Strengthening our Community Tree Canopy Through Education Module #3: Pruning Young Trees in the Urban Landscape Laura Sanagorski, Environmental Horticulture Extension Faculty

Strengthening Our Community Tree Canopy 2012 Urban Forestry Series This series is a part of a project titled “Strengthening Our Community Tree Canopy Through Education”. This project is made possible by  a grant through the 2011 National Urban and Community Forestry Grant Program and the Florida Department of Agriculture and Consumer Services, and the Florida Forest Service.

Pruning Young Trees in the Urban Landscape

STRUCTURALLY SOUND TREES Straight, single leader Evenly spaced branches and full, even canopy Free of pests, disease, and injury Roots grow away from the trunk; do not circle or girdle Photo: UF Laura Sanagorski

EFFECTS OF PRUNING Creates potential entry points for decay organisms Every pruning cut: Creates potential entry points for decay organisms Promotes shoot elongation Reduces photosynthesis Causes consumption of stored carbohydrates Photo: UF Laura Sanagorski

EFFECTS OF PRUNING May create or enhance structural defects Improper pruning cuts: Cause the above negative impacts, plus May create or enhance structural defects May increase insect and disease problems May increase maintenance needs Could reduce tree longevity Could injure or kill you Photo: UF Laura Sanagorski

EFFECTS OF PRUNING - CODIT CODIT: Compartmentalization of decay in trees Compartmentalization ~ trees don’t heal Xylem cells form 6-sided compartment with four walls Wall (s) 1 : plugging of xylem vessels above and below wound Wall 2: Thick cell growth on ring Wall(s) 3: Cell growth on radial xylem rays Wall 4: New xylem formation Photo: UF Laura Sanagorski

Compartmentalization Of Decay In Trees (CODIT) Wall (s) 1 : plugging of xylem vessels above and below wound Wall 2: Thick cell growth on ring Wall(s) 3: Cell growth on radial xylem rays Wall 4: New xylem formation USDA Forest Service - Northeastern Area Archive, USDA Forest Service, Bugwood.org

TREES DO NOT HEAL The tree will either: Seal off the wounded area, preventing the decay from spreading to the healthy, uninjured parts of the tree, allowing the tree to survive Not seal off the wounded area, allowing the decay to spread throughout the tree. Trees with excessive decay are prone to branch failure and may have shortened life spans Photo: UF Laura Sanagorski

PRUNING OBJECTIVES Remove dead and diseased branches Maintain proper structure and tree health Central Leader Strong Branch Connections Balanced Canopy Keep Branches < ½ Trunk Diameter Improve and maintain tree appearance Provide clearance beneath tree Reduce weight of stressed limbs Increase safety of landscape environment Photo: UF Laura Sanagorski

Photos: UF Laura Sanagorski

Photos: UF Laura Sanagorski

WHEN ASSESSING PRUNING NEEDS, CONSIDER Species’ form Tree’s age Tree’s reaction to pruning and strength of compartmentalization Photos: UF Laura Sanagorski

Angle of Cuts Make cut at a slight slant ¼” above healthy bud. Proper pruning cuts should be made above a bud growing in the direction desired Photos: Stephen Davis

Photo: Stephen Davis

Reduction Cut Leader Branch bark ridge Imaginary line Final Cut should be at a 45 degree angle Drawing: Stephen Davis

Pruning Tools 3/4”=Hand Pruners ¾”-1 ¾”=Lopping Shears Up to 2 ½”=Fine Toothed Hand Saw 3”-10”=Coarsely Textured Hand Saw 3”-10”=Chainsaw Pole Pruners=Up to 2” Photos: Stephen Davis

PROPER CUTS Remain just outside a tree’s branch bark collar Should not leave a stub Should not be flush with the trunk or adjacent branch Photo: UF Laura Sanagorski

Larger angles = stronger attachments Branch bark collar or included bark?? Photo: UF Laura Sanagorski

FLUSH CUT VS PROPER CUT Natural Target Pruning (NTP) USDA Forest Service - Northeastern Area Archive, USDA Forest Service, Bugwood.org

Healthy Wound Closure Photo: Stephen Davis

STRUCTURAL DEFECTS THAT MAY LEAD TO TREE FAILURE Co dominant stems Included bark Cavities Multiple attachments Cross branching Girdling roots Leaning Decay Splits or cracks Fungus Loose or cracked bark Previous failure Deadwood, stubs Termites, ants, other Insects Wounds Over pruned palms, trunk constrictions Nesting holes Laura Sanagorski

Before Photo: Roy Cuellar

After Photo: Roy Cuellar

…remove harmful synthetic materials! While you’re at it… …remove harmful synthetic materials! Photos: UF Laura Sanagorski

Strengthening our Community Tree Canopy Through Education Module #3: Pruning Young Trees in the Urban Landscape Laura Sanagorski, Environmental Horticulture Extension Faculty