Question
QUESTION: I reside in a private community in Long Beach, CA which has an urban forest which includes more than 100 mature Alder trees.  The builder installed mature trees 20 years ago and know we have a large number of trees that seem to be at the end of their life and also seem to be diseased.  We were told by one of our visiting Arborist that Alders in CA have been infected with a fungus and there really isn't anything that can be done.  Are you familiar with this problem?

Thank you, Shawna

ANSWER: Yes there seems to be a problem with alder in the Western US--it is classified as a decline. due mainly to drought conditions. I would try to water the trees during droughts and fertilize this winter with 10-10-10 fertilizer at the rate of 1 lb per inch of trunk diameter scattered around the tree and watered in good. This should help the overall health of the tree, here is a web link that discusses this problem with alders. http://www.uaf.edu/ces/newsletters/infoideas/2006/0606anchinfoideas.pdf

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QUESTION:
Thank you for the quick and informative response and I will absolutely provide positive feed back.

I do have one more question before going back to my tree committee, the article provide in your link focuses on Alaska; is the same problem occurring throughout the western states?

Thank you again for your time and expertise.  

Answer
Here is a reference for Calif.

Dr. Deborah Mathews, UC Riverside, Riverside, CA
A new canker disease of alder trees in California and an update
on Xylella fastidiosa in landscape plants
In November 2007 alder trees were inspected with upper canopy
dieback and some trees failing. Trunk bark exhibiting dark
brown, moist spots were chiseled out to find cankers in the wood.
Along with phytophthora disease specialist Dr. Michael Coffey,
samples were taken of similar trees in Orange County and Los Angeles.
A fungal culture was obtained in Costa Mesa from a single
sample identified as Phytophthora siskiyouensis, a quarantined
pathogen fairly new to California.
If you come across similar Alder problems please contact Deborah
for possible sample collection. (951.827.3864)
[email protected]
Phytophthora alni is another disease found in Europe which
has decimated over 30% of the Alders there. Found in the U.S. in
Alaska and possibly the Colorado Rocky mountains, it prefers cold
climates and hopefully will not be a threat in California. As a
popular landscape tree, either of these fungi (and the possibility of
another) could be a serious threat to this tree crop.