Today is cool and rainy and I noticed suds accumulating at the base of a tree. They seem to be oozing out of the tree (on one side only) and dripping down from a height of about four feet. There is some sort of lichen (?) growing on this side of the tree, but I don't see the same suds on nearby trees, some of which have the same lichen growing. Any idea what this is, and whether I need to take action?
Update: Today it's not raining and the "suds" are totally gone, so it was definitely something caused or made visible by the rain.