Foam is bubbling out of my Chinese elm. Any ideas?

Q. Foam is bubbling out of my Chinese elm. Any ideas?

A. The foam is called "slime flux." It occurs sometimes when a tree is wounded and sap is exuded. Bacteria growing in the sap causes it to ferment and foam. Insects might be attracted to it to feed. Before long you have a stinky mess. If left untreated, the slime mold can weaken the tree to the point of death.

To treat it, remove any bark that may be covering the wound, then wipe away as much of the slime mold as possible. Brush the area with rubbing alcohol or a dilution of plain household bleach and water - 1 part bleach to 9 parts water. You will probably have to repeat the treatment several times to keep the slime flux in check.

Tree wounds may result from pathogens such as those that cause cankers. More often, mechanical damage from string trimmers, lawn mowers, garden tools and poor pruning cause wounds.

Prevention is the best medicine. Try to keep your plants in good health, and avoid mechanical damage.