Gardening and Horticulture - Tree Foaming

I am noticing the past few days that one of my White Oak trees has a white, wet foam coming out of it near the base of the tree. Any ideas?

Sounds like slime flux. The symptoms usually occur where tree has been damaged by man or nature. Near bases of trees this is often due to weedeater damage or other injury. Sometimes a wood boring insect opens up the protective bark. Once injured, sap begins to flow and bacteria enters the wound. Sometimes there is a foul odor. When the sap begins to ferment, it foams and comes out of the tree. It apparently eventually stops without interference.

http://www.ces.ncsu.edu/depts/pp/notes/oldnotes/od8.htm