Bacterial wetwood or slime flux is a common disease of many hardwood trees, such as maple, elm, cottonwood, and aspen. Symptoms include the bleeding or oozing of clear slime from the tree causing dark streaking on the trunk or branch crotches. This wet material is sometimes colonized by fungi and other bacteria and can smell bad. When the slime dries, it leaves a yellowish residue on the bark.
The bacteria associated with this disease are common in nature. They can enter the tree through wounds in the trunk, roots, or branches. High pressure builds inside trees from bacterial activity. Eventually the gasses and fluids work their way out of the tree, sometimes causing bark to split. Bacterial wetwood or slime flux is more common in years when trees are drought stressed.
Preventing wounds and avoiding stress is the best way to deter wetwood problems. Once a tree is oozing fluid, there is no way to eliminate the disease. Proper pruning, adequate watering when needed, and avoiding soil compaction over roots are other ways to minimize wetwood or slime flux problems.
This article originally appeared in the August 23, 2002 issue, p. 115.