1) Oak spangle or saucer gall                                                        2) Fuzzy bead gall

OAK LEAF GALLS -Galls are irregular plant growths which are stimulated by the reaction between plant hormones and powerful growth regulating chemicals produced by some insects or mites. Galls may occur on leaves, bark, flowers, buds, acorns, or roots. Leaf and twig galls are most noticeable. The inhabitant gains its nutrients from the inner gall tissue. Galls also provide some protection from natural enemies and insecticide sprays.Important details of the life cycles of many gall-makers are not known so specific recommendations to time control measures most effectively are not available. Gall makers must attack at a particular time in the year to be successful. Otherwise, they may not be able to stimulate the plant to produce the tissue which forms the gall. Generally, initiation of leaf galls occurs around "bud break" or as new leaves begin to unfold in the spring.Leaf galls rarely affect tree health so control is rarely justified.


This web site was created for the Morris Arboretum of the University of Pennsylvania's Plant Clinic.
Created by C. Hetzel and revised by S. Eisenman on 3/7/02.
URL = http://www.upenn.edu/PaFLORA/Plantclinic/oakgalls.html