A crotch is formed in a tree where two larger branches grow away from the main trunk. The cavity at the base of the two branches forms a crotch that is often susceptible to splitting. Filling the crotch of a tree is only recommended when continued damage to the tree is possible if treatment is not performed. Filling the crotch involves the use of a synthetic filler that is also commonly used as insulation.
Remove any water from the crotch of the tree. Use rags to absorb any standing water that could interfere with filling the crotch.
Scrape away any loose, dead or decaying wood from the crotch of the tree, using a knife. Carefully remove only the loose, dead or decaying wood so that the healthy tree tissue is not damaged.
Perform any bracing necessary to prevent further splitting of the tree at the crotch. Use straps, for example, to pull the branches together for support to keep the crotch from splitting any more.
Shake a can of expanding foam insulation to thoroughly mix the contents. Attach the spray tube to the nozzle on the can. Spray the foam insulation into the crotch of the tree.
Leave the foam to expand and fill the crotch. Allow the foam to dry and cure for at least one hour. Trim the excess expanded foam from the tree with a knife so only the crotch is filled.