Anatomy of cranberry stem gall and localization of bacteria in galls.

ABSTRACT Cranberry stem gall is characterized by tumors that girdle stems, thereby killing all distal leaves, flowers, and fruit. Bacteria that produce high levels of the plant growth hormone indole-3-acetic acid (IAA) are associated with and believed to cause cranberry stem gall. The anatomy of naturally occurring galls on woody cranberry plants and galls caused by inoculation of micropropagated cranberry plants with Pantoea agglomerans strain 4/99 was consistent with elevated levels of IAA in plants.