Cottage Q&A
QUESTIONAfter a spring storm, we found that a large limb had broken off one of our big old oak trees. The tree seems to be fine except for that ragged piece sticking out from the trunk. Should we trim it off? Is there anything we should do to help the wound heal?
ANSWER
If the limb was alive when it broke, you'll see fresh, moist wood at the wound site, and sap may be leaking out. You should trim off this ragged part in order to create a clean wound that's harder for disease vectors to enter. Prune it back to the parent trunk, to the outside of the "branch collar," or shoulder, where the branch thickens just before it joins the main trunk. Here, the cells divide rapidly, explains Bartlett's Steven Mann, allowing the tree to begin sealing off the wound. A wounded tree doesn't need a painted-on sealing product, which may even interfere with the tree's natural process.
Whereas our bodies normally deal with a broken limb by repairing the damage - eventually allowing the wounded part to function normally - trees deal with wounds by sealing off the damage. Cells surrounding the wound change chemically and physically, isolating the injury from the rest of the tree. A vigorous tree is thus capable of overcoming very serious damage, but the isolated part - whether it's a section of root, part of the main trunk, or a big limb - is no longer of any use to the tree.
If, on the other hand, the limb was long dead, the tree will have sealed off the wound already, so trimming the stump is mostly a matter of aesthetics. Just trim it up neatly, removing only the dead part and cutting no closer than the collar, about 7-10 cm from the trunk.
* Published in the June 2005 issue of Cottage Life
