Developing a preventive pruning program in your community:
Mature trees
Dr. Ed Gilman and Amanda Bisson
Presenter
Presentation Notes
A preventive pruning program should be designed to create structurally sound trunk and branch architecture that will sustain the tree for a long period. Structural pruning can be conducted on older trees by pruning on the younger portions of the trees in the top half of the canopy. On some tees it may be too late to make meaningful changes in the lower half of the canopy because pruning cuts would be too large. Medium-aged and mature trees can be cleaned, thinned, reduced, raised, or restored to manage risk. The choice among these pruning types depends on the tree and the situation.
Inaction can cause structural problemsYoung trees are
easier to fixOlder trees are more challenging to treat
Codominant stems with bark inclusions
Presenter
Presentation Notes
It may be too late to make meaningful structural changes on mature trees. The tree on the right is young and the codominant stems are still relatively small. Subordinate the stem on the right with reduction cuts to slow its growth. This branch will eventually need to be removed because of the bark inclusion and to provide clearance for traffic underneath the canopy. It is too late to correct the structure for tree on the right. The bark inclusion runs almost completely to the ground. Not much can be done in a situation like this because removal of a codominant stem of this proportion would promote extensive decay and greatly weaken the tree. The only option is to try and reduce the end weight of each stem through reduction and thinning. This may help to prevent the tree from splitting apart in a storm. Cabling and bracing may also help to prevent tree failure.
Poor structure such as codominant stems often cause branch failure in
storms
Presenter
Presentation Notes
Researchers at UF have visited several hurricane sites, and found time and time again that trees failed due to structural issues like codominant stems and bark inclusions. This tree is ruined and should be cut down.
Pruning can reduce damageA recent study at UF showed that pruning reduces canopy movement when trees are exposed to high winds.
Not pruned
Reduction pruning
Presenter
Presentation Notes
In a research project in 2006, we blew trees up to 120 mph with a wind machine and found that pruning significantly reduced trunk movement. Trunk movement on some pruned trees was approximately 1/3 movement on unpruned trees. The photos above show a live oak that was not pruned and one that was reduced in size using structural pruning techniques.
Poor management
Better management
Your goal
Single trunk
Multiple trunks
Presenter
Presentation Notes
Your goal with mature trees is to develop or maintain a sound structure. The task is easier provided a good structure was established earlier. Maintaining a sound structure means maintaining a dominant leader, spacing major scaffold limbs along the trunk, and ensuring that branch connections to the trunk are structurally sound with no bark inclusions. With mature trees it is important to minimize hazards such as branch failure. Failures damage the tree and can also cause damage to people and property.
Common mature treeproblems
codominant stems
included bark
dead branch
water sprouts
broken branch
sucker
dead branch
decay
Presenter
Presentation Notes
Common problems that can develop on trees include codominant stems; included bark; broken and dead branches; decay from removal of large branches; and large, low limbs that require removal.
Preventive Pruning: mature trees
• Set objectives• Determine pruning cycle
and dose• Execute pruning plan
- make good cuts- prioritize trees with high risk structural issues- choose appropriate pruning type
Presenter
Presentation Notes
Preventive pruning helps to minimize the damage caused by winds and storms.
Pruning objectives:• Reduce risk of failure – minimize storm damage• Promote human safety • Allow for safe passage• Increase sun penetration to the ground• Maintain health
Presenter
Presentation Notes
Here are several common objectives of pruning older trees.
• Reduce conditions that could lead to catastrophic branch or tree loss.
reduce
Presenter
Presentation Notes
Reduce failure risk by learning to recognize the structural problems in trees that can lead to failure. One of these problems is branches and stems with bark inclusions shown above. Risk of tree failure can be reduced by establishing a structural pruning program to treat this. Risk of failure on the tree to the upper left can be reduced by making a pruning cuts toward the end of the stem indicated with a red arrow.
Collar
Strong union without a bark inclusion
Presenter
Presentation Notes
Strong unions are typically U shaped and have no bark inclusion. The branch on the right appears well secured to the tree and does not need treatment of any kind.
Close-up of included bark
Presenter
Presentation Notes
Here is a close-up of an inclusion and a crack that developed down from the inclusion. Cracking is common and leads to stem failure.
Failure due to bark inclusion
Presenter
Presentation Notes
Here is the same tree that was shown in the previous slide a couple years latter. A 70 mph wind peeled this codominant stem out from the rest of the tree. There was a severe bark inclusion in the union.
Cracks are evident and indicate weakness
Crack
Presenter
Presentation Notes
Cracks in branches can result in branch failure, damage to structures, and injury to people. Health can be maintained by cleaning the crown, especially in medium-aged and mature trees. Removing dead, diseased, and rubbing branches in the crown of young trees also is important.
reduceReduce branch with crack
Horizontal crack
Presenter
Presentation Notes
Here is a hidden crack. Hidden cracks often have elongated swellings such as seen at the arrow. A horizontal crack greatly affects the structural integrity of this branch. As such, it is a good candidate for reduction and or thinning. The goal is to alleviate forces at the base of the branch. This is accomplished by reducing weight at the end of the branch so that the risk of breaking is minimized. Unfortunately, this tree has been lions-tailed which means that interior branches have been removed from the main branches. As a result, there are no smaller branched to cut back to. In some cases the only option is to completely remove the limb, leaving behind a very sizable pruning wound.
Broken branch
Presenter
Presentation Notes
Large branches with excessive end weight may break easily in storms, especially if there is a crack.
Reduction could have prevented this
Presenter
Presentation Notes
Reducing the length of the codominant stems could have reduced the likelihood of failure in this live oak.
Before pruning a leaning tree After pruning
Presenter
Presentation Notes
Leaning trees are good candidates for treating since they are more prone to falling in storms than upright trees. Branches were removed from the left side of the canopy using reduction and removal cuts to bring the center of balance back toward the right.
Severed and decayed root systems
Presenter
Presentation Notes
Trees with decayed or severed roots fall over in storms. Roots should be evaluated on large trees located close to targets such as buildings, parking lots,, streets, park benches, etc.
Stem girdling roots may cause trees to topple
Location of girdling roots. Notice that there are few supporting roots on this side of the tree.
Presenter
Presentation Notes
Trees with roots that circle close to the trunk can become stem girdling roots. Here are two examples of trees that fell in hurricanes. Both had severe stem girdling roots around the base of the trunk. The root defect was so bad on the pine (above) that the trunk and root system on that side of the tree was completed decayed and dead.
Stem girdling roots
• Roots that circle around the base of the trunk
Girdling root
Presenter
Presentation Notes
Young trees with stem girdling roots can be easily fixed by carefully removing the defect. This girdling roots grew around the trunk in the mulch that was piled against the trunk. Over-mulching can cause stem girdling roots resulting in tree failure in hurricanes and other storms. The next slide shows the root pruned away.
After removing girdling roots
Presenter
Presentation Notes
Carefully remove the stem girdling roots by pruning it at the point where it begins to circle. The best cut will be positioned tangential (i.e. before the root begins to circle) with the trunk. Notice the trunk damage on the extreme left portion of the trunk. This is a common symptom of stem girdling roots on thin barked trees.
Objective: Promote human safety• Avoid expensive damage
Broken branch pruned away to free the car
Presenter
Presentation Notes
Pruning can prevent expensive damage to people and or property. If hazardous structural issues in trees can be recognized prior to a storm, pruning can help to mitigate their damaging effects. Developing a preventative pruning program for mature trees will help to reduce the likelihood of serious damage from trees.
Objective: Allow for safe passage
Notice the large limbs located close to the ground – these will eventually have to be removed for clearance.
Presenter
Presentation Notes
Growth can be directed away from an object such as a building, security light, or power line by reducing or removing limbs on that side of the tree. However, trees often grow back to fill the void created by pruning. Regular pruning is required to maintain artificial clearance. Shortening or removing low branches can raise the crown.
Objective: Reduce shade
Before thinning
After thinningMore light here
Presenter
Presentation Notes
A lawn, ground covers, or shrubs can receive more sunlight when live foliage is removed from the crown of large overstory trees. The tree’s resistance to wind also can be reduced with pruning. Thinning, reduction, and pollarding are used to accomplish this objective.
Objective: Maintain tree health
Presenter
Presentation Notes
Health can be maintained by cleaning the crown, especially in medium-aged and mature trees. Removing dead (as shown above), diseased, and rubbing branches in the crown of young trees also is important.
Preventive Pruning: mature trees
• Set objectives• Determine pruning
cycle and dose• Execute pruning plan
-make good cuts- prioritize trees with high risk structural issues-choose appropriate pruning type
Presenter
Presentation Notes
Preventive pruning helps to minimize the damage caused by winds and storms.
Pruning cycle
• Pruning cycle is the time period between pruning episodes
• Pruning every 2 years results in trees better prepared for storms than longer cycles
• The sooner you begin pruning the less you will need to remove at each pruning
Presenter
Presentation Notes
Pruning often results in trees better prepared for hurricanes.
Pruning dose
• Old trees can decline as a result of removing too much live tissue.
• Try not to remove more than 10% of the live foliage on a mature tree.
• Remove more than 10% only for a good reason such as a cracked live branch over a house.
Presenter
Presentation Notes
Energy reserves (starch, sugars, and oils) are stored in branches, stems, trunk, and roots. Energy reserves can be preserved by removing the fewest number of live branches necessary to accomplish the desired objective. Excessive branch removal depletes reserves and reduces the ability of the tree to photosynthesize more energy. Many trees generate adventitious sprouts in response to overpruning as they attempt to replace the stored energy.
Remove live foliage only for a good reason!
Excessive sprouting as a result of stress caused from over pruning.
Presenter
Presentation Notes
Refrain from removing any live foliage from a stressed tree. Removing live tissue on a mature tree forces it to react and expend energy to form sprouts as shown above. This is an attempt by the tree to rebuild the energy reserves that were removed with the over-pruning. The national ANSI A300 pruning standards suggest that up to 25% of live foliage can be removed on mature trees, but this is too much in many circumstances. A good reason for removing more than 10% is to reduce a large branch with included bark to minimize risk the of failure.
Risks of removing too much tissue
• Forces use of energy by initiating defense mechanisms.
• Removes energy reserves.• Can cause cracks.• Can cause sprouting.• Can cause branch death.• Can cause tree mortality.• Reduces energy storage space.
Preventive Pruning: mature trees
• Set objectives• Determine pruning cycle
and dose• Execute pruning plan
- make good cuts- prioritize trees with high risk structural issues- choose appropriate pruning type
Presenter
Presentation Notes
Preventive pruning helps to minimize the damage caused by winds and storms.
Reduction cut shortens the length of a stem by pruning back to a smaller limb.
Removal cut prunes a branch back to the trunk or parent branch.
Types of pruning cuts:
Make good pruning cutsStep 1Make an undercut about 12 inches from the trunk.
Step 2Make a top cut farther out on the limb.
Step 3Remove the stub with final cut, being careful not to cut flush against the trunk. Leave the collar intact.
Presenter
Presentation Notes
Most good removal cuts leave a round-shaped wound, whereas flush cuts are oval-shaped.
Branch bark ridge
Collar: swollen area at the base of the branch where it joins the trunk. The tissue is rich in energy reserves and chemicals that hinder the spread of decay. Good pruning cuts avoid cutting into the collar.
Collar
Presenter
Presentation Notes
The branch bark ridge is where trunk bark pushes up into the union as it grows against branch bark. This indicates a strong union. Never cut off the branch bark ridge since this removes the branch protection zone inside the collar. The protection zone helps retard decay organisms from entering the trunk. Cutting along the “yes” line represents an appropriate removal cut. Cutting through the “no” line cuts through the collar and represents a flush cut.
No collar visiblePruningcut
A B Angle ‘A’ should equal angle ‘B’
imaginary line
Presenter
Presentation Notes
If a collar is not visible then draw an imaginary line parallel with the trunk. Angle A should equal angle B. The pruning cut begins at the point where the top of the branch makes an abrupt turn toward the trunk.
Bad cut- called a flush cut
Woundwood does not develop evenly
Presenter
Presentation Notes
Flush cut removes the top of the branch bark ridge (look at the photo to see that it is gone) Flush cuts prevent the wound from sealing over properly. Flush cuts typically expose more bark on top of the cut than on the sides and bottom (see blue arrow). Flush cuts typically close first on the sides then on the top and bottom. Severe decay can occur behind flush cuts, especially when they are large in diameter.
Reduction cut
Presenter
Presentation Notes
Reduction cut bisects the angle between an imaginary line (dotted line) drawn perpendicular to the stem to be removed (wrapped in yellow) and the branch bark ridge (dotted line)
1 Primary - do not remove2 Secondary - almost never remove3 Tertiary- carefully consider removal4 Quaternary – could remove some5 Quinary- could remove several
Presenter
Presentation Notes
Only the lower right branch on this tree has been drawn to completion. The rest has been truncated for illustration purposes. If you decide to prune an old tree that has good structure with no defects, make cuts primarily on smaller branches toward the canopy edge only. Removing primary branches such as scaffold limbs often leave large pruning wounds and remove too much live tissue. Large pockets of decay in the trunk could result. Consider shortening or thinning the limb by removing tertiary and smaller branches instead of removing the branch entirely. The branch in the upper right canopy with the bark inclusion is a good candidate for reducing. The branch with the inclusion could be removed or reduced.
Types of preventive pruning: Mature Trees
Structural pruningCleaningThinningRaising
ReducingBalancing
Root pruningPalm pruning
Pruning to restore
Presenter
Presentation Notes
Pruning strategies for mature trees is quite different than those used for young trees. It is too late to make drastic structural changes to a mature tree. Good structure is something that should have been instilled in the beginning years of the trees life. For mature trees your preventative pruning tactics are to 1) minimize hazardous conditions by cleaning and reducing weight where needed, 2) raise canopy where needed, and 3) maintain small-diameter interior branches for health and vigor. These tactics are achieved through cleaning, thinning, raising, reducing, and balancing.
Structural pruning shortens or thins certain
stems and branches
Presenter
Presentation Notes
Structural pruning shortens stems and branches (indicated by red arrows) that are competing with the leader or main trunk. Pruning cuts range in size from 1 – 3 inches for trees that are prone to decay. Pruning cuts can be up to 6 inches or more for trees that resist decay. A medium aged tree such as this one can withstand up to about 25�percentage of foliage at one pruning. More can be removed on any individual branch.
Before After
Presenter
Presentation Notes
Arrow points to a codominant stem with a bark inclusion. Reduce the smaller stem with a reduction cut to slow its growth. This makes the tree more resistant to wind damage.
Before After
1
23
4
Presenter
Presentation Notes
Before pruning this tree has 4 codominant stems (red arrows). Stem 1 was shortened with a reduction cut; stem 3 was removed back to its origin.
1 yearlater
2 years later
Presenter
Presentation Notes
The two pruning cuts can still be seen one year later (red arrows). Two years after pruning the stem in the center of the tree is beginning to become dominant. This indicates that the tree is becoming more storm resistant.
Preventive structural pruning
Before pruning 3 years later
After pruning
Presenter
Presentation Notes
Several stems and branches were growing aggressively and competing with the leader on this 70 foot tall tree. Pruning cuts will be made on several of the competing stems (3 are indicated with red lines). Pruning cuts were executed and two can be seen in the lower left photo (red arrows). Three years after pruning the tree came through a 70 mph tropical storm without damage (right photo).
Three years later
Showing three cuts
Presenter
Presentation Notes
Here is the same tree at a different angle with three pruning cuts made three years ago clearly visible. Now it is time to prune the tree again.
Close-up of sweetgum
Presenter
Presentation Notes
This is a closeup of the three cuts.
Presenter
Presentation Notes
The tree leafs out in spring to fill the canopy with foliage. The tree clearly needs pruning as shown by the relatively heavy top right hand portion of the canopy. The two stems indicated in orange should be shortened.
First cut
Presenter
Presentation Notes
On one of these stems, the first cut removes a 3.5 inch diameter stem with a reduction cut. See next slide for the branch removed.
3.5 inch stem removed
Presenter
Presentation Notes
This 3.5 inch diameter stem was removed from the top portion of the canopy with a reduction cut.
First cut
Second cut
Presenter
Presentation Notes
The second cut finished the pruning job on this stem. About 30% of the foliage was removed with these two cuts on this stem.
After pruning Before pruning
Presenter
Presentation Notes
The canopy is thinner and more balanced after pruning. A balanced canopy twists less in hurricanes, and a thinner canopy moves less in hurricanes.
Pruning to: Clean• Removal of dead, broken, rubbing,
or diseased branches, and foreign objects.
• Reduces the risk of branches falling from the tree
Presenter
Presentation Notes
Cleaning improves tree value, appearance, and health. It also reduces risk of damage to people or property. It is good for mature trees because it does not remove live branches unnecessarily.
Cleaning takes care of these
Broken branches
Presenter
Presentation Notes
Although dead branches normally cause less damage in hurricanes than live branches with defects, removing dead branches represents good tree care. Any damage caused by these small broken branches would be minimal compared to the threat of damage from larger branches.
Pruning to: Thin• The selective removal of small live branches to
reduce crown density . • Increases light and air penetration.• Reduces the risk of storm damage.
Presenter
Presentation Notes
Appropriate thinning reduces damage in storms and hurricanes. Proper thinning retains crown shape and should provide an even distribution of foliage throughout the crown. This means removing branches that have foliage at the edge of the canopy. Increased light and air stimulates and maintains interior foliage, which can encourage taper on scaffold branches. Thinning reduces the wind-sail effect of foliar clumps in the crown and reduces the load on branch unions. Do not remove branches from the interior of the canopy since this can make a tree more susceptible to damage by encouraging branches to grow taller and wider.
How to thin a canopy
Presenter
Presentation Notes
Excessive branch removal on the lower two-thirds of a branch or stem (center illustration) can have adverse effects on the tree and therefore is not an acceptable pruning practice. Some arborists call this lionstailing.
Dense canopy
Presenter
Presentation Notes
This tree has a very dense canopy because it is growing out in the open with little competition from other trees. Thinning can reduce wind resistance and decrease the chance of storm damage.
Thinning removes entire branches back well into the canopy
Presenter
Presentation Notes
Note that the arborist is making the pruning cut well back inside the canopy to thin the canopy. Thinning in this manner presents a smaller cross-sectional area to the wind and therefore reduces damage in hurricanes and other wind storms. Removing branches from the outer portion of the canopy like this reduces the force of the wind on the canopy more than removing it from the bottom of the canopy.
Inappropriate thinning
Lions-tailing: trees with foliage concentrated at the tips of branches because inner branches were removed.• More susceptible to hurricane damage• Difficult to restore
Presenter
Presentation Notes
Lions-tailed trees are cleared of live foliage all along the lower and interior parts of the main branches. This may reduce storm damage if the storm occurs in the weeks following a wind storm but professionals believe this makes them more susceptible to storm damage in the long run. Lions-tailing encourages more growth at the tips of the branches resulting in a taller and wider tree because new growth occurs primarily from the branch ends. This places more foliage exactly where you do not want it; that is, higher off the ground. Sprouts routinely form along the portion of the main branches where branches were removed from quickly filling the canopy back in with foliage. Branch diameter on the end of the branch closest to the trunk increases more slowly following this type of pruning. Some branches can break easily as a result. In addition, lions-tailed trees that are damaged in storms are difficult to restore because the branches arborists would normally cut back to have already been removed.
HELP!
Presenter
Presentation Notes
The lower portion of this canopy was completely stripped of interior branches. This puts a lot of stress on the tree by unbalancing the canopy and removing excess foliage for no good reason. This type of pruning accomplishes nothing of merit.
Two years later
Presenter
Presentation Notes
Here is the same tree two years later. Notice the vigorous production of water sprouts on interior limbs. This is a common sign of over thinning or lion tailing.
Pruning to: Reduce• The selective removal of branches and stems to
decrease the height and/or spread of a tree
Presenter
Presentation Notes
Trees sometimes grow larger than desired for aesthetic or safety considerations. These trees may interfere with overhead utility wires, grow into buildings or other trees, or become hazardous because of their size, length, or condition. Reduction can be used to make the entire tree or portions of the tree smaller which can reduce the likelihood of failure, and it can direct branch growth away from buildings or signs. Reduction can open a view, or bring one side of the canopy in balance with another. Crown reduction should be accomplished with reduction cuts, not heading cuts.
Reduction• May be necessary to
direct growth • A better option is to
plant a smaller tree
Think right tree right place!
Presenter
Presentation Notes
Trees pruned around wires can bring wires to the ground during hurricanes so it’s a good idea to plant small tree near wires.
Proper canopy reduction
Reduction cut
Presenter
Presentation Notes
Some of the reduction cuts made on this tree are inappropriate because they were cut back to lateral branches too small too assume dominance. However, notice that there are branch tips present in the outer canopy. This indicates good intentions and a knowledgeable person performed the work. Using reduction cuts is the proper way to reduce a tree canopy. Topping or heading cuts would have removed these branch tips.
Excessive sprouting
Presenter
Presentation Notes
Notice that topping results in excessive sprouting. This creates the need for more frequent pruning and promotes poor structure in the canopy that can become more susceptible to hurricane winds. Proper reduction cuts limit sprouting and regrowth. These trees will have to be pruned less often to clear the utility lines from branch interruptions.
Reduction PruningProper vs. Improper (Topping)
Proper reduction
• reduces size while maintaining form
• minimizes re-growth• cuts barely noticeable• branch tips visible in
outer canopy
Improper reduction
• drastic form change• sprouting• cuts very noticeable• branch tips not visible
in outer canopy• compromises structure• promotes defects and
decay
Presenter
Presentation Notes
Canopy reduction makes a tree smaller by removing the end portion of branches with reduction cuts. Inappropriate reduction uses heading cuts and can result in more problems in the future such as decay and structural defects.
Topping trees promotes bad structure!
Sprouts
Presenter
Presentation Notes
Topped disfigures trees and causes decay and sprouting. None of this is good for trees or people.
Not all tree species can be reduced
• Consider species and plant health before reducing the canopy
• More decay can enter the tree following reduction than following removal cuts
Presenter
Presentation Notes
Old, stressed, or mature trees can be preserved with light canopy reduction conducted every year. Severe reduction can cause decline or increase stress and can kill the tree. Tree species such as pines do not respond well to pruning in this manner. Poor compartmentalizers of decay such as laurel oaks are also poor candidates for canopy reduction.
Pruning to: Raise• The selective removal of branches to provide
vertical clearance • Best done over a period of years, not all at
once
Presenter
Presentation Notes
Crown raising shortens or removes lower branches of a tree to provide clearance for buildings, signs, vehicles, pedestrians, and vistas.
Large pruning cuts
Presenter
Presentation Notes
The trunk can be seriously injured if too many lower branches are removed at one time. Excessive removal of lower limbs can slow development of trunk taper, can cause cracks or decay in the trunk, and transfers too much weight to the top of the tree. Mature trees could become stressed if large-diameter lower branches are removed.
Over-lifting causes stress resulting in sprouting
Presenter
Presentation Notes
Trees raised all at once often sprout making the tree unsightly and could cause trunk defects.
Two years later
After lifting the canopy
Sprouts
Large lower branch removed
Presenter
Presentation Notes
A large lower limb was removed from this tree to provide clearance for people and cars that utilize the parking area. Two years later the tree has developed sprouts where the cut was made. The sprouts are a result of stress from removal of such a large branch that probably functioned as a major source of photosynthetic energy for the tree. The pruning cut also left a sizable wound which could result in future decay in that area of the trunk. A better option may have been to reduce end weight which would have help prevent the branch from drooping in the way.
Big cuts can result in decay and cracks.
Presenter
Presentation Notes
Large cuts like these should not be made on this decay prone species. Attempt to reduce the length of these large low branches and retain them on the tree. This tree should have been pruned many years ago to keep these low branches small relative to the trunk. The goal is to keep branches smaller than half the trunk diameter if they will require removal later.
Sprouts develop from large pruning cuts
Presenter
Presentation Notes
Sprouts can indicate over-pruning.
Clearance can be achieved by shortening low branches rather than removing them.
Presenter
Presentation Notes
Here is a more moderate method of raising compared to removing many low branches all at once. Lower branches a and b can be removed to raise the crown. However, subordinating branches a and b by removing upper and lower branches a-1, a-2, b-1, and b-2 will cause less stress for the tree. Removing a-2 and b-2 helps raise the crown. Removing a-1 and b-1 ensures that the branches will not grow up to become part of the permanent canopy. Left unpruned, these branches are likely to remain vigorous-forming low, codominant stems. Because it is important to also remember structural pruning issue, branch c should be reduced to keep it from competing with the leader.
Raising: a stepwise process
• Thin/reduce/remove the largest branches in the lower part of the tree.
• Leave smaller branches intact for one year. • If necessary remove branches back to trunk
one to several years later. • Do not forget to correct any structural pruning
needs.
Presenter
Presentation Notes
Thinning or reducing lower branches may provide enough clearance for 1-2 years because the branch will often rise after removing end weight. One or two low branches could be removed at one time but removing multiple large branches all at once can cause trunk defects. Small branches left intact may help to shade the trunk and minimize the injury from sudden sun exposure. Small branches can also speed closure of pruning wounds.
Don’t forget structural pruning!
Presenter
Presentation Notes
It is poor practice to remove lower branches without correcting structural problems. The canopy on this live oak was raised, but the needed structural pruning issues were ignored. The large diameter stem on the right should have been subordinated to allow the stem in the left to dominate. Five years later the tree’s form has worsened. Codominant stems have developed with included bark. The tree is also taller placing more stress on this weak union and placing the canopy in a greater wind speed zone higher off the ground.
Pruning to: Balance• Removes live branches to redistribute wind
and gravity loads in the canopy.
Presenter
Presentation Notes
A well balanced tree is considered more stable, safer, and more aesthetically pleasing than a tree with foliage or branches mostly missing on one side. Branches may need to be shortened to balance the canopy or to prune it away from a structure or a sidewalk. This can be accomplished with small or large doses or reduction (above).
Unbalanced canopyReduce this side of the canopy
Presenter
Presentation Notes
Use reduction cuts on the right side of the tree to bring the canopy into balance with the left side of the tree.
Balance the right side of the canopy by reducing the large limb
Presenter
Presentation Notes
Reduction of the left side will bring the canopy more in balance. This will also relieve excessive end weight on the large over extended limb and may prevent it from breaking in a storm. The entire stem indicated with the arrow should be removed now.
before
afterExcessive end weight
Large pruning cut
Presenter
Presentation Notes
Remove the lower left branch now to balance the canopy.
Yikes!!
Clumped trees can fall over without treatment
Presenter
Presentation Notes
Clumped trees form a nice symmetrical canopy but each individual tree is very one-sided. These individual trees are leaning away from the others as they grow and there is a severe bark inclusion between each trunk. This tree is a high risk of failure and should be treated immediately.
One side of this clumped tree broke off at the base
Presenter
Presentation Notes
The trunks in the previous slide are likely to fail in this manner.
No roots present here
Presenter
Presentation Notes
Illustration of three clumped trees (a, b, and c) and their root development. Notice that each tree is missing roots on the side touching another tree so the root system is far from symmetrical. Roots on the opposite side of a lean play a large role in keeping a tree upright. Trees that lack roots to one side are prone to falling over.
Balance canopies of clumped trees to prevent them from falling over
Reduce branched indicated with dotted lines
Presenter
Presentation Notes
This clump of trees can be reduced to help keep them erect. This reduces the weight experienced be each individual tree, especially those that may be leaning. Also consider installing some hardware such as cables or braces to help in holding the stems together.
Pruning to: Correct root problems
Presenter
Presentation Notes
This circling root should be pruned from the tree now so it does not contact the trunk. This will prevent it from becoming a stem girdling root.
Airspades show you what’s
underground and may help uncover
girdling roots
Presenter
Presentation Notes
Here is a convenient tool for exposing roots near the base of the trunk. This can make it easy to see root defects.
Pruning to: Restore
Presenter
Presentation Notes
This pruning type is covered in great detail in another Powerpoint that is part of this hurricane recovery series.
Palm Pruning
• Retain all green fronds
Presenter
Presentation Notes
This makes it simple doesn’t it?
Coconut palmsHotel
sign
Presenter
Presentation Notes
Over-pruned palms such as those in the right photo were damaged more in the hurricanes than palms that were not yet pruned on this property. Many arborists reported this from across Florida.
Remember your goals and objectives…Produce a structurally sound tree • Reduce risk of failure • Promote human safety • Allow for safe passage• Reduce shade and wind resistance• Maintain tree health and vigor
With dedication to a management plan, your community can become a model for others
