Pruning Young Trees: Success Stories Start at Planting. Minnesota Landscape Arboretum February 4, 2017

Transcription

1 Pruning Young Trees: Success Stories Start at Planting Minnesota Landscape Arboretum February 4, 2017

2 Chad Giblin Research Fellow Department of Forest Resources University of Minnesota - giblin@umn.edu trees.umn.edu

3 Here s the Plan Basics of Developmental Pruning Permanent Canopy High-Canopy Shade Tools of the Trade Type of Pruning Cuts Thinning, Reduction, Heading Temporary Branches Leader Management Included Branches & Strong Branches Case Studies

4 Permanent Canopy Shade trees on streets: 12 to 14 feet. Parks and yards, can be lower High-Canopy Shade Crown begins above 12 feet Often extend above 20 to 24 feet. These trees easily clear utility lines to reveal and complement architecture

5 High Canopy Shade

6 Shades a Few Windows Maybe

7 Tools You NEED!

8 Hand Shears

9 Hand Saws

10 A New Tree Biology Alex L. Shigo Shigo & Tree, Associates, 1989 When the hand saw was the major tool for pruning, most cuts were proper.

11 A New Tree Biology Alex L. Shigo Shigo & Tree, Associates, 1989 It was much faster and took less work to cut the branch at its smallest point.

12 Pole Pruner

13 Pole Saw

14 How to Make a Pruning Cut

15 Types of Pruning Cuts Thinning Cut Removing a branch to parent limb of larger diameter

16 Diagram: USDA

17 Diagram: USDA

18

19

20 Temporary Branches Any branch below the mature crown They build a strong trunk when small Contribute to stem taper Remove before they are 50% size of stem

21

22

23

24

25 Branch Union Morphology Affects Decay Following Pruning E. F. Gilman and J. C. Grabosky Arboriculture & Urban Forestry 32(2): March 2006 In cases where branch collars were not readily apparent, the cut was made from just outside the branch bark ridge perpendicularly through the branch.

26

27

28

29 Types of Pruning Cuts Reduction Cut Removing branch back to lateral branch with diameter at least ⅓ of parent limb, ideally ½ diameter

30 Response of Two Oak Species to Reduction Pruning Cuts Jason C. Grabosky and Edward F. Gilman Arboriculture & Urban Forestry 33(5): Reduction cuts are commonly used in reduction, subordination, and directional pruning (ANSI 2001; Gilman and Lilly 2002)

31

32 Suppression Cuts: A Type of Reduction Cut Multiple Points of Suppression Help Slow Down Vigorous Temporary Branches

33 Pole Pruners Suppress Quickly and Safely from the Ground

34

35 Types of Pruning Cuts Heading Cut Removing branch back to lateral branch less than ⅓ diameter of parent or to node Used infrequently in arboriculture

36 NOT a Type of Pruning Cut! Topping Cut Indiscriminate, internodal cutting of a branch Unacceptable practice which destroys tree structure and causes premature failure

37

38 Rounded-Over Princeton Elm - Multiple Leaders

39 Pollarding Not the same as topping! Very old practice of European origin Growing interest in the USA!

40 Photo: Russell Kennedy

41 Photo: Russell Kennedy

42 Photo: Russell Kennedy

43 Photo: Russell Kennedy

44 How These Cuts are Used

45 Leader Management Select the most vigorous and upright leader Sometimes there are MANY in young trees If there are codominant leaders do your best to choose only one

46 This is Really Just a Very Large Shrub

47 There Can Be Only ONE!

48

49 Branch clusters, Included Branches and Defects These branches weaken as they grow Can cause major failures Lack structural integrity No place in the mature crown Prompt removal is necessary

50 Too Many Branches in Too Small a Space

51 Included Branches are Weak Attachments: How Long Before this Tree Splits in Two?

52 Strongly Attached Branches: Show a Branch Collar and/or a Branch Bark Ridge

53 Pruning at Planting

54 Prune em like I used to! Photo: Minneapolis Park & Recreation Board

55 Case Studies

56 Autumn Blaze Freeman Maple Large Shade Tree 50 to 60 ft.

57 Missed Opportunities

58 Leader Management: Codominant Removal

59 Suppression Cuts

60 Primed for Success

61 and with Red Fall Color!

62 Boulevard American Linden Large Shade Tree 60+ ft

63 Large Temporary Branches - Many Included Branches

64 Too Many Codominant Leaders

65 Too Late for These Neighbors

66 Climb Young Trees & Climb Them Safely

67 Suppression from Ground

68 Post-Pruning - Multiple Suppressions

69 Set Up for Success & High Canopy Shade

70 Greenspire Littleleaf Linden Medium Sized Shade Tree ft.

71 Many, Large Temporary Branches Only Getting Bigger!

72 Temporary Branch Removal

73 Face Branches for Best Cuts

74 Set Up a Tiered Removal System

75 Discovery Elm Smaller Ornamental

76

77

78

79

80

81

82

83

84

85

86

87

88

89

90

91

92 Chad Giblin Department of Forest Resources University of Minnesota - giblin@umn.edu trees.umn.edu elms.umn.edu

93

94 2014 Regents of the University of Minnesota. All rights reserved. The University of Minnesota is an equal opportunity educator and employer.