Trees for Tennessee Landscapes - Maintaining and Protecting
Wetwood is a water-soaked condition of wood in the trunk and branches of trees. This condition has been attributed to bacterial infection in the inner sapwood and outer heartwood area of the tree. Infection is normally associated with wounding or environmental stress on the tree. The bacteria, Enterobactor cloacae, has been implicated as the cause of wetwood in elm, but numerous other bacteria have been associated with this condition in other trees such as cottonwood, willow, ash, maple, birch, hickory, beech, oak, sycamore, cherry and yellow-poplar. Bacteria alter wood cell walls, causing moisture content of the wood to increase. Infected wood may also have a high (basic) pH and a high concentration of microelements.
"SP631 Bacterial Wetwood Disease of Trees," The University of Tennessee Agricultural Extension Service, SP631-14M-9/04 R12-4910-045-005-05 05-0081, http://trace.tennessee.edu/utk_agexfores/77