Question
I have a forty foot Colorado Spruce which is planted to close
to our deck.  The base of the tree is approximately 8 feet from the decking.  It seems to be irritating these branches. With what we have read on pruning we are not sure what to do to make sure our tree does not die.  Do we prune, and if so how. The branches are midway up the tree that touch the deck and seat on the deck.  Thanks Marilyn K.

Answer
No it will not harm the tree as long as you do not prune off more than half the crown branches. I would only prune the branches that are rubbing the deck or that hang over the deck low enough to bother you. Current pruning recommendations advise against pruning branches flush to the trunk. Flush cutting is harmful in several ways: it damages bark as pruning tools rub against the trunk, it removes the branch collar, and it goes behind the branch bark ridge. The branch collar is the swollen area of trunk tissue that forms around the base of a branch. The branch bark ridge is a line of rough bark running from the branch-trunk crotch into the trunk bark, less prominent on some trees than on others.

The best pruning cut is made outside the branch collar, at a 45 to 60 degree angle to the branch bark ridge. Leave the branch collar intact to help prevent decay from entering the trunk.

Whenever removing limbs greater than one inch in diameter, use the three-cut method to avoid tearing bark. First, about 12 inches from the trunk, cut halfway through the limb from the underside. Second, about 1 inch past the first cut, cut through the limb from the top side. The limb's weight will cause it to break between the two cuts. Make the third cut outside the branch collar.

Don't coat pruning cuts with tree paint or wound dressing. These materials won't prevent decay or promote wound closure.