9. Branch Collar… … a swelling at the branch union from the yearly addition of tissues to the branch and trunk. Branch Bark Ridge forms where trunk tissue contacts branch tissue
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13. C ompartmentalization O f D ecay I n T rees Barrier 1 is weakest - movement up and down in tree Barrier 2 is next weakest - movement toward center of tree Barrier 3 is stronger - movement laterally around Barrier 4 is strongest - movement into new wood formed after injury 3 3 4 4 4 4 2 1
14. Trunk Wound Each year, a tree grows a new ring… … covering the wound a bit more Wound
48. Topping is cutting straight across the branch.
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56. Family A’s Tree - Not Pruned When Young At Planting 3-4 Yrs. 5-7 Yrs. 15 Years later Family B’s Tree - Pruned When Young
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58. Scaffold branches give shape to the tree’s canopy Spaced minimum of 12” apart Radiate around the tree Best 1/3 size of trunk No more than 2 at any point
101. Effects of soil pH on the availability of soil nutrients to plants The width of the bar indicates the relative availability of each element with a change in soil reaction (pH).
Many great resources exist. For pruning, this is what I use.
To understand pruning, we need to understand how tree grow. Primary growth… Secondary growth…
Bark is the protective outer covering of the tree. Inside is the phloem, xylem, and cambium. Phloem moves photosynthate (sugars) from source to sink (mostly leaves to places of useage or storage). Xylem moves water from roots to shoots and stores sugars. The cambium is a layer of meristematic cells producing phloem and a new xylem ring each year. When we look a a cross section of a trunk and examine the xylem, we see sap wood and heart wood. Sap wood is 7-12 years of xylem rings used to store sugars. The most current year’s growth is responsible for moving the water up the tree. Ray cells move storage products between the sapwood. The heart wood is dead xylem used for mechanical support of the tree.
An animation to reiterate how the secondary growth occurs.
Discuss how branches are attached and the difference between stem and branch tissue. Trunk and branch tissue is complicated: Layers of branch tissue overlap layers of trunk tissue. This complicated mess can be simplified by thinking of it as your arm (branch tissue) coming out of your shirt (trunk tissue)
The branch collar…. The branch bark ridge…. Notice the “arm” coming out of the “shirt” and the resulting “sleeve”
In nature, we can see this very clearly.
Point out the dark “barriers” forming to compartmentalize the branches. Notice the trunk tissue vs branch tissue
Example of the stem tissue going around branch tissue. Decay present in branch tissue…
Explain CODIT.
CODIT: Simplified.
Trees do not heal, they seal. Sometime, not very successfully!
From inside the tree. From using our knowledge of tree biology, we use this information to properly prune our trees.
Show how the tree compartmentalizes a branch after it’s cut.
Proper cuts - explain diagram.
Trees generally do not require much pruning, but the removal of broken or misshapen or low branches may be necessary. Larger branches are removed first making an undercut to prevent bark from tearing down the trunk of the tree if it remains attached to the falling limb. The branch is then "stub cut" which removes most of the branch to facilitate a clean final cut. The final cut is made just outside the branch bark ridge, which is the swollen area between the branch and the trunk. Cuts made here will heal most readily and prevent rot from invading the main trunk of the tree, a common occurrence when branches are cut flush with the trunk. Smaller branches (approximately 1" diameter or less) may be removed with a singly cut using a hand pruner, but should still be made outside of the branch bark ridge. Trees should be trained to a single dominant leader through the removal of competing leaders, especially those that form narrow crotch angles which develop into weak and potentially dangerous branches. Heavy branch removal should be done when the plant is dormant (late fall to early spring), but light trimming may be done anytime.
The donut callous of a proper cut.
A “sealed” wound
Irregular shaped wounds are caused when cuts are not made properly
A flush cut. Not only is it more work for us, it’s bad for the tree.
Example of flush and proper cut. Point out the discoloration of decay in the flush cut branch.
Proper cuts - also discuss problems with leaving a stub.
Stub cuts: aesthetically unappealing. Also, acts as a food reservoir for the decay fungi to penetrate further into tree.
Not making the undercut first.
Some affects of flush cuts - decay organisms.
A properly pruned tree is one to last longer in our environment- less likely to have branch breakage in storms, etc. A properly pruned tree is safer to have in our environment- branch failure is reduced, as well as overall risk of the tree A properly pruned tree is more appealing to look at.
Explain what happens at each point in graph. 1. Tree wakes up from the winter and begins taping into energy supply. 2. Buds swell, break and leaves are put on. Energy level drops because without leaves there is no photosynthesis and no energy returned to tree yet. This is when many pathogens attack. Don’t mess with the tree during this time. 3. Wood is being formed - energy coming in but a lot still being used for growth, so replenishment is not great. 4. Wood has formed so most energy is going into the bank - an ok time to prune. At end of four the leaves turn color and energy level drops (not sure why - buds being set, etc.) another good time to stay away from the tree. Water well at this time. 5. Tree goes dormant - new roots form and myccorhizae are shed and reformed. Tree at an energy high - best time to prune.
Trees generally do not require much pruning, but the removal of broken or misshapen or low branches may be necessary. Larger branches are removed first making an undercut to prevent bark from tearing down the trunk of the tree if it remains attached to the falling limb. The branch is then "stub cut" which removes most of the branch to facilitate a clean final cut. The final cut is made just outside the branch bark ridge, which is the swollen area between the branch and the trunk. Cuts made here will heal most readily and prevent rot from invading the main trunk of the tree, a common occurrence when branches are cut flush with the trunk. Smaller branches (approximately 1" diameter or less) may be removed with a singly cut using a hand pruner, but should still be made outside of the branch bark ridge. Trees should be trained to a single dominant leader through the removal of competing leaders, especially those that form narrow crotch angles which develop into weak and potentially dangerous branches. Heavy branch removal should be done when the plant is dormant (late fall to early spring), but light trimming may be done anytime.
Severe topping - not good for the tree.
Discuss the rapid, weakly attached sprouts.
Show how the sprouts are really attached - Note that this isn’t a normal branch attachment. Note that barrier four is still holding, barriers 2 and 3 are moot and barrier one is going to allow the decay to just keep going down, making branches even weaker.
Consider the natural shape of the tree. Don’t fight it! Work with it.
Where do trees grow naturally? They occur in the woods, closely spaced together. In this setting, they are naturally pruned by shade. When a branch no longer receives adequate sunlight to do photosynthesis, the tree will selectively kill off the branch. When we take a tree out of the woods and put it in an open field, it responds by growing branches all over and we have to act as the shade to select which branch stays, which one goes! In this picture, trees are growing in the UW-Arboretum. They are not pruned for shape or form, but maybe only for mower clearance. This is typical of many trees in a park setting.
Trees along State Street have a different set of demands on them; we recognize their importance for attracting business and customers, their cooling affects, and more. But trees also have a the demand of clearance for buses. Shops want to be visible from the street. Student vandalism is a concern. These trees operate under a different set of parameters than those in the Arbretum or a park, so they must be pruned accordingly.
Show the differences between pruned and unpruned trees through time. Note that family B are the trees in the audience’s yards and tree A is their neighbors. Again, the diagrams are exaggerations but show the general point. Describe how the health of tree A is compromised.
Included vs. excluded bark
Real life example. See the ridge on the excluded and the incurling on the included.
Splitting caused by included bark - note there is bark between the stems that wedge it apart as it gets larger in diameter.
Tools for pruning (explain difference between anvil and bypass pruners.
Explain that you need to know what nutrients are missing and why before you decide how and with what to fertilize. Show you pH affects available nutrients.
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