Grayish, white foam runs down the trunk of the tree. This bacterial ooze builds up pressure behind the bark and eventually can rupture the bark and begin to ooze out. This is particularly common with willow trees. Other trees that get slime flux (wet-wood) are aspen, poplar, cottonwood, elm, ash, boxelder and Russian Olive.
Common points of entry are through bark wounds caused by poor pruning, insects, and mechanical injuries like mowers. Depending on the bacterial type, there are two types of slime flux: bark and heartwood.
Heartwood slime flux builds up in high pressure within the tree. Often times, the pressure becomes high enough that it causes failure in a crack in the bark and oozes out and down the trunk. The bacteria kills bark tissue and plants or turf it contacts. Trees can usually survive heartwood infection.
Bark infection occurs just beneath the bark and often has a foul odor associated with it. Bacterial ooze is released as pressure builds up and cracks the bark. This type of infection typically results in death in just a couple years.
Proper pruning and avoiding tree wounding are the best preventable measures for slime flux.
Heartwood infections can be managed by alleviating the pressure drilling a hole and inserting a tube to drain out the bacteria. This does not eliminate infection, but does help the overall tree health and prevents catastrophic injury. There is no cure-all for heartwood infection.
If a bark infection is caught quickly enough (early signs of oozing), trees can be saved by cutting out the infected areas. Prune out small, infected branches. If the infection is in large branches or the trunk, remove all infected bark and wood, disinfecting your knife or other cutting tool with rubbing alcohol between cuts. Also, apply rubbing alcohol to the wound you created to disinfect the entire area. Monitor for signs of reinfection.