Frothy

I’ve often observed this phenomenon on trees on rainy days and there was a lot of it about today so I googled ‘frothy trees’ and here’s the low-down, if of interest:

This occurs when rain water dissolves chemicals from the treebark as it flows down the stem of the tree. This changes the surface tension of the water, so that when it drips down towards the base of the tree, air is introduced due to the turbulence of the water, and foam is formed because of the altered surface tension. If there is foam on your tree during or after rain it is nothing to worry about.

So there you have it: nothing to worry about (in case you were).