A plan for training shade trees
See: more on young trees
See: more on older trees
Strategies
- Establish and maintain a dominant leader by subordinating all but one codominant stem.
- Space main scaffold limbs apart by removing or shortening nearby branches.
- Anticipate future form and function by training and pruning early to avoid cutting large branches latter; don't remove large branches because this initiates decay in the trunk (i.e. instead of allowing a low branch from growing large then removing it when it is too low, anticipate this by shortening it earlier).
- Position the lowest main scaffold limb high enough so it will not droop and have to be removed latter.
- Prevent all branches from growing larger than half the trunk diameter.
- Maintain a live crown ratio of greater than 60%.
- Remove stem girdling roots.
Putting the plan into action
Begin pruning at planting and continue for 25 years. This strategy will provide a good branch and trunk structure.
- At
planting
- all branches will eventually be removed on trees less than 4" caliper
- do not remove more than 25% of live foliage
- shorten or remove all leaders and branches competing with the one stem that would make the best leader
- remove broken, cracked or severely damaged branches
- cut circling roots so they do not develop into stem girdling roots
- Two
years
- all branches will eventually be removed on trees less than 4" caliper
- do not remove more than 40% of live foliage
- shorten or remove all competing leaders (may have to do in two stages if there are more than 3 leaders)
- shorten or remove large, low vigorous branches to improve clearance
- shorten or remove branches within 12" of largest diameter branches in top half of trees greater than about 4 inches caliper
- cut circling roots so they do not develop into stem girdling roots - Four
years
- most branches are still temporary and will eventually be removed from the tree
- do not remove more than 35% of live foliage
- shorten or remove competing leaders
- shorten or remove large, low vigorous branches to improve clearance
- shorten or remove branches within 12" of largest diameter branches in top half of tree
- there should be only one large branch per node (no clustered branches) so shorten branches that are nearby so only one is present
- remove stem girdling roots - Eight
years
- shorten or remove competing leaders
- do not remove more than 25 to 35% of foliage
- determine where you want the lowest permanent scaffold limb and shorten any aggressive branches lower than this limb
- shorten branches within 12-18" of largest diameter branches (there should be only one large branch per node (no clustered branches)
- shorten low branches that will have to be removed latter so they do not become large
- remove stem girdling roots - Fourteen
years
- shorten or remove competing leaders
- identify several permanent scaffold limbs
- shorten vigorous branches within 18-36" of permanent scaffold limbs
- shorten or remove large branches lower (on the trunk) than the first permanent limb
- there should be only one large branch per node (no clustered branches)
- shorten low vigorous branches that will have to be removed latter
- remove stem girdling roots - Twenty years
- shorten or remove competing leaders
- identify 5 to 10 permanent scaffold limbs
- shorten vigorous branches within 18-36" of permanent scaffold limbs
- shorten or remove large branches lower (on the trunk) than the first permanent limb
- there should be only one large branch per node (no clustered branches)
- shorten low vigorous branches that will have to be removed latter
- remove stem girdling roots - Twenty-five years
- shorten or remove competing leaders
- continue to develop and space permanent scaffold limbs
- shorten branches within 36" of permanent scaffold limbs
- shorten or remove large branches lower (on the trunk) than the first permanent branch
- there should be only one large branch per node (no clustered branches)
- shorten low branches that will have to be removed latter
- remove stem girdling roots
With seven prunings in the first 25 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.
