The document provides an overview of pruning techniques and concepts for trees. It defines key pruning terms and describes the various types of pruning including structural pruning, pruning for health, safety and aesthetics, crown thinning, raising and reduction. Improper pruning techniques like topping are explained. Compartmentalization and wound dressings are also covered.

1. Pruning Mike Walsh Forestry Programs Manager Forest ReLeaf of Missouri [email_address]

2. Background Mike Walsh B.S. Forestry, Missouri 2005 M.S. Forestry, Missouri 2007 ISA Certified Arborist 2008 MW-4822A Worked with the MDC, USDAFS, HARC, & MU Forestry Department conducting research in flood tolerance of MO hardwoods, controlled black walnut breeding, nursery production and more. I love trees, learning/teaching about trees, fishing, golfing, watching & listening to Cardinals Baseball, Rams Football?, & Tiger Football (& basketball).

3. Trick Question? If a tree branch is located five feet from the ground, and the tree grows 6” each year, how far from the ground will the branch be in 6 years?

4. Objectives Know why, when and how a tree should be pruned. Understand how trees respond to pruning and the effects of severe pruning on a tree. Understand the relationship of the branch collar and branch size to wound closure and the potential for decay. Describe the procedures and techniques used in pruning. Become familiar with the terms used to describe pruning techniques.

5. Key Terms The Key Terms as listed in the Arborist’s Certification Study Guide will be defined and highlighted throughout the presentation.

6. Key Terms - Chapter 8 ANSI 3000 standards Antigibberellins Branch bark ridge Branch collar Branch protection zone Codominant Compartmentalization Crown cleaning Espalier Fronds Heading back Included bark Internodal Lateral Leader Lion tailing Permanent branches Plant growth regulators Pollarding Raising Reduction Restoration Scaffold branches Structural pruning Subordinate Temporary branches Thinning Topping Utility pruning Vista pruning Watersprouts Wound dressing

7. Introduction to pruning Why prune? Who prunes trees in the woods? Open vs. forested grown trees People reasons – people stresses! Health, Safety, & Aesthetics Tree Biology (review) ANSI A300 Standards

8. Open vs. Forested Growth

9. Open vs. Forested Growth

10. Why do we prune? 1) Health To maintain the overall health of the tree Remove broken & diseased branches Rubbing branches / limbs that create wounds Improve taper on branches and limbs Remove codominant stems Attempt to improve overall structure and health of the tree to reduce the risk of failures

11. Why do we prune? 2) Safety Trees in high use areas (playgrounds, e.g.) Removal of broken and dead material (widow makers) Look for poor branch attachments (V-crotches) Excessive leaning (may indicate root problems) Trees in construction areas (10+ year lag time) Interference with line of sight on streets Utility pruning (safety of workers, keep the lights on) Topped trees (will be a hazard down the road)

12. Why do we prune? 3) Aesthetics Improve views (vista pruning) Provide clearance (car, mowers, pedestrians) Pathways & sidewalks to 8’ Streets to 15’ Reduce shade & wind resistance Lawns, groundcovers, mulch beds with flowers Influence fruit & flower production

13. Broken Branches

14. Rubbing Branches

15. Codominant Stems

16. Safety

17. Poor Branch Attachment

18. Trees in Power Lines

19. Clearance

20. When to prune? (some examples) It depends on the desired results: Maximized growth = early spring Minimize risk of pests and decay = dormant season Minimize effects to flowers and fruit = immediately after flowering Timing of year may not always be an option Storm Damage, e.g.

21. Tree Biology How a tree grows Where growth occurs in a tree ‘Types’ of trees How this affects pruning

22. Tree Biology Primary Growth Secondary Growth Branches and Trunk Attachments Excurrent/Decurrent

23. Primary Growth Twigs Stems Roots Terminal Buds Lateral Buds

24. Primary Growth Growth of stems, twigs, and roots (elongation) Terminal buds have apical dominance Lateral buds near terminal bud stay dormant

25. Secondary Growth Diameter Growth Taper

26. Secondary Growth Growth from cambium for diameter (expansion) Provides taper and strength Reaction wood: formed on stems to counter leaning of the tree

27. Branches & Trunk Attachments Branch collar Included bark Codominant stems Crotches

28. Branch collar Branch Collar: area where a branch joins another branch or trunk created by overlapping xylem tissues

30. Branch Bark Ridge

31. Codominant Stems – forked branches of nearly the same size in diameter and lacking a normal branch union Frequent site of structural failure due to included bark [bark that becomes embedded in a crotch between branch and trunk or between codominant stems and causes a weak structure] Hmmm…what tree tends to form these?

32. Included Bark

33. Included Bark

34. Crotches &Codominant Stems

35. Excurrent vs. Decurrent Know the form a tree will take Excurrent: tree growth habit with a pyramid shaped crown and dominate central leader Examples: sweetgum, tuliptree, most conifers Decurrent: tree growth habit with a rounded or spreading growth habit in the crown Examples: most hardwoods like oaks, maples, and elms

36. Excurrent vs. Decurrent

37. Excurrent vs. Decurrent

38. Break

39. CODIT Compartmentalization Of Decay In Trees

40. CODIT Wall 1 – Limits vertical spread of decay Wall 2 – Formed from last growth ring and limits spread inward Wall 3 – Composed of ray cells that limit lateral spread of decay Wall 4 – Is the strongest wall and is the new growth ring that forms after injury

41. Seven main types of pruning Structural pruning Pruning to clean Pruning to restore Crown thinning Crown raising Crown reduction Utility pruning

42. Structural Pruning Removal of live branches and stems to influence the growth, rate, spacing, strength of attachments, and ultimately the size of the branch Five steps

43. Structural Pruning Remove broken, dead, dying or damaged branches Select and establish a dominant leader [the primary terminal shoot or trunk of a tree]. Competing stems should be subordinated [pruning to reduce the size and growth of a branch in relation to other branches or leaders

44. Structural Pruning Select and establish the lowest permanent branch [branches that will be left in place, often forming the initial scaffold framework of a tree] Select and establish scaffold branches [the permanent or structural branches of a tree]; 12 -18” spacing depending on the ultimate size of the tree

45. Structural Pruning Select and subordinate temporary branches [branches left in place when training young trees; such branches will be removed later] Why leave them? Proper taper Prevent Sunscald Energy production Try to do this over time 25% rule

46. Pruning to clean Removal of any dead, broken, and diseased branches Any age and almost any time

47. Pruning to restore Select removal of branch, sprouts, and stems from trees that have been topped, headed, lion tailed, or broken in a storm Can take up to several years 1/3 of sprouts removed each year until sprouts have developed into branches

48. Crown thinning Select removal of small live branches to reduce crown density Increases light penetration and air movement Avoid lion tailing: removal of excessive amount of foliage on inner branches and leaves most of foliage at end of canopy = weak branches Never remove more than 25% of the entire crown Water sprouts and sunscald may result

49. Dangers of over-thinning Sunscald Production of watersprouts [an upright, adventitious shoot arising from the trunk or branches of a plant; although incorrect, it is also called “sucker [shoot arising from the roots.” Lion tailing [limbs are thinned from the inside of the crown to a clump of terminal foliage]

51. Crown raising Select removal of branches to provide vertical clearance On younger trees it can reduce taper like lion tailing On mature trees: Never remove a branch that is ½ the size of the diameter of the trunk Never take away more than 1/3 of the crown Raise limbs by removing small amounts of branches at a time

52. Crown Raising – removing lower limbs from a tree to provide clearance; vista pruning

53. Crown Reduction Select removal of branches to reduce height/spread of tree 25% rule…again! 1/3 rule too Clear vegetation away from buildings Used by utility crews Reduce weight NOT TOPPING!!

54. Now this is topping ! or heading back, is the cutting back of a tree to buds, stubs, or laterals not large enough to assume apical dominance

55. 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 May necessitate pruning outside of the scope of landscape pruning guidelines Maintain ANSI A300 standards

56. Pruning cuts Branch removal cuts 3 cut method Reduction cuts Improper pruning cuts Wound dressings

57. Branch removal cuts Removal of a branch at its point of origin on the trunk, stem, or limb Use the 3-cut method 1.) undercut the limb to prevent peeling (>1”) 2.) outside the undercut, begin 2 nd cut from top of branch to remove it and leave a stub 3.) final cut is made just outside the branch collar Take care not to leave torn bark or jagged edges This allows for compartmentalization [natural process of defense in trees by which they wall off decay in the wood ] to occur – NOT HEALING!!

62. Some more terms… Branch protection zone – tissues inside the trunk or parent branch at the base of a subordinate branch that protect against the spread of decay Laterals [secondary or subordinate branch] don’t compartmentalize as well Compartmentalization ability depends on species, vigor, climate and size of cut.

63. Reduction cuts Removal of stem or branch to a smaller lateral branch that will assume the terminal role Remaining branch should be at least 1/3 the diameter of the stem removed Reducing a lateral should bisect the angle between the branch bark ridge

65. Pruning Mature Trees Factors to consider: site, time of year, species, size, growth habit, vitality and maturity Younger trees are more tolerant of pruning Consider the size of the cut…or…one big branch and the 25% rule

66. Improper pruning cuts

67. Stub cutting, flush cutting

68. Dressings… not good(?)! Once thought to accelerate wound closure and stop/slow the spread of decay… not anymore May be beneficial in reducing borer attack, oak wilt infection, or sprout formation

69. More on dressings Seal in moisture and decay Can prevent callus tissue from forming May inhibit compartmentalization Has been used to help stop the spread of oak wilt and DED If used: apply a ligt coating of a non-phytotoxic material… something water-based

70. Specialty Pruning Espalier – a combination of cutting and training branches that are oriented in one plane, usually supported on a wall, fence or trellis Used on fruit trees to grow on trellis Pollarding – a training system that involves severe heading the first year, and sprout removal annually or every few years to keep large-growing trees to a modest size or maintain a formal appearance Internodal – cuts are made at specific locations to begin the pollarding process. Trivia: Besides aesthetics, why was pollarding done?

73. Pruning tools

74. Why not to top? Starvation Shock Insects & diseases Weak limbs Rapid new growth Tree death Ugliness Cost

75. Weak Branch Attachment

78. Plant Growth Regulators PGR: compounds, effective in small quantities that affect the growth and development of plants Antigibberelllins: PGRs that inhibit the action of the plant hormone gibberellin Gibberellin: plant hormones that regulate growth and influence various developmental processes, including stem elongation, germination, dormancy, flowering, sex expression, enzyme induction and leaf and fruit senescence Why use PGR? Reduce rotation for utility crews, e.g.

79. Additional Resources ANSI A300. Standard Practices for Tree, Shrub and Other Woody Plant Maintenance, Part 1: Pruning Costello, 2000. Training Young Trees for Structure and Form. Gilman, 1997. An Illustrated Guide to Pruning Trees. ISA, 1995. Tree Pruning Guidelines.

80. The end Questions? Complaints?