ash tree problem

[jape]

I live in the chicago area, in a suburb that is about 15 years old. Many of the ash trees that are in our neighborhood have a green cluster that develops where the leaves usually are. These clusters turn brown and most of them fall off by the spring. This is only the second year for this problem. The tree looks fine otherwise. Does anyone have a clue what this might be, or how to treat this problem? I have lived here for eight years & this is new. I did loose an ornamental plum tree to some kind of borer several years ago.
I hope that this is not the same type of problem.
Any help, advice appreciated

 

[Elmore]

Sounds like...

Ash Yellows : http://www.extension.umn.edu/distribution/horticulture/DG5898.html

 

[Tree Wizard]

Sounds more like

Sounds more like Ash Flower Gall

http://www.uwex.edu/ces/wihort/gardenfacts/X1048.pdf

 

[treeseer]

Some--well, at least me--think the gall adds winter interest and is ornamental.

Enjoy it!

 

[pbtree]

Could you post a photo - it would help a lot...