Rick wrote:

Anyone seen this before? My neighbors tree has these odd, hard nodules
forming on most of the leaves of his oak tree. A Google search came up bare,
but I'm not sure what to search for anyway. It seems to drop bunches of
leaves all summer, still connected to twigs. Otherwise looks healthy.
http://www.rauth.com/pix/oakleaves.jpg
Thanks,
Rick

Large, round growths are oak galls, caused by the larva of a tiny
wasp. It irritates the leaf tissues, causing the gall to form.
Inside, it's somewhat corky. Older galls show small holes through
which the mature wasp exits. These are generally harmless to the
tree. In colonial times, settlers would gather the galls and boil
them to extract the tannic acid, which they would then use to tan
leather, set dyes in yarn, and make ink.

It's quite common for an oak tree to shed leaves in bunches, still
attached to twigs. However, if the tree is being defoliated, then
there is likely some insect causing damage. Such damage two or
three years in a row can severely injure or even kill the tree.
Since a mature oak can be quite valuable, it's worth the price to
have a professional treat the tree to stop such insects.

--

David E. Ross
URL:http://www.rossde.com/

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