Why we cut to the collar

enlarge this image

The branch bark collar did an excellent job of growing over this pruning wound, but it can't close it completely while that stub is there. Determined pests have a toehold for their attack on the rich cambium below the bark. 

The branch bark collar can't cover a stub

New tissues form at the branch bark collar, that place where the branch's and trunk's cambiums meet -- the thin layer under the bark which can produce new wood and bark.

Whenever you prune, cut to leave the collar in place, unharmed. Make sure there's no stub or other impediment to this growth that can close the hole with successive rings of new "wound wood."



Below, left: That stub which remains from an earlier pruning prevents the woundwood from capping the opening.

Below, right: Seen from the side it's clear that the woundwood can build up to a certain extent to cover a protruding stub, but there are limits!

AcerStubDead4173s.jpg  StubRemains4380s.jpg


For more about proper pruning cuts and how a tree heals, check What's Coming Up #26 and What's Coming Up #112.

Below: In What's Coming Up #26 is the full story of the proper pruning cut and how a tree can close over even a large wound if the branch bark collar is left in place.

BarkCollarShade0024s.jpg CollarTriesClosingA2626s.jpg CollarClosingB2653s.jpg CollarClosedC2630s.jpg

WoundWood1small.jpg WoundWood2cropsml.jpg WoundWood3small.jpg