Prevention and Control of Tree Slime Flux

Bacterial Wetwood or Tree Slime Flux Can be Managed

Advanced Slime Flux. Joseph OBrien, USDA Forest Service, Bugwood.org

Bacterial Wetwood or Slime Flux

Bacterial wetwood, oftem called slime flux disease of trees, is a major bole rot of trunk and branches of hardwood trees. The cause of slime flux has been attributed to bacterial infection in the inner sapwood and outer heartwood areas of the tree. The bacterial infection is normally associated with wounding or environmental stress or both.

The bacteria Enterobactor cloacae, is determined to cause bacterial wetwood in elm, but numerous other bacteria have been associated with this condition in other trees such as willow, ash, maple, birch, hickory, beech, oak, sycamore, cherry and yellow-poplar.

 These similar bacteria include species of Clostridium, Bacillus, Klebsiella, and Pseudomonas. These bacteria are feeding and growing inside the tree wound and use tree sap as their favorite source for nutrients.

Symptoms of Slime Flux

A tree with slime flux disease has water-soaked patches and "weeps" from visible wounds and even from healthy looking bark. The actual "weeping" from the patch  may be a good thing as it is having a slow, natural draining effect on a bacterium that needs a dark, damp environment. A tree with this bole rot is trying its best to compartmentalize the damage.

The attacking bacteria alter wood cell walls, causing moisture content of the wood to increase at the point of injury. One interesting thing is that the weeping liquid is fermented sap which is alcohol based and toxic to new wood. The things to look for are dark liquid streaks running vertically below an injury and a foul smelling and slimy seepage running down the bark.

Control of Slime Flux

Several United States Forest Service reports that say not to bore holes to drain the rotting wood as it will further spread the bacterium. Drilled holes were bored to allow both the liquid and gas to drain. There is still some debate about this practice but the consensus is to refrain from drilling holes.

 It is not recommended now by certified arborists.

Actually, nothing can stop further rot except the tree's ability to isolate the spot by growing good wood around the diseased portion (the late Dr. Alex Shigo's research). Affected trees will usually overcome the problem and seal off the damage.

Using an insecticide will not help prevent the rot going on inside. You do see secondary insects feeding on sap and the rotting remains but they have caused nor affect the disease process. It is not thought they spread the infection so don't waste your money spraying for insects.

The basic control is prevention. Avoid wounding the tree and plant the tree where there are limited stresses from urban soil compaction including walking and vehicle traffic. Remember that a healthy tree will usually overcome slime flux.