Bacterial Wetwood or Slime Flux:
Bacterial wetwood, also called slime flux, is a major bole rot of trunk and branches of trees. Slime flux has been attributed to bacterial infection in the inner sapwood and outer heartwood area of the tree. The bacterial infection is normally associated with wounding or environmental stress. The bacteria, Enterobactor cloacae, is determined to cause 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.
Symptoms of Slime Flux:
A tree with slime flux is water-soaked and "weeps" from visible wounds and even from healthy looking bark. The "weeping" 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.
This bacteria alters wood cell walls, causing moisture content of the wood to increase. One interesting thing is that the weeping liquid is fermented sap which is alcohol based and toxic to new wood.
Several USFS "books" say not to bore holes to drain the rotting wood as it will further spread the bacterium. There is some debate about this practice. 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).
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 do not affect the disease process. It is not thought they spread the infection. Don't waste your money spraying for insects.