Please help newbie identify this disease

We moved into our house last August. Ever since we have lived here, our very large Oak in the backyard has had these tumor looking growths all over it. There are none on the trunk, just on the branches. I didn't know if anyone could help me identify what this might be. They break apart very easily.

Thank you for your help!

Amanda

P.S. Couldn't figure out how to post more than one picture. I have another picture I could show, if that would be helpful.

This message was edited Mar 26, 2006 7:19 PM

Ah, here we go. Does this other photo help?

Your photos were pretty good. What type of an oak do you have there?

First thought is a gall. Now whether the gall is a result of a fungus, bacterium, insects, or mites is sort of beyond me. This one sort of looks like it might be a crown gall. Crown galls are a result of a bacterial infection and it has been my experience they are difficult to deal with without professional help.

Maybe the galls are the result of a non-stinging wasp? Do a search for Horned Oak Gall Wasp (Callirhytis cornigera) and see if that might not be a match. If that is it, no big deal and just leave them alone. Unsightly, but they won't destroy your tree. Don't bother with an insecticide, the gall protects the developing wasp so you'd be wasting money. Next try a search on Gouty Oak Gall (Callirhytis quercus punctataIf). If you think that might be it, call a professional arborist out as that one can be destructive. There's a Horned Oak Gall (Callirhytis cornigera) too. I'd call a professional arborist if you think it might be that too. Your tree may need to be heavily pruned.

Next thought is for you to quick fast run to the Trees and Shrubs Forum and post your photos because there are quite a few arborists and pathologists over there who might be able to take one look at your photos and tell you exactly what it is.

I'll do that, thanks for your help. I am hoping it is not "Crown Gall" as I have read that that is eventually fatal.

Often times, bacterial as well as fungal infections come hand in hand with heavy insect and mite infestations.

You have your answer from one of the best of the best over in Trees. You've got Horned Oak Gall (Callirhytis cornigera) which I typed in twice in my post above... oops. Normally up north here, a healthy tree can withstand that and I have seen a few trees that have it and they do just fine. One problem, the man who responded to you is down south where you are and if he is saying the existance of them is a problem down south, it's a problem down south. So, scratch what I wrote about them being no big deal because I'm way up here in far northern Illinois where red oaks have not been overplanted or stressed to the max.