What is this white foam under my tree?

Question

South Florida. Photo of tree that I can't identify. It's been raining heavily for twelve hours and this white foam has appeared on the trunk, possibly due to water dripping. What is this foam?

I've lived with this tree for 2 years and have never seen it happen before. It is not there today now that it's dry. I observed a piece of bark overhanging the area, channeling water to drip infrequently at the top portion of the bubbles, likely creating them somehow. These do not appear to be eggs or a fungus. When I hit them with a stick, they pop. Has less the consistency of spittle bubbles; more like soap bubbles. I do not use soap or detergent on my trees.

Full tree, foam to the left of the lawn gnome

Closeup of foam

Answer 1

If this foam has appeared only during the heavy rain you've been experiencing, its a natural phenomenon. It occurs because some trees contain chemicals in the bark which can cause a soap like foam as the two interact, but this only occurs if the weather is very wet indeed; this phenomenon is not uncommon on pine trees in particular, but can happen with other trees.

If, though, you've noticed a particular area on the trunk foaming at other times, when it's not wet, check the area to make sure its not a slime flux, which indicates a bacterial infection. Info here http://www.wonderofeverydaynature.com/2016/03/26/155/

Answer 2

I have seen this phenomenon on plants that were sprayed heavily with insecticidal soaps or dishsoap. I've been in rains in Florida! This could happen after spraying and the next hard rain will wash the soap off and in the type of rain you get would certainly cause this bubbles!

Did you spray those trees? Recently at all? A surfactant is used for sprayed pesticides, sort of a 'sticker'. That would cause the same effect as well.

If your trees have not been sprayed then we need to rethink this phenomenon.