Intro to Tree Pruning; Intro to Tree Pruning; R l ti T Bi l d R l ti T Bi l d Relating Tree Biology and Relating Tree Biology and
Structure to PruningStructure to Pruning
B B B db kBy Beau BrodbeckREA: Forestry, Wildlife & Natural Resources
Alabama Cooperative Extension SystemAlabama Cooperative Extension System
In the next 40 minutes You willIn the next 40 minutes…You will learn about the WHY?
R l i T Bi l P i• Relating Tree Biology to Pruning
• Relating tree structure to Pruning
What is tree biology?
The study of the Life ProcessesThe study of the Life Processesof a tree.
That includes a study of the GROWTH, ySTRUCTURE, EVOLUTION, etc. of a tree.
The CrownThe Crown
The canopy is made up of the f li d b hfoliage and branches…
Biologically this is where most of your photosynthesis isof your photosynthesis is
occurring.
Tree Biology…gyLeaves are the factories of the tree….
Inputs Outputs
WoodBarkLeavesLeavesRoots
GrowthSoil Minerals
Wh i ftWhen pruning you are often removing limbs with
photosynthesis/food producingphotosynthesis/food producing leaves…
L i i l b tt t t hi it tLess pruning is always better or stretching it out over several years….
There are two primary reasons why not to top or over-prune
damages treesdamages trees…
1. Reduction of growth
2. Formation of poor structure
1. Growth Reduction;
Where are the carbsWhere are the carbs stored?
• No leaves no photosynthesis• Carbohydrates/sugars are stored in the woody• Carbohydrates/sugars are stored in the woody
tissue of branches and trunk• Excessive pruning/storms will removed storedExcessive pruning/storms will removed stored
energy• This weakens trees and make them susceptibleThis weakens trees and make them susceptible
to insects & disease
2. Poor Structure; ;What is the Responses to over/incorrect pruning?
Sucker growth - Water sprouts - Epicormic branching
Why do trees respond this way?y p y• Apical meristem or dominant bud…is gone • That means:
– No more hormones suppressing thousand of dormant buds
– Resulting in excessive re-sprouting
Reason not to top trees:• Tree responds with rapid uncoordinated• Tree responds with rapid uncoordinated
growthP b h ll f i• Poor branch collar formation
• Introduces decay to key branches• Increases risk of insects and disease• Branches are poorly attachedBranches are poorly attached• Increases future risk of failure
If i t t b tt k t i• If your going to top you better keep topping to maintain the problem – Expensive$$$
Don’t Top!!!Don t Top!!!
There are other optionsp
It won’t Work Its Ugly
Pictures: www.plantamnesty.orgIt dangerous
The biology of reduction pruning
• Reduction pruning - removes branches back to a leader larger genough to assume appical dominance. – (i.e. hormones won’t release
hundreds of dormant buds…))– This prevents epicormic branching– Also can help limit size of cut or p
cutting back to the trunk
The Trunk:The trunk provides the support and strength to pp gthe tree…avoid damage to tree trunks at all costs!!!!
Avoid Large Pruning Cuts Especially thoseCuts…Especially those back to the trunk!
Trees don’t heal…
Trees compartmentalize or “wall-off” decayoff decay
Some species are better than others at keeping decay form spreading
Trees that resist decay make better ycandidates for restoration
Trees that resist decay Trees prone to decay
Bald Cypress Laurel oakRiver Birch
HickoryWater Oak
Willow OakPecan
American HollyWhite Oak
MapleShumard Oak
Slide by Ed Gilman, UFL
Improper pruning allows decay to enter and decay the tree
Avoid the following:1. Leaving stubsg
2. Making large pruning cuts back to the trunk
3. Removing the branch collarbranch collar
Leaving Stubs…
• Is an avenue for decay & insects todecay & insects to enter the tree
• Tree cannot seal over the wound
Large pruning cuts backLarge pruning cuts back to the trunk:
As pruning cuts get larger itAs pruning cuts get larger it becomes increasingly difficult for
the tree “seal” or compartmentalize that woundcompartmentalize that wound
Large Cuts take:
• More energy reserves to grow gover wounds
• More time to seal over (i e moreover (i.e. more time for decay and insects)and insects)
Si e/Age of the treeSize/Age of the tree• Larger more mature
trees are more difficult to restore;
d– More prone to decay due to larger branches
– Recovery moreRecovery more difficult due to more canopy loss
– Recovery will be a multiyear process due to pruning dosesp g
Slide by Ed Gilman, UFL
Pruning dose; storms excluded….g ;
Old d li• Old trees can decline as a result of over pruningOn o ng trees remo e less• On young trees remove less than 20% of live foliage.
• On mature trees remove less• On mature trees remove less than 10% of the live foliage
• Try to prune trees when theyTry to prune trees when they are young to avoid large cuts
Pruning; Storms ConsideredPruning; Storms Considered• You cant pick how much the
storms removed Sostorms removed…So…• Remove as little foliage as
possiblepossible• Prune away broken or stubbed
b hbranches• Take a long term approach. • Be prepared to spend several
years restoring your trees• Train future trees for better
structure
In the next 25 minutes…
• Relating Tree Biology to Pruningg gy g
• Relating tree structure to Pruning• Relating tree structure to Pruning
Tree Structure
It is important to train young trees to develop good structure
that will help them survive future storm events…
What is good structure?
Outline of topics
1. Forest grown vs. open grown treeg p g
2. Codominant stems
3. Good branch attachment
Slide by Ed Gilman, UFL
1. Forest grown treevs..
O tOpen grown tree
• How do they develop on their own?
Slide by Ed Gilman, UFL
Trees in the forest grow with one trunk, and codominant stems toward the top of the tree
Slide by Ed Gilman, UFL
Open grown treesp g
• Canopy develops low on the trunk
• Canopy spreads wide
• Tree is often wider than tall
Slide by Ed Gilman, UFL
What is good structure?
Outline of topics
1. Forest grown vs. open grown treeg p g
2. Codominant stems
3. Good branch attachment
Slide by Ed Gilman, UFL
Codominant stems often cause branch failure in stormsbranch failure in storms
Slide by Ed Gilman, UFL
What is good structure?
Outline of topics
1. Forest grown vs. open grown treeg p g
2. Codominant stems
3. Good branch attachment
Slide by Ed Gilman, UFL
3. Good branch attachment
• How does a BRANCH form?How does a BRANCH form?
• What are the indicators?
• Why are branch collards i ?important?
Slide by Ed Gilman, UFL
Branch bark ridge present1st indicator of good branch attachment
• Some branch
branch attachment
unions have a prominent branch bark ridge
• Indicator of good branch gattachment
Slide by Ed Gilman, UFL
2nd indicator of good b h hbranch attachment
No branch bark ridge
CollarAnother indicator of
d b h good branch attachment
Slide by Ed Gilman, UFL
Why is the branch collarWhy is the branch collar important?
• Specialized wood orientation helps:orientation helps:– Strengthens branch
attachmentattachment– Trees heal over the
wound quickly q ywhen pruning
– Limits decay from yentering the tree when pruning
What happens if you remove theWhat happens if you remove the branch collar?
• Create larger wound
• Increase healing timetime– More decay
More insects– More insects– Weaker tree
Image by Steve Houser
Some trees naturally developSome trees naturally develop good structure in the urban
i d i lenvironment and require less pruning maintenance and p gsustain less storm damage
Species: trees with good structure will p grequire less pruning attention
Trees with good structure Trees with poor structure
Baldcypress Silver MapleSweetgum
Southern magnoliaRed maple
PecanLive oak
Shumard oakLaurel oak]Water Oak
Overcup Oak Bradford PearSlide by Ed Gilman, UFL
I R i St t l b hIn Review: Structural branch problems to correct:
1. Codominant stems2. Branches with steep angles and2. Branches with steep angles and
included bark3. Branches that are too close in
diameter to the main stem
Correct these early regularlyCorrect these early…regularly…
Don’t allow these problems to become l d b ilarge and overbearing…
Special Thanks:Special Thanks:
Edward F. GilmanDepartment of Environmental HorticultureDepartment of Environmental Horticulture
University of Floridahttp://hort.ufl.edu/woody/planting
Beau BrodbeckAlabama CooperativeAlabama Cooperative
Extension SystemTel: 251-937-7176Tel: 251 937 7176
Email: [email protected]