Odd little bumps on leaves and funny protuberances on your plant’s foliage may be a sign of pest, bacterial or fungal problems. They are called gall. This is an abnormal growth of plant tissue that can occur on leaves, twigs, branches, flower, roots, and fruit. They can be caused by insects, mites, nematodes, fungus or viruses. Galls are considered unsightly (in the eye of the beholder) but are rarely ever a serious problem. Because gall poses no risk to the plant, no action is required.
The exception to this is the root-knot nematode that is found in vegetable gardens. If you find evidence of these tiny life suckers, the link below will help.
