2. Pruning Young Street Trees, Using Pole Tools Dr. Ed Gilman and Traci Jo Partin, adapted by Guy Meilleur, Guy@HistoricTreeCare.com

11. Pruning improves stability Reduction pruning reduces trunk bend in high winds. Not pruned Reduced by pruning

12. Proactive Pruning: young trees Set the objectives: health, safety, longevity Frequency? (pruning cycle) Inspect structure—forks! Locate permanent branches Keep temporary branches as long as they are needed

13. Over-raising = Giraffe Pruning Select and train lowest permanent branches. Keep temporary branches as long as they are needed!

14. Poor formGood form Principles of strong structure: One (or more)dominant trunks Strong branch unions Balanced crown

15. Mitigate structural issues: avoid failure Codominant stems: stems of equal size originating from the same point on the tree Included bark: bark pinched between two stems = weakness in the union Unbalanced crown: one side heavier = asymmetric heavy ends = overextended Large low branches:

16. Collar Strong connection: Subdominant

17. Weak connection: bark inclusion, codominants

18. ANSI Z60 NURSERY STANDARD: 1.3.2 Minimum quality requirement All nursery stock transacted within the terms of the Standard shall, at time of shipment, be substantially free of damaging insects and diseases, in good living condition, and typical in habit for the species in the region of the country in which it is grown.1.3.3 Co-dominant stems - Type 1 and Type 2 shade trees Unless specified as multi-stem trees (see Section 1.2, above), Type 1 and Type 2 shade trees (see Section 2) with co- dominant stems occurring within the lower half of the crown do not meet the minimum quality requirement set forth in Section 1.3.2 (see Figure 6, below).

19. 1.4.3 Lowest branch height for street trees Bid specifications for trees to be used as street trees shall include the minimum height of the lowest branch, or the height to which the trunk shall be free of branches, which shall bear a relationship to the size and kind of tree so that the crown of the tree is in good balance with the trunk. Examples: Acer platanoides, 2 in. cal., 12 to 14 ft., trunk free of branches 6 ft. Quercus rubra 3½ in. cal., 14 to 16 ft., lowest branch 7 ft. Soil above the root flare, from being deeply planted in the nursery as a young plant, as a result of maintenance practices in the nursery, or added during harvest, shall not be included in ball depth measurement, and should be removed.

20. Tearout failures of codominants with included bark

21. Split failure due to bark inclusion

22. Unbalanced canopy Liontailing: trees with overextended branches after inner branches were removed. Susceptible to breakage Restoring requires ‘stubs’ Large trunk wound will decay the attachment point

23. Liontailed trees failed

24. No laterals to cut back to after damage

25. Large lower limb will be removed for 14’ clearance. Overpruning: small limbs removed instead of reduced 8

26. Big cuts can result in decay and cracks and sunscald and imbalance and starvation and loss of contributions and...

27. Structural Pruning Strategies: 1.Develop or maintain dominant leader(s) 2.Identify lowest permanent branches 3. Reduce temporary branches below the permanent crown to build and protect trunk, nourish roots 4. Space scaffold branches along dominant trunk(s) 5.Keep all branches ~< ½ trunk diameter 6.Subordinate codominants with included bark Trees require about 25 years of training to develop strong structure. Objective: Promote strong structure

28. Trace included bark to inosculate (From an “innie” to an “outie”)

29. 14 months later: re-clean

30. 1 year later: Fini! From included bark to a bark ridge in 2 seasons.

31. Preventive Pruning: young trees Set the objectives: health, safety… Frequency and amount (cycle and dose) Prioritize structure Locate permanent branches Keep temporary branches as long as they are needed

32. Pruning cycle: the time between each pruning event Depends on quality of nursery stock, growth rate, climate, species, availability of technicians. Shorter for faster-growing or defective trees. “Longer cycles force larger cuts to correct structural issues”: ??Theory, or fact?? This can be mitigated by avoiding horizontal cuts. Extrapolating research on small trees to the care of big trees does NOT work!

36. Determine a pruning cycle Pruning cycle: (very generally) - more than 3-5 years = higher pruning dose - every 1-2 years = smaller pruning dose Suggested program: - At planting: Despite the myth to avoid this! - Year two or three - Year five or six - Year ten - Year fifteen

37. Pruning dose: the amount of live tissue removed at one pruning Depends on customer expectations, the size of the stems, and the pruning cycle. Low pruning dose ( < than 20%) Higher pruning dose ( > than 20%) Mature or recently planted trees (Veterans: <10%) Young, established trees (or even at planting time) Cooler climates with short growing season Warm climates where trees have longer growing season Decay prone speciesGood compartmentalizers

38. Appropriate Pruning Dose for Specific Applications Large Pruning DoseSmall Pruning Dose Municipality with no money or volunteers available. Residences, commercial properties Long pruning cycleShort pruning cycle Aesthetics of less concernAesthetics are a concern Effects on the Tree from Applying Pruning Doses Large Pruning DoseSmall Pruning Dose Larger pruning woundsSmaller pruning wounds Larger void in canopySmaller void in canopy Greatly encourages growth in unpruned portions of tree Encourages some growth in unpruned portions of the tree

39. Impact of pruning dose on co-dominant stem growth beforeafter 75% dose

40. Impact of pruning dose on co-dominant stem growth Foliage removed for 75% dose

43. Maximum critical diameter: the largest diameter pruning cut you are willing to make on a certain species This limit should be specified in advance Should be smaller for decay-prone species. Is controlled by the pruning cycle *and angle: horizontal cuts should be smaller* The amount of heartwood or growth rings exposed

44. Branch size: - proportion relative to trunk - actual diameter of stem Branch sizeConsequences of Removal Recommended Action Less than ½ trunk diameter Few consequencesRemove if needed 1/3 to ½ trunk diameter Some trunk defects could result Consider shortening instead More than ½ trunk diameter Defects likelyReduce instead of removing Large enough to have heartwood Defects likelyReduce instead of removing

45. Proactive Pruning: young trees Set the objectives: health, safety… Frequency and amount (cycle and dose) Prioritize structure Locate permanent branches Keep temporary branches as long as they are needed

46. Make good cuts Step Shorten the branch to get the weight off. When using a saw, undercut first. **Image wrong: 2 nd cut should align with the first** Step 2 Pull away the cut section. Step 3 Remove the stub, outside the wrinkles. Do not cut flush against the trunk. Leave the collar intact.

47. Branch bark ridge Collar: swollen area at the base of the branch where it joins the trunk. The wood is denser and rich in energy reserves and defensive chemicals. These same qualities exist at all growth points (nodes, forks). Good pruning cuts are made where diameter (taper) narrows. Collar

48. Bad- flush cut Wound wood does not develop evenly.

51. Obsolete Illustration of Reduction Cut Too big a wound Too close to another wound Reduce further out!

52. Prioritize: Structural pruning not as important on these

53. Temporary vs. permanent branch management 14’ 8’ 0’-8’

58. A Hook is Handy Pull down branch to stabilize and position for precise cutting Pull out webworms, balloons, cats…

70. Pruning Plan: First 5 years Identify architectural type and select leader(s) Do not remove more than 35% of live foliage at a pruning visit. Reduce all branches greater than ½ trunk diameter. Reduce or remove all branches or stems competing with the one(s) selected to be the leader. Reduce or remove large, low vigorous branches and broken, cracked, and damaged branches.

71. Reduce growth rate of low aggressive branches Push

72. BeforeAfter Year two Push back

73. After Before Structural pruning is a three step process: 1.Identify the stem(s) that will make the best leader(s). 2.Identify which stems are competing with the leaders. 3.Decide where to shorten these competing stems.

74. AfterBefore

75. Pruning Plan: 5 – 20 years Do not remove more than 25-35% of live foliage. Reduce all branches greater than ½ trunk diameter. Identify lowest scaffold limbs of the permanent canopy and reduce all aggressive lower branches. Reduce branches with included bark. Reduce or remove competing leaders (if there are more than 3 competing leaders, this can be done in stages). Reduce branches within 18’’ of largest limbs.

76. BeforeAfter Push

77. Two years later Before after

78. Before After

79. Dominant leader structure after two pruning visits

80. Before pruningAfter pruning Transforming a bush into a tree

81. Two years later

82. Pruning Plan: 20 – 30 years Identify 5 to 10 permanent scaffold limbs and reduce branches within 18-36’’ to avoid clustered branches. Space permanent scaffold limbs to reduce wind resistance. Remove many or all of the branches below the first permanent limb. Reduce codominants with included bark. Reduce and/or remove competing leaders.

83. Pruning at planting time and 10 years later built good form. In the mature tree, a stable skeleton of scaffolds are developed. The left image shows large uprights removed, which makes the ends heavier and the branch more likely to fail. Another way to subordinate large limbs Is to remove downright laterals, and reduce or retain uprights.

84. Reduce growth on branches below permanent canopy

85. 2 years later After

86. before after

88. Here is a tree that was damaged in a storm. As a result, many stems are growing upright

89. Remove two upright, interior stems

94. After removing right codominant stem Before

95. Before - year 8 After Debris

96. Before - year 8 After Debris One year after pruning

97. Before - year 8 One year after pruning 18 months after pruning

98. With dedication to a management plan, your community can become a model for others