ost landscape trees benefit from pruning. Good pruning can help trees grow strong and stable, improve health, influence size and shape, and increase longevity and beauty.
Recognizing what needs pruning on your tree involves looking at your tree from all sides. Sometimes a tree looks fine from one side and a serious defect shows up from the other side.
Below we show several common tree problems that can be improved by proper pruning. Look your tree over and see if it has any of these problems:
Broken or damaged branches can be hazardous or lead to decay. Pruning them properly removes the hazard and helps the tree close the wound quickly, minimizing decay.
Co-dominant main trunks are two vertical trunks that are similar in size and are competing for dominance. These usually are joined by a weak crotch (see below) that can fail as the trunks get large.
Weak crotches have a poor connection between the two limbs. Because
the angle between the branches is narrow the branches grow together, pinching the bark between the limbs. This prevents the two limbs from forming a strong connection at the crotch. This type of crotch is prone to failure; typically one side breaks away from the other.
How to recognize weak crotches; look for the bark being pulled down between the branches.
Almost half of this tree blew apart in a wind storm due to multiple weak crotches. The tree was so weak structurally that it had to be removed.
Strong crotches have wider angles and are strong because the wood from each branch grows across the crotch. These layers add to the strength of the crotch and cause the bark to push up in a ridge.
How to recognize strong crotches; Look for the tell-
tale bark ridge being pushed up between the limbs.
Signs of decay, like large wounds with rotten wood or fungal fruiting bodies, indicate decay inside the trunk or branch.
Fungus on tree can indicate decay inside. Sometimes it looks like shelves, sometimes more like mushrooms.
Branches with diseases should be removed if they are not too large; this helps to reduce disease spread. Mistletoe is a flowering plant that grows its roots into a tree branch and "steals" from the tree. Removing the mistletoe can reduce damage and it improves the health of the tree.
Weakly attached branches are usually the result of topping
a tree. When large branches are cut off, new branches sprout around the edges of the cut from just under the bark. Since they don't have many layers of wood surrounding them as a normal branch would, they can break off.
This tree was topped many years ago and many small branches have sprouted from the cut ends. These are not well attached to the trunk and are susceptible to breaking off.
This tree was cut down to about 3' many years ago, and two sprouts (left and right of the photo) sprouted from just under the bark of the stump. They have grown to be sizable trunks, but are not well connected to each other or the trunk. I would recommend removing this tree to reduce the possible hazard.
Crossing or rubbing branches can cause open wounds that diseases can invade, and they can make harvesting fruit difficult. It's best to remove them before they actually are rubbing.
Suckers are common on grafted plants like roses and fruit trees. These plants actually consist of one plant grafted to the roots of another plant. If suckers are allowed to take over, the desirable plant will weaken or die; so remove as soon as you see them.
Water sprouts are vigorous, vertical branches that sprout off of a branch. These branches can start to dominate the tree canopy and should be removed before the tree puts too much weight on the limb.
Branches too close to buildings, walkways, or roads cause problems. These branches will never move, but they will grow larger every year. Remove them before they get big.
Trees with awkward or ungainly shapes can be improved with judicious pruning. This is frequently a multi-year task, but can really make a difference in the structural stability and beauty.
Winter is a great time to check out your trees to see if they could benefit from pruning.
Here are some great resources for pruning plants:
U.C. Davis pruning and training fruit trees provides extensive information for home fruit growers. Different fruit types require different pruning. They also have up-to-date pest management information.
University of Florida has excellent website with information on pruning many kinds of trees and shrubs.
Cornell University has a very useful guide to planting and maintaining trees and shrubs. It includes great information about pruning.
The American Rose Society website will help you prune your roses to encourage blooms and vigorous health.
Our recommendations on how to hire an arborist to prune your trees.