Essentials of good pruning techniques - 2010

Essentials of good pruning techniques. By: Dr. Abdul Sattar Salih Al Mashhadani

Parks Recreation Facilities (PRFD), Infrastructure & Municipal Assets Sector, Municipality of Abu Dhabi City.

June 2010

Infrastructure & Municipal Assets SectorParks Recreation Facilities (PRFD)

Essentials of good pruning techniquesأساسيات تقنيات التقليم الجيد



Some Professional Terms

Bark – outer layer of stems and trunks; protective tissue.Branch – stem originating from another, larger stem.Branch bark ridge – protruding bark at the top of the junction (crotch) of two branches; continues downward from crotch.Branch collar – junction (overlap) of tissues of two branches or branch and trunk.Bud – small dormant apical or lateral meristem; may be foliar or floral tissue; undeveloped flower or stem.Canopy – branch and leaf portion of tree (also called ‘crown’).Cavity – open wound or hollow in trunk of tree; result of decay.Central leader – main growing terminal stem of a tree.Co-dominant stems – two equally competing terminal branches.Crotch – top of the union of two branches or of branch and trunk.Crown – aboveground portion of tree.Crown cleaning – removal of water sprouts, suckers, dead, dying, diseased, deformed and damaged branches.Crown reduction – alternative to topping; reducing canopy by appropriate pruning techniques.Crown restoration – technique to restore growth habit of topped or damaged tree. Decay – deterioration of woody tissue by diseases and due to bad maintenance.Dieback – condition of death of many terminal branches.Dormant – at rest, or in a state of reduced activity.Drop cut – second cut in 3-cut process of removing a branch.Drop zone – area where cut branches may fall during pruning.Evergreen – trees that keep their leaves or needles year-round.Flush cut – improper pruning technique; removes branch collar and damages trunk.Heading back – pruning shoots back one-half to one-third to buds or twigs with potential for growth.Heartwood – inner wood (nonfunctioning xylem) that gives strength to the trunk.



Some Professional Terms

Included bark – bark tissue lodged in the crotch of two branches or branch and trunk indicating weak attachment.Lateral bud – vegetative bud on side of a branch.Leader – primary terminal stem of a tree .Lowest permanent branch – lowest limb that will remain in tree canopy.Main branches – those that make up the canopy of the tree (scaffold branches).Mature height – tallest expected growth of a tree.Mature tree – has reached approximately 75% of its full canopy growth.Multiple leaders – co-dominant stems competing for central growth of tree.Natural target pruning – technique of removing branch that protects the branch collar; 3-cut process.Permanent branch – branch that will remain on tree; initial scaffold framework.Pollarding – specific pruning technique for height Lateral – side branch or smaller twig of a limb. restriction of trees.Pruning – cutting away undesirable parts of a tree.Raising – removing lower branches to provide clearance.Reduction – pruning to reduce height and/or spread of canopy.Respiration – cellular process releasing energy from stored foods.Restoration – pruning to recover shape and strength of damaged canopies.Scaffold limb – permanent, main branch of the canopy. Abundant vertical and radial spacing improves tree structure.Site considerations – factors to take into account when determining what trees to select for the location.Structural pruning – pruning to develop a sound scaffold branch system in a tree.Sucker – shoot originating from a root or lower trunk.Temporary branches – shoots that remain during training of young trees, to be removed as tree matures.Terminal bud – bud at the apex of a stem.Tree- woody vegetation 5 cm or greater in diameter to be measured at ground level.Tree protection zone – area of tree roots to be designated by fencing to prohibit access during construction activities. Minimum 2.4 m radius, or usually 30 cm radius per 2.5 cm diameter at breast height.Thinning – selective pruning of entire stems to increase air or light penetration to canopy or to decrease branch weight.Trunk – base stem of tree that supports canopy.Undercut – first of 3-cut process in natural target pruning. Prevents bark tearing.





BranchesBranches are attached to the tree trunk by interlocking branch and trunk tissue. A new layer of interlocking tissue is producedeach year over the previous layers. A woody branch collar, produced by the trunk, holdsthe branch base. When branches on the maintrunk that have a narrow angle increase in Diameter they eventually run out of room togrow. The branch bark becomes surrounded by woody trunk and branch tissue. The bark that becomes overgrown is referred to as included bark (Figure). The union is weak andlikely to split.

V - shaped crotches can lead to included bark



The branch collar is the swollen area of trunk tissue that forms around the base of a branch.

The branch bark ridge is a line of rough bark running from the branch-trunk crotch into the trunk bark, less distinguished on some trees than on others



WHAT IS PRUNING?

Pruning is a regular part of plant maintenance involving the selective removal of specific plant parts. Although shoots and branches are the main targets for removal, roots, flower buds, fruits and seed pods may also be pruned.

Pruning wounds plants, but plants respond differently to wounding than do animals. In plants, damaged areas are covered by callus tissue to close wounds.

Another response to pruning occurs inside plants. Chemical boundaries form around wounded areas, walling off the wounds. Compartmentalization limits any decay that results from wounding.

Use proper pruning techniques that minimize plant wounding and speed wound closure.



Common Pruning Mistakes

Flush Cut

Flush cuts cause underlying tissues to dryout slowing callous formation, are subject to insect invasion and promote tissuedie-back.





Stub Pruning

Pruning cuts that leave a branch stump can result in tissue die-back (A) or reproductionof unwanted branches (B). Stumps may also be a hazard to pedestrians by snagging clothing or causing injury to passersby.

























Common Mistakes



What is "topping"?Topping occurs when the vertical stem (leader) and upper primary limbs (scaffold branches) on mature trees are cut back to stubs at uniform height. Topping is also referred to as heading, stubbing, or dehorning.

How does topping damage trees?1) Topping reduces food-making capacity. Trees require a large leaf surface area to provide food for maintenance and growth. Topping cuts off a major portion of the tree's food making potential and depletes the tree's stored reserves.2) Topping stimulates undesirable "water sprout" growth. While removing most of the buds that would form a normal branch system, topping often stimulates the regrowth of dense, unattractive, upright branches (water sprouts) just below the pruning cut. Water sprout regrowth is vigorous. A topped tree will rapidly return to its original height, but will lack its original form.

Common Mistakes

TOPPING



What is "topping"?

3) Topping leaves large wounds. The branch wounds left from topping are slow to close, therefore more vulnerable to insect attacks and fungal decay. An invasion by either pest can spread into the trunk, killing the tree.4) Topping creates a hazard. Weakened stubs are more prone to wind and storm breakage because they generally begin to die back or decay.5) Topping injures bark. Increased sun exposure on trunk and branches can lead to severe bark damage.6) Topping disfigures trees. Ugly branch stubs, conspicuous pruning cuts, and a broom-like branch growth replace natural beauty and form. Topping reduces the real estate value of trees by 20 - 100 percent. A correctly trimmed tree increases in value at each pruning



Why are trees topped?

Some unprofessional tree pruners practice topping whenever trees reach an undesirable height. They mistakenly believe that topping will reduce the storm hazard of falling branches, when in fact, topping has the opposite effect. People also top trees when they interfere with utility wires, buildings, solar collectors, or sunny garden areas.

Can topping be corrected ?A professional arborist can improve the condition of a tree, even after it's been severely topped and shows heavy water sprout regrowth. As the water sprouts begin to gain caliper, they can be selectively "thinned out" using properly placed branch collar cuts. New growth can be directed outward to expand and round out the crown.

This process will need repeating for a few years. The scars, both physical and visual, will never completely disappear.

Topping is only appropriate when sections of limbs are cut off during the

removal of a tree.



What are the alternatives ?A wiser alternative to topping is careful selection and training of the young trees. Avoid topping altogether. Allow your trees to realize their full potential for health and beauty in the landscape.

In order to avoid topping we have to consider :

Selection of trees that only reach desired maximum heights eliminates severe pruning later.

Newly planted trees should be properly pruned todevelop a good branch structure as they grow.

When a mature tree's height must be reduced, an alternative to topping is drop-crotching.

The tree must prune heavily every five to seven years.

If the tree is too large for the site, replace it with a smallerspecies ( last option).

Alternatives



Why Should Trees Be Pruned?

Pruning should be done properly with an understanding of how the tree responds to each cut aswell as which branches needto be removed

Pruning is the most common tree maintenance procedure.Trees that grow in the forest grow quite well with only natures pruning. This is due to their richness in soil and other natural conditions. Landscape trees require a higher level of care and proper pruning to:

improve their structural strength, maintain their safetymaintain their health, enhance their beauty, increase their value.



• Pruning is advisable if:

trees have crossing branches, weak crotches, or other defects

branches are dead, dying, decayed, or hazardous

lower branches interfere with people or vehicles, or block visibility of signs

branches are growing into buildings or utility wires

limbs have been broken by storms

trees have grown too large and might injure people or damage property

• Landscape trees not only make homes and communities more beautiful,but they also improve our environment and can increase the value of a property up to 20 percent.

• Trees are truly assets that need to be enhanced and protected. Proper pruning is definitely a worthwhile investment!



Who is Qualified to Prune Trees?• Simple types of pruning, such as cutting lower

branches from small trees, can be done by anyone who understands plants and has the proper tools.

• Only qualified arborists should train young trees or climb into larger trees to prune them.

This type of tree work requires knowledge of scientifically based pruning techniques, tree physiology, and safety practices, as well as working experience with various tools and tree species. Because proper pruning is complicated and examples of shoddy and unsafe work abound.

Any potentially hazardous activity associated with climbing trees, using power tools, and especially working near electric lines should be left to qualified professionals who know how to follow the tree safety means.



Types of Pruning Cuts

When using thinning cuts, always remove or shorten a branch to a side branch that is at least one-third the size of the one being cut. A branch that is 7.5 cm in diameter would be pruned back to a side branch that is at least 2.5 cm in diameter. Do not remove more than 25 % of a mature tree’s foliage in any year.

1)Thinning cut : removes a branch at its point of origin on the trunk, or shortens a limb to a lateral branch large enough to resume the growth of the pruned limb. Thinning cuts leave no stubs. They are used to remove damaged, dead, or weak branches, reduce the length and weight of heavy limbs, or reduce the height of a tree. Thinning cuts are placed so as to distribute ensuing growth throughout a tree and retain or enhance a tree’s natural shape.



2) A heading cut trims a branch back to a bud, or trims a branch or leader back to a small branch not large enough to simulate the growth of the pruned branch.

Heading cuts are only appropriate for specific reasons that apply to some species.

Heading cuts should only be used when pollarding trees or shaping terminal flowering plants such as roses

they should not be used for topping trees. Topping has been described as the “ultimate in destructive practices,” and in almost all cases it permanently damages a tree’s health, structure, and appearance

• 3) A stub cut is like a heading cut but is made indiscriminately to a point on a branch or leader where no bud or branch exists.

It, like a heading cut, is used when a tree is topped.



Thinning a tree removes unwanted branches, reduces weight, and allows

light and air penetration

Tree Care ProfessionalIt is very difficult, if not impossible, to repair damage

that has been done by poor pruning.

In tree work, the old proverb “you get what you pay for” is usually true

Proper pruning Indicators :use of thinning cuts, rather than topping, heading, orstub cuts, so that the natural form and branching habitof the species is preservedcuts placed just outside the branch collar, not flush cutsabsence of torn bark where branches have been cut.



Training Young TreesFor pruning a young tree, it is important to

consider :It’s natural formdesired future growth of the treeA few minutes of thoughtful pruning spent can eliminate hours of costly future maintenance and corrective pruning on mature treesIdeally, pruning should be done over several years to train a young tree. Prune as little as possible in the first two years after a tree has been planted, so there will be enough temporary branches and leaves to produce food for the growth of roots, trunk, and branches.Newly planted trees will gradually restore the balance between roots and branches; excessive pruning can be detrimental and delay the return

to normal growth.



Training Young Trees

When a tree is planted, prune only broken, malformed, or diseased branches.

Remove any double leader so that one dominant trunk is maintained.

Removing branches before they exceed 2 .5 cm in diameter will keep pruning wounds small.

Street trees or trees along walkways and driveways must have limbs high enough to safely accommodate pedestrians and vehicular traffic, signs, and lights ( 1.8 m ) .



To promote good structure and lessen the need for future pruning, branches that should be properly pruned from newly planted trees during the first one to five years



Pruning Mature TreesNot all mature trees need to be pruned. Some only require pruning every 5 to 10 years.

The need for pruning can be reduced by planting the right speciesof tree in the proper place and by properly

pruning a tree when it is young

Mature trees should only be pruned for specific purposes and in a manner that protects and preserves the tree’s natural form.

Pruning should focus on maintaining tree structure, shape, health, and safety.

Types of recommended pruning :

Crown cleaning—removes dead, dying, diseased, crowded, weakly attached, or low-vigor branches and water sprouts.

Crown thinning—selectively removes branches to increase light penetration and air movement and reduce the weight of heavy limbs.

Crown raising—removes lower branches to provide clearance for buildings, vehicles, pedestrians, and signs.





Pruning Mature TreesCrown reduction— reduces the size and spread of crowns using thinning cuts, resulting in fewer sprouts than heading or stub cuts, and maintainingthe structural integrity and natural form of the tree (Fig).

Crown restoration—improves the structure and appearance of trees that have been storm-damaged or deformed by heading or stub cuts.

Vista pruning—thins selectively to open a specific view of an object or scenery.



Pruning Mature Trees

The ideal mature tree will have lateral branches that are 45- 60 cm apart on the trunk and one strong leader. However, some trees differ, such as many ornamentals, which are meant to have a more bushy appearance.

The preferred method for reducing the size of a crown is the use of small thinning cuts.

Using larger thinning cuts that remove a large branch or leader to a large branch is commonly called crotching or drop-crotching.

Even though large wounds may result from drop-crotching, this method of pruning is preferable to heading or stub cuts.



Drop crotching

Drop-crotching is a type of thinning cut that reduces a tree's size while preserving its natural shape.To drop-crotch,

select and cut higher branches back to laterals at least one-third the diameter of the limbs being removed.

Cut outside the branch collar at a 45 to 60 degree angle to the branch bark ridge.

Leave the branch collar undamaged to help prevent decay from entering the trunk.

This type of thinning cut will stimulate growth throughout the tree and discourage water sprout development.Lateral limbs are pruned where they join large diameter side branches.The center leader is cut back to a large diameter secondary branch so that a modified leader remains.

This does not change the direction of growth. It encourages stimulation of the apical growth point.



Drop-crotching



dominant leaders-Correct cut for co



Correct cut for co-dominant leaders



Proper pruning

A tree branch has a branch bark ridge, often referred to as a branch collar, that separates the branch from the tree trunk (Figure). The collar is the swelling located at the base of a branch where the branch meets the trunk. The callus that forms the collar is an area of tissue that contains a chemically protective zone. The natural decay of a dead branch stops when it reaches the collar. When pruning a dead branch, do not create a new wound by cutting into the ring that forms around the dead branch.

The angle A created be the branch bark ridge and an Imaginary line with the tree trunk is the approximate angle B at which to

make the pruning cut



Whenever removing limbs greater than 2.5 cm in diameter, use the three-cut method to avoid tearing bark.

1)First, about 30 cm from the trunk, cut halfway through the limb from the underside.

2)Second, about 2.5 cm past the first cut, cut through the limb from the top side. The limb's weight will cause it to break between the two cuts.

3)Make the third cut outside the branch collar, as described earlier. Use a handsaw to provide greater control.

Don't coat pruning cuts with tree paint or wound dressing, except for control of certain disease-carrying insects. These materials won't prevent

decay or promote wound closure

Three-cut Method



Proper pruning



Properly pruning young trees means loweringfuture maintenance costs and creating

a beautiful and safe mature trees.

Proper pruning



Pruning cut angles dictate the patternof wound tissue formation

Improper pruning cut angles result in incomplete distribution of wound healing tissue that will slow the healing process and can lead to die-back, infestation by insects or infection by fungi and bacteria.



Proper Pruning and HealingCorrect cut results with good wound wood pattern

Cuts that preserve the branch collar form a complete ring of callus tissue, heal rapidly, help prevent invasion by pests and ultimately promote healthy growth.



Pruning Cut Angle and PlacementIf the cut is …..

too steep (A) the tissue can dry before healing and cause die back.too flat an angle (B) leaves a blunt surface that can collect dust & water which slow wound healing and can promote decay. too far (C) from a lateral branch or bud can over stimulate new growth resulting in undesirable multiple, tightly packed branches, die-back and defeat the original

purpose of pruning.

Make pruning cut directly above a bud or lateral branch at about a 45 degree angle. Such cuts result in controlled growth of the cut branch and healing of the pruning wound.



Sharp blades leave smooth cuts









• Finally, we advise that, from today, all pruners are required to practice the remedial pruning of woody plants by implementing the Five D's (prune these branches at any time) :

• Dead branches• Dying branches• Damaged branches• Diseased branches• Deformed branches

In almost all cases, thinning cuts are the proper type of cut to use in tree pruning



Recommendation

we need to prepare and develop our national standards for the best methods and tree safety means.



References

• Al Mashhadani Lectures. • Al Mashhadani A. S.(2001). "Pruning & its rules and hazards".Al-Asimma Mg. No.64-

2001, Abu Dhabi, Municipality, UAE. • Klingeman,B. et al.(2008). Best Management Practices for Pruning Landscape

Trees, Shrubs and Ground Covers, University of Tennessee, USA. (http://www.utextension.utk.edu/publications/pbfiles/pb1619.pdf)

• Shigo. A. L, (1998), Modern Arboriculture, third printing (2003), Sherwin Dodge Printers, USA.

Data base

• http://forestry.about.com/od/arboriculture/ss/why_prune_7.htm • http://forestry.about.com/od/treeandforestcare/ss/sucker_sprout.htm • http://home.howstuffworks.com/how-to-plant-trees-shrubs-and-vines7.htm • http://if-srvv-edis.ifas.ufl.edu/document%20mg087 • http://web1.msue.msu.edu/msue/imp/modzz/00001781.html • http://www.afmanconsulting.com/articles/pollarding.html • http://www.bakker.co.uk/G_515/Pruning-tools-for-trees-hedges-and-shrubs.htm • http://www.derby.gov.uk/LeisureCulture/ParksRecreation/Treepruningtechniques.htm • http://www.extension.umn.edu/distribution/horticulture/dg0628.html • http://www.gotreecare.com/shrubpruning/pruningequipment.html • http://www.passionfortrees.co.uk/html/pollard.html • http://www.treedictionary.com/DICT2003/tree_pruning/history/history-1.html • http://www.treedictionary.com/DICT2003/tree_pruning/pollarding/starting.html • http://www.treesaregood.com/treecare/pruning_mature.aspx • http://www.treesaregood.com/treecare/topping.aspx

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Essentials of good pruning techniques - 2010