Galls are abnormal growths of plant tissue caused by a wound, infection by a microorganism, or the feeding and egg-laying activity of certain Insects and mites. Although galls are conspicuous and unattractive, they rarely cause serious damage. Once galls start, formation is largely irreversible. Under most circumstances, control is not recommended. How Galls Are Formed Galls are abnormal growths of plant tissue that form in response to a wound, infection by various microorganisms, or the feeding and egg-laying activity of certain Insects and mites.
Galls occur on almost any plant tissues.
The most common are leaf, stem and flower galls produced by Insects and mites. Galls produced by the hackberry nipplegall psyllid. Severe galling produced by the honeylocust podgall midge. Galls often are unusual in form, conspicuous, and frequently cause considerable concern. Galls produced by Insects and mites rarely cause serious threat to plant health.