Plant galls are abnormal growths on leaves, branches, or roots; they can range from a tiny blister to a sizable irregular swelling. Calls can cause stunted growth; parts beyond the gall may die. Often they have larvae of insects (wasps, mites, aphids) inside. Some galls are caused by fungal, bacterial, or viral diseases.
Although galls look harmful, most do not seriously injure plants. You can try to control them by handpicking them and discarding them. If a shrub is severely infested, cut off and burn all affected parts. This will help prevent future infestations. If the cause is microscopic nematodes on a plant’s roots, fumigation of the soil may be necessary. Check with your Cooperative Extension Service or local garden center.
One gall that seriously harms and often kills plants is the crown gall. Caused by a bacterium, these rough, spongy tumors, whose color ranges from pink to dark green, appear close to the soil level. Dig up and discard any plant that has them.