Growing Green: Tree Pruning
Now is the time to start pruning your fruit trees. Pruning your trees while they are in dormancy reduces the possibility of fire blight in crabapples, apples and pears, as well as minimizing canker diseases in cherries and plums.
A good pair of pruning shears is probably one of your most important tools. Cuts up to 3/4 inches in diameter may be made with them. (Anvil pruning shears work well for removing dead wood, Bypass pruners work well with living wood.) Lopping shears are similar to pruning shears, but their long handles provide greater leverage needed to cut branches up to 11/2 inches in diameter. Pruning saws are very important for cutting branches over 1 inch in diameter. Make sure your pruning tools are sharp and clean before starting. Sharp tools make for good clean cuts. Clean tools do not spread disease.
How do you know what to cut? Start by removing broken, dead or diseased branches. Cut out thin or weak wood and remove branches that rub together so that light can penetrate and air can move freely through the tree. Remove suckers around the base of the tree and waterspouts from the inner branches.
To remove a branch, undercut the branch halfway through about 18” from the trunk. Top cut an inch further out until the branch breaks free. Finally, cut off the remaining stub. Make this cut as close to the trunk as possible without removing the branch collar (the swollen area on the trunk where the branch attaches). When trimming branches, cut back to a side branch, or make a cut ¼ of an inch above a bud. Leave the wound open to heal naturally. Wound dressing is not needed and could actually slow the healing process.
Trees and shrubs that set their buds on last year’s wood and flower in early spring should not be pruned until after they have finished blossoming. These include: apricot, clove currant, June berry, azalea, flowering plum, lilac, chokeberry, magnolia, chokecherry, forsythia, and early blooming spirea. To avoid oak wilt, do not prune oaks in April, May, or June when the disease is most likely to be spread. Prune honey locusts now to avoid stem cankers. To prevent bleeding, sap producing trees should be pruned once their leaves are fully out. These include: all maples, (including box elder), butternut, walnut, birch, ironwood and blue beech.
Properly timed and executed pruning promotes plant health, improves plant appearance and protects people and property. Plan now for late winter pruning, and enjoy your trees and shrubs come summer.
Robin Trott is a Horticulture Educator with University of Minnesota Extension.