There are myriad oak galls formed by an array of insects, mites, or other factors, though wasps are a common culprit. We don't recommend using insecticide to treat for these insects, but you can prune off any galls you find, since the deformed tissue will likely die off anyway eventually, and to physically remove any immature wasp generations still present. Oaks are valuable sources of food for many insect species (and in turn, birds and other predators that eat those insects), and no treatment for gall wasps would pose no threat to those insects, since the pesticide would not be that targeted. Plus, once the gall starts forming, not much will affect the larva(e) inside.

For general tree health protection, we recommend removing all grass or weedy vegetation around its base (for at least a foot or two out from the trunk in all directions) and mulching instead. These plants compete with the young tree's roots for moisture and nutrients, and also increase the risk of trunk damage if the plants are being mown, string-trimmed, or treated with herbicide for weed control. An accidental injury from equipment cutting into the bark could be fatal for the tree, and the wound, even if not serious in terms of causing canopy dieback directly, might become colonized by wood-decay organisms, similarly threatening the tree's longevity and stability.

Clearing away the base so the trunk gets good airflow will also let you check to make sure it's not planted too deeply, which might not bother a young tree right away, but which can lead to serious problems later in its life. Make sure a mulch layer is not piled against the bark; it only needs to be about a couple inches thick, in a flat disc around the tree, and the root flare should remain at the soil surface and not covered by soil or mulch. The linked pages provide more information.

Miri