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Appendix 6 A plan for training shade trees in the urban landscape.

Trees are like children; they require about 25 years of training to create good, solid structure that will last them a lifetime.

FIRST THINGS FIRST

Establish a pruning cycle and objectives. Pruning cycle depends on quality of nursery stock, growth rate, climate, and species. Then decide on strategies to meet objectives.

Objectives: (25yrs)

1) Establish and maintain a dominant leader--subordinate all but one codominant stem.

2) Space main scaffold limbs apart--remove or shorten nearby branches.

3) Anticipate future form and function--train and prune early to avoid cutting large branches later; removing large branches can initiate decay in the trunk (i.e., instead of allowing a low branch to get large then removing it when it droops, anticipate this by shortening it earlier).

4) Position the lowest main scaffold limb high enough so it will not droop and have to be removed later.

5) Keep all branches less than half the trunk diameter.

Strategies:

At planting

* If structure is good with one dominant leader, do not prune.

* All branches will eventually be removed on trees less than 4 inches caliper.

* Do not remove more than about 25 percent of live foliage.

* Shorten or remove leaders and branches competing with the main leader.

* If there is no dominant leader, create one by cutting back all leaders except one.

Two or three years after planting

* All branches will eventually be removed on trees less than 4 inches caliper.

* Do not remove more than 35 percent of live foliage.

* Shorten or remove all competing leaders (may have to do in two stages if > 3).

* Shorten or remove large, low branches to improve clearance.

* Shorten or remove branches within 12 inches of largest diameter branches in top half of trees greater than about 4 inches caliper.

Five years after planting

* Most branches are still temporary and will eventually be removed from the tree.

* Do not remove more than 35 percent of live foliage.

* Shorten or remove competing leaders.

* Shorten or remove large, low branches to improve clearance.

* Shorten or remove branches within 12 inches of largest diameter branches in top half of tree.

* Shorten aggressive branches growing from the bottom half of the canopy that have reached into the top third of the tree.

* There should be only one large branch per node (no clustered branches); shorten those nearby so only one is present.

Ten years after planting

* Shorten or remove competing leaders.

* Do not remove more than 25 to 35 percent of foliage.

* Determine where you want the lowest permanent scaffold limb and shorten all aggressive branches lower than this limb.

* Shorten branches within 12 to 18 inches of largest diameter branches (there should be only one large branch per node (no clustered branches).

* Shorten aggressive branches growing from the bottom half of the canopy that have reached into the top third of the tree.

* Shorten low branches that will have to be removed later.

Fifteen years after planting

* Shorten or remove competing leaders.

* Identify several permanent scaffold limbs.

* Shorten aggressive branches within 18 to 36 inches of permanent scaffold limbs.

* There should be only one large branch per node (no clustered branches).

* Shorten or remove large branches lower (on the trunk) than the first permanent scaffold branch.

* Shorten aggressive branches growing from the bottom half of the canopy that have reached into the top third of the tree.

* Shorten low branches that will have to be removed later.

Twenty years after planting

* Shorten or remove competing leaders.

* Identify five to ten permanent scaffold limbs.

* Shorten aggressive branches within 18 to 36 inches of permanent scaffold limbs.

* There should be only one large branch per node (no clustered branches).

* Shorten or remove large branches lower (on the trunk) than the first permanent scaffold branch.

* Shorten aggressive branches growing from the bottom half of the canopy that have reached into the top third of the tree.

* Shorten low branches that will have to be removed later.

Twenty-five years after planting

* Shorten or remove competing leaders.

* Continue to develop and space permanent scaffold limbs.

* Shorten branches within 36 inches of permanent scaffold limbs.

* There should be only one large branch per node (no clustered branches).

* Shorten or remove large branches lower (on the trunk) than the first permanent branch.

* Shorten aggressive branches growing from the bottom half of the canopy that have reached into the top third of the tree unless they are permanent scaffold limbs.

* Shorten low branches that will have to be removed later.

With seven prunings in the first twenty-five years after planting, a good structure can be developed that can place the tree on the road to becoming a permanent fixture in the landscape. Less-frequent pruning may be needed if good-quality nursery trees were planted with a dominant leader, and trees were irrigated appropriately until established.
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Article Details
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Author:Gilman, Edward F.
Publication:An Illustrated Guide to Pruning, 2nd ed.
Article Type:Professional standards
Geographic Code:1USA
Date:Jan 1, 2002
Words:794
Previous Article:Appendix 5 Sample pruning specifications.
Next Article:Appendix 7 Nursery production protocol for upright trees.
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