Pruning trees is important to remove hazards, improve structure, and provide clearance. It should be done at the proper time of year and using proper techniques like the three cut method to avoid included bark and promote compartmentalization. Pruning types include structural pruning to establish a strong structure, crown cleaning to remove deadwood, and crown thinning to improve health and appearance while following the 25% rule. Topping is not recommended as it can damage a tree.

1. Pruning
ISA Arborist Pre-exam study Course
Andrew Geiser and Austin Lampe
Jefferson City Parks, Recreation,
and Forestry

2. Objectives
 Know why, when and how to prune
 Understand Compartmentalization and its
relationship to the branch collar
 Know the proper procedures and techniques
used in pruning
 Understand how trees respond to proper and
improper pruning

3. Why do we prune?
 To remove broken, dead, & diseased branches
 Improve the structure of trees and reduce the
risk of future failures
 Remove rubbing branches
 Remove co-dominant stems
 Provide clearance for sidewalks, roads, and
utilities

4. Pruning to reduce hazards
 Removing broken and dead limbs.
 Broken and dead limbs can be a hazard depending
on the trees location. Trees in high traffic areas
(pedestrian and vehicular) usually have more
targets where as trees in low traffic areas pose less
of a hazard.

5. Hazard
 Hazard tree in high traffic area

6. Broken branches

7. Structural Pruning
 Defined as: Pruning that influences the
orientation, spacing, growth rate, strength of
attachment, and ultimate size of branches and
stems resulting in a strong tree

8. Rubbing branches

9. Rubbing branches
 Rubbing branches should be removed as part
of structural pruning to prevent damage to
other limbs.

10. Codominant stems

11. Codominant stems
 Codominant stem: A stem growing at about
the same rate, and with nearly the same
diameter, as another stem originating from the
same union.

12. Clearance

13. When should we prune
 What is the desired result?
 Maximize growth: early spring
 Minimize risk of pest and decay: dormant season
 Minimize effects to flowers and fruit: immediately
after flowering
 Time of year may not always be an option.
 Storm damage
 Hazard mitigation

14. Branch Collar
 A swelling at the base of a branch where it
joins the trunk, or larger branch, resulting from
overlapping trunk and branch tissue.

15. Branch Protection Zone
 This is a thin zone of starch-rich tissue at the
base of a branch where chemicals are
deposited to retard the spread of discoloration
and decay.
 Pruning in this zone allows for
compartmentalization of the wound.

16. Branch Bark Ridge

17. Pruning procedure and techniques
 All pruning should be done in accordance with
ANSI A300 standards.
 The three cut method should be used when
removing a branch.
 Reduction cut is used when reducing a limb or
stem.

18. Three cut method

19. Reduction cut
 Removal of stem to a smaller branch (at least
1/3 diameter) that will assume the terminal
role.

20. Main types of pruning
 Structural pruning
 Crown cleaning
 Crown thinning
 Crown raising
 Crown reduction
 Crown restoration
 Utility pruning

21. Structural pruning
 Pruning to remove dead, broken, damaged
branches
 Select a dominate leader or multiple strong
leaders in ornamentals and fruit trees.
Competing stems should be subordinated
(Removing the terminal, typically the end
portion of a branch or stem to slow growth rate
so other portions of the tree grow faster).

22. Structural pruning
 Select and establish the lowest permanent
branch (Branches that will remain on the tree
for many years, perhaps until maturity).
 Select and establish scaffold branches
(Branches that are among the largest in
diameter on the tree that will provide the
structure of the tree). Scaffold branches should
be well spaced, both vertically and radially.

23. Structural pruning
 Select and subordinate temporary branches
(Branches that will remain on the tree for only
a short period).
 Why do we leave these branches?
 Energy production
 Strengthen the trunk
 Protection from the sun
 Protection from mechanical injury

24. Structural pruning
 As the trunk gains strength, temporary
branches can be gradually removed.
 25% rule should be followed, where no more
than 25 percent of the canopy should be
removed in one year.

25. Structural pruning

26. Codominant stems
 Codominant stems are forked branches of
nearly the same size in diameter and lacking a
normal branch union.
 Frequent site of included bark (bark that
becomes embedded in a crotch as the two
branches grow and develop causing a weak
point).

27. Included bark

28. Good union vs. Codominant

29. Crown cleaning
 Removal of dead, diseased, rubbing and
broken branches.
 Cleaning can be done at almost any time of the
year and on any age of tree.

30. Crown cleaning

31. Crown thinning
 Select removal of lateral and parallel branches,
especially from the edge of the canopy.
 Reasons we may thin the canopy
 Improve light penetration and air movement
 Thinning may reduce risk of storm damage
 Reduce limb weight
 Show off attractive bark or trunk form

32. Crown thinning
 Care must be taken to not over thin a tree
 The removal of excess interior branches and
foliage and leaving most of the foliage at the end
of the canopy is referred to as lion tailing.
 The over thinning of the interior growth and lower
branches has many negative effects.
 Weak branches
 Reduces stored energy reserves
 Increases damage from storms

33. Crown thinning
 Production of water sprouts (Stems arising from the
interior branches often growing upright and vigorously)
 Even death of the tree may result
 Never remove more than 25% of the entire
crown

34. Lion tailing

35. Water sprouts

36. Crown raising
 Select removal of branches to provide vertical
clearance under the canopy.
 Raising should be done gradually over a period
of time.
 Never remove 1/3 of the crown
 Never remove a branch that is ½ the size of the
diameter of the trunk

37. Crown raising

38. Crown reduction
 Select removal of branches to decrease height
or spread on entire tree.
 Some reasons to reduce the canopy might be
 Reduce weight to reduce failure potential
 Direct growth away from an object of structure
 Open a view
 Again make sure to follow the 25% rule and
the 1/3 rule.

39. Crown reduction
 Do not mistake this as topping.
 Reduction cut

40. TOPPING
 Topping or heading back is the cutting back of
limbs more than two years of age to buds,
stubs, or laterals not large enough to assume
apical dominance.

41. TOPPING
 This is topping and is not recommend!

42. Crown restoration
 Process of improving the structure of a tree that was
previously topped, over-thinned, damaged, or
vandalized.
 This process is not a quick fix. It can, and probably
will, take several years.
 The process involves removing some sprouts, all
stubs, and dead branches. One to three sprouts are
selected to become permanent branches and to reform
a more natural appearing crown.
 Restoration will not make the tree what it once was.

43. Utility pruning
 The removal of branches or stems to prevent the loss
of service, prevent damage to utility equipment, avoid
impairment, and uphold the intended usage of utility
facilities.
 Only qualified line clearance trimmers should engage
in line clearance work.
 May be necessary to prune outside the scope of
landscape pruning guidelines, but when practical cuts
should be made, to A300 standards.

44. Utility pruning

45. Pruning

46. Specialty pruning
 Espalier, Pollarding are both conducted to
create special aesthetic effects.

47. Specialty pruning
 Espalier is a combination of cutting and training
branches that are oriented in one plane, usually
supported on a wall, fence or trellis.
 Used for fruit trees when space is limited
 Pollarding is a training system that involves severe
heading the first year, and sprout removal annually or
every few years to keep large trees to a modest size or
to maintain a formal appearance.
 Internaodal are cuts made at a specific locations to begine
the pollarding process

48. Wound dressings
 Once thought to accelerate wound closure and
reduce decay, but research does not support
this.
 May be beneficial in reducing borer attack, oak
wilt, or sprout formation.
 May inhibit compartmentalization.
 If used, apply a light coating of a non-
phytotoxic material.

49. Pruning tools
 Use tools that are adequate for the size of cuts
being made.
 In some instances, sterilization of tools
between trees and even between cuts maybe
necessary.

50. Pruning tools

51. Plant growth regulators
 Plant growth regulators are substances,
effective in small quantities, that enhance or
alter the growth and development process of a
plant.
 Used to increase or decrease normal growth,
flowering or fruiting of plants
 May also be used to reduce the production of water
sprouts on trees

52. Plant growth regulators
 May be applied in several ways
 Foliar spray
 Basal bark spray
 Soil applied
 Injection of the tree

53. Plant growth regulators