GardenNotes #615

Structural Training of  Young Shade Trees Pruning Flow Chart

Has the root system established since planting (as evidence by current growth)?

Non-established trees
o No pruning required at this point (heavy pruning slows root regeneration).
o Minimal pruning needed to correct:
o Broken branches
o Maintain single trunk.

o  No

o  Yes

Established trees

  1. Maximum amount of foliage/live wood to remove.
    • Actively growing tree without stress and growth limiting factors (such as dry site or restricted rooting zone) – up to 25% of foliage per season
    • Reduced growth with growing limiting factors and/or stress – up to 10-15% of foliage per season
    • Minimal growth – do not remove life wood/foliage
  2. Natural growth habit?
    • Decurrent tree (develop multiple scaffold branches)
    • Excurrent tree (single trunk to top)

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Authors: David Whiting, Extension Consumer Horticulture Specialist, Dept. of Horticulture & LA, Colorado State University.

o Colorado Master Gardener GardenNotes are available on-line at www.cmg.colostate.edu.
o Colorado Master Gardener training is made possible, in part, by a grant from the Colorado Garden Show, Inc.
o Colorado State University, U.S. Department of Agriculture and Colorado counties cooperating.
o Extension programs are available to all without discrimination.
o No endorsement of products mentioned is intended nor is criticism implied of products not mentioned.
o Copyright © 2006. Colorado State University Extension. All Rights Reserved. CMG GardenNotes may be reproduced, without change or additions, for non-profit educational use. Revised December 2006

Updated Wednesday February 11 2009, David Whiting

 

Excurrent Tree


Single trunk to top

Decurrent Tree


Multiple scaffold branches
1.   Broken, damaged and competing branches
   Broken branches
   Competing branches
 1.   Broken, damaged and competing branches
   Broken branches
   Competing branches
2.   Maintain single trunk to top
   Co-dominant trunks or competing trunks
   Secondary branches becoming trunk-like
 2.   Maintain single dominant trunk to at least 2/3s of the tree’s mature height
   Co-dominant trunks or competing trunks
   Secondary branches becoming trunk-like
3.   Select lowest permanent branch
   Lowest permanent branch previously selected
   Select lowest permanent branch
   Tree needs to grow more before selection
 3.   Select lowest scaffold branch
   Lowest scaffold branch previously selected
   Select lowest scaffold branch
   Tree needs to grow more before selection
4.   Branches less than 1/2 the diameter of adjacent trunk (less than 1/3 preferred).
   Prune back side branch to slow growth
 4.   Select other scaffold branches as tree grows in height.
Factors to consider:
  ✓  Minimum branch spacing (6” per 10 feet of mature tree height)
  ✓  Wide branch union (crotch) angles
  ✓  Avoid multiple branches originating at one site
   Select 2nd scaffold branches
   Select 3rd scaffold branches
   Select 4th scaffold branches
   Select 5th scaffold branches
   Select other scaffold branches
   Tree needs to grow more in height
5.   Manage temporary branches, removing them over time (before they reach a 2-inch diameter).
   Remove temporary branches
   Thin or reduce temporary branches to slow growth
 5.   Manage temporary branches, removing them over time (before they reach a 2-inch diameter).
   Remove temporary branches
   Thin or reduce temporary branches to slow growth

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