Question
we live in northern ohio and we have several maples with little orange and green ball type things on the leaves not all our trees have this, some of the other trees have black holes in the leaves,while others are starting to fall off.It is memorial day 2007  

Answer
HI,Scott                                                        How r u? The green /balls u talk about r called a (GALL).Which occurs in early spring when a insect like a MITE-or/MIDGE/or Aphid injects laves with a egg/Hormone/with its salivia.Then in early summer late may early June The tree Starts to show signs in the effect of a ball/Growth n some trees lose there leaves Early.It is not much to stop or prevent this ,but the good thing it does not harm tree much.Its main problem is its ugly!It does stress tree a lil so u could treat trees with a good fertilizer rich with organic matter like compost tea/leaf litter/and humic acids.You can get a product like this at the garden center.Read label and u will b fine.GOOD luck!!