Before we know it, spring will be here. Before getting too busy planting the garden, make sure to take some time to prune your trees (if they need it). Most deciduous trees are best pruned while they are in full dormancy. This happens to be February or March for this part of the country. It is important that they are pruned while they are fully dormant. If pruned too early, and not fully dormant, they may produce new shoots that can be killed by cold temperatures. Another important reason to prune most deciduous trees during colder months, especially trees like oak and elms, is that pruning wounds can attract borers. These beetles can carry diseases such as Dutch elm disease and oak wilt.
Pruning in the winter also allows you to see framework of the tree. This will make determining which branches and stems you want to remove easier. Start by pruning dead and dying parts of the plants first (this can be done at any point of the year). After that, identify any problems you may see in the tree, such as crossed and/or rubbing branches (rubbing branches cause wounds that can allow diseases to enter), branches growing towards the center of the tree, branches with narrow crotch angles (these are more likely to break), multiple leaders, and branches that may pose hazards to people or property. By eliminating potential problems in younger established trees you can avoid extensive, and potentially expensive repair work to older mature trees. If you have large mature trees that need to be pruned, it may be best to contact a certified arborist. They will have the necessary tools and safety equipment to safely prune large trees.
Having the proper tools to prune trees is also important. Some of the tools you may want are hand shears for small branches up to ¼” in diameter and lopping shears for branches up to 1 ½” in diameter. Pruning saws should be used for branches over 1” in diameter and pole pruners can be used to reach branches beyond your reach. For many years it was recommended that pruning wounds should be sealed (painted) to prevent pathogens from entering and to prevent the wood from decaying. However, this is not the case. Research has shown that it is not as helpful as previously believed. Often times the coating will crack, allowing moisture to get in and accumulate. This is an ideal environment for wood rotting organisms. Trees will naturally heal the wound themselves (callusing) and sealing the wound actually slows this process down.
If you would like to learn more about pruning trees (and shrubs) join us for Gardener’s Day on March 24. For more information, or to register visit go.illinois.edu/gardenersday.