Guidelines for Correct Pruning

By Dr. Alex Shigo

Excerpted from "Homeowner's Guide for Beautiful, Safe, and Healthy Trees," NE-INF-58-84. At its previous site this page was awarded the Top 5% Award by Point Survey.

Correct pruning is the best thing you can do for your tree. Here are the guidelines:

Natural Target Pruning

Locate the branch bark ridge (BBR)

Find target A -- outside BBR

Find target B -- where branch meets collar

If B cannot be found, drop an imaginary line at AX. Angle XAC equals XAB.

Stub cut the branch.

Make final cut at line AB (with powersaws make final cut on upstroke.)

Do Not:

Make flush cuts behind the BBR

Leave living or dead stubs

Injure or remove the branch collar

Paint cuts

The best time to prune living branches is late in the dormant season or very early in spring before leaves form. Dead and dying branches can be pruned anytime. Use sharp tools! Make clean cuts. Be careful with all tools. Safety first!

Wound Dressings

Wound dressings do not stop rot! Do Not:

Apply house paints or wood preservatives

Apply heavy coats of any material

Research shows that wound dressings do not stop decay or stall rot. Trees respond effectively to their wounds without the aid of additional chemicals. Do not interfere with this natural process. Keep your tree healthy and it will take care of its wounds. In a short time the wound surface will blend perfectly with the tree bark.

Tree Treatments

Tree Wounds. If trees are wounded, remove injured bark with a sharp knife. Make cuts as shallow as possible. Forming an elongated ellipse is not necessary. Make all margins rounded; do not point tips. Do not enlarge the wound. Do not paint. Do everything possible to maintain health -- water, fertilize, prune.

Cavities. If cavities are filled, do not clean so thoroughly that the boundary between decayed wood and sound wood is broken. Fill with nonabrasive materials. Leave for professionals.

Injections and implants. If you plan to have chemicals injected or implanted in your trees, make certain that it is done only by highly skilled professionals. Check injection and implant holes after one season to make certain they are closed. Injection and implant holes should be very small and shallow at the tree base, not in the roots.

If you have any questions or are not certain about what is best for your tree, contact an ISA-certified arborist. Listings are usually available in the Yellow Pages. Or, you can check the ISA's Online Arborists Directory. Also, see our Consulting Arborists and Commercial Arborists lists for selected Pacific Northwest arborists who provide varying consulting and commercial tree care services. And, see the USDA Forest Service, S&PF, Northeastern Area, SPFO site that includes the Forest Service's document on How to Prune Trees.