Industry News: Tree Care Tips (Pruning, Water, and More)

Q: Is it advisable to fill a cavity in the crotch of a tree with Great Stuff spray foam insulation?

Monday, January 4, 2016  

A: It seems that there is little academic research to support the use of spray foam to fill a tree cavity and much of what is out there is anecdotal. I think the idea is to keep water out and thereby reduce decay. The only problem with the concept is that there is no proof that keeping the water out actually reduces decay. Some research suggest that dressing a wound actually promotes certain types of tree decay. If the cavity is full of water and usually it stays that way, I would not drain it and fill it with foam. The constant presence of water in a cavity is usually a good inhibitor of decay organisms which need oxygen to survive.

If the cavity is dry and you want to keep it that way, I don't see any harm in filling it with foam, but I can't say with certainty that it will do any good either. If preserving wildlife habitat is of benefit to you, tree cavities are an important habitat to many forms of wildlife. Mammals, insects, birds, and other forms of wildlife need tree cavities to survive and thrive. Wildlife resource agencies recommend that you have at least one habitat cavity about every acre or so to support wildlife.


Responder: Marty Shaw, RCA #470, Franklin, TN