Q: I have a white ash that has weird green cauliflower-looking growths where the seeds clusters used to be. When I break them open, I find a little worm.

A: The malformation is caused by ash flower gall. A tiny eriophyid mite causes male flowers to grow into an odd greenish, tumor-like structure. Sometimes the lumpy growths also cause leaf distortions.

Despite being unsightly, the galls don’t hurt your tree.

Simply prune them out.

see
Ash Flower Gall