borers. Can I save my tree?

ANSWER:

"Autumn Blaze" maple is a commercial trade name given to a hybrid of Acer rubrum (Red maple) and Acer saccharinum (Silver maple), neither of which is native to Colorado, although both are native to North America. From the Growing Conditions of the Red Maple, we extracted these Growing Conditions:

"Soil Description: Moist, slightly acidic soils.
Conditions Comments: Though usually found in moist woodlands and wet swamps, also found in drier Post Oak woods"

And on the Silver Maple:

"Soil Description: Rich, wet to moist, slightly acid soils."

Since we are dealing with a hybrid, we don't know which characteristics of each tree are dominant, but their soil and moisture preferences are practically identical. We don't know what the pH of your soil is, but are guessing alkaline, although probably not enough so to kill the tree.

From the Entomology Department of Oklahoma State University, Redheaded Ash Borer, here is a description of the trees they attack:

"Redheaded ash borers will attack nearly all dying and dead hardwoods, but chiefly ash, oak, hickory, persimmon, and hackberry."

From about.com, courtesy of the United States Forestry Services, here is a discussion of common pests and diseases of the maple.

The puzzle here is whether there is a sudden decline of your tree. It is pointed out in the articles on the redheaded ash borer that it only attacks dead or dying trees. The other article, about pests and diseases, also says most of them are not serious, but rather opportunistic pests taking advantage of an already weakened tree. If you noticed no problem earlier than a week ago, it's hard to see how any of these things could have been the cause. We are wondering if it could possibly be aphids, which are small bugs that pierce the leaves and draw nutrition out of them. Please read this University of California Integrated Pest Management article on Aphids, and see if that might be your problem. A good hard spray of water on the leaves, as suggested in the article, might alleviate your problem.

In that does not prove to be the case, we suggest that you contact a licensed, certified arborist and have the tree examined; it is beyond our abilities to diagnose from a distance.

 

 

 

 

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