Pin oak, known botanically as Quercus palustri, is a flowering and fruit forming medium size shade tree that takes a softly pyramidal shape at maturity. The branches are horizontal and spreading and have large numbers of small twigs on each branch that give a slightly spiny appearance. Pin oak does not require heavy regular pruning but can tolerate light pruning every few years to refine the shape and remove dead or diseased limbs and foliage.
Remove dead, cracked, diseased or otherwise compromised twigs, branches or limbs as needed in winter when the tree is dormant. If the damage causes imminent harm such as falling limbs or disease is present, prune out the problem wood when you see it.
Thin the interior of the canopy to remove any branches that grow inwards toward the trunk instead of outwards. Cut back or remove any branches that abrade one another which can become entry points for disease and insects. Remove up to a third of the interior branches to improve sunlight penetration and fresh air flow through the canopy, if it seems dense and congested. Be sure to spread pruning cuts evenly throughout the canopy to retain balance, even weight and symmetry.
Raise the height of the canopy to allow walk-by access or improve the appearance by removing lower branches on the crown, if desired. Place cuts nearly parallel and flush with the trunk and just outside the slightly swollen branch collar.
Trim the tips of the branches to perfect the shape of the outer canopy of the tree or to prevent entanglement with other trees, structures or utility lines. Branch tips that extend beyond the line of the soft pyramid can be trimmed back as needed, but sparingly, in order to preserve the natural form of the canopy.