Upload
sherylwil
View
1.796
Download
3
Tags:
Embed Size (px)
Citation preview
Colorado Master Gardener Training
Pruning: Training Young Shade Trees
Training Young Trees
Few cuts are needed.
Training sets the structural integrity of the tree for life!
Gibberellins produced in the root growing tips stimulate growth in the canopy.
Auxins produced in the canopy growing tips
stimulate root growth.
Pruning at planting slows root regeneration.
On new plantings, keep pruning to a minimum until significant canopy growth cycle begins.
Remove damaged & broken branches
Maintain single trunk
1 year / inch of caliper
Overall best pruning time: late winter-early spring
Wound dressings/paints?
Growth habit determines training objectives.
ExcurrentCentral leader trees
DecurrentMultiple scaffold branches
Excurrent (central leader) trees
Pruning objectives to develop structural integrity:
1. Remove broken/problem branches
2. Maintain single trunk to top
3. Establish lowest permanent branch
4. Remove lower branches over time, if desired
Excurrent (central leader) trees Training objective #1
Remove branches that are: Broken or damaged Diseased or dead Competing
Excurrent (central leader) trees Training objective #2
Single trunk
If multiple trunks develop, remove all but one.
If central leader is killed back, start, train a branch as a new central leader.
Excurrent (central leader) trees Training objective #3
Diameter of branches less than 1/2 the diameter of trunk.
Less than 1/3 diameter preferred.
If larger branches develop
1. Remove
2. Prune back to slow growth
Excurrent (central leader) trees Training objective #4
Establish lowest permanent branch
Sidewalk: 7’ to 10’Street: 14’Wooded area: 10”
When pruning-up the trunk, always keep at least 1/2 of the foliage in lower 2/3s of tree.
Pruning up too fastLess trunk taper
Sunscald
Temporary branchesLow vigor (horizontal)Southwest side
branches provide sunscald protection
1/3
1/3
1/3
Training Excurrent (central leader) trees
Excurrent, central leader trees typically need little training and pruning.
Pruning objectives for training excurrent trees
1.2.3.4.
Pruning objectives for training excurrent trees
1. Removed broken, damaged and, competing branches.
2. Maintain single trunk to top.
3. Branches less than 1/2 trunk diameter; less than 1/3 preferred.
4. Select lowest permanent branch, removing temporary branches over time, but before they reach 2” diameter.
Training objectives: Decurrent trees (multiple scaffold branches)
Lack of training when young predisposes decurrent trees to wind and storm damage.
Training objectives: Decurrent trees (multiple scaffold branches)
5 pruning objectives to develop structural integrity for life:1. Remove broken/problem
branches2. Single, dominant trunk well
into tree’s upper region3. Establish lowest permanent
branch4. Select permanent
branches5. Remove temporary branches
over time
Decurrent TreesTraining Objective #1
Remove branches that are: Broken or damaged Diseased or dead Competing
Decurrent TreesTraining Objective #2
Single, dominant trunk well into tree’s upper region
Branches < 1/2 trunk diameter
< 1/3 preferred
Decurrent TreesTraining Objective #3
Establish lowest permanent branch
Sidewalk: 7’ to 10’Street: 14’Wooded area: 10”
When pruning-up the trunk, always keep at least 1/2 of the foliage in lower 2/3s of tree.
Pruning up too fastLess trunk taper
Sunscald
Temporary branchesLow vigor (horizontal)
Southwest side branches provide sunscald protection
1/3
1/3
1/3
Decurrent TreesTraining Objective #4
Select permanent scaffold branches
Branch spacing Crotch Angles Co-dominant trunks/branches Multiple branches at one spot
Potentially permanent branches spaced 6” to 12” apart, moving up and around the trunk.
Branch directly above another: 60” minimum vertical spacing
Branch spacing Mature height > 30’ tall
18” minimum
Mature height < 30’6” minimum
Branches spaced around tree
Multiple branches originating in the same area are structurally weak.
Branch collars can not form completelyBranch defense zone incomplete
This is a natural branching pattern for many trees, (elms, maple, crabapple, flowering plum) predisposing a mature tree to wind and storm damage.
A narrow crotch angle means take a closer look for included bark.
V - Crotch Narrow angle with
included bark = weak
U - CrotchWide angle = strong
Branch bark ridge sticks up in crotch like “mountain range in a valley” = strong attachment
Branch bark ridge disappears in the crotch = weak attachment, may develop included bark
AshAspen
Honeylocust
Ash
Co-dominant leaders (~ equal size) are structurally weak.
Co-dominant leaders develop included bark.
1/2 (1/3 preferred) rule
Correct while smallRemove one leader
Decurrent TreesTraining Objective #5
Remove temporary branches over time, but before they reach 2” (3” maximum) diameter.
Decurrent TreesTraining Objective #5
Temporary branches
Selection Small, less vigorous shoots Prune larger, more
vigorous shoots back to suppress growth
Spacing 4” to 6” minimum >6” from potentially
permanent branches
Pruning objectives for training decurrent trees
1. Remove broken, damaged and competing branches.
2. Maintain single trunk into upper portion of mature tree.
3. Select lowest permanentbranch.
4. Select scaffold branches.
5. Remove temporary branches over time, but before they reach 2” diameter.
Decurrent TreesLateral branches along limbs
Size < 1/2 diameter of parent branch
< 1/3 diameter preferred
Spacing > 24” from trunk > 6” spacing
Ash
Ash
Linden
Crabapple