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

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

STRUCTURALLY SOUND TREES

Photo: UF Laura Sanagorski

Every pruning cut:Creates potential entry

points for decay organisms

Promotes shoot elongation

Reduces photosynthesis

Causes consumption of stored carbohydrates

EFFECTS OF PRUNING

Photo: UF Laura Sanagorski

Improper pruning cuts: Cause the above negative impacts, plusMay create or enhance

structural defectsMay increase insect

and disease problemsMay increase

maintenance needsCould reduce tree

longevityCould injure or kill you

EFFECTS OF PRUNING

Photo: UF Laura Sanagorski

CODIT: Compartmentalization of decay in trees

Compartmentalization ~ trees don’t heal

Xylem cells form 6-sided compartment with four wallsWall (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

EFFECTS OF PRUNING - CODIT

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

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

TREES DO NOT HEAL

Photo: UF Laura Sanagorski

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

PRUNING OBJECTIVES

Photo: UF Laura Sanagorski

Photos: UF Laura Sanagorski

Photos: UF Laura Sanagorski

Species’ form Tree’s age Tree’s reaction to

pruning and strength of compartmentalization

WHEN ASSESSING PRUNING NEEDS, CONSIDER

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 P

hoto

s: S

tep

hen

D

avi

s

Photo: Stephen Davis

Imaginary line

Final Cut should be at a 45 degree angle

Reduction

Cut

Leader

Branch bark ridge

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

Remain just outside a tree’s branch bark collar

Should not leave a stub

Should not be flush with the trunk or adjacent branch

PROPER CUTS

Photo: UF Laura Sanagorski

Photo: UF Laura Sanagorski

Larger angles = stronger attachments

Branch bark

collar or included bark??

FLUSH CUT VS PROPER CUT

USDA Forest Service - Northeastern Area Archive, USDA Forest Service, Bugwood.org

Natural Target Pruning (NTP)

Photo: Stephen Davis

Healthy Wound Closure

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

Laura Sanagorski

Fungus Loose or

cracked bark Previous failure Deadwood,

stubs Termites, ants,

other Insects Wounds Over pruned

palms, trunk constrictions

Nesting holes

Before

Photo: Roy Cuellar

After

Photo: Roy Cuellar

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