Late winter is an excellent time to prune deciduous trees. Branches are easier to remove when not weighted down by leaves and the tree's branching structure is easier to see. Proper tree pruning is essential in developing trees with strong structures and desirable form. Young trees that receive appropriate pruning require little corrective pruning as they mature.

When to Prune
Pruning can be done at any time during the year, but growth is maximized and wound closure is fastest if it takes place before spring growth.

Specimen flowering trees, like Japanese lilac and magnolia, should be pruned right after they finish blooming to prevent the removal of flower buds during pruning.

How to Prune
Pruning should be done with an understanding of how trees respond to each cut. Improper pruning can cause damage that will last for the life of the tree, or worse, shorten the tree’s life.

Pruning cuts should be made so that only branch wood is removed and the trunk is not injured. If only branch wood is removed, the wound is smaller, the tree will be able to seal the wound more effectively, and the chance of problems with wood decay will be greatly reduced.

To locate the proper place to make a pruning cut, first look for the "branch bark ridge" on the upper surface of the branch where it joins the trunk. This is a line of bark that is pushed up between the branch and trunk as they have grown. (Some branch unions will not have this if they did not form properly. Instead the branch will simply press into the supporting stem, forming a sharp V-shaped union.) On the underside of the branch look also for the "branch collar", which is a slightly swollen area of trunk tissue that wraps around the base of the branch. A proper pruning cut begins just outside the branch bark ridge and angles down and slightly away from the trunk, avoiding injury to the branch collar.

3-Cut Pruning Method
Branches should be pruned using a series of three cuts. The first cut is to the underside of the branch, approximately 8-10 inches from the tree's trunk, and goes less than half way through the branch. The first cut does not remove any of the branch; it's purpose is to prevent the bark from ripping down the side of the tree when the branch falls. The second cut is made an inch or two further out from the first cut, away from the tree trunk, and removes the majority of the branch. The second cut should be made from the top side of the branch down. The final cut removes the remaining stump, also going from the top of the branch down, being careful not to cut into either the branch bark ridge or the branch collar.

Where to Start
Begin by removing dead, broken or diseases branches, and crowded or rubbing limbs. Also remove suckers and watersprouts.

Developing Branch Structure
When pruning, it’s important to establish a strong scaffold structure. Scaffold branches provide the framework for mature trees. The goal in training young trees is to establish a strong trunk with sturdy, well-spaced branches. Scaffold branches should be spaced alternate up the trunk of the tree, and evenly around the circumference of the trunk.

Branches forming wide angles with the trunk have greater strength than those that form narrow angles with the trunk. Good pruning techniques remove structurally weak branches while maintaining the natural form of the tree. For most young trees, maintain a single, dominant trunk leader.

How Much To Remove
The amount of live tissue that should be removed depends on the tree size, species and age as well as the pruning objectives. Younger trees will tolerate the removal of more living tissue than mature trees. Never remove more than one-third of the tree's canopy in any growing season.

It’s important to maintain an even distribution of foliage along large limbs and in the lower portion of the crown. Routine thinning of the tree's inner canopy does not improve its health, but can actually make the tree more susceptible to stress from high summer temperatures. Over-thinning reduces the tree’s sugar production capacity and can create tip-heavy limbs that are prone to failure.

Pruning Dont's
Do not make flush cuts that remove the branch collar. Wounds created by flush cuts cause substantially more injury to the tree than wounds left by proper pruning.

Do not "top" trees. Topping results when branches are cut flat, leaving a long stub beyond the next viable branch. The flat cut can allow water to remain on the wood and promote wood rot. The stub dies and also promotes wood rot. Trees respond to this type of pruning by producing a quick flush of fast-growing, weakly attached branches called watersprouts. Because of their weak attachement, watersprouts are prone to breakage as they grow larger. Topping can cause a decline in the tree's health and ruin the beauty of your tree.

Do not apply wound dressings to the cut surface. Wound dressing release chemicals that can be harmful to the tree and can hold moisture against the cut surface that promotes wood rot. Instead allow the area to dry naturally. The tree will seal off the wounded tissue and begin growing callus tissue to cover it.

Don’t be overly concerned if some trees “bleed” or leak sap in spring after late winter pruning. Maples, willow and birches are prone to bleeding and should ideally be pruned in late summer. However, bleeding is not harmful to the tree, the sap that is lost was intended for the branches that are now gone, so the tree is not weakened. However, sap can attract insects and provide a place for fungal spores to grow; so frequently wash the sap off the tree until it stops bleeding.

Don’t take on the pruning of a large tree if it is beyond your skill. Pruning large trees is dangerous work. If pruning involves working above the ground, or using power equipment, it’s best to hire a professional arborist who can determine what type of pruning is necessary to improve the health, appearance and safety of trees. An arborist will not cause any additional damage to the tree through improper pruning cuts and should be fully insured with liability, property damage and workmen’s compensation insurance.

Important points to keep in mind when contracting with an arborist:

1. Checking in your local yellow pages is a good way to find companies that offer tree services. Asking friends or neighbors for information on tree care companies with whom they have had good experiences is another good reference source.
   
2. Call several companies to find out if they are certified by the Nebraska Arborists Association or the International Society of Arboriculture. Certification is not required by the state of Nebraska but will indicate a company with a high level of training. Also ask if the company is a member of any professional organizations such as The National Arborists Association, the Nebraska Arborists Association or the International Society of Arboriculture. Although certification or professional memberships do not guarantee the work of each company, they do indicate a high level of professional commitment.
   
3. To protect yourself , the company you choose should have current personal liability, property damage and worker’s compensation insurance. Ask for certificates of insurance and call the insurance company to make sure the policy is current.
   
4. Finally, good tree care is not inexpensive. A professional arborist will never ask for payment before the work is done and won’t go door to door soliciting business. Also, be cautious of estimates for tree care services that are much less expensive than the other estimates you have received. These companies may not have full insurance coverage or the necessary equipment.

Find a Nebraska Certified Arborist in your area by visiting the Nebraska Arborist Association, http://www.nearborists.org/.