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I have two maple trees in my parking strip. I believe they are the Autumn Blaze variety. They have a light green to yellow small leaf. The leaves are starting to die as if it needs water. They are spotted and turning brown and brittle. The branches are still green when I scrape the them. I do not think it is under heat stress since June has been mostly wet. We spoke with someone who lives about a mile from us who had the same problem last year and now the top of his tree is dead. We did see two other trees in his neighborhood with the same problem. It looks as though next year we may have the same dead trees if we do not do something to prevent them from dying. Can you tell me what is wrong and what I can do to save the trees?

Answer(s)

A

There may be a couple of different things happening to your maple trees.  The first possibility is a fungal disease called anthracnose.  When we have long periods of cool wet weather, like we did this spring, fungal diseases can be more problematic.  Below is a link with more information on this disease.

http://utahpests.usu.edu/PLANTDISEASES/htm/ornamental/anthracnose


Fungal diseases usually start out as dark brown to black spots.  These spots will spread and eventually grow together and in severe cases the leaves may die and fall off. Control of this disease isn't easy but there are some things that you can do to help your tree out. Make sure to pick up and discard any fallen leaves.  This will help reduce the spread of the fungus.  Also, when working around the tree make sure that the lawnmower and weed eater do not run into it and damage the trunk. And when watering the tree try to avoid getting water on the leaves.  Below is a link with more information on watering trees.

http://extension.usu.edu/files/publications/publication/HG-523.pdf

You can also apply a protective fungicide spray at bud break and to the newly emerging foliage next spring. If you choose to use a fungicide make sure that maple trees are specifically mentioned on the label. 


The second possibility is that your tree may have a disease called verticillium wilt.  This disease is also fungal but the symptoms usually show up in hotter weather.  The main symptom of this disease is that whole branches of leaves will suddenly wilt and dry up.  Below is a link with more information on this disease.

http://utahpests.usu.edu/PLANTDISEASES/htm/ornamental/verticilliumshade


If either of these options do not sound like what is happening to your tree or if you are unsure you can bring a sample of your tree into our office at 2001 S. State Street # S1200 and we will help identify the problem. 
 

Posted on 16 Jul 2009

Heidi Wayman
Horticulture Intern, Salt Lake County

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