North American Fruit Explorers mailing list at ibiblio

[Alan Haigh <alandhaigh@gmail.com>]

http://www.puyallup.wsu.edu/~Linda%20Chalker-Scott/Horticultural%20Myths_files/index.html

This has a bunch of articles by Dr. Linda Chalker-Scott, who often writes
interpretations of hort research that we can all easily understand.  One of
the things she covers in this collection is arborist wood  chips which
should answer any of your questions.

I've used wood chips to mulch trees for decades and thousands of trees.
Never had a problem- fresh or aged.  In the vegetable garden the story is
slightly different as I once had a batch that mysteriously stunted my
vegies- maybe there was some black walnut in there, but I doubt it.  It
wasn't N deficiency and seemed alleopathic.