Young Trees

Young trees may need to be pruned to maintain a central leader. All cuts should be made at the nodes or back to the next limb. Do not remove more than one-third of the living branches. To develop a strong, straight trunk, start early in the life of a tree to remove branches at positions 1, 2 and 3 (See Figure 10). The trunk should be limbed up only one-third to one-half of the height. For instance, if a small tree is 6 feet tall, remove the limbs about 2-3 feet above the soil line. For a more compact tree, remove the C's. For a more upright tree, remove the A's. For a more open tree, remove the B's.

Diagram Pruning Tree Limbs
Figure 10. Training small trees

Do not remove or head the leader except to correctly position the lowest main branch, to space or scaffold branches or to remove a tight group of terminal twigs so a more vigorous dominant shoot will develop.

For greatest strength, branches selected for permanent scaffolds must have wide angle of attachment with the trunk. Branch angles of less than 30 degrees from the main trunk result in a high percentage of breakage, while those between 60 and 70 degrees have a small breakage rate. Narrow crotch angles are weak as a result of bark inclusion, which is dead tissue in the space between two branches or limbs. Bradford pears that have been in the landscape more than 10-12 years are susceptible to limb breakage. Often, as limbs break due to bark inclusion, they tear bark down the trunk or damage supporting branches.

Tree Pruning Crotch Too Narrow
Figure 11. Branch angles

Bark

Cambium

Wood (xylem) Wide crotch

Cambium

Bark

Wood (xylem) Wide crotch dollar tissue

Bark inclusion dollar tissue

Bark inclusion

Narrow Crotch Gardening
Narrow crotch

Figure 12. Bark inclusion

On young trees, branches can be spaced about 6 to 12 inches apart. By the fifth year, potential major scaffold branches of shade trees should be spaced at least 8 inches and preferably 20-24 inches vertically. Closely spaced scaffolds will have fewer lateral branches. The result will be long, thin branches with poor structural strength. Temporary branches can be left on the lower trunk for the first few years to help increase lower-trunk size and protect the trunk from sun.

There should be five to seven scaffolds for radial branch distribution to fill the circle of space around a trunk. Radial spacing prevents one limb from overshadowing another. Remove or prune shoots that are too low, too close or too vigorous in relation to the leader, and to the branches selected as the scaffold branches.

Shrub Spacing Diagram

Figure 13. Diagram of radial spacing

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