Pruning Windbreaks Prepared by: L. Robert Barber, & Ilene Iriarte For: Guam Cooperative Extension Service & Guam Department of Agriculture Funding provided by: United States Department of Agriculture Natural Resources Conservation Service, Western Region Sustainable Agriculture Research and Education, Administration for Native Americans,, & Sanctuary Incorporated

What is Pruning Removal of plant parts to: –Improve health –Form –Control growth –Manipulate flowering, fruiting Pruning should be routine maintenance –Do not prune if unnecessary –Do not wait until overgrown Can harm plants if over pruned

Why Prune? Number of reasons to prune, the three main reasons are: –Safety, Health, & Aesthetics As trees mature reasons would change to: –Structure, Form, Health and Appearance. Determine why you are pruning before you start

Pruning Steps The first steps in pruning are: –Removing dead or decaying branches –Diseased branches –Broken branches –Narrow crotch angles Proper plant selection can reduce pruning requirements Pruning & training should start when trees are young –May help prevent serious problems

Training Young Plants Starting early can influence long-term: –Health –Function –Longevity Pruning should focus on structure Begin 1 st year of transplant & gradually over several years Promote only one central trunk to develop Photo Courtesy of USDA Forest Service

Pruning Large Trees Thinning Trees: –Opens canopy to allow sunlight to penetrate –Resists wind damage better than unpruned trees –Reduce drought stress DO NOT REMOVE MORE THAN 25% Photo Courtesy of USDA Forest Service

Safety Pruning Branches with narrow V-shaped angles: –Should be removed –Forms included bark Prevents strong attachment of branches Branches with U-shaped angles: –Should be retained –Strong attachment

U & V Shaped Branches Strong AttachmentWeak Attachment Photo Courtesy of USDA Forest Service

Proper Pruning Cuts Proper pruning cut does not damage either branch collar, or branch bark ridge To find the Branch Collar: –Grows from the stem tissue at the underside of the base of branch (mango’s show this well) Upper surface, there is usually a Branch Bark Ridge –Parallel to the branch angle, along the stem of the tree

Photo Courtesy of USDA Forest Service

Proper Pruning Cuts Proper cut is just outside the branch bark ridge, avoid injury to branch collar If stem tissue is not injured the wound will seal in shortest amount of time If cut is too far from stem: –Branch tissue normally dies –Can provide entry to diseases & insects –Delays or prevents wound wood formation

Stub Cut

Proper Pruning Cuts Proper pruning cut: –A concentric ring of wound wood will form Flush Cuts: –Made inside the branch bark ridge or branch collar –Pronounced development of wound wood on sides of pruning cuts –Very little wound wood forming on top & bottom

Proper Cut Sealing Naturally

Types of Pruning Cuts Pruning Small Branches: –Use sharp hand pruners Pruning branches with hand saw: –Support the branch with one hand, make cut with another Pruning Large Branches: –Make a 3-step pruning cut

3-Step Pruning Cut 1 st cut is made (6-8”) underneath the branch outside the branch collar –Prevents branch from tearing the stem 2 nd cut is made 2-4” outward from the 1 st cut on the topside of the branch –Cut until branch breaks off 3 rd cut is cut just outside branch bark ridge/branch collar

3-Step Pruning Cut Photo Courtesy of Lowe’s

Harmful Pruning Practices TOPPING: –Random pruning of large upright branches –Reduce height of tree Photo Courtesy of USDA Forest Service

Harmful Pruning Practices TIPPING: –Cutting Lateral branches between nodes –Reduction of crown width Photo Courtesy of USDA Forest Service

Crown Reduction or Drop Crotch Pruning Instead of topping & tipping use this method Used when trees have out grown their space More natural form Less Pruning & reduces stress Last resort method, can result in large pruning wounds Better solution is to replace with a smaller tree Photo Courtesy of USDA Forest Service

Harmful Pruning Practices These pruning practices normally: –Result in death of branch –More susceptible to pests & diseases –Stresses out the tree –Forces rapid growth (survival mechanism) –Sprouts that grow are weakly attached Will be eventually supported by decaying branch

Summary For more information please contact your local Cooperative Extension Service at