RT Journal Article SR Electronic JF Arboriculture & Urban Forestry (AUF) JO JOA FD International Society of Arboriculture SP 140 OP 140 DO 10.48044/joa.1976.2.7.140 VO 2 IS 7 YR 1976 UL http://auf.isa-arbor.com/content/2/7/140.abstract AB Schuder, D.L 1976. Galls on Shade Trees and Shrubs. Purdue University Coop. Ext. Service Publ. E-56. 4 p.Galls are abnormal growth on plants. They are caused by certain feeding organisms, including bacteria, fungi, nematodes, mites, and insects. These organisms stimulate plant cells in such a way that the cells grow into galls, which serve as protection for the pests. There are hundreds of kinds of galls, each characteristic of the organism producing it. This publication deals only with galls caused by mites and insects. In general, mite and insect-produced growths do not seriously affect the health or vigor of the host plant. They may disfigure twigs and foliage, but if the plant is unhealthy or dying, something else is usually causing the trouble. Included are some of the common galls found on trees and shrubs in Indiana, and suggestions on how to prevent or control them.