(Contributed photo.)

Winter is the best time to prune oak trees in Iowa, according to Iowa State University Extension and Outreach horticulturists. Pruning oak trees between December and February reduces the risk of an oak wilt infection. When removing a branch, the cut should be made just beyond the branch collar and branch bark ridge. The branch collar is at the base of the branch and the bark ridge is the rough, dark area that separates the branch from the main branch or trunk.

It is advised to not make flush cuts, as close as possible to the trunk or main branch, when pruning trees. Doing such destroys the tree’s natural defense mechanisms that promote wound compartmentalization and callus formation.